The URL can be used to link to this page

Home My WebLink AboutDRC-2014-003821 - 0901a068804467b5 HYDRO GEO CHEM, INC. Environmental Science & Technology HYDROGEOLOGY OF THE WHITE MESA URANIUM MILL BLANDING, UTAH June 6, 2014 Prepared for: ENERGY FUELS RESOURCES (USA) INC. 225 Union Boulevard, Suite 600 Lakewood, Colorado 80228 (303) 628-7798 Prepared by: HYDRO GEO CHEM, INC. 51 W. Wetmore, Suite 101 Tucson, Arizona 85705-1678 (520) 293-1500 Project Number 7180000.00-02.0 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 i TABLE OF CONTENTS 1. INTRODUCTION.............................................................................................................. 1 2. BACKGROUND AND OVERVIEW ................................................................................ 3 2.1 Overview of Site Hydrogeology.............................................................................4 2.1.1 Geology/Stratigraphy.................................................................................. 4 2.1.2 Hydrogeologic Setting................................................................................ 6 2.1.3 Perched Water Zone.................................................................................... 6 2.1.4 Seeps and Springs in Relation to Perched Zone Hydrogeology................. 8 2.1.5 Tailings Cells............................................................................................ 11 3. DETAILED SITE HYDROGEOLOGY........................................................................... 13 3.1 Stratigraphy and Formation Characteristics..........................................................13 3.1.1 Brushy Basin Member.............................................................................. 13 3.1.2 Burro Canyon Formation/Dakota Sandstone............................................ 13 3.1.2.1 Dakota Sandstone....................................................................... 14 3.1.2.2 Burro Canyon Formation........................................................... 15 3.1.3 Mancos Shale............................................................................................ 17 3.1.4 Pyrite Occurrence in the Dakota Sandstone and Burro Canyon Formation.......................................................................... 19 3.2 Contact Descriptions.............................................................................................19 3.2.1 Brushy Basin Member/Burro Canyon Formation Contact Elevations ..... 20 3.2.2 Mancos Shale/Dakota Contact Elevations................................................ 20 3.2.3 Soils Above Dakota and /or Mancos ........................................................ 21 3.3 Perched Water Elevations, Saturated Thicknesses, and Depths to Water ............21 3.4 Interpretation of Cross-Sections ...........................................................................22 3.4.1 Central and Northeast Areas.....................................................................22 3.4.2 Southwest Area......................................................................................... 23 3.5 Perched Water Occurrence and Flow ...................................................................24 3.5.1 Overview................................................................................................... 25 3.5.1.1 General Site Flow Pattern.......................................................... 25 3.5.1.2 Influence of Pumping and Wildlife Pond Seepage on Flow and Dissolved Constituent Concentrations...................... 26 3.5.2 Nitrate Investigation Area......................................................................... 29 3.5.3 Area of Chloroform Plume....................................................................... 31 3.5.4 Beneath and Downgradient of Tailings Cells........................................... 34 3.5.4.1 Overview.................................................................................... 34 3.5.4.2 Water Balance Near DR-2 and DR-5......................................... 35 3.5.4.3 Water Balance Near Ruin Spring and Westwater Seep............. 37 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 ii TABLE OF CONTENTS (Continued) 3.6 Perched Water Migration Rates and Travel Times...............................................38 3.6.1 Nitrate Investigation Area......................................................................... 38 3.6.2 Area of Chloroform Plume....................................................................... 39 3.6.3 Beneath and Downgradient of Tailings Cells........................................... 41 3.6.3.1 Vadose Zone .............................................................................. 41 3.6.3.2 Perched Water Zone Downgradient of Tailings Cells............... 43 3.7 Implications For Seeps and Springs......................................................................44 3.7.1 Westwater Seep and Ruin Spring ............................................................. 45 3.7.2 Cottonwood Seep...................................................................................... 45 3.7.3 Potential Dilution of Perched Water Resulting From Local Recharge of the Dakota and Burro Canyon Near Seeps and Springs....................... 46 3.8 Implications For Transport of Chloroform and Nitrate........................................47 4. COMPOSITION OF DAKOTA SANDSTONE AND BURRO CANYON FORMATION.................................................................................. 49 4.1 Mineralogy............................................................................................................49 4.2 Pyrite Occurrence..................................................................................................49 4.3 Expected Influence of Transient Conditions, Oxygen Introduction, and the Mancos and Brushy Basin Shales on Dakota/Burro Canyon Chemistry..............51 4.4 Implications For Perched Water Chemistry and Natural Attenuation of Nitrate and Chloroform.........................................................................................54 4.4.1 Pyrite Degradation by Oxygen.................................................................. 54 4.4.2 Nitrate Degradation by Pyrite...................................................................55 4.4.3 Chloroform Reduction.............................................................................. 57 5. SUMMARY OF INTERA WORK AND FINDINGS...................................................... 59 6. SUMMARY AND CONCLUSIONS............................................................................... 61 6.1 Perched Water Pore Velocities in the Nitrate Plume Area...................................68 6.2 Perched Water Pore Velocities in the Chloroform Plume Area ...........................68 6.3 Hydrogeology and Perched Water Pore Velocities in the Southwest Area..........69 6.4 Fate of Chloroform and Nitrate.............................................................................70 7. REFERENCES ................................................................................................................. 73 8. LIMITATIONS STATEMENT........................................................................................ 81 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 iii TABLE OF CONTENTS (Continued) TABLES 1 Results of Slug test Analyses Using KGS and Bouwer-Rice Solutions 2 Results of Recovery and Slug Test Analyses Using Moench Solution 3 Estimated Perched Zone Hydraulic Properties Based on Analysis of Observation Wells Near MW-4 and TW4-19 During Long Term Pumping of MW-4 and TW4-19 4 Summary of Hydraulic Properties White Mesa Uranium Mill from TITAN (1994) 5 Properties of the Dakota/Burro Canyon Formation White Mesa Uranium Mill from TITAN (1994) 6 Hydraulic Conductivity Estimates for Spring Flow Calculations 7 Hydraulic Conductivity Estimates for Travel Time Calculations Paths 1, 2A, and 2B 8 Hydraulic Conductivity Estimates for Travel Time Calculations Paths 3-6 9 Estimated Perched Zone Pore Velocities Along Path Lines 10 Results of XRD and Sulfur Analysis in Weight Percent 11 Tabulation of Presence of Pyrite, Iron Oxide, and Carbonaceous Fragments in Drill Logs 12 Sulfide Analysis by Optical Microscopy 13 Summary of Pyrite in Drill Cuttings and Core FIGURES 1A White Mesa Site Plan Showing Location of Perched Wells, Piezometers, and Lithologic Cross=Sections 1B White Mesa Site Plan Showing Location of Perched Wells, Piezometers, and Nitrate and Chloroform Plume Boundaries 2 Lithologic Column 3 White Mesa Stratigraphic Section Based on Lithology of MW-3 from TITAN (1994) 4 Photograph of the Contact Between the Burro Canyon formation and the Brushy Basin Member 5 Kriged 1st Quarter, 2014 Water Levels, White Mesa Site 6 Annotated Photograph Showing East Side of Cottonwood Canyon (looking east toward White Mesa from west side of Cottonwood Canyon) 7 Extent of the Western Interior Sea (Cretaceous) 8 Kriged Top of Brushy Basin, White Mesa Site 9 Kriged Top of Bedrock, White Mesa Site 10 Kriged Top of Dakota Sandstone, White Mesa Site 11 Kriged Top of Bedrock and Mancos Shale Thickness, White Mesa Site 12 Approximate Geoprobe Boring and Cross-Section Locations, White Mesa Site 13 Soil Cross Sections East of Ammonium Sulfate Crystal Tanks, White Mesa Site 14 1st Quarter, 2014 Perched Zone Saturated Thicknesses and Brushy Basin Paleoridges and Paleovalleys, White Mesa Site 15 1st Quarter, 2014 Depths to Perched Water, White Mesa Site Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 iv TABLE OF CONTENTS (Continued) FIGURES (Continued) 16A Interpretive Northeast-Southeast Cross Section (NE-SW), White Mesa Site 16B Interpretive Northeast-Southwest Cross Section (NE2-SW2), White Mesa Site 17 Interpretive Northwest-Southeast Cross Section (NE-SE), White Mesa Site 18 Interpretive East-West Cross Sections (W-E and W2-E2) Southwest Investigation Area 19 Interpretive North-South Cross Sections (S-N) Southwest Investigation Area 20 DR Series Piezometer Depths to Water 2Q 2011 to 1Q 2014 21 Kriged 1st Quarter, 2014 Water Levels Showing Inferred Perched Water Pathlines and Kriged Nitrate and Chloroform Plumes 22 Kriged 1st Quarter, 2014 Water Levels and Estimated Capture Zones, White Mesa Site (detail map) 23 Kriged 4th Quarter, 2011 Water Levels, White Mesa Site 24 TW4-4 and TW4-6 Water Levels 25 Kriged 1st Quarter, 2014 Water Levels Showing Inferred Perched Water Pathlines Downgradient of the Tailings Cells, White Mesa Site 26 Kriged 1st Quarter, 2014 Water Levels Showing Inferred Perched Water Flow Pathlines Near Ruin Spring and Westwater Seep 27 Kriged 1st Quarter, 2014 Water Levels Showing Inferred Perched Water Flow used for Travel Time Estimates and Kriged Nitrate and Chloroform Plumes 28 Photograph of the Westwater Seep Sampling Location July 2010 29 Photograph of the Contact Between the Burro Canyon Formation and the Brushy Basin Member at Westwater Seep 30 Kriged 1st Quarter, 2014 Water Levels showing Kriged Nitrate and Chloroform Plums and Inferred Perched Water Pathlines, White Mesa Site 31 Water Level in Wells Near TW4-12 and TW4-27 32 White Mesa Site Plan Showing Pyrite Occurrence in Perched Borings APPENDICES A Lithologic Logs B Well Construction Schematics C INTERA Soil Boring Logs D Historic Water Level Maps E Topographic and Geologic Maps Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 1 1. INTRODUCTION In response to the Utah Department of Environmental Quality Division of Radiation Control (DRC) letter to Energy Fuels Resources (USA) Inc. (EFRI) dated March 26, 2014 (RFI letter), an updated site hydrogeological report has been prepared which discusses the hydrogeology of the White Mesa Uranium Mill, (the Mill or the site) located south of Blanding, Utah as per Part 1.F.10 of the amended Utah Department of Environmental Quality (UDEQ) Ground Water Quality Discharge Permit UGW370004 (the Permit). Part I.F.10 of the Permit describes requirements for the report which consist of: a) Local hydrogeologic conditions in the shallow aquifer, including, but not limited to: local geologic conditions; time relationships and distribution of shallow aquifer head measurements from facility wells and piezometers; local groundwater flow directions; and distribution of aquifer permeability and average linear groundwater velocity across the site, and b) Well specific groundwater quality conditions measured at facility monitoring wells for all groundwater monitoring parameters required by this Permit, including, but not limited to: temporal contaminant concentrations and trends from each monitoring well; statistical tests for normality of each contaminant and well, including univariate or equivalent tests; calculation of the mean concentration and standard deviation for each well and contaminant. As per the RFI letter the hydrogeologic report is to focus on part a). Part b) is covered by INTERA site ‘background’ reports (INTERA, 2007a; INTERA 2007b; INTERA, 2008), and more recent reports (including INTERA, 2008; INTERA, 2009; INTERA, 2010; INTERA, 2012a; INTERA 2012b; INTERA, 2013a; INTERA, 2013b; INTERA, 2014a; INTERA, 2014b; and INTERA, 2014c) that are updates to the background reports. Specifically, DRC requests that a site hydrogeological report submitted in August, 2009 (HGC, 2009), be updated with relevant hydrogeological information provided in the following: 1. Southwest Investigation Report (November 7, 2012) describing work to better characterize the perched groundwater zone downgradient (southwest) of the tailings cells, 2. EFR Nitrate contamination investigation activities (through September 2011) that included installation of soil borings and upgradient perched groundwater monitoring wells, Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 2 3. Implementation of a Nitrate Corrective Action Plan (May 7, 2012) and ongoing activities to address a perched nitrate groundwater plume, 4. Continued implementation of corrective actions related to the chloroform plume that were initiated in 2003, 5. October 12, 2012 Source Assessment Report for groundwater monitoring wells in Out of Compliance (OOC) status, 6. November 9, 2012 pH Report which included proposed revised GWCL’s for all MW- series wells after determination that OOC status for pH in certain wells was not due to cell leakage, 7. December 7, 2012 Pyrite Investigation Report which included analysis of core samples for pyrite content and modeling to demonstrate that pH trends were plausibly the result of aeration of the formation due to wildlife pond recharge and/or monitoring well development, overpumping, and sampling, 8. Infiltration and Contaminant Transport Modeling to assess contaminant transport times from tailings cells to local receptors, 9. Ongoing collection and analysis of groundwater samples and water level data, and 10. Discontinuance of recharge to the two upper (northern) wildlife ponds to dissipate the associated perched groundwater mound. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 3 2. BACKGROUND AND OVERVIEW Figure 1A is a site map showing general site features and the locations of wells, piezometers, springs, and lithologic cross-sections. Hydrogeologic investigation of the site has been ongoing since the initial investigation in 1977-1978 (Dames and Moore, 1978). Major hydrogeologic and groundwater investigations include UMETCO (1993); UMETCO (1994); TITAN (1994); International Uranium (USA) Corporation (IUSA) and Hydro Geo Chem, Inc. (HGC) [2000]; IUSA and HGC (2001); HGC (2004); HGC (2007); INTERA (2007a); INTERA (2007b); INTERA (2008); Hurst and Solomon (2008); INTERA (2009); HGC (2010e); INTERA (2012a); INTERA (2012b); HGC (2012b); HGC (2012c); and HGC (2014). Investigations to date and more than 30 years of perched groundwater monitoring indicate that tailings cell operation has not impacted perched groundwater. The lack of tailing cell impact is detailed in Hurst and Solomon (2008) and various INTERA documents (INTERA, 2007a; INTERA 2007b; INTERA, 2008; INTERA, 2010; INTERA, 2012a; INTERA 2012b; INTERA, 2013a; INTERA, 2013b; INTERA, 2014a; INTERA, 2014b; and INTERA, 2014c). Perched groundwater was impacted by disposal of laboratory wastes to two (now abandoned) sanitary leach fields in the early years of Mill operation (prior to about 1980) before tailings cells were operational (HGC, 2007). Disposal of laboratory wastes to the abandoned scale house and former office leach fields (HGC, 2007) is considered the source of a chloroform plume (defined by concentrations greater than 70 micrograms per liter [µg/L]) located upgradient to cross- gradient (northeast to east) of the tailings cells (Figure 1B). The eastern portion of the chloroform plume likely originated from the abandoned scale house leach field (located immediately north-northwest of TW4-18 [Figure 1B]), and the western portion from the former office leach field (located in the immediate vicinity of TW4-19 [Figure 1B]). Perched groundwater has also been impacted by nitrate (INTERA, 2009). A nitrate plume (defined by concentrations greater than 10 milligrams per liter [mg/L]) that contains elevated chloride extends from upgradient (northeast) of the tailings cells to a portion of the area beneath the tailings cells as described in the Nitrate Corrective Action Plan (nitrate CAP)[HGC, 2012a]. The precise source(s) of the nitrate plume are not well defined. However, the footprint of a former agricultural/stock watering pond referred to as the ‘historical pond’ is located beneath the upgradient portion of the nitrate plume and extends to the north of the plume (1B). This pond was active from the early part of the 20th century until the area was regraded as part of Mill construction circa 1980 (HGC, 2012a). This pond is considered one of the likely historical sources of nitrate and chloride to the nitrate plume. Ammonium sulfate handling in the vicinity of the ammonium sulfate crystal tanks (southeast of TWN-2 [Figure 1B]) is considered the only Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 4 potential current source of nitrate to the nitrate plume and is being addressed through implementation of Phase 1 of the nitrate CAP [HGC (2012a) and EFRI (2013)]. Both the chloroform and nitrate plumes are under remediation by pumping and are discussed in more detail in Section 3. Appendix A contains copies of lithologic logs from site perched monitoring wells and piezometers. Appendix B contains copies of perched well construction schematics. Appendix C contains logs of borings installed by INTERA as part of the nitrate investigation that supported the nitrate CAP. Logs of soil borings installed as part of Phase I of the nitrate CAP implementation are provided in EFRI (2013). 2.1 Overview of Site Hydrogeology TITAN (1994) provides a detailed description of site hydrogeology based on information available at that time. A brief summary of site hydrogeology that is based in part on TITAN (1994) and updated with information from the literature and more recent site investigations listed in Section 1 is provided below. 2.1.1 Geology/Stratigraphy The White Mesa Uranium Mill is located within the Blanding Basin (the Basin) of the Colorado Plateau physiographic province. Bedrock units exposed in the Basin include Upper Jurassic through Cretaceous sedimentary rocks (Figure 2, from Doelling, 2004). The general succession, in ascending order, is the Upper Jurassic Brushy Basin Member of the Morrison Formation, the Lower Cretaceous Burro Canyon Formation, and the Upper Cretaceous Dakota Sandstone and Mancos Shale. Typical of large portions of the Colorado Plateau province, the rocks within the Basin are relatively undeformed. The Mill has an average elevation of approximately 5,600 feet above mean sea level (ft amsl) and is underlain by unconsolidated alluvium and indurated sedimentary rocks. Indurated rocks include those exposed within the Basin (described above), and consist primarily of sandstone and shale. The indurated rocks are relatively flat lying with dips generally less than 3º. The alluvial materials consist primarily of aeolian silts and fine-grained aeolian sands with a thickness varying from a few feet to as much as 25 to 30 feet across the site. The alluvium is underlain by the Dakota Sandstone and Burro Canyon Formation, and where present, the Mancos Shale. The Dakota and Burro Canyon are sandstones having a total thickness ranging from approximately 55 to 140 feet. Beneath the Burro Canyon Formation lies the Morrison Formation, consisting, in descending order, of the Brushy Basin Member, the Westwater Canyon Member, the Recapture Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 5 Member, and the Salt Wash Member. The Brushy Basin and Recapture Members of the Morrison Formation, classified as shales, are very fine-grained, have a very low permeability, and are considered aquicludes. The Brushy Basin Member is primarily composed of bentonitic mudstones, siltstones, and claystones. The Westwater Canyon and Salt Wash Members also have a low average vertical permeability due to the presence of interbedded shales. Beneath the Morrison Formation lie the Summerville Formation, an argillaceous sandstone with interbedded shales, and the Entrada Sandstone. Beneath the Entrada lies the Navajo Sandstone. The Navajo and Entrada Sandstones constitute the primary aquifer in the area of the site. The Entrada and Navajo Sandstones are separated from the Burro Canyon Formation by approximately 1,000 to 1,100 feet of materials having a low average vertical permeability. Groundwater within this system is under artesian pressure in the vicinity of the site, is of generally good quality, and is used as a secondary source of water at the site. Stratigraphic relationships beneath the site are summarized in Figure 3 (adapted from TITAN, 1994 and based on the lithology of water supply well WW-3, located just northwest of TWN-2 [Figure 1B]). The Upper Jurassic Morrison Formation is the youngest Jurassic unit in the Basin. In many places an unconformity separates the Morrison Formation from underlying Middle Jurassic strata. The Morrison was deposited in a variety of depositional environments, ranging from eolian to fluvial and lacustrine. Much of the Morrison is composed of fluvial sandstone and mudstone that have sources to the west and southwest of the Basin (Peterson and Turner- Peterson, 1987). The upper Brushy Basin Member (typically described as a bentonitic shale), was deposited in a combination of lacustrine and marginal lacustrine environments (Turner and Fishman, 1991). The contact between the Morrison Formation and overlying strata has been the subject of much discussion. In the southeastern part of the Basin, the Lower Cretaceous Burro Canyon Formation overlies the Morrison Formation. The contact between the Burro Canyon Formation and the Morrison Formation has been interpreted as a disconformity (Young, 1960); however, Tschudy et al., (1984) indicated that the Burro Canyon Formation may be a continuation of deposition of the Morrison Formation. Recent studies by Aubrey (1992) also suggest interfingering between the Morrison Formation and overlying units. Kirby (2008) indicates that the contact between the Morrison Formation and the Burro Canyon Formation (between the Brushy Basin Member of the Morrison and the Burro Canyon Formation) near Blanding, Utah is disconformable with “local erosional relief of several feet”. Data collected from perched borings at the site that penetrate the Brushy Basin are consistent with a disconformable, erosional contact in agreement with Kirby (2008). Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 6 2.1.2 Hydrogeologic Setting The site and vicinity has a dry to arid continental climate, with an average annual precipitation of approximately 13.3 inches, and an average annual lake evaporation rate of approximately 47.6 inches. Recharge to major aquifers (such as the Entrada/Navajo) occurs primarily along the mountain fronts (for example, the Henry, Abajo, and La Sal Mountains), and along the flanks of folds such as Comb Ridge Monocline. Although the water quality and productivity of the Navajo/Entrada aquifer are generally good, the depth (approximately 1,200 feet below land surface [ft bls]) makes access difficult. The Navajo/Entrada aquifer is capable of yielding significant quantities of water to wells (hundreds of gallons per minute [gpm]). Water in WW-series supply wells completed across these units at the site rises approximately 800 feet above the base of the overlying Summerville Formation (TITAN, 1994). 2.1.3 Perched Water Zone Perched groundwater occurs within the Dakota Sandstone and Burro Canyon Formation beneath the site and is used on a limited basis to the north (upgradient) of the site because it is more easily accessible than the Navajo/Entrada aquifer. Perched groundwater originates mainly from precipitation and local recharge sources such as unlined reservoirs (Kirby, 2008) and is supported within the Burro Canyon Formation by the underlying, fine-grained Brushy Basin Member of the Morrison Formation. Water quality of the Dakota Sandstone and Burro Canyon Formation is generally poor due to high total dissolved solids (TDS) in the range of approximately 1,100 to 7,900 milligrams per liter (mg/L), and is used primarily for stock watering and irrigation. The saturated thickness of the perched water zone generally increases to the north of the site, increasing the yield of the perched zone to wells installed north of the site. The generally low permeability of the perched zones limits well yields. Although sustainable yields of as much as 4 gallons per minute (gpm) have been achieved in site wells penetrating higher transmissivity zones near wildlife ponds, yields are typically low (<1/2 gpm) due to the generally low permeability of the perched zone. Many of the perched monitoring wells purge dry and take several hours to more than a day to recover sufficiently for groundwater samples to be collected. During redevelopment (HGC, 2011b) many of the wells went dry during surging and bailing and required several sessions on subsequent days to remove the proper volumes of water. Although in areas having greater saturated thicknesses perched groundwater extends into the overlying Dakota Sandstone, perched groundwater at the site is hosted primarily by the Burro Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 7 Canyon Formation, which consists of a relatively hard to hard, fine- to medium-grained sandstone containing siltstone, shale and conglomeratic materials. As discussed above, the Burro Canyon Formation is separated from the underlying regional Navajo/Entrada aquifer by approximately 1,000 to 1,100 feet of Morrison Formation and Summerville Formation materials having a low average vertical permeability. As discussed above, the Brushy Basin Member of the Morrison Formation (a bentonitic shale), lying immediately beneath the Burro Canyon Formation, forms the base of the perched water zone at the site. Figure 4 is a photograph of the contact between the Burro Canyon Formation and the underlying Brushy Basin Member taken from a location along Highway 95 north of the Mill. This photograph illustrates the transition from the cliff-forming sandstone of the Burro Canyon Formation to the slope-forming Brushy Basin Member. Figure 5 is a perched groundwater elevation contour map generated from first quarter, 2014 data. Historic water level maps based on data from 1990, 1994 and 2002 are provided in Appendix D. As shown in Figure 5 and Appendix D, perched water flow across the site is generally from northeast to southwest. Beneath and south of the tailings cells, in the west central portion of the site, perched water flow is south-southwest to southwest. Flow on the western margin of the mesa is also south, approximately parallel to the rim (where the Burro Canyon Formation is terminated by erosion). On the eastern side of the site perched water flow is also generally southerly. Because of mounding near wildlife ponds, flow direction ranges locally from westerly (west of the ponds) to easterly (east of the ponds). Perched water discharges in seeps and springs located to the west, south, east, and southeast of the site. In general, perched groundwater elevations have not changed significantly at most of the site monitoring wells since installation, except in the vicinity of the wildlife ponds and pumping wells. For example, relatively large increases in water levels occurred between 1994 and 2002 at MW-4 and MW-19, located in the east and northeast portions of the site, as discussed in HGC (2007). These water level increases in the northeastern and eastern portions of the site are the result of seepage from wildlife ponds. Piezometers PIEZ-1 through PIEZ-5, shown in Figure 5, were installed in 2001 for the purpose of investigating these changes. The mounding associated with the wildlife ponds and the general increase in water levels in the northeastern portion of the site have resulted in a local steepening of groundwater gradients over portions of the site. Conversely, pumping of chloroform wells MW-4, TW4-4, TW4-19, TW4-20, and MW-26, and nitrate wells TW4-22, TW4-24, TW4-25, and TWN-2 has depressed the perched water table locally and reduced average hydraulic gradients to the south and southwest of these wells. Pumping is designed to remove chloroform and nitrate associated with the chloroform and nitrate plumes shown on Figure 1B. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 8 Hydraulic testing of perched zone wells yields a hydraulic conductivity range of approximately 2 x 10-8 to 0.01 centimeters per second (cm/s) as discussed in HGC (2012b). Hydraulic conductivity estimates are summarized in Tables 1 through 4. Table1 provides estimates of hydraulic conductivity from slug test data analyzed using the KGS and Bouwer-Rice solutions available in AQTESOLVE (HydroSOLVE, 2000). Table 2 summarizes recovery and slug test data analyzed using the Moench solutions in WHIP (HGC, 1988) and AQTESOLVE. The estimates provided in Tables 1 and 2 are based on HGC (2002); HGC (2005); HGC (2010a); HGC (2010b); HGC (2010c); HGC (2010d); HGC (2011a); HGC (2011c); HGC (2013a); and HGC (2013b). Table 3 summarizes analyses of test data collected during long-term pumping within the chloroform plume area using the Theis solutions available in AQTESOLVE (HGC, 2004). Table 4 (from TITAN, 1994) summarizes hydraulic conductivity estimates based on testing prior to 1994. In general, the highest permeabilities and well yields are in the area of the site immediately northeast and east (upgradient to cross gradient) of the tailings cells. A relatively continuous, higher permeability zone associated with the chloroform plume and consisting of poorly indurated coarser-grained materials has been inferred to exist in this portion of the site (HGC, 2007). Permeabilities downgradient (southwest) of the tailings cells are generally low. The low permeabilities and shallow hydraulic gradients downgradient of the tailings cells result in average perched groundwater pore velocity estimates that are among the lowest on site. 2.1.4 Seeps and Springs in Relation to Perched Zone Hydrogeology Hydro Geo Chem (2010e) discusses the relationships between the perched water zone and seeps and springs at the margins of White Mesa. The relationships between seeps and springs and site geology/stratigraphy are provided in Figure E.1 and Figure E.2 of Appendix E. Key findings of HGC (2010e) include the following: 1. Incorporating the seep and spring elevations in perched water elevation contour maps produces little change with regard to perched water flow directions except in the area west of the tailings cells and near Entrance Spring. West of the tailings cells, incorporation of Westwater Seep creates a more westerly hydraulic gradient. Westwater Seep appears to be nearly downgradient of the western portion of the cell complex (Figure 5). Ruin Spring is downgradient of the eastern portion of the cell complex (Figure 5). Westwater Seep is the closest apparent discharge point west of the tailings cells and Ruin Spring is the closest discharge point south-southwest of the tailings cells. Including the Entrance Spring elevation on the east side of the site creates a more easterly gradient in the perched water contours, and places Entrance Spring more directly downgradient of the northern wildlife ponds. Seeps and springs on the east side of the mesa are either Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 9 cross-gradient of the tailings cells or are separated from the tailings cells by a groundwater divide 2. Ruin Spring and Westwater Seep are interpreted to occur at the contact between the Burro Canyon Formation and the Brushy Basin Member. Corral Canyon Seep, Entrance Spring, and Corral Springs are interpreted to occur at elevations within the Burro Canyon Formation at their respective locations but above the contact with the Brushy Basin Member. All seeps and springs (except Cottonwood Seep which is located near the Brushy Basin Member/Westwater Canyon Member contact) are associated with conglomeratic portions of the Burro Canyon Formation. Provided they are poorly indurated the more conglomeratic portions of the Burro Canyon Formation are likely to have higher permeabilities and the ability to transmit water more readily than finer- grained portions. This behavior is consistent with on-site drilling and hydraulic test data that associates higher permeability with the poorly indurated coarser-grained horizons detected east and northeast of the tailing cells associated with the chloroform plume) 3. Cottonwood Seep is located more than 1,500 feet west of the mesa rim in an area where the Dakota Sandstone and Burro Canyon Formation (which hosts the perched water system) are absent due to erosion. Cottonwood Seep occurs near a transition from slope- forming to bench-forming morphology (indicating a change in lithology). Cottonwood Seep (and 2nd Seep located immediately to the north) are interpreted to originate from coarser-grained materials within the lower portion of the Brushy Basin Member (or upper portion of the Westwater Canyon Member) and are therefore not (directly) connected to the perched water system at the site. 4. Only Ruin Spring appears to receive a predominant and relatively consistent proportion of its flow from perched water. Ruin Spring originates from conglomeratic Burro Canyon Formation sandstone where it contacts the underlying Brushy Basin Member, at an elevation above the alluvium in the associated drainage. Westwater Seep, which also originates at the contact between the Burro Canyon Formation and the Brushy Basin Member, likely receives a significant contribution from perched water. All seeps and springs other than Ruin Spring (and 2nd Seep just north of Cottonwood Seep) are located within alluvium occupying the basal portions of small drainages and canyons. The relative contribution of flow to these features from bedrock and from alluvium is indeterminate. 5. All seeps and springs are reported to have enhanced flow during wet periods. For seeps and springs associated with alluvium, this behavior is consistent with an alluvial contribution to flow. Enhanced flow during wet periods at Ruin Spring, which originates from bedrock above the level of the alluvium, likely results from direct recharge of Burro Canyon Formation and Dakota Sandstone outcropping near the mesa margin in the vicinity of Ruin Spring. This recharge would be expected to temporarily increase the flow at Ruin Spring (as well as other seeps and springs where associated bedrock is directly recharged) after precipitation events. 6. The assumption that the seep or spring elevation is representative of the perched water elevation is likely to be correct only in cases where the feature receives most or all of its flow from perched water and where the supply is relatively continuous (for example at Ruin Spring). The perched water elevation at the location of a seep or spring that receives Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 10 a significant proportion of water from a source other than perched water may be different from the elevation of the seep or spring. The elevations of seeps that are dry for at least part of the year will not be representative of the perched water elevation when dry. The uncertainty that results from including seeps and springs in the contouring of perched water levels must be considered. Although there are uncertainties associated with incorporation of seep and spring elevations into maps depicting perched water elevations or maps depicting the Burro Canyon Formation/Brushy Basin Member contact elevations, perched water elevation maps now incorporate seep and spring elevations other than Cottonwood Seep, and contact elevation maps now incorporate Westwater Seep and Ruin Spring elevations. As discussed in item c), Cottonwood Seep was interpreted in HGC (2010e) to be associated with coarser-grained materials within the lower portion of the Brushy Basin Member. The justification for this interpretation is based primarily on 1) the rate of flow at Cottonwood Seep, which is estimated to be between 1 and 10 gpm (consistent with Dames and Moore, 1978), 2) the need for relatively permeable materials to transmit this rate of flow, and 3) the change in morphology near Cottonwood Seep indicating a change in lithology. The change in morphology from slope-former to bench-former just east of Cottonwood Seep can be seen in the topographic map included in Appendix E (Figure E1) and the annotated photograph provided in Figure 6. The upper portion of the Brushy Basin Member, which hydraulically isolates the perched zone from underlying materials, is composed primarily of bentonitic mudstone, claystone, and shale. The rate of flow at Cottonwood Seep is inconsistent with the materials found within the upper portion of the Brushy Basin but is consistent with coarser-grained materials expected either within the lower portion of the Brushy Basin Member or within the upper portion of the underlying Westwater Canyon (sandstone) Member. The relationship between Cottonwood Seep and lithology is shown on the geologic map provided in Appendix E (Figure E.2) and Figure 6. As shown in Figures 6 and E.1, Cottonwood Seep is located approximately 230 feet below the base of the perched zone defined by the contact between the cliff-forming Burro Canyon Formation and the underlying slope-forming Brushy Basin Member. The change in morphology from slope-former to bench-former occurs within the lower portion of the Brushy Basin Member (or the upper portion of the Westwater Canyon Member), between the termination of the perched zone at the mesa rim and Cottonwood Seep. The bench-like area hosting Cottonwood Seep begins at the change in morphology east of Cottonwood Seep and terminates west of Cottonwood Seep where a cliff-forming sandstone, interpreted to be within the Westwater Canyon Member, is exposed. The contact between the Westwater Canyon Member and the Brushy Basin Member is interpreted to be located between this sandstone outcrop and the change in morphology from slope-former to bench-former. This places Cottonwood Seep at the Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 11 transition between the Brushy Basin Member and the underlying Westwater Canyon Member. This is consistent with the stratigraphy provided in Figure 3 which places the contact between the Brushy Basin Member and the Westwater Canyon Member at elevations between approximately 5,220 and 5,230 ft amsl in this portion of the site, within 5 to 15 feet of the elevation of Cottonwood Seep (5234 ft amsl). Details of the coarse-grained nature of the lower portion of the Brushy Basin Member are consistent with Shawe (2005) as will be discussed in Section 3.1.1. 2.1.5 Tailings Cells Details of the construction of tailings cells 2 though 4A are provided in UMETCO (1993). Mill tailings are disposed in lined cells excavated below grade into the upper Dakota Sandstone. Cells 2 and 3 are underlain by a synthetic liner placed over compacted bedding material. The bedding material serves as a drain layer. The drain layer and a sand drain on the downstream embankment are connected to a leak detection lateral. Slime drains were installed above the liner in each cell within the area having the lowest topographic elevation. Cell 4A and cell 4B have a clayey liner overlain by geotextile and a synthetic liner. Leak detection laterals drain to the southwest and southeast corners of cells 4A and 4B, respectively. Although the cells are equipped with leak detection systems, and monitoring activities have not detected impacts to the perched aquifer from tailings cell disposal (as discussed in Section 2), the Mill installed additional perched monitoring wells between existing wells on the downgradient margin of the cell complex and between existing cells to function as an ‘early warning system’ for any potential impacts to perched water. These additional wells, MW-23 through MW-25, and MW-27 through MW-31, were installed and tested in 2005 (HGC 2005). At this time, temporary wells TW4-15 and TW4-17, located at the eastern edge of the cell complex and installed in 2002 (HGC, 2002), were converted to permanent status and renamed MW-26 and MW-32, respectively. Subsequently, upon installation of tailings cell 4B, MW-33 through MW-37 were added to the west and south (downgradient) edges of the cell. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 12 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 13 3. DETAILED SITE HYDROGEOLOGY A detailed description of site hydrogeology is provided in the following Sections. 3.1 Stratigraphy and Formation Characteristics The site stratigraphy is summarized in Figure 3. Details of formations underlying the site that are stratigraphically above the Westwater Canyon Member of the Morrison Formation are provided in the following Sections. 3.1.1 Brushy Basin Member As discussed in Sections 2.1.1 and 2.1.3, the upper portion of the Brushy Basin Member is composed of bentonitic mudstone, claystone, and shale, which hydraulically supports the perched zone and isolates it from underlying materials. The upper portion of the Brushy Basin Member is described by Shawe (2005) as “principally mudstone; it contains only minor amounts of sandstone, conglomeratic sandstone, and conglomerate as discontinuous lenses”. Shawe (2005) describes the lower portion of the Brushy Basin as coarser-grained, having “mudstone layers which contain, near their base, lenses lithologically similar to sandstone of the Salt Wash Member, and near their top, conglomeratic sandstone lenses”. With regard to the vicinity of Cottonwood Seep (discussed in Section 2.1.4), the expectation of coarser-grained materials is consistent with its location near the transition from the lower coarser-grained portion of the Brushy Basin Member into the underlying Westwater Canyon Member. As discussed in Craig et al. (1955), and Flesch (1974), the Westwater Canyon Member intertongues with the Brushy Basin Member. Craig et al. (1955) state “The Westwater Canyon Member forms the lower portion of the upper part of the Morrison in northeastern Arizona, northwestern New Mexico, and places in southeastern Utah and southwestern Colorado near the Four Corners, and it intertongues and intergrades northward into the Brushy Basin Member”. 3.1.2 Burro Canyon Formation/Dakota Sandstone Although the Dakota Sandstone and Burro Canyon Formations are often described as a single unit due to their similarity, previous investigators at the site have distinguished between them. The Dakota Sandstone is a relatively hard to hard, generally fine-to-medium grained sandstone cemented by kaolinite clays. The Dakota Sandstone locally contains discontinuous interbeds of siltstone, shale, and conglomeratic materials. Porosity is primarily intergranular. The underlying Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 14 Burro Canyon Formation is the primary host of the perched groundwater at the site. The Burro Canyon Formation is similar to the Dakota Sandstone but is generally more poorly sorted, contains more conglomeratic materials, and becomes argillaceous near its contact with the underlying Brushy Basin Member (TITAN, 1994). The permeabilities of the Dakota Sandstone and Burro Canyon Formations at the site are generally low. Porosities and water contents measured in samples of Dakota Sandstone and Burro Canyon Formation collected from borings MW-16 and MW-17 are described in Sections 3.1.2.1 and 3.1.2.2 below. Porosity estimates from these borings agree with measurements reported by MWH (MWH, 2010) for archived samples collected from borings MW-23 and MW-30. No significant joints or fractures within the Dakota Sandstone or Burro Canyon Formation have been documented in any wells or borings installed across the site (Knight-Piésold, 1998). Any fractures observed in cores collected from site borings are typically cemented, showing no open space. 3.1.2.1 Dakota Sandstone The Dakota Sandstone, named by Meek and Hayden (1862) for exposures in northeastern Nebraska, is exposed in the Blanding Basin. Where the Burro Canyon Formation is present the Dakota Sandstone rests disconformably upon it. In many localities a three-fold lithologic sequence is present, consisting of a basal conglomeratic sandstone with an underlying disconformity, a middle unit of carbonaceous shale and coal, and an upper unit of evenly-bedded sandstone which intertongues with the overlying Mancos Shale. These strata have been described as deposits of transitional environments which accompanied the westward transgressing Mancos Sea (Young, 1973). The basal conglomerate represents floodplain braided channel deposits which continue into the adjacent paludal environment. The carbonaceous shales are partly marshy but most formed in lagoon ponds, tidal flats and tidal channels of the lagoonal environment just seaward of the marsh belt. The evenly-bedded sandstone was formed at the shoreline as a mainland or barrier beach deposit of the littoral marine environment. Faunal evidence summarized by O'Sullivan et al., (1972) indicates that the lower part of the Dakota Sandstone is of Early Cretaceous age and the upper part is of Late Cretaceous age. Based on samples collected during installation of wells MW-16 (abandoned) and MW-17, located beneath and immediately downgradient of the tailings cells at the site (Figure 1B), porosities of the Dakota Sandstone range from 13.4% to 26%, and average 20% (Table 5) which is nearly the same as the average porosity of 19% reported by MWH (MWH, 2010) for archived sandstone samples collected from MW-23 and MW-30. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 15 Water saturations from MW-16 and MW-17 range from 3.7% to 27.2%, averaging 13.5%, and the average volumetric water content is approximately 3% (Table 5). The permeability of the Dakota Sandstone based on packer tests in borings installed at the site ranges from 2.71 x 10-6 cm/s to 9.12 x 10-4 cm/s, with a geometric average of 3.89 x 10-5 cm/s (TITAN, 1994). 3.1.2.2 Burro Canyon Formation As defined by Stokes and Phoenix (1948), the Burro Canyon Formation at its type locality near Slick Rock, Colorado, consists of alternating conglomerate, sandstone, shale, limestone and chert ranging in thickness from 150 to 260 feet. In the Blanding Basin the Burro Canyon Formation consists of deposits of alluvial and floodplain materials up to about 100 feet thick consisting of medium to coarse grained sandstone, conglomerate, pebbly sandstone, and claystone. At several horizons in the formation are persistent, widely traceable, conglomeratic sandstones interpreted as deposits of a braided channel subenvironment. Sandwiched between these sandstones are variegated mudstone units with some sandstone and siltstone lenses, the products of interchannel and meandering channel subenvironments. Fossils collected from the Burro Canyon Formation at various localities include freshwater invertebrates, dinosaur bones and plants. None are truly diagnostic but all suggest an Early Cretaceous (Aptian) age. The average porosity of the Burro Canyon Formation is similar to that of the Dakota Sandstone. Based on samples collected from the Burro Canyon Formation at MW-16 (abandoned, located beneath tailings cell #4B as shown in Figure 1B), porosity ranges from 2% to 29.1%, averaging 18.3%, similar to the average porosity of 19% reported by MWH (MWH, 2010) for archived sandstone samples collected from MW-23 and MW-30. Water saturations of unsaturated materials collected from MW-16 range from 0.6% to 77.2%, and average 23.4% (Table 5). TITAN (1994), reported that the hydraulic conductivity of the Burro Canyon Formation ranges from 1.9 x 10-7 to 1.6 x 10 -3 cm/s, with a geometric mean of 1.01 x 10-5 cm/s, based on the results of 12 pumping/recovery tests performed in monitoring wells and 30 packer tests performed in borings prior to 1994 (Table 4). As discussed in Section 2, subsequent testing of wells by HGC yields a hydraulic conductivity range of approximately 2 x 10-8 to 0.01 cm/s (HGC, 2012b). In general (as discussed in Section 2.1.3), the highest permeabilities and well yields are in the area of the site immediately northeast and east (upgradient to cross gradient) of the tailings cells. A relatively continuous, higher permeability zone (associated with poorly indurated coarser- grained materials in the general area of the chloroform plume) has been inferred to exist in this portion of the site (HGC, 2007). As discussed in HGC (2004), analysis of drawdown data collected from this zone during long-term pumping of MW-4, MW-26 (TW4-15), and TW4-19 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 16 (Figure 1B ) yielded estimates of hydraulic conductivity ranging from approximately 4 x 10-5 to 1 x 10-3 cm/s (Table 3). The decrease in perched zone permeability south to southwest of this area (south of TW4-4), based on tests at TW4-6, TW4-26, TW4-27, TW4-29 through TW4-31, and TW4-33 and TW4-34 (Table 1), indicates that this higher permeability zone “pinches out”, consistent with the interpretation provided in HGC (2007). Relatively high conductivities measured at MW-11, located on the southeastern margin of the downgradient edge of tailings cell 3, and at MW-14, located on the downgradient edge of tailings cell 4A, of 1.4 x 10-3 cm/s and 7.5 x 10-4 cm/s, respectively (UMETCO, 1993 and Table 4), may indicate that this higher permeability zone extends beneath the southeastern portion of the tailings cell complex. However, based on hydraulic tests south and southwest of these wells, this zone of higher permeability does not appear to exist within the saturated zone downgradient (south-southwest) of the tailings cells Slug tests performed at groups of wells and piezometers located northeast (upgradient) of, in the immediate vicinity of, and southwest (downgradient) of the tailings cells indicate generally lower permeabilities compared with the area of the chloroform plume. The following results are based on analysis of automatically logged slug test data using the KGS solution available in AQTESOLVE (HydroSOLVE, 2000). Testing of TWN-series wells installed in the northeast portion of the site as part of nitrate investigation activities (HGC, 2009) yielded a hydraulic conductivity range of approximately 3.6 x 10-7 to 0.01 cm/s with a geometric average of approximately 6 x 10-5 cm/s. The value of 0.01 cm/s estimated for TWN-16 is the highest measured at the site, and the value of 3.6 x 10-7 cm/s estimated for TWN-7 is one of the lowest measured at the site. Testing of MW-series wells MW- 23 through MW-32 (HGC, 2005) installed between and at the margins of the tailings cells in 2005 (and using the higher estimate for MW-23) yielded a hydraulic conductivity range of approximately 2 x 10-7 to 1 x 10-4 cm/s with a geometric average of approximately 2 x 10-5 cm/s. Hydraulic tests conducted at DR-series piezometers installed as part of the southwest area investigation (HGC 2012b) downgradient of the tailings cells yielded hydraulic conductivities ranging from approximately 2 x 10-8 to 4 x 10-4 cm/s with a geometric average of 9.6 x 10-6 cm/s. The low permeabilities and shallow hydraulic gradients downgradient of the tailings cells result in average perched groundwater pore velocity estimates that are among the lowest on site (approximately 0.26 feet per year (ft/yr) to 0.91 ft/yr based on calculations presented in HGC, 2012b). The extensive hydraulic testing of perched zone wells at the site indicates that perched zone permeabilities are generally low with the exception of the apparently isolated zone of higher Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 17 permeability associated with the chloroform plume east to northeast (cross-gradient to upgradient) of the tailings cells. The geometric average hydraulic conductivity (less than 1 x 10-5 cm/s) of the DR-series piezometers which cover an area nearly half the size of the total monitored area at White Mesa (excluding MW-22), is nearly identical to the geometric average hydraulic conductivity of 1.01 x 10-5 cm/s reported by TITAN (1994), and is within the range of 5 to 10 feet per year (ft/yr) [approximately 5 x 10-6 cm/s to 1 x 10-5 cm/s] reported by Dames and Moore (1978) for the (saturated) perched zone during the initial site investigation. 3.1.3 Mancos Shale Conformably overlying the Dakota Sandstone is the Upper Cretaceous Mancos Shale. The Mancos Shale was deposited in the Western Interior Cretaceous seaway (Figure 7) and is primarily composed of uniform, dark-gray mudstone, shale, and siltstone. It was deposited in nearshore and offshore neritic subenvironments of the Late Cretaceous Sea during its overall southwestern transgression and subsequent northeastward regression. The Mancos Shale was named by Cross and Purington (1899) from exposures near Mancos, Colorado. Outcrops of the Upper Cretaceous Mancos Shale occur as hills and slopes generally near or directly beneath overlying Quaternary pediment remnants across portions of the Blanding Basin. Mancos Shale is absent in most of the Blanding Basin (due to erosion) where rocks of the Dakota Sandstone and Burro Canyon Formation are either exposed or mantled by thin unconsolidated deposits. The Mancos Shale in the Blanding Basin consists of marine shale and interbeds of thin (less than 2 feet) sandstone and siltstone beds. Various pelecypod fossils are common in Mancos Shale outcrop areas (Huff and Lesure, 1965; Haynes et al., 1972). Total thickness is estimated at 30 to 40 feet, but is generally negligible to 20 feet, a small erosional remnant of its original thickness of approximately 2,000 feet. The Mancos Shale was deposited during transgression and highstand of the Cretaceous Interior Seaway during the Late Cretaceous (Elder and Kirkland, 1994). Where present, the Mancos Shale may act as an important impermeable layer reducing the amount of potential infiltration and recharge to the underlying Dakota-Burro Canyon perched aquifer (Avery, 1986; Goodknight and Smith, 1996). The Mancos Shale belongs to the group of thick marine organic muds (or black shales) generally thought of as deposited in geosynclinal areas. Bentonitic volcanic ash layers are abundant in the Mancos Shale (Shawe, 1968). An abundance of pyrite in the layers may indicate that iron was an important constituent of the ash, possibly being liberated by devitrification of glass and redeposited with the diagenetic development of pyrite. Hydrogen sulfide was abundant in the organic rich sediments accumulating at the bottom of the Mancos Sea, if it was a typical Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 18 sapropelic marine environment, as seems likely, and may have been especially abundant in the volcanic ash (Fenner, 1933). Trapped sea water that is buried in the mud of the Mancos Shale likely had a high content of organic material consistent with the abundance of diagenetic pyrite. Chemical reduction resulting from hydrogen sulfide generated in carbon-rich sediments is characteristic of stagnant sea bottoms. In the Early Tertiary, the original clay and silt deposited in the Mancos Shale became compacted to about a third to a tenth of its original water saturated volume by the time it was buried to a depth of about 10,000 feet (Shawe, 1976). Pore water throughout the Colorado Plateau, driven from compacting mud, moved largely upward into younger sediments (Yoder, 1955), but much water must have moved into the lower more porous strata because of local conditions of rock structure (Hedberg, 1936), because of the relatively high water density, and because of abnormally high fluid pressures. Expulsion of water likely occurred throughout the deposition of the Mancos Shale in the Late Cretaceous and during deposition of younger sediments in the Early Tertiary. Therefore expulsion occurred during a period of many millions of years and at depths ranging from near- surface to nearly maximum depths of burial. Faulting occurred in many places on the Colorado Plateau, including the Blanding Basin during the Late Cretaceous and Early Tertiary when the Mancos was being deeply buried by younger strata, and this provided numerous avenues to allow water movement into underlying porous strata. It seems likely therefore that the Dakota Sandstone at the base of the Mancos Shale and the dominantly sandy underlying Burro Canyon Formation contained pore water which was expelled from the Mancos and was under abnormally high fluid pressures (Shawe, 1976). Compaction of bedding around pyrite crystals shows the early development of part of the diagenetic pyrite, and indicates that pore fluids were being squeezed out of the Mancos Shale during the period of diagenesis. As pore fluids became trapped in the Mancos Shale following deposition of sediment in the Late Cretaceous, they immediately began to react with black opaque minerals, with magnetite deposited with the abundant ash fall material and possibly with volcanic glass and other iron-bearing material to form pyrite. Faulting that occurred on the Colorado Plateau in the Late Cretaceous and Early Tertiary facilitated movement of the Mancos pore water into underlying beds, causing removal of hematite coating on sand grains, destruction of detrital black opaque minerals, and growth of iron sulfide minerals (Shawe, 1976). Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 19 3.1.4 Pyrite Occurrence in the Dakota Sandstone and Burro Canyon Formation As discussed above, downward movement of the Mancos Shale pore water into underlying beds of the Dakota Sandstone and Burro Canyon Formations caused removal of hematite coatings on sand grains, destruction of detrital black opaque minerals, and the growth of iron sulfide minerals. Shawe (1976) classifies the Dakota Sandstone and Burro Canyon Formations as “altered-facies” rocks primarily as a result of the invasion of pore waters expelled from the overlying Mancos Shale during compaction. Shawe states that “altered facies rocks that developed by solution attack are notable for their almost complete loss of black opaque minerals and gain of significant pyrite.” Shawe further states that “altered-facies rocks contain only sparse black opaque minerals but appreciable pyrite” and that “alteration caused destruction of most detrital back opaque minerals, precipitation of substantial pyrite, and recrystallization of carbonate minerals that took up much of the iron liberated from the solution of black opaque minerals.” According to Shawe (1976), “altered-facies sandstone is light gray or, where weathered, also light buff to light brown. It contains only a small amount of black opaque heavy minerals and may or may not contain carbonaceous material. The light buff to light brown colors are imparted by limonite formed from oxidation of pyrite in weathered rock.” Furthermore Shawe (1976) states “In weathered rocks as observed in thin sections pyrite has been replaced by ’limonite’, but preservation of original pyrite crystal forms and lack of abundant limonite ‘wash’ or dustlike limonite suggest that the forms of most limonite are indicative of the original forms of pyrite before oxidation. Pyrite (or limonite) in sandstone occurs as isolated interstitial patches as much as 2 millimeters (mm) in diameter enclosing many detrital grains, or as cubes 1 mm across and smaller that are mainly interstitial but that also partially replace detrital grains.” Also “limonite pseudomorphs after marcasite have been recognized in vugs in altered-facies sandstone of the Burro Canyon Formation.” Shawe (1976) also notes that pyrite is more common below the water table and iron oxides (likely formed by oxidation of pyrite) are more common in the vadose zone. These observations are consistent with the occurrence of and oxidation of pyrite in the formations hosting the perched water at the site as will be discussed in Section 4. 3.2 Contact Descriptions Lithologic contacts between the Brushy Basin Member of the Morrison Formation, and between the Dakota Sandstone and the overlying soils and/or the Mancos Shale, are described in the Sections 3.2.1 and 3.2.2. Cross-sections through soils based on soil borings installed as part of implementing Phase I of the nitrate CAP are presented and discussed in Section 3.2.3. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 20 3.2.1 Brushy Basin Member/Burro Canyon Formation Contact Elevations Figure 8 is a contour map of the Burro Canyon Formation/Brushy Basin Member contact generated from perched well, piezometer, DR-series boring data and the locations and elevations of Westwater Seep and Ruin Spring. Figure 8 was generated based on data indicating that only Westwater Seep and Ruin Spring are located at the contact between the Burro Canyon Formation and the Brushy Basin Member (HGC, 2012b). As discussed in HGC (2012b) examination of the area near Cottonwood Seep in July 2010 and re-examination in October 2011 revealed no evidence for a hydraulic connection with the perched zone. The absence of any visible seeps or anomalous vegetation in the Brushy Basin Member east and northeast of Cottonwood Seep is consistent with dry conditions in the upper portion of the Brushy Basin Member. Figure 8 shows that the erosional Brushy Basin/Burro Canyon contact surface dips generally to the south-southwest and is very irregular in the northeast portion of the site. A paleoridge in the Brushy Basin erosional paleosurface extends from beneath cell 4B to the southwest near abandoned boring DR-18. To the east of this paleoridge, a paleovalley extends from south of cell 4A to the northeast, extending into the vicinity of the northern wildlife ponds. A paleovalley subparallel to the cell 4B paleoridge is also present on the west side of the paleoridge, between the paleoridge and the western mesa margin. The approximate axes of these and other paleoridges and paleovalleys in the southwest portion of the site are indicated on Figure 8. These features are especially important in this portion of the site due to the generally small saturated thicknesses and the consequently relatively large impacts these features are expected to have on perched water flow in this area. Other notable features include a paleoridge surrounded by paleovalleys that trend northwest – southeast (rather than northeast – southwest) in the area northeast of the millsite, a paleovalley extending from the area of cell 4B to Westwater Seep, and paleovalleys converging on Ruin Spring. 3.2.2 Mancos Shale/Dakota Contact Elevations Figures 9 through 11 are elevation contour maps of the top of bedrock (top of the Dakota Sandstone or Mancos Shale [where present]), the top of the Dakota Sandstone, and the top of bedrock showing Mancos thickness. Based on these maps, the top of Dakota and top of bedrock surfaces dip generally to the south-southwest consistent with the general dip of the top of Brushy Basin surface. In the northeast portion of the site these surfaces are generally less irregular than the top of the Brushy Basin surface. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 21 Notable features include a structural high in the top of Dakota and top of bedrock surfaces near tailing cell 4B, and a north-south trending structural high in the top of bedrock surface east to northeast of the tailing cell complex. The latter feature is primarily the result of a ridge-like remnant of the Mancos Shale that reaches thicknesses greater than 30 feet along the axis of the feature. Structural highs near cell 4B are present in the top of Brushy Basin surface (Figure 8), the top of bedrock (Figure 9), and the top of Dakota (Figure 10) surface. These features are ridge-like in all three surfaces but the paleoridge in the top of Brushy Basin is not coincident with the paleoridge in the top of bedrock and top of Dakota surfaces except in the vicinity of cell 4B. The primary axis of the paleoridge in the Brushy Basin surface extends from MW-33 at the southwest corner of cell 4B through DR-10, MW-21 and DR-18. The axis of the paleoridge in the top of bedrock surface extends from MW-35 through DR-11, DR-15, and DR-21. The axis of the paleoridge in the top of Dakota surface appears to extend from the vicinity of MW-24 (at the southwest corner of cell 1) through MW-33, DR-11, and possibly DR-15 (but is less well-defined near DR-15). 3.2.3 Soils Above Dakota and /or Mancos Figure 12 depicts the locations of soil borings installed near the ammonium sulfate crystal tanks as part of implementing Phase I of the nitrate CAP (HGC, 2012a). Borings were installed to depths of refusal using a drive-point rig as described in EFRI (2013). The depth of refusal is assumed to represent competent bedrock. Figure 13 depicts soils cross-sections developed from these borings. Unconsolidated soils consist primarily of silts with interbedded sands and clays. Weathered Mancos Shale was encountered in many of the borings. Detailed logs of all soil borings are provided in EFRI (2013). Soils present above the Mancos Shale in this portion of the site are dominated by the same fine- grained materials typical of other portions of the site. Soil types encountered in borings installed by INTERA (Appendix C) are generally consistent with those found in the vicinity of the ammonium sulfate crystal tanks and other portions of the site. 3.3 Perched Water Elevations, Saturated Thicknesses, and Depths to Water As discussed in Section 2.1.3, Figure 5 is a contour map of perched water elevations generated from first quarter, 2014 water level data. Figure 5 contains perched well and piezometer water level data, and the elevations of all seeps and springs except Cottonwood Seep (for which there Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 22 is no evidence to establish a connection to the perched water system and which is located near the Brushy Basin Member/Westwater Canyon Member contact, indicating that its elevation is not representative of the perched potentiometric surface). Fill-in contours between the 10-foot elevation contours are provided over portions of the site, including the area immediately west- southwest of the tailings cells to allow detail in an area having relatively flat hydraulic gradients. Figure 5 was generated assuming that each seep or spring (except Cottonwood Seep) is a known discharge point for perched water and that the elevation of the seep or spring is representative of the elevation of perched water at that location (HGC, 2010e). As discussed in Section 2.1.4 this may not be appropriate for seeps/springs that are dry for portions of the year. Figure 14 shows the saturated thicknesses of the perched zone based on first quarter, 2014 water level data. Figure 15 shows depths to water as of the first quarter of 2014. Depths to perched water range from approximately 29 feet below top of casing (btoc) northeast of the tailings cells (at TWN-2) to approximately 117 feet btoc at the southwestern margin of tailings cell 3. Prior to cessation of water delivery to the northern wildlife ponds the shallowest depths to water were encountered in piezometers and wells near these ponds. Saturated thicknesses range from approximately 86 feet at MW-19 near the northern wildlife ponds to less than 5 feet in the southwest portion of the site, downgradient of the tailings cells. A saturated thickness of approximately 2 feet occurs in well MW-34 along the south dike of tailings cell 4B, and the perched zone has been consistently dry at MW-33 located at the southwest corner of cell 4B, and at MW-21 located south-southwest of cell 4B. Both are located on a structural high in the top of Brushy Basin Member surface (Figure 8). 3.4 Interpretation of Cross-Sections Lithologic and soils cross-sections prepared for various portions of the site are discussed in the following Sections. In general, the lithologies encountered in the borings used to construct the cross-sections are consistent with the literature and with past investigations at the site (prior to TITAN, 1994). 3.4.1 Central and Northeast Areas Figures 16A, 16B and 17 are lithologic cross-sections in the central to northeast portions of the site, as shown on Figure 1A. Figure 16A is a northeast-southwest oriented cross-section (NE- SW) extending from MW-3 to TWN-12. Figure 16B is a parallel cross section (NE2-SW2) extending from TWN-18 to TWN-19. Figure 17 is a northwest-southeast cross-section (NW-SE) extending from TWN-7 to Piez-3. Figures 16A, 16B, and 17 indicate site features located near the cross-sections. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 23 These cross-sections indicate that the top of Brushy Basin surface is irregular in the northeast portion of the site and that, as discussed in Sections 3.1.2.1 and 3.1.2.2, the Burro Canyon Formation and Dakota Sandstone contain shale/claystone and conglomerate interbeds of varying thickness and continuity. Where poorly indurated, coarser sand and conglomeratic horizons are expected to be relatively permeable, shale/claystone horizons are expected to be at least partial barriers to perched groundwater flow, and where present in the vadose zone, to represent at least partial barriers to downward percolation of recharge. That local saturated conditions have not been encountered above shale/claystone horizons during drilling within the Dakota Sandstone and Burro Canyon Formations suggests that recharge rates over most of the site are generally low, except near unlined ponds or surface depressions, or other areas having enhanced recharge due to their locations within drainages or due to relatively flat, poorly drainable topography. The perched water table surface is relatively elevated in the vicinities of the wildlife ponds and in the vicinity of the historical pond near TWN-2 (Figure 1B). As will be discussed in Section 3.5.2, the persistently high water level at TWN-2 likely results from low permeability and possibly enhanced recharge in the vicinity of TWN-2 due to graded areas of the millsite having relatively flat topography and poor runoff. 3.4.2 Southwest Area Figures 18 and 19 are cross-sections showing the hydrogeology of the perched zone in the area southwest of the tailings cells located as shown in Figure 1A. Figure 18 provides west-east cross- sections (W-E and W2-E2) across the area immediately west and southwest of cell 4B. Figure 19 is a south-north cross-section (S-N) from the south dike of cell 4B to Ruin Spring. Cross-sections W-E and S-N are oriented approximately parallel to perched water flow and W2-E2 is oriented roughly perpendicular to perched water flow. Except for abandoned DR-series borings, water levels in the cross sections are based on first quarter, 2014 data. Water levels for abandoned DR- series borings are from the second quarter, 2011. Water levels for DR-series piezometers have not changed significantly between the third quarter of 2011 and the first quarter of 2014 (as shown in Figure 20) suggesting that second quarter, 2011 water levels for abandoned borings are likely representative of current conditions. As shown in cross-section W-E in Figure 18 (and in Figure 14) the saturated thickness of the perched zone in the southwest area of the site varies from negligible to more than 20 feet. The variable saturated thickness has implications regarding the flow of perched water to known discharge points Westwater Seep and Ruin Spring. Perched water moving downgradient from the area of the tailings cells westward toward abandoned boring DR-2 must pass through a region of low saturated thickness occupied by DR-6 and DR-7 (Figures 5, 14 and 18). This implies (by Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 24 Darcy’s Law) that some downgradient areas having larger saturated thicknesses must receive local recharge from precipitation because the water supplied by lateral perched flow is inadequate to maintain the large saturated thicknesses in areas near sinks such as Westwater Seep and Ruin Spring. Two areas of relatively large saturated thickness that are downgradient of areas of small saturated thickness are of particular interest: the area near DR-2 (abandoned) and DR-5 located west of the area near DR-6 and DR-7 as shown in Figure 18 (cross-section W-E), and the area near DR-25 located south of the area near MW-20 as shown in Figure 19 (cross-section S-N). Each of the above areas of larger saturated thickness is downgradient of the corresponding area of small saturated thickness, and each downgradient area of larger saturated thickness is near a perched water sink. The primary known perched groundwater sinks downgradient of DR-2 abandoned) and DR-5 are Westwater Seep to the northeast and the paleovalley leading south to Ruin Spring (Figures 8 and 14). The primary sink near abandoned boring DR-25 is Ruin Spring. Lateral flow from areas of larger saturated thickness that may exist to the east of cross-section S- N may supply the water needed to maintain the relatively large saturated thickness near DR-25. However, the reported temporary increases in flow from Ruin Spring (and Westwater Seep) after precipitation events (HGC, 2010e) are problematic unless flow is temporarily enhanced by local recharge. As discussed in HGC (2010e), enhanced local recharge is likely near the mesa margins where weathered Dakota Sandstone and Burro Canyon Formation are exposed by erosion (Figure E.2, Appendix E). Logs at DR-2 and DR-5 show only a few feet of unconsolidated material above the Dakota Sandstone and visual inspection of the mesa near DR-2 (abandoned) and DR-5 shows that weathered Dakota is often exposed (consistent with the geology presented in Dames and Moore (1978). Due to the thin veneer of alluvium overlying the Dakota Sandstone, and thin or absent Mancos Shale, recharge near DR-2 and DR-5 (cross-section W-E, Figure 18) will be facilitated. Similarly, in the area near abandoned boring DR-25 and Ruin Spring, recharge will be facilitated by the thinness or absence of the Mancos Shale and the surface exposure of the Dakota Sandstone and Burro Canyon Formation between DR-25 and Ruin Spring (cross-section S-N, Figure 19). 3.5 Perched Water Occurrence and Flow Description of the occurrence and flow of perched water at the site focuses on three general areas: 1) the nitrate investigation area, 2) the area of the chloroform plume, and 3) areas beneath and downgradient of the tailing cells, as per Sections 3.5.2, 3.5.3, and 3.5.4 respectively. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 25 3.5.1 Overview As discussed in Section 2.1.3, perched groundwater at the site occurs primarily within the Burro Canyon Formation as well as the overlying Dakota sandstone where saturated thicknesses are greater. Flow onto the site occurs as underflow from areas northeast of the millsite where perched zone saturated thicknesses are generally greater. Flow exits the Mill property in seeps and springs to the east, west, southwest and southeast. Any flow that does not discharge in seeps or springs presumably exits as underflow to the southeast. Perched water flow is generally from northeast to south-southwest across the site. 3.5.1.1 General Site Flow Pattern First quarter 2014 perched water elevations (Figure 5) show the typical south-southwesterly flow pattern at the site. The historic water level contour maps in Appendix D demonstrate the persistence of the generally southwesterly perched flow pattern As discussed in Section 2.1.3, beneath and downgradient of the tailings cells, on the west side of the site, perched water flow is south-southwest to southwest. On the eastern side of the site perched water flow is more southerly. Perched zone hydraulic gradients currently range from a maximum of approximately 0.075 feet per foot (ft/ft) east of tailings cell 2 (near the eastern portion of the chloroform plume) to approximately 0.0022 ft/ft in the northeast corner of the site (between TWN-19 and TWN-16. Hydraulic gradients in the southwest portion of the site are typically close to 0.01 ft/ft, but the gradient is less than 0.005 ft/ft west/southwest of tailings Cell 4B, between Cell 4B and DR-8. The overall average site hydraulic gradient, between TWN-19 in the extreme northeast to Ruin Spring in the extreme southwest, is approximately 0.011 ft/ft. Perched groundwater discharges in springs and seeps along the mesa margins. These features are located along Westwater Creek Canyon and Cottonwood Canyon to the west-southwest of the site, and along Corral Canyon to the east of the site, where the Burro Canyon Formation is exposed. Based on the data presented in Figure 5, the discharge points located most directly downgradient of the tailings cells are Westwater Seep and Ruin Spring. Westwater Seep is located approximately 2,200 feet west of the tailings cell complex at the site; Ruin Spring is located approximately 9,400 feet south-southwest of the tailings cell complex at the site (Figure 1B). Dry areas beneath cell 4B and southwest of cell 4B (south of MW-21) affect perched water flow and are defined in Figure 5 by areas where the kriged contact between the Burro Canyon Formation and the Brushy Basin Member is higher in elevation than the kriged perched water elevation. The dry areas shown in Figure 5 encompass abandoned dry well MW-16, dry well Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 26 MW-21, dry well MW-33, and abandoned dry boring DR-18. The areas defined by the heavy yellow dashed contour lines have saturated thicknesses less than 5 feet. As shown in Figure 5 and southwest area cross-sections (Figures 18 and 19), a large portion of the perched zone west and southwest (downgradient) of the tailings cells has a saturated thickness less than 5 feet. This zone has been persistent based on measurements since the third quarter of 2011. An apparent perched water divide exists in the vicinity of DR-2 (abandoned) and DR-5 (Figure 5). Perched water north of this apparent divide is expected to flow primarily northeast toward Westwater Seep and perched water south of this apparent divide is expected to flow primarily south toward Ruin Spring (as will be discussed in Section 3.5.4). Figure 14 shows the axes of paleoridges and paleovalleys in the Brushy Basin Member erosional paleosurface and posted first quarter, 2014 saturated thicknesses. As indicated, paleoridges in the southwest area of the site are associated with dry areas and with areas of low saturated thicknesses; paleovalleys are associated with areas of higher saturated thicknesses. Westwater Seep and Ruin Spring are located in paleovalleys. The average saturated thickness based on measurements at MW-35, DR-7, and DR-6, which are the points closest to a line between the southeast portion of tailings Cell 3 and Westwater Seep, is approximately 5 feet. The average saturated thickness based on measurements at MW-37, DR-13, MW-3, MW-20, and DR-21, which lay close to a line between the southeast portion of tailings cell 4B and Ruin Spring, is approximately 9 feet. Perched water mounding associated with the wildlife ponds locally changes the generally southerly perched water flow patterns. For example, northeast of the Mill site, mounding associated with the northern wildlife ponds results in locally northerly flow near PIEZ-1. Mounding also causes the hydraulic gradient to be more westerly west of the ponds and more easterly east of the ponds. The impact of the mounding associated with the northern ponds, to which water has not been delivered since March 2012, is diminishing and is expected to continue to diminish as the mound decays due to reduced recharge. 3.5.1.2 Influence of Pumping and Wildlife Pond Seepage on Flow and Dissolved Constituent Concentrations Figures 1A and 1B show the locations of chloroform and nitrate pumping wells at the site. MW- 4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells, and TWN-2, TW4-22, TW4-24, and TW4-25 are nitrate pumping wells. Figure 21 is a map showing kriged first quarter 2014 perched water levels, the extents of the nitrate and chloroform plumes at the site, and inferred perched water flow paths. Figure 22 is a detail map showing the locations of pumping Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 27 wells, first quarter, 2014 kriged water levels, and inferred capture zones associated with the pumping wells. As described in HGC (2012a) the nitrate pumping system, which became operational in the first quarter of 2013, is designed to (eventually) establish hydraulic capture of the nitrate plume upgradient (north of) TW4-22 and TW4-24. MW-30 and MW-31, located at the downgradient edge of the plume, are not pumped to minimize the potential for downgradient chloroform migration As described in HGC (2007), the chloroform pumping system, which became operational in 2003 with the pumping of MW-4, TW4-19, and MW-26 (TW4-15), and later enhanced by the addition of TW4-20 in 2005 and TW4-4 in 2010, is designed primarily to reduce mass in upgradient portions of the plume where saturated thicknesses, concentrations, and well productivities are higher. Mass reduction is thereby maximized, the source of chloroform to downgradient areas cut off, and natural attenuation facilitated. Local depression of the perched water table occurs near chloroform pumping wells MW-4, TW4- 4, TW4-19, TW4-20, and MW-26 (Figure 22). Pumping of chloroform wells MW-4 and TW4-19 began in 2003 (HGC, 2004). Well-defined cones of depression are evident near all chloroform pumping wells except TW4-4, which began pumping in the first quarter of 2010, and was the last chloroform well to be brought on-line. Although operation of chloroform pumping well TW4-4 has depressed the water table in the vicinity of TW4-4, a well-defined cone of depression is not clearly evident. The lack of a well-defined cone of depression near TW4-4 likely results from 1) variable permeability conditions in the vicinity of TW4-4, and 2) persistent relatively low water levels at adjacent well TW4-14, as will be discussed in Section 3.5.3. Local depression of the perched water table also occurs near nitrate pumping wells TW4-22, TW4-24, TW4-25, and TWN-2 (Figure 22), which are operated to reduce nitrate mass in the perched groundwater as per the nitrate CAP (HGC, 2012a). Cones of depression are in the process of development in the vicinities of nitrate pumping wells which were brought on-line in the first quarter of 2013. Relatively slow development of capture zones is expected due to generally low permeability within the nitrate plume. The hydraulic effects of the chloroform and nitrate pumping systems overlap. Figure 22 shows the inferred capture of both chloroform and nitrate pumping systems as of the first quarter, 2014. Capture zones are calculated by hand based on the kriged water level contours following the rules for flow nets. From each pumping well, stream tubes that bound the capture zone are reverse-tracked, and perpendicularity is maintained between each stream tube and the intersected kriged water level contours. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 28 Recharge from the wildlife ponds has impacted perched water elevations and flow directions at the site by creating perched groundwater mounds as discussed in Section 3.5.1. Furthermore, the March 2012 cessation of water delivery to the northern ponds, which are generally upgradient of the nitrate and chloroform plumes at the site, has resulted in changing conditions that are expected to impact constituent concentrations and migration rates within the plumes. Specifically, past recharge from the ponds has helped limit many constituent concentrations within the plumes by dilution while the associated groundwater mounding has increased hydraulic gradients and contributed to plume migration. Since use of the northern wildlife ponds ceased in March 2012, the reduction in recharge and decay of the associated groundwater mound are expected to increase many constituent concentrations within the plumes while reducing hydraulic gradients and rates of plume migration. The impacts associated with cessation of water delivery to the northern ponds are expected to propagate downgradient (south and southwest) over time. Wells close to the ponds are generally expected to be impacted sooner than wells farther downgradient of the ponds. Therefore, constituent concentrations are generally expected to increase in downgradient wells close to the ponds before increases are detected in wells farther downgradient of the ponds. Although such increases are anticipated to result from reduced dilution, the magnitude and timing of the increases are difficult to predict due to the complex permeability distribution at the site and factors such as pumping and the rate of decay of the perched groundwater mound. The potential exists for some wells completed in higher permeability materials to be impacted sooner than some wells completed in lower permeability materials even though the latter may be closer to the ponds. Localized increases in concentrations of constituents such as chloroform and nitrate within and near the chloroform plume, and of nitrate and chloride within and near the nitrate plume, may occur even when these plumes are under control. Ongoing mechanisms that can be expected to increase constituent concentrations locally as a result of reduced wildlife pond recharge include but are not limited to: 1. Reduced dilution - the mixing of low constituent concentration pond recharge into existing perched groundwater will be reduced over time. 2. Reduced saturated thicknesses – dewatering of any higher permeability layers receiving primarily low constituent concentration pond water will result in wells intercepting these layers receiving a smaller proportion of the low constituent concentration water. The combined impact of the above two mechanisms may be especially evident at chloroform pumping wells MW-4, MW-26, TW4-4, TW4-19, and TW4-20; nitrate pumping wells TW4-22, TW4-24, TW4-25, and TWN-2; and non-pumped wells adjacent to the pumped wells. The Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 29 overall impact is expected to be generally higher constituent concentrations in these wells over time until mass reduction resulting from pumping and natural attenuation eventually reduces concentrations. Short-term changes in concentrations at pumping wells and wells adjacent to pumping wells are also expected to result from changes in pumping conditions. 3.5.2 Nitrate Investigation Area The extent of the nitrate plume addressed by the nitrate CAP (HGC, 2012a) and referred to as the ‘nitrate plume’ is shown in Figure 21. Figure 21 also displays kriged first quarter, 2014 perched water level contours and inferred flow paths and shows the extent of the chloroform plume which overlaps the nitrate plume in the vicinity of TW4-22. Nitrate exceeding 10 mg/L also occurs to the southeast of the plume in relatively isolated pockets (near TW4-10, TW4-12, TW4- 18, and TW4-27). As discussed in HGC (2014), this southeastern nitrate is attributed to sanitary leach field discharge associated with the chloroform plume and/or with former cattle ranching operations at the site. Nitrate exceeding 10 mg/L at far down gradient location MW-20 is also likely associated with former cattle ranching operations. The potential for cattle to contribute nitrate to soil is discussed in McFarland et al (2006). Elevated nitrate in soil can then act as a source to groundwater. Perched groundwater flow within the area of the nitrate plume varies from southwest to west- southwest. The generally southwesterly gradient typical of the majority of the site is influenced by past recharge from the northern wildlife ponds, and elevated water levels in the vicinities of wells TWN-2 and TWN-3. TWN-2 is within the footprint of the historical pond and TWN-3 is immediately east of the footprint of the pond, as shown in Figure 1B. Recharge from the northern wildlife ponds, located immediately northeast of the nitrate plume, caused a shift in gradient in the northern portion of the plume from southwesterly to west-southwesterly (compare Appendix D 1990 and 1994 water level maps with Figure 21). The persistently high water level at TWN-2, which has functioned as a nitrate pumping well since the first quarter of 2013, likely results from low permeability and possibly enhanced recharge in the vicinity of TWN-2 due to graded areas of the millsite having relatively flat topography and poor runoff. Cones of depression associated with nitrate pumping wells TW4-22, TW4-24, TW4-25, and TWN-2, have been developing since initiation of pumping during the first quarter of 2013. Hydraulic capture associated with these wells is developing slowly due to low permeability conditions. That sufficient capture will eventually develop is indicated by calculations presented in EFRI (2014a) showing that nitrate pumping exceeds pre-pumping flow through the nitrate plume by a factor between approximately 1.2 and 2.5. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 30 Water level patterns near nitrate pumping wells are expected to be influenced by the presence of, and the decay of, the groundwater mound associated with the northern wildlife ponds, and by the persistently low water level elevation at TWN-7. Chloroform and nitrate pumping wells interact. The long term interaction between nitrate and chloroform pumping systems will require more data to be collected as part of routine monitoring. Criteria regarding control and potential migration of the nitrate plume are detailed in the nitrate CAP (HGC, 2012a). As stated in the CAP, MW-5, MW-11, MW-30, and MW-31 are located downgradient of TW4-22 and TW4-24. MW-30 and MW-31 are within the nitrate plume near its downgradient edge and MW-5 and MW-11 are outside and downgradient of the plume. Per the CAP, hydraulic control based on concentration data is considered successful if the concentrations of nitrate in MW-30 and MW-31 remain stable or decline, and concentrations of nitrate in downgradient wells MW-5 and MW-11 do not exceed the 10 mg/L standard. Based on these criteria, the nitrate plume is under control. The plume has not migrated downgradient to MW-5 or MW-11 because nitrate has not been detected at MW-11 and has been detected at concentrations less than 1 mg/L at MW-5. Nitrate concentrations in both MW-30 and MW-31 at the downgradient edge of the plume have been relatively stable, demonstrating that plume migration is minimal or absent (EFRI, 2014a). Chloride has been relatively stable at MW-30 but appears to be increasing at MW-31 (EFRI 2014a). The apparent increase in chloride and stable nitrate at MW-31 suggests a natural attenuation process that is affecting nitrate but not chloride. A likely process that would degrade nitrate but leave chloride unaffected is reduction of nitrate by pyrite. The likelihood of this process in the perched zone is discussed in HGC (2012c). Understanding of perched water level behavior in the area northeast of the millsite was enhanced by the installation of TWN-series wells northeast of the nitrate plume in 2009. Prior to the installation of these wells, upgradient information was limited to that provided by MW-1, MW- 18, MW-19, PIEZ-1, and PIEZ-2. As shown in Figure 1B, nitrate wells TWN-5, TWN-8, TWN- 9, TWN-10, TWN-11, TWN-12, TWN-13, TWN-15, and TWN-17 have been abandoned as per the nitrate CAP. In general, water level data provided by these wells and existing wells and piezometers in the northeast portion of the Mill property indicated that perched water flow is to the southwest. Data from many of these wells helped to better define the extent of the perched groundwater mound resulting from former recharge at the northern wildlife ponds. Figure 23 is a water level contour map from the fourth quarter, 2011 constructed prior to both TWN well abandonment and cessation of water delivery to the northern wildlife ponds. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 31 3.5.3 Area of Chloroform Plume As noted in Section 3.5.1.2, the area of the chloroform plume is shown in Figure 21. Water level and concentration data presented in this Section are from EFRI (2014b) unless otherwise indicated. Perched groundwater flow within the area of the chloroform plume has been generally southerly to southwesterly. As discussed in HGC (2007) the chloroform plume resulted from disposal of laboratory wastes to the abandoned scale house and former office sanitary leach fields. Disposal took place in the early years of Mill operation before the tailings cells were functional. Laboratory wastes have been disposed to tailings cells since cells became operational circa 1980. As discussed in HGC (2007), the abandoned scale house leach field accepted laboratory wastes prior to the former office leach field. The abandoned scale house leach field was located immediately north-northwest of well TW4-18 (Figure 1B). Historic perched water flow in this area was to the south or south-southeast (Appendix D). Chloroform disposed in the abandoned scale house leach field migrated primarily southerly to the vicinity of well MW-4 where it was detected in 1999. Hydraulic gradients in this area were enhanced by recharge from the northern wildlife ponds located north of MW-4. The former office leach field is located in the immediate vicinity of well TW4-19 (a chloroform pumping well) and immediately northeast of tailings cell 2 (and chloroform pumping well TW4- 20) [Figure 1B]. Perched water flow in this area was historically southwest (Appendix D), and hydraulic gradients have been enhanced by recharge from the northern wildlife ponds (located to the northeast). Once chloroform pumping began in 2003 and nitrate pumping began in 2013, changes to the flow regime formerly dominated by wildlife pond recharge in the vicinity of the chloroform plume began to change locally under the influence of the pumping. Well defined cones of depression are evident in the vicinity of all chloroform pumping wells except TW4-4, which began pumping in the first quarter of 2010. Although operation of chloroform pumping well TW4-4 has depressed the water table in the vicinity of TW4-4, a well-defined cone of depression is not clearly evident. As discussed in Section 3.5.1.2 variable permeability conditions likely contribute to the lack of a well-defined cone of depression near chloroform pumping well TW4-4. Changes in water levels at wells immediately south of TW4-4 resulting from TW4-4 pumping are expected to be muted because TW4-4 is located at a transition from relatively high to relatively low permeability conditions south (downgradient) of TW4-4. The permeability of the perched zone at TW4-6 and Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 32 TW4-26 (and recently installed well TW4-29) is approximately two orders of magnitude lower than at TW4-4 (Table 1). Any drawdown of water levels at wells immediately south of TW4-4 resulting from TW4-4 pumping is also difficult to determine because of the general, long-term increase in water levels in this area due to recharge from the wildlife ponds. Water levels at TW4-4 and TW4-6 increased by nearly 2.7 and 2.9 feet, respectively, between the fourth quarter of 2007 and the fourth quarter of 2009 (just prior to the start of TW4-4 pumping) at rates of approximately 1.2 feet/year and 1.3 feet/year, respectively. However, the increase in water level at TW4-6 has been reduced since the start of pumping at TW4-4 (first quarter of 2010) to approximately 0.5 feet/year suggesting that TW4-6 is within the hydraulic influence of TW4-4 (Figure 24). Water level elevations at these wells are eventually expected to be influenced by cessation of water delivery to the northern wildlife ponds as discussed above. Recharge from the southern wildlife pond is expected to continue to have an effect on water levels near TW4-4, but the effects related to recharge from the northern ponds are expected to diminish over time as water is no longer delivered to the northern ponds. The lack of a well-defined cone of depression at TW4-4 is also influenced by the persistent, relatively low water level at non-pumping well TW4-14, located east of TW4-4 and TW4-6. For the first quarter of 2014, the water level at TW4-14 (approximately 5528.8 feet ft amsl) is approximately 11 feet lower than the water level at TW4-6 (approximately 5539.7 ft amsl) and 15 feet lower than at TW4-4 (approximately 5544.1 ft amsl) even though TW4-4 is pumping. Well TW4-27 (installed south of TW4-14 in the fourth quarter of 2011) has a static water level of approximately 5527.6 ft amsl, similar to TW4-14 (approximately 5528.8 ft amsl). TW4-27 was positioned at a location considered likely to detect any chloroform present and/or to bound the chloroform plume to the southeast and east (respectively) of TW4-4 and TW4-6. Groundwater data collected since installation indicates that TW4-27 does indeed bound the chloroform plume to the southeast and east of TW4-4 and TW4-6 (respectively), however chloroform exceeding 70 µg/L has been detected at recently installed temporary perched well TW4-29 (located south of TW4-27) since the second quarter of 2013. Prior to the installation of TW4-27, the persistently low water level at TW4-14 was considered anomalous because it appeared to be downgradient of all three wells TW4-4, TW4-6, and TW4- 26, yet chloroform was not detected at TW4-14. Chloroform had apparently migrated from TW4-4 to TW4-6 and from TW4-6 to TW4-26, which suggested that TW4-26 was actually downgradient of TW4-6, and TW4-6 was actually downgradient of TW4-4, regardless of the flow direction implied by the low water level at TW4-14. The water level at TW4-26 (5538.5 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 33 feet amsl) is, however, lower than water levels at adjacent wells TW4-6 (5539.7 feet amsl), and TW4-23 (5542.4 feet amsl). Hydraulic tests indicate that the permeability at TW4-27 is an order of magnitude lower than at TW4-6 and three orders of magnitude lower than at TW4-4 (Table 1). The similar water levels at TW4-14 and TW4-27, and the low permeability estimate at TW4-27 suggest that both wells are completed in materials having lower permeability than nearby wells. The low permeability condition likely reduces the rate of long-term water level increase at TW4-14 and TW4-27 compared to nearby wells, yielding water levels that appear anomalously low as will be discussed in Section 3.8. This behavior is consistent with hydraulic test data collected from recently installed wells TW4-29, TW4-30, TW4-31, and new wells TW4-33 and TW4-34, which indicate that the permeability of these wells is one to two orders of magnitude higher than the permeability of TW4-27 (HGC, 2014). The low permeability at TW4-14 and TW4-27 is expected to retard the transport of chloroform to these wells (compared to nearby wells). First quarter, 2014 chloroform concentrations at TW4-26 and TW4-27 are 1.4 ug/L and non-detect, respectively and both wells are outside the chloroform plume. Although chloroform exceeding 70 µg/L was detected at recently installed well TW4-29 (located south of TW4-27) and at new well TW4-33 (located between TW4-4 and TW4-29), chloroform was not detected at recently installed well TW4-30, located east and downgradient of TW4-29, nor at recently installed well TW4-31, located east of TW4-27, nor at new well TW4-34, located south and cross-gradient of TW4-29. The detections at TW4-29 and TW4-33 suggest that chloroform migrated southeast from the vicinity of TW4-4 to TW4-33 then TW4-29 in a direction nearly cross-gradient with respect to the direction of groundwater flow implied by the groundwater elevations. Such migration is possible because the water level at TW4-29 is lower than the water level at TW4-4 (and TW4-6). The hydraulic conductivities of TW4-29, TW4-30, and TW4-31 are one to two orders of magnitude lower than the conductivity of TW4-4, and one to two orders of magnitude higher than the conductivity of TW4-27 (Table 1). The permeability and water level distributions are generally consistent with the apparent nearly cross-gradient migration of chloroform around the low permeability zone defined by TW4-14 and TW4-27. Data from existing, recently installed and new wells indicate that: 1. Chloroform exceeding 70 µg/L at TW4-29 is bounded by concentrations below 70 µg/L at wells TW4-26, TW4-27, TW4-30 and TW4-34. TW4-30 is downgradient of TW4-29; TW4-26 is upgradient of TW4-29; and TW4-27 and TW4-34 are cross-gradient of TW4- 29. 2. Chloroform concentrations at TW4-33 that are lower than concentrations at TW4-29, and the likelihood that a pathway exists from TW4-4 to TW4-33 to TW4-29, suggests that Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 34 concentrations in the vicinity of TW4-33 were likely higher prior to initiation of TW4-4 pumping, and that lower concentrations currently detected at TW4-33 are due to its closer proximity to TW4-4. Furthermore, TW4-4 pumping is likely to reduce chloroform at both TW4-33 and TW4-29 by cutting off the source. The decrease at TW4-33 is expected to be faster than at TW4-29 because TW4-33 is in closer proximity to TW4-4 pumping. Such behavior is expected by analogy with the decreases in chloroform concentrations that occurred at TW4-6 and TW4-26 once TW4-4 pumping began (HGC, 2014). Chloroform exceeding 70 ug/L was detected at TW4-8 during the first quarter, 2014 sampling event. A new well (shown in Figure 1B) is therefore planned immediately to the east of TW4-8. To ensure that chloroform in the vicinity of TW4-29 is completely bounded, a new well is also planned to the south of TW4-30 (Figure 1B). 3.5.4 Beneath and Downgradient of Tailings Cells More than 30 years of groundwater monitoring beneath and downgradient of the tailings cells indicates that the tailings cells have not impacted groundwater as discussed in Section 2. In the event that seepage from tailings cells should impact groundwater at a future date, the likely pathways to known discharge points Westwater Seep and Ruin Spring are calculated in Section 3.5.4.1. Perched zone water balances within the areas near DR-2 (abandoned) and DR-5, and flow within the vicinities of Westwater Seep and Ruin Spring are calculated in Sections 3.5.4.2 and 3.5.4.3. 3.5.4.1 Overview Figure 25 is a water level contour map showing inferered pathlines from various locations on the west or south (downgradient) dikes of the tailings cells toward known discharge points Westwater Seep and Ruin Spring. These pathlines show the primary expected directions of perched water flow. As indicated, perched water passing beneath the west dike of cell 4B has the potential to travel to either of known discharge points Westwater Seep or to Ruin Spring because of an apparent groundwater divide in the vicinity of DR-2 (abandoned) and DR-5. Perched water north of this apparent divide is expected to flow primarily northeast to Westwater Seep and perched water south of this apparent divide is expected to flow primarily south toward Ruin Spring. The presence of this apparent divide is consistent with enhanced local recharge. The path to Ruin Spring from the area south of the apparent divide is sub-parallel to the western rim of the mesa. The path is generally along a paleovalley between the mesa rim and the dry portion of the Brushy Basin Member paleoridge defined by MW-21 and abandoned boring DR- Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 35 18. Perched water passing beneath the south dike of Cell 4B is expected to travel south- southwest to Ruin Spring, to the east of the dry paleoridge defined by MW-21 and abandoned boring DR-18. As discussed previously, the data suggest that flow in the southwest portion of the site is influenced by paleotopography to a greater extent than in other areas of the site due to the prevalence of small saturated thicknesses. As discussed in Section 2.1.4, there is no evidence to hydraulically connect Cottonwood Seep to the perched water system; therefore no inferred flow pathway depicted in Figure 25 leads to Cottonwood Seep. Section 3.6.3 posits a potential pathway that may hypothetically exist between the perched zone near DR-8 and Cottonwood Seep for purposes of travel time calculations, and to allow for the possibility that an as yet unidentified pathway may exist. 3.5.4.2 Water Balance Near DR-2 and DR-5 Enhanced recharge south/southwest of Westwater Seep near DR-2 (abandoned) and DR-5 is likely needed to maintain the relatively large saturated thicknesses there, considering the slow rate of perched water flow into that area via the zone of small saturated thickness and the presence of known sinks to the northeast (Westwater Seep) and to the south (paleovalley leading to Ruin Spring). Because the water columns in most piezometers penetrating the area of low saturated thicknesses were inadequate for hydraulic testing, only one estimate of hydraulic conductivity was obtained, at DR-10. As shown in Table 1, the KGS method hydraulic conductivity estimates at DR-10 (located within the area of low saturated thickness) were one to two orders of magnitude lower than at DR-5 and DR-9, located west of the area of low saturated thickness. Assuming the estimate at DR-10 is representative of the area of low saturated thickness, the transmissivity (the product of hydraulic conductivity and saturated thickness) of the area of low saturated thickness is two to three orders of magnitude lower than for the area of larger saturated thickness to the west (near DR-2, DR-5, and DR-9). Figures 5 and 25 show that the hydraulic gradient in this area is relatively flat, and the gradient does not change significantly across the area of low saturated thickness. Water flows westward from the area of the tailings cells through the area of low saturated thickness between DR-6 and DR-10 (Figure 25). Using Darcy’s Law, and assuming a hydraulic conductivity of 3 x 10-6 cm/s (0.0084 feet per day [ft/day], based on the KGS estimate provided for DR-10 in Table 1), an average hydraulic gradient of 0.0057 ft/ft, an average saturated thickness of 2.4 ft, and a width of approximately 1,600 feet (the approximate distance between Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 36 DR-6 and DR-10), the rate of perched water flow westward through the area of low saturated thickness is approximately 0.18 cubic feet per day (ft3/day) or 0.001 gpm. Water flows out of the area of larger saturated thickness (near DR-2 [abandoned] and DR-5) to the northeast toward known discharge point Westwater Seep and to the south through the paleovalley leading towards known discharge point Ruin Spring. The rate of flow out of this area northeast to Westwater Seep is expected to be smaller than the discharge rate at Westwater Seep which also receives water from the east and northeast. The discharge rate at Westwater Seep is too small for a reliable estimate. However, the rate of flow south through the paleovalley leading towards Ruin Spring can be calculated using the geometric average hydraulic conductivity of 0.0089 ft/day (based on KGS estimates for DR-8, DR-9, and DR-10 in Table 1), an approximate hydraulic gradient of 0.0088 ft/ft, an average saturated thickness of 12 ft, and a width of approximately 2,250 ft (between DR-8 and DR-10), as 2.1 ft3/day, or 0.011 gpm, an order of magnitude larger than the calculated flow into the area. The difference between calculated inflow and outflow is approximately 0.01 gpm. These calculations indicate that an additional water source is needed to maintain the relatively large saturated thicknesses west of the area of low saturated thickness between DR-6 and DR-10; otherwise Westwater Seep and the paleovalley to the south would drain the area of larger saturated thickness more quickly than water was supplied. The most likely source of additional water is infiltration of precipitation enhanced by the direct exposure of weathered Dakota Sandstone and Burro Canyon Formation, and the thinness or absence of any overlying low permeability materials such as the Mancos Shale. Assuming uniform recharge over an area of approximately 175 acres (the portion of the mesa west of Westwater Seep and north of DR-8 and DR-9), the calculated difference of 0.01 gpm implies a conservatively low recharge rate of 0.0011 inches per year (in/yr). Most of the recharge likely occurs near the mesa rim where the Dakota and Burro Canyon are exposed (Figure E.1 and Figure E.2, Appendix E). Such recharge is expected to be enhanced within drainages where they cross weathered Dakota Sandstone and Burro Canyon Formation. Furthermore, these calculations indicate that perched water flow in the portion of the site south of Westwater Seep is inadequate as a primary supply to Cottonwood Seep. Perched water flow from the area of the tailings cells through the area of low saturated thickness towards Cottonwood Seep would have to be more than three orders of magnitude higher than calculated above to provide a supply of between 1 and 10 gpm. The required flow would have to be even larger considering that some of the incoming flow is diverted to known discharge point Westwater Seep and to the paleovalley that leads south to known discharge point Ruin Spring. Even if this calculation were performed using the geometric average of the KGS hydraulic Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 37 conductivity estimates for all tested DR-series piezometers (approximately 1 x 10-5 cm/s or 0.028 ft/day) rather than the estimate for DR-10 (3 x 10-6 cm/s or 0.0084 ft/day), the calculated rate of flow through the area of low saturated thickness would be approximately 0.0032 gpm, which is still approximately three orders of magnitude lower than the estimated discharge rate of Cottonwood Seep. The inadequacy of the perched zone as the primary supply to Cottonwood Seep indicates that the primary source or sources of Cottonwood Seep lie elsewhere. 3.5.4.3 Water Balance Near Ruin Spring and Westwater Seep Figure 26 is a map showing inferred perched water pathlines in the immediate vicinities of Ruin Spring and Westwater Seep. These pathlines were used to estimate expected flow rates to these features based on Darcy’s Law using local hydraulic gradients, saturated thicknesses, and hydraulic conductivity estimates. Saturated thicknesses posted on Figure 26 were calculated as the difference between kriged first quarter, 2014 water level and top of Brushy Basin Member surfaces. The area of the perched zone providing flow to Ruin Spring was estimated by assuming the flow is divided between Ruin Spring to the west and Corral Spring to the east. This division coincides approximately with a groundwater divide that extends southwest from the southern wildlife pond toward Ruin Spring, approximately parallel to the southeasternmost flow path depicted on Figure 21. Using the geometric average hydraulic conductivity based on estimates at DR-21, DR-23, and DR-24 (2.2 x 10-5 cm/s or 0.06 ft/day based on KGS analysis of automatically logged slug test data [Table 6]), which are closest to Ruin Spring, an average hydraulic gradient of 0.01 ft/ft, and an average saturated thickness of approximately 18 feet over a width of approximately 7,700 feet (along the 5420 foot elevation contour), yields a rate of perched flow of approximately 83 ft3/day or 0.43 gpm. The calculated value of 0.43 gpm is slightly less than the estimated average flow for Ruin Spring of 0.5 gpm. Assuming that the difference between the calculated perched water flow and the estimated flow at Ruin Spring (0.07 gpm or 13 ft3/day) is due to local recharge over the area of Figure 26 covered by the inferred flow paths (approximately 420 acres or 18.3 x 106 ft2), then the local recharge rate needed to make up the difference is approximately 7.1x 10-7 ft/day or 0.0031 in/yr. Flow to Westwater Seep was estimated in a similar fashion. Hydraulic conductivities used in the calculations are summarized in Table 6. Hydraulic conductivity estimates at DR-5, DR-8, DR-9, DR-10, and DR-11 are based on automatically logged slug test data analyzed using the KGS solution method; estimates at MW-12, MW-14, and MW-15 are based on pumping test analyses reported in TITAN (1994) [Table 4]. Estimates from DR-2, DR-16, and DR-17 are not available Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 38 as hydraulic tests could not be performed because these borings were abandoned after surveying and water level collection based on the criteria presented in HGC (2012b). Tests also could not be performed at DR-6 nor DR-7 due to an insufficient water column. Using a geometric average hydraulic conductivity of 9.8 x 10-6 cm/s (0.027 ft/day), an average hydraulic gradient of 0.013 ft/ft, and an average saturated thickness of 4.5 feet over a width of approximately 3,300 feet, yields a rate of perched flow of approximately 5.2 ft3/day or 0.027 gpm. If the geometric average of the hydraulic conductivities estimated at the four closest wells (MW-23, MW-24, MW-35, and DR-5) is substituted (1.8 x 10-5 cm/s [0.05 ft/day]), the calculated rate of perched flow is 9.6 ft3/day or 0.05 gpm. In calculating the latter average, the highest estimate from the MW-24 test was used. Because the flow to Westwater Seep is too small to be reliably measured (as discussed in Section 3.7), either result is considered reasonable. 3.6 Perched Water Migration Rates and Travel Times Perched water pore velocities and travel times along selected pathlines shown in Figure 27 were calculated using Darcy’s Law. The calculated pore velocities and travel times are representative of the movement of a conservative solute assuming no hydrodynamic dispersion. Hydraulic conductivity estimates used for pathlines 1, 2A, and 2B are summarized in Table 7, and for pathlines 3 through 6 in Table 8. Pore velocity estimates are summarized in Table 9. 3.6.1 Nitrate Investigation Area Perched water pore velocities and travel times were calculated along Path 1 (Figure 27) located within the nitrate plume. Path 1 is approximately 1,250 feet long. Under current conditions, a particle migrating along Path1 would be captured by nitrate pumping well TW4-24. The average hydraulic conductivity along Path 1 is assumed to be the geometric average of the conductivities of wells located within and immediately upgradient and downgradient of the nitrate plume (wells TWN-2, TWN-3, TWN-18, TW4-21, TW4-22, TW4-24, MW-11, MW-30, and MW-31) as estimated by analyzing automatically logged slug test data using the KGS solution (Table 7). Using a geometric average conductivity of 1.31 x 10-4 cm/s (0.37 ft/day), a hydraulic gradient of 0.028 ft/ft, and a porosity of 0.18, the estimated average pore velocity along Path 1 is approximately 21 ft/yr. This implies that approximately 60 years would be required to traverse Path 1. Historic hydraulic gradients within the area of the nitrate plume were likely much larger than 0.028 ft/ft during the time prior to Mill construction when the historical pond was active (Figure 1B). The depth to water at TWN-2, located within the former footprint of the historical pond Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 39 (Figure 1B), was approximately 16 feet bls prior to its conversion to a nitrate pumping well. The relatively small depth to water is interpreted to result from the relatively low perched zone permeability at TWN-2 (approximately 1.5 x 10-5 cm/s) and slightly elevated recharge by precipitation resulting from the relatively flat topography in that portion of the site. When the historical pond was active and ponded water was present in the vicinity of TWN-2, depths to water were likely negligible as the associated groundwater mound likely reached an elevation just beneath the pond bottom. Historic water level maps (Appendix D) show that water levels in the vicinities of MW-30 and MW-31, located along the downgradient margin of tailings cell 2, and at the downgradient margin of the nitrate plume, were approximately 5,520 feet amsl. Assuming that the perched water level beneath the historical pond was close to the pond bottom (approximately 5,625 feet amsl), the perched water level at the downgradient edge of cell 2 was approximately 5,520 feet amsl, and the distance between the southern edge of the historical pond and the downgradient edge of cell 2 was approximately 2,200 feet, the historic hydraulic gradient is calculated as approximately 0.048 ft/ft. This estimate is more than four times the overall average site hydraulic gradient of approximately 0.011 ft/ft (calculated between TWN-19 and Ruin Spring). Using the geometric average hydraulic conductivity of 0.36 ft/day (as discussed above), an historic hydraulic gradient of 0.048 ft/ft, and a porosity of 0.18, the estimated historic pore velocity downgradient of the historical pond is approximately 35 ft/yr, implying that nitrate originating from the historical pond could have migrated to the downgradient edge of cell 2 within 63 years. Assuming the historical pond was active circa 1920, that nitrate was conservative, and ignoring hydrodynamic dispersion, nitrate originating from the historical pond could have reached the vicinities of MW-30 and MW-31 by 1983. 3.6.2 Area of Chloroform Plume Perched water pore velocities and travel times along Paths 2A and 2B (Figure 27), located within the chloroform plume area, were calculated. Path 2A is approximately 1,200 feet long and path 2B is approximately 1,450 feet long. Under current conditions, a particle migrating along Path 2A would be captured by chloroform pumping well MW-26, and. a particle migrating along Path 2B would be captured by chloroform pumping well MW-4. In evaluating average hydraulic conductivities along these paths, estimates assuming both confined and unconfined conditions were used. This methodology is considered appropriate for this area of the site because of the potential for semi-confined conditions to exist at least locally (HGC, 2004). The average hydraulic conductivity along Path 2A is assumed to be the geometric average of the conductivities of nearby wells MW-26, TW4-5, TW4-9, TW4-10, and TW4-18 (Table 7). Using Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 40 a geometric average conductivity of 4.88 x 10-4 cm/s (1.4 ft/day), a hydraulic gradient of 0.0275 ft/ft, and a porosity of 0.18, the estimated average pore velocity along Path 2A is approximately 76 ft/yr. This pore velocity implies that approximately 16 years would be required to traverse Path 2A. The average hydraulic conductivity along Path 2B is assumed to be the geometric average of the conductivities of nearby wells MW-4A, TW4-2, TW4-5, TW4-9, and TW4-32 (Table 7) (no data are available for nearby wells TW4-3 or TW4-11.) Estimates based on the early time data for MW-4A (formerly located 10 feet south of MW-4) were used in calculating the averages because these data are considered more representative of conditions in the immediate vicinity of MW-4. Using a geometric average conductivity of 2.53 x 10-4 cm/s (0.71 ft/day), a hydraulic gradient of 0.026 ft/ft, and a porosity of 0.18, the estimated average pore velocity along Path 2B is approximately 38 ft/yr. This pore velocity implies that approximately 38 years would be required to traverse Path 2B. Historic hydraulic gradients within the northern (upgradient) areas of the eastern portion of the chloroform plume (prior to about 1990) were likely larger and contributed to relatively rapid movement of chloroform from the abandoned scale house leach field (located immediately north of TW4-18) to MW-4 where chloroform was detected in 1999. The assumptions are made that water levels near the abandoned scale house leach field were affected relatively early by wildlife pond seepage (owing to the close proximity of the northern wildlife ponds) and that the water level at TW4-18, which has been relatively stable since installation in 2002, is representative of the water level at the leach field circa 1980. Based on these assumptions and the historic water level maps provided in Appendix D, the hydraulic gradient between the abandoned scale house leach field and MW-4 was approximately 0.048 ft/ft in 1990 and approximately 0.029 ft/ft in 1999, averaging 0.038 ft/ft. This is more than three times the overall average site hydraulic gradient of approximately 0.011 ft/ft (calculated between TWN-19 and Ruin Spring) and is approximately the same as the current hydraulic gradients at the leading edge of the southeastern portion of the chloroform plume. Using a geometric average hydraulic conductivity of 1.1 ft/day (Table 3) based on estimates from wells MW-4A, TW4-5, TW4-9, TW4-10, and TW4-18 (located near a line connecting MW-4 with the abandoned scale house leach field), a hydraulic gradient of 0.038 ft/ft, and a porosity of 0.18, and ignoring hydrodynamic dispersion, the calculated average pore velocity prior to 1999 was approximately 84 ft/yr. This is sufficient for chloroform to have migrated from the abandoned scale house leach field to MW-4 between 1978 and 1999. This calculation implies that chloroform could have migrated nearly to TW4-4 by 1999. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 41 3.6.3 Beneath and Downgradient of Tailings Cells Estimated times for a hypothetical conservative solute originating from the tailings cells and migrating downgradient to known discharge points Westwater Seep and Ruin Spring are calculated in the following Sections. Because the hypothetical conservative solute is assumed to originate from the tailings cells, the time for the solute to migrate downward from the base of a tailings cell to the perched water must be taken into account. Vadose zone travel times are estimated in Section 3.6.3.1. Total travel times are estimated in Section 3.6.3.2. 3.6.3.1 Vadose Zone Depths to perched water near tailings cell 2 vary from approximately 60 feet btoc near the northeast (upgradient) corner of the cell to approximately 114 feet btoc at the northwest corner of the cell. Depths to water near tailings cell 3 vary from approximately 67 feet btoc near the northeast (upgradient) corner of the cell to approximately 117 feet btoc at the southwest (downgradient) corner of the cell. Depths to water near tailings cells 4A and 4B vary from approximately 73 feet btoc near the northeast (upgradient) corner of cell 4A to approximately 114 feet btoc at the southern (downgradient) margin of cell 4B. The average depth to water near cell 2 is approximately 73 feet btoc; near cell 3 approximately 90 feet btoc; and near cells 4A and 4B approximately 94 feet btoc. Because the cells are installed a maximum of approximately 25 feet below grade, the average depth to perched water from the base of cell 2 is approximately 48 feet; beneath cell 3 approximately 65 feet; and beneath cells 4A and 4B approximately 69 feet. Any seepage from the cell liners would have to travel downward through approximately 48 feet of vadose materials to impact perched water beneath cell 2; through approximately 65 feet to impact perched water beneath cell 3; and through approximately 69 feet to impact perched water beneath cells 4A and 4B. Knight-Piésold (1998) estimated a maximum volumetric seepage rate for tailings cell 3 based on cell construction and liner characteristics, of approximately 80 cubic feet per day (ft/day) or 0.42 gpm over the entire cell. Most of this seepage was estimated to be via diffusion through the liner. This rate was estimated to decrease over time as the cell desaturates once the final cover is emplaced. Assuming a cell footprint of 3.38 x 106 ft 2, this maximum rate is equivalent to 2.37 x 10-5 ft/day or 0.0086 ft/yr. The average saturation expected in vadose bedrock beneath the tailings cells is approximately 20% based on saturations measured in bedrock samples presented in Table 5 (from TITAN, 1994). Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 42 Assuming that the Knight-Piesold estimates from cell 3 are also representative of cell 2 and cells 4A and 4B, and assuming that this rate of seepage would not significantly raise the average saturation of the underlying vadose zone materials, the average rate of downward movement of a conservative solute dissolved in the seepage, assuming 1) no hydrodynamic dispersion, 2) an average water saturation of 0.20, and 3) an average porosity of 0.18, can be approximated as: yrftyrft/24.0)18(.)20(. /0086.0 = The average times to travel from cell liners to the perched water zone would then be approximately 200 years beneath cell 2;. 270 years beneath cell 3; and 288 years beneath cells 4A and 4B. These are conservative estimates because the maximum estimated seepage rate is used, and the average vadose zone water saturations would be likely to increase, thereby reducing the downward rates of travel, and increasing the travel times. Numerical modeling of potential tailings cell seepage and rates of downward migration of solutes are provided in MWH (2010). Based on Figure A-3 from MWH (2010), the simulated seepage rates beneath tailings cells 2 and 3 would reach a maximum of approximately 7.7 millimeters per year (mm/yr) [0.025 ft/yr] by year 25, then drop to approximately 0.7 mm/yr (0.0023 ft/yr) by year 70. The average seepage rate over the 240 year simulation period is approximately 0.0043 ft/yr, half the estimate used in the above calculations. Using this rate with the above assumptions would double the travel times estimated for seepage to reach perched water beneath cells 2, 3, and 4A and 4B. However, the MWH analyses used smaller initial water saturations for the vadose zone which correspondingly reduced travel time estimates. Based on personal communication with MWH personnel, a 200+ year vadose zone travel time estimate for cells 2 and 3 is considered reasonable. The estimates calculated above for cell 2 (200 years), cell 3 (270 years) and cells 4A and 4B (288 years) will be used in subsequent calculations. Because cells 2 and 3 are at least 30 years old, the travel times starting from the present time will be 170 years for cell 2, and 240 years for cell 3. Cell 4B was installed in 2010 and cell 4A refurbished and put into use shortly thereafter so the effective travel time will be assumed to be 255 years for these cells. Furthermore, the estimates for cells 4A and 4B are considered even more conservative because of improvements in tailings cell design and liner quality that were incorporated in these cells but were not available during construction of cells 2 and 3. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 43 3.6.3.2 Perched Water Zone Downgradient of Tailings Cells Perched water pore velocities and travel times along selected paths between the tailings cells and perched water discharge points were calculated for pathlines 3 through 6 shown in Figure 27. The Figure 27 pathlines were selected as the shortest Figure 25 paths from the tailings cells to a) Westwater Seep (Path 3), b) Ruin Spring via the west side of the Brushy Basin paleoridge (Path 5), and c) Ruin Spring via the east side of the Brushy Basin paleoridge (Path 6). A pathline from the tailings cells to the vicinity of DR-8 (Path 4) is also shown in Figure 27. From the vicinity of DR-8 perched water is expected to flow primarily south (within a paleovalley) toward Ruin Spring. However, a potential pathline from the vicinity of DR-8 is also shown in Figure 27 that posits a hypothetical connection between the perched zone and Cottonwood Seep. Path 4 provides the shortest pathline between the tailings cells and the western edge of the perched zone near DR-8, and the potential path provides the shortest hypothetical connection between the western edge of Path 4 and Cottonwood Seep. Hydraulic conductivities used in the calculations are summarized in Table 8. Hydraulic conductivity estimates are based on automatically logged slug test data analyzed using the KGS solution method, except for MW-12, MW-14, and MW-15. Hydraulic conductivity estimates at MW-12, MW-14, and MW-15 are based on pumping test analyses reported in Table 4 (from TITAN, 1994). Hydraulic tests could not be performed at DR-2, DR-16, DR-18, nor DR-25. These borings were abandoned after surveying and water level collection based on the criteria presented in HGC (2012b). Tests also could not be performed at DR-6 nor DR-7 due to insufficient water column height. Pore velocity calculations for pathlines 3 through 6 are summarized in Table 9. Path 3 is approximately 2,200 feet long with an average hydraulic gradient of 0.0123 feet per foot (ft/ft) based on the first quarter, 2014 water level at MW-23 (5,495 ft amsl) and the elevation of Westwater Seep (5,468 ft amsl). The geometric average hydraulic conductivity of the perched zone in the vicinity of Path 3 (based on data from DR-5, DR-8, DR-9, DR-10, DR- 11, MW-12, MW-23, MW-24, and MW-36) is 9.8 x 10-6 cm/s (0.027 ft/day). Assuming an effective porosity of 0.18, the average perched water pore velocity along Path 3 is 0.68 feet per year (ft/yr), yielding a travel time of approximately 3,230 years. Including a vadose zone travel time of approximately 240 years for cell 3, the total travel time is approximately 3,470 years. Path 4 is approximately 4,125 feet long with an average hydraulic gradient of 0.0046 ft/ft based on the first quarter, 2014 water level at MW-36 (5,493 ft amsl) and the water level at DR-8 (5,474 ft amsl). The geometric average hydraulic conductivity of the perched zone in the vicinity of Path 4 (based on data from DR-5, DR-8, DR-9, DR-10, DR-11, MW-12, MW-23, MW-24, Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 44 and MW-36) is 9.8 x 10-6 cm/s (0.027 ft/day). Assuming an effective porosity of 0.18, the average perched water pore velocity along Path 4 is 0.26 feet per year (ft/yr), yielding a travel time of approximately 15,850 years. Including a vadose zone travel time of approximately 250 years for cell 4A, the total travel time is approximately 16,100 years. The additional time to travel along the hypothetical pathway to Cottonwood Seep is not calculated because of the hypothetical nature of the pathway and because the hypothetical pathway is through the Brushy Basin Member which is considered an aquiclude. If such a pathway exists, the combined travel time along Path 4 and the hypothetical pathway (which adds approximately 2,150 horizontal feet to the total path length), would be significantly greater than 16,100 years. Path 5 is approximately 11,800 feet long with an average hydraulic gradient of 0.0096 ft/ft based on the first quarter, 2014 water level at MW-36 (5,493 ft amsl) and the elevation of Ruin Spring (5,380 ft amsl). The geometric average hydraulic conductivity of the perched zone in the vicinity of Path 5 (based on test data from DR-5, DR-8, DR-9, DR-10, DR-11, DR-14, DR-17, DR-19, DR-20, DR-21, DR-23, DR-24, MW-23, MW-24, and MW-36) is 1.1 x 10-5 cm/s (0.031 ft/day). Assuming an effective porosity of 0.18, the average perched water pore velocity along Path 5 is 0.60 ft/yr, yielding a travel time of approximately 19,650 years. Including a vadose zone travel time of approximately 250 years for cell 4A, the total travel time is approximately 19,900 years. Path 6 is approximately 9,685 feet long with an average hydraulic gradient of 0.0116 ft/ft based on the first quarter, 2014 water level at MW-34 of 5,492 ft amsl and the elevation of Ruin Spring (5,380 ft amsl). The geometric average hydraulic conductivity of the perched zone in the vicinity of Path 6 (based on test data from DR-11, DR-13, DR-21, DR-23, DR-24, MW-3, MW-14, MW- 15, MW-20 and MW-37) is 1.38 x 10-5 cm/s (0.039 ft/day). Assuming an effective porosity of 0.18, the average perched water pore velocity along Path 6 is 0.91 ft/yr, yielding a travel time of approximately 10,650 years. Including a vadose zone travel time of approximately 250 years for cell 4B, the total travel time is approximately 10,900 years. 3.7 Implications For Seeps and Springs The lithologic and hydraulic data collected from the southwest area investigation (HGC 2012b) allow a more comprehensive assessment of the hydrogeology of the site and have implications with regard to seeps and springs southwest of the site. The data indicate that dilution of perched water by local recharge is expected to occur in the vicinities of Westwater Seep and Ruin Spring, and that perched zone permeabilities and flow rates in the southwestern portion of the site are too low (by several orders of magnitude) for the perched zone to serve as the primary source of water for Cottonwood Seep Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 45 3.7.1 Westwater Seep and Ruin Spring As discussed in HGC (2010e) the water source for both Westwater Seep and Ruin Spring is lateral flow from upgradient portions of the perched zone enhanced by local recharge near the edge of the mesa. Most of this recharge likely occurs near the mesa rim where weathered Dakota Sandstone and Burro Canyon Formation are exposed. Such recharge is likely to be enhanced within drainages where they cross weathered Dakota Sandstone and Burro Canyon Formation. The results of the southwest area investigation (HGC, 2012b) indicate that the permeability of the perched zone in the southwest area of the site is on average lower than previously estimated (as in HGC, 2009) and that the contribution to flow at Westwater Seep and Ruin Spring by local recharge may be more significant than previously thought. 3.7.2 Cottonwood Seep The low perched zone permeabilities and small saturated thicknesses in the southwest area of the site are consistent with low rates of perched water flow, as shown by the calculated flow through the area of small saturated thickness southwest of the tailings cells (between DR-6 and DR-10) provided in Section 3.5.4.2. This low rate of perched water flow (approximately 0.001 gpm) is inadequate (by more than three orders of magnitude) to function as the primary supply to Cottonwood Seep which has flows estimated to be between 1 and 10 gpm. As discussed in Section 3.5.4.2, the estimated flow of between 1 and 10 gpm at Cottonwood Seep is consistent with Dames and Moore (1978). In summary, the perched zone cannot be the primary source of water to Cottonwood Seep for the following reasons: 1. Cottonwood Seep occurs in the lower third of Brushy Basin Member, approximately 230 feet below the contact between the Burro Canyon Formation and the Brushy Basin Member, more than 1,500 ft west of the termination of the perched zone, and just west of a change in morphology from slope-former to bench-former. The change in morphology is indicative of a change in lithology. As discussed in HGC (2010e) Cottonwood Seep likely originates from coarser-grained materials within the lower portion of the Brushy Basin Member. Alternatively, Cottonwood Seep may originate from coarser-grained materials of the Westwater Canyon (sandstone) Member intertongueing with the overlying Brushy Basin Member at the transition between the two Members. The presence of coarser-grained materials similar to the Salt Wash (sandstone) Member within the lower portion of the Brushy Basin member is discussed in Shawe (2005). The intertongueing of the Westwater Canyon and Brushy Basin Members is discussed in Craig et al. (1955) and Flesch (1974). Based on lithologic cross sections provided in TITAN (1994), the elevation of Cottonwood Seep (5,234 ft amsl) is within 5 to 15 feet of the elevation of the contact between the Brushy Basin Member and the underlying Westwater Canyon Member (5,220 to 5,230 ft amsl). This is also shown in Figure 3. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 46 2. The flow at Cottonwood Seep exceeds the flow in the perched zone in the area southwest of the tailings cells by several orders of magnitude. Flows at Cottonwood Seep are also relatively large compared to seeps and springs known to originate from the perched zone, consistent with a primary source other than perched water. 3. There is no evidence to establish a direct hydraulic connection between the perched zone and Cottonwood Seep, located more than 1,500 ft west of the termination of the Burro Canyon Formation which hosts the perched water zone. Examination of the area between Cottonwood Seep and mesa rim (the edge of the perched zone) reveals that the upper portion of the Brushy Basin Member appears dry and no previously undiscovered seeps originating from the Burro Canyon Formation near Cottonwood Seep were identified. Because the results of the southwest area investigation do not provide evidence that Cottonwood Seep is hydraulically connected to the perched water system at the site, and because the perched zone near Cottonwood Seep is inadequate as a primary supply, the primary source (or sources) of water to Cottonwood Seep must lie elsewhere. The primary source(s) must be significant to supply consistent flows at rates between 1 and 10 gpm. By contrast, flows at Ruin Spring (estimated at approximately 1/2 gpm, consistent with Dames and Moore, 1978) are lower than at Cottonwood Seep (between 1 and 10 gpm), and flows at Westwater Seep are too small to measure reliably. Westwater Seep generally consists of damp soil that can be sampled only by excavating and waiting for enough water to seep in for sample collection (see Figures 28 and 29 taken from HGC, 2010e). Although no evidence of a direct hydraulic connection between the perched zone and Cottonwood Seep was provided by the southwest area investigation, the possibility of a hypothetical, as yet unknown, connection was postulated for the purpose of calculating a travel time from the tailings cells to the western edge of the perched zone (near DR-8), and thence along a potential pathway to Cottonwood Seep. The total travel time from the tailings cells to DR-8 was calculated as approximately 16,100 years. Should a potential pathline such as that shown in Figure 27 exist, the total time needed to travel from the tailings cells to Cottonwood Seep would be significantly larger than 16,100 years. 3.7.3 Potential Dilution of Perched Water Resulting From Local Recharge of the Dakota and Burro Canyon Near Seeps and Springs As discussed in Section 3.5.4.2, the rate of flow in the perched water zone in the southwest area of the site is small and a contribution from local recharge is needed to explain many areas of relatively high saturated thickness near sinks such as Westwater Seep and Ruin Spring that are downgradient of areas of relatively low saturated thickness. The presence of local recharge is expected to affect the water quality of seeps and springs and has the potential to dilute any dissolved constituents that may migrate from upgradient areas. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 47 3.8 Implications For Transport of Chloroform and Nitrate Chloroform and nitrate plumes are under remediation by pumping. Pumping systems are designed to remove chloroform and nitrate mass from the perched zone as quickly as is practical to allow natural attenuation in the far downgradient portions of the plumes to be more effective. Furthermore, nitrate pumping is designed to capture approximately the northern 2/3 of the nitrate plume. Pumping at the downgradient margin of the chloroform plume is impractical primarily due to low permeability and low productivity conditions. Pumping at the downgradient margin of the nitrate plume is also impractical primarily because of the potential to draw chloroform downgradient. In the absence of remedial pumping, the western portion of the nitrate plume would eventually migrate towards Westwater Seep and the eastern portion toward Ruin Spring (Figure 30). In the absence of remedial pumping, the western portion of the chloroform plume would eventually migrate towards Ruin Spring and the eastern portion toward the perched groundwater low centered on TW4-31 (near the southeastern tip of the plume [Figure 30]). Should the low at TW4-31 eventually disappear, chloroform within the eastern portion of the plume would be expected to migrate towards Corral Springs. As indicated by calculations in Section 3.6, thousands of years would be required for either constituent to reach a discharge point. That is sufficient time for either constituent to degrade naturally prior to reaching a discharge point as will be discussed in Section 4.4. The groundwater low at TW4-31 (located immediately east of TW4-27) is interpreted to result from partial hydraulic isolation from upgradient and cross-gradient areas that were more strongly affected by wildlife pond seepage. Wildlife pond seepage resulted in increases in water levels at wells in the vicinity of TW4-27 as shown in Figure 31. Water levels in wells TW4-6, TW4-26, and TW4-13 rose relatively rapidly compared with water levels at TW4-14. The permeabilities of TW4-6 and TW4-26 are similar (Table 1) and both exhibit similar water level behavior. The permeability at TW4-27 is low (Table 1) and the similarity in water level behavior at TW4-14 and TW4-27 indicates that TW4-14 is also installed in low permeability materials. These low permeability materials are the likely cause of the partial hydraulic isolation of TW4-31. Because the groundwater low at TW4-31 is interpreted to result from variable permeability and from transient hydraulic conditions brought on by wildlife pond seepage, water levels in this area are expected to ‘catch up’ eventually with water levels in less hydraulically isolated areas. One result of these conditions is the development of relatively steep hydraulic gradients at the leading edge of the chloroform plume in this area. Water balance calculations near Westwater Seep and Ruin Spring (Section 3.5.4.3) indicate that local recharge is needed to maintain areas having relatively large saturated thicknesses that Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 48 supply water to known discharge points Westwater Seep and Ruin Spring but that are isolated from other portions of the perched zone by areas of relatively low saturated thickness. The presence of local recharge near these discharge points at least in part explains increased flow at these features after precipitation events (HGC, 2010e). In the unlikely event that nitrate or chloroform not removed by pumping did not degrade within the thousands of years needed to reach a discharge point, local recharge would act to reduce concentrations prior to discharge. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 49 4. COMPOSITION OF DAKOTA SANDSTONE AND BURRO CANYON FORMATION As discussed in HGC (2012c), samples of selected archived drill core and drill cuttings were analyzed visually and quantitatively by an analytical laboratory. Table 10 summarizes the mineralogy of samples submitted to the contract laboratory for quantitative analysis. Table 11 summarizes the occurrence of pyrite, iron oxides, and carbonaceous material in site drilling logs having sufficient detail. Table 12 summarizes the results of laboratory visual (microscopic) analyses for sulfides. Table 13 and Figure 32 summarize the occurrence of pyrite in site borings based on both lithologic logs and laboratory analyses. 4.1 Mineralogy As discussed in Section 3.1.2, the Dakota Sandstone is a relatively hard to hard, generally fine- to-medium grained sandstone cemented by kaolinite clays. The underlying Burro Canyon Formation is similar to the Dakota Sandstone but is generally more poorly sorted, contains more conglomeratic materials, and becomes argillaceous near its contact with the underlying Brushy Basin Member of the Morrison Formation. Based on quantitative analysis of samples for major and minor mineralogy (Table 10), the primary mineral occurring in the Burro Canyon Formation is quartz (greater than or equal to 80% in all analyzed samples except SS-26 which consisted of ‘play sand’). Other detected minerals (not necessarily present in all the samples) include potassium feldspar, plagioclase, mica, kaolinite, calcite, dolomite, anhydrite, gypsum, pyrite, hematite, and magnetite. Because of their relatively high reactivity, pyrite, calcite and dolomite are expected to have the most potential to impact perched water chemistry. The presence of carbonaceous matter (Table 11) is also expected to impact perched water chemistry. 4.2 Pyrite Occurrence As discussed in Section 3.1.4 pyrite occurs within the Dakota Sandstone and Burro Canyon Formations which host the perched water at the site. Table 11 summarizes the occurrence of pyrite, iron oxides, and carbonaceous material in site boring logs. Pyrite has been noted in approximately 2/3 of site borings having detailed lithologic logs. These borings are located upgradient, cross-gradient and downgradient of the millsite and tailings cells. In addition, carbonaceous material has been noted at many locations which is consistent with at least locally reducing conditions and the existence of pyrite (Table 11). Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 50 As discussed in HGC (2012c), samples of selected archived drill core and drill cuttings were analyzed visually and quantitatively by a contract analytical laboratory. Table 13 and Figure 32 summarize the occurrence of pyrite in site borings based on lithologic logs and laboratory analyses. The results of the visual and quantitative analysis verify the site-wide, apparently ubiquitous existence of pyrite in the perched zone at the site. The existence of pyrite is confirmed at locations upgradient, cross-gradient, and downgradient of the millsite and tailings cells. The results are consistent with Shawe’s (1976) description of the Dakota Sandstone and Burro Canyon Formations as “altered-facies” rocks within which pyrite formed as a result of invasion by pore waters originating from compaction of the overlying Mancos Shale. Pyrite and/or marcasite were detected in all samples submitted for visual (microscopic) analysis (Table 12) having pyrite noted in their respective lithologic logs. Pyrite occurs primarily as individual grains and as a cementing material, and more rarely as inclusions in quartz grains. Pyrite and/or marcasite were detected at volume percents ranging from approximately 0.05 to 25. Grain sizes ranged from approximately one micrometer to nearly 2,000 micrometers. Small grain sizes suggest that much of the pyrite present in the formation may not be detectable during lithologic logging of boreholes and that the actual abundance of pyrite is larger than indicated by the lithologic logs. The detection of marcasite (orthorhombic crystalline FeS2), which is more reactive than pyrite (cubic crystalline FeS2), is an important result of the investigation because its reaction rate with either oxygen or nitrate will likely be higher. The laboratory visual (microscopic) analysis confirms the visual observations made during initial well logging. Pyrite was detected by quantitative x-ray diffraction (XRD) analysis in samples from MW-3A, MW-24, MW-26, MW-27, MW-28, and MW-32 at concentrations ranging from 0.1% to 0.8% by weight (Table 10). Based on the iron content via XRD analysis and the total sulfur analysis, pyrite may also be present in samples from MW-23, MW-25, and MW-29 at concentrations ranging from 0.1% to 0.3%. The presence of pyrite is not indicated in MW-30 or MW-31 by either method of analysis, although it was noted in the lithologic logs. This suggests that the samples submitted for analysis from these borings may not have been representative, or that pyrite degraded over time during storage. Except for MW-30 and MW-31, the quantitative analysis confirms the visual observations made during initial well logging. Although pyrite was not directly detected by XRD in samples from MW-23, MW-25, or MW-29, the detected iron and sulfur in these samples is consistent with the presence of pyrite. While at least a portion of the detected sulfur may result from the gypsum or anhydrite detected in some of these samples (Table 10), iron not in the form of pyrite would be expected to exist primarily in Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 51 the form of iron oxides or perhaps iron carbonates. The absence of detected iron oxides or carbonates in samples from these borings suggests iron in the form of pyrite. Furthermore, pyrite was either directly detected or possibly detected based on the presence of iron and sulfur in samples from MW-3A, MW-23, MW-24, MW-28, and MW-29, which did not have pyrite noted in the associated lithologic logs. These results are consistent with the small grain sizes noted via the laboratory visual (microscopic) analysis indicating the absence of pyrite in a lithologic log does not necessarily mean pyrite is not present in the associated boring, and that pyrite occurrence at the site has likely been underestimated based on the lithologic logs. 4.3 Expected Influence of Transient Conditions, Oxygen Introduction, and the Mancos and Brushy Basin Shales on Dakota/Burro Canyon Chemistry Current conditions within the perched groundwater system hosted by the Burro Canyon Formation and Dakota Sandstone do not approach steady state over much of the monitored area. A large part of the site perched water system is transient and affected by long-term changes in water levels due to past and current activities unrelated to the disposal of materials to the site tailings cells. Changes in water levels have historically been related to seepage from the wildlife ponds; however past impacts related to the historical pond, and to a lesser extent the sanitary leach fields, are also expected. Water levels have decreased at some locations due to chloroform and nitrate pumping and cessation of water delivery to the northern wildlife ponds. The transient nature of a large portion of the perched water system, manifested in long-term changes in saturated thicknesses and rates of groundwater flow, is expected to result in trends in pH and concentrations of many dissolved constituents that are unrelated to site operations. Changes in saturated thicknesses and rates of groundwater flow can result in changes in concentrations of dissolved constituents (or pH) for many reasons. For example, as discussed in HGC (2012c), groundwater rising into a vadose zone having a different chemistry than the saturated zone can result in changes in pH and groundwater constituent concentrations. If the rise in groundwater represents a long-term trend, long-term changes in groundwater constituent concentrations (or pH) may result. Under conditions where vadose zone chemistry is not markedly different from saturated zone chemistry, changing groundwater flow rates may result in changing constituent concentrations due to changes in dilution. For example, relatively constant flux of a particular solute into the groundwater zone that results in a relatively constant groundwater concentration under conditions of steady groundwater flow, will likely result in changing concentrations should groundwater flow become unsteady. If the change in flow rate is in one direction over a long Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 52 period of time, a long-term trend in the solute concentration is expected to result. Examples include oxygen dissolved in recharge or a constituent present in vadose zone materials overlying perched groundwater that dissolves in recharge and leaches into perched water at a steady rate. An increase in perched flow may cause an increase in dilution and a reduction in constituent concentration and vice-versa. For example, a decrease in dilution related to cessation of water delivery to the northern wildlife ponds is expected to result in increases in dissolved constituent concentrations within chloroform and nitrate plumes as discussed in Section 3.4.1.2. Furthermore, the mere presence of the tailings cells as barriers to natural recharge and exchange of gas with the atmosphere may result in changes in perched water chemistry. Any such changes are likely to be relatively slow and in one direction, potentially yielding long term trends in parameter values. The perched groundwater chemistry at the Mill is also expected to be impacted by the following factors: 1. The relatively low permeability of the perched zone. This condition increases groundwater residence times and the time available for groundwater to react with the formation. 2. The location of the perched system between two shales, the underlying Brushy Basin Member of the Morrison Formation and the overlying Mancos Shale. Both are potential sources of numerous dissolved constituents. Potential interaction between the Brushy Basin Member and perched water are discussed in TITAN (1994). 3. The rate of interaction between the shales and the perched water. Interaction with the Mancos Shale at any particular location will depend on the presence, thickness, and composition of the Mancos, the rate of recharge through the Mancos into the perched zone, and the saturated thickness and rate of groundwater flow in the perched zone. Interaction with the Brushy Basin Member at any particular location will depend on the composition of the Brushy Basin, and the saturated thickness and rate of flow in the perched zone. Oxygen introduced into site monitoring wells may also react with the Brushy Basin and affect overlying perched water chemistry. 4. The rate of oxygen introduction into the perched zone via recharge or via site groundwater monitoring wells. Introduced oxygen is available to oxidize constituents such as pyrite, which impacts the local groundwater chemistry near each recharge source and near each well by releasing acid and sulfate. The resulting increased acidity can also destabilize various mineral phases in the aquifer matrix. The degree of impact on groundwater chemistry will depend on the amount of pyrite, the rate of oxygen transfer, the neutralization capacity and saturated thickness of the perched zone, and the rate of groundwater flow. 5. Elements other than iron and sulfur as contaminants in pyrite. Pyrite reacting with oxygen introduced into the formation will release these elements, potentially altering both the Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 53 vadose zone and the groundwater chemistry. The potential for pyrite to have significant contaminants (such as selenium) is enhanced by its origin from fluids expelled from the Mancos Shale. Changes in perched zone constituent concentrations and pH are therefore expected to result from the introduction of oxygen into the subsurface, the oxidation of pyrite and other constituents, changes in recharge rates, and past and current recharge passing through the Mancos Shale. For example, the Mancos Shale is a significant source of selenium (Baker, 2007; Colorado Department of Health and Environment, 2011; Tuttle, 2005). Because the Mancos overlies the perched zone over much of the site (Figure 11) it could represent a past and ongoing source of selenium. Selenium originating from the Mancos Shale could potentially increase concentrations in the perched zone by three mechanisms: 1) Ongoing leaching from the Mancos Shale via recharge; 2) oxidation of Mancos-derived selenium in the Burro Canyon Formation and Dakota Sandstone by dissolved nitrate in the perched water and/or oxygen introduced into the perched zone via perched well casings; and 3) oxidation of pyrite containing Mancos-derived selenium by dissolved perched zone nitrate and /or oxygen introduced into the perched zone via perched well casings. Selenium already present in the Dakota Sandstone and Burro Canyon Formation (including as a constituent in pyrite) could have originated from the Mancos in the past, and could affect the entire formation rather than just the areas beneath the current erosional remnants of the Mancos. Precipitation percolating downward from the land surface is expected to leach selenium from the Mancos Shale and carry it downward into the perched zone. Beneath the tailings cells, any such leaching is expected to have occurred for the most part prior to the installation of the cells which represent a barrier to infiltration of precipitation. Vadose pore waters in the Dakota Sandstone and Burro Canyon Formation beneath the cells may thus be expected to contain selenium leached from the Mancos in the past. Perched water rising into vadose pore waters containing selenium may enhance mass transfer and result in increased selenium concentrations in the perched water. Potentially increasing selenium concentrations may also result from the oxidation of selenium already present in the Dakota Sandstone and Burro Canyon Formation. Oxidation of selenium by nitrate present in perched water and/or by oxygen introduced into the formation via the well casings may result in increasing dissolved selenium concentrations. The possibility of nitrate oxidation of selenium is presented in Potoroff (2005). A third potential source for increasing dissolved selenium concentrations in perched water is oxidation of pyrite by nitrate and/or oxygen introduced into the formation via well casings. Pyrite typically contains trace elements including selenium. Selenium has been measured at concentrations as high as 0.2% by weight in pyrite (Deditius, 2011). As discussed in HGC Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 54 (2012c), pyrite oxidation is expected to result in other changes that include an increase in dissolved sulfate (unless a sink for sulfate is present). Oxidation of pyrite by dissolved oxygen is expected to result in a decrease in pH as acid is released in the reaction: FeS2 + 33/4O2 + 31/2H2O = Fe(OH)3 + 2SO42- + 4H+ Oxidation of pyrite by nitrate may also occur as discussed in HGC (2012c). This process may result in either an increase or decrease in pH depending on the reaction pathway: 5 FeS2 + 14NO3- + 4H+ = 7N2 + 10SO42- + 5Fe2+ + 2H2O; or 2 FeS2 + 6NO3 - + 2H2O = 3N2 + 4SO4 2- + 2FeOOH + 2H+ The interaction between nitrate and pyrite will be discussed in more detail in the following Section. 4.4 Implications For Perched Water Chemistry and Natural Attenuation of Nitrate and Chloroform As discussed above, past, current, and future interaction of the perched water zone with the overlying Mancos Shale and underlying Brushy Basin Member can be expected to affect perched water chemistry at the site. Changes in perched water chemistry related to oxidation of pyrite by oxygen introduced into the subsurface dissolved in recharge and via well casings is also expected to occur. Concentrations of chloroform and nitrate already present in the perched zone will be affected over time by various processes, including direct mass removal by pumping. Natural attenuation of both constituents is expected to result from physical processes that include dilution by recharge and hydrodynamic dispersion. Volatilization into the vadose zone is another physical process that is expected to lower chloroform concentrations in perched water. Mass reduction processes expected to lower both nitrate and chloroform concentrations include chemical and biologically-mediated processes. The impacts of pyrite degradation by oxygen, degradation of nitrate by pyrite, and reductive dechlorination of chloroform are discussed in Sections 4.4.1 through 4.4.3. 4.4.1 Pyrite Degradation by Oxygen As discussed in HGC (2012c), the pH values measured in many site groundwater monitoring wells located upgradient, within the vicinity of, and downgradient of the millsite and tailings cells displayed decreasing trends. pH decreases in many of these wells were accompanied by Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 55 increases in sulfate concentrations. Ten of the MW-series groundwater monitoring wells were out of compliance (OOC) with respect to pH due to a decreasing trend. As discussed in INTERA (2012a and 2102b) and Section 5 below, changes in pH were determined to result from natural causes unrelated to the operation of the tailings cells. Based on work described in HGC (2012c), the decreases in pH and increases in sulfate in OOC wells were explainable by oxidation of pyrite, which releases acid and sulfate as described above. Screening-level calculations and geochemical modeling using PHREEQC (Parkhurst and Appelo, 1999) indicated that pyrite measured in samples from the perched zone existed in more than sufficient quantity to have resulted in the measured changes in pH and sulfate at three representative wells located immediately upgradient (MW-27), immediately downgradient (MW- 24), and far downgradient (MW-3A) of the tailings cells. The calculations also indicated that pyrite existed in sufficient quantity to maintain these trends provided sufficient oxygen was available. Continued release of any contaminants within site pyrite is expected as is release of pH sensitive constituents present in the Burro Canyon Formation and Dakota Sandstone. 4.4.2 Nitrate Degradation by Pyrite As discussed in HGC (2012c), nitrate will degrade in the presence of pyrite. Nitrate will also degrade, and more readily, in the presence of organic matter. Both pyrite and organic material in the form of carbonaceous matter have been logged in drill cuttings from the perched zone. As discussed in (Korom, 1992), the thermodynamically favored electron donor for reduction of nitrate in groundwater is typically organic matter. This process under neutral conditions is represented via the following generalized reaction (e.g. van Beek, 1999; Rivett et al., 2008; Tesoriero and Puckett, 2011; Zhang, 2012): 2 3 2 3 2 3 2 5 4 2 4 2CH O NO N HCO H CO H O - -+ = + + +(Reaction 1); In acidic (pH<6.4) aquifer conditions, reduction of nitrate by organic matter can be generalized by the following pathway: 2 3 2 2 3 2 5 4 4 2 5 2CH O NO H N H CO H O - ++ + = + +(Reaction 2). In both cases, five moles of organic matter are required to reduce four moles of nitrate. Under acidic conditions the alkalinity generated by denitrification by organic matter consumes acid. In the absence of dissolved oxygen, pyrite can also be oxidized by nitrate. Denitrification by pyrite may occur via two primary reaction pathways. The pathway most commonly applied in Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 56 geochemical studies (Kolle et al., 1983, 1985; Postma et al., 1991; Korom, 1992; Robertson et al., 1996; Pauwels et al., 1998; Hartog et al., 2001, 2004; Spiteri et al., 2008) is a bacteria- mediated reaction that yields ferrous iron, sulfate, water, and nitrogen gas as follows: 2 2 2 3 2 4 2 5 14 4 7 10 5 2FeS NO H N SO Fe H O - + - ++ + = + + + (Reaction 3). By Reaction 3, five moles of pyrite reduce 14 moles of nitrate, consuming four moles of acid. Reaction 3 is considered applicable when pyrite concentrations exceed nitrate concentrations (van Beek,1999). Where nitrate concentrations exceed pyrite concentrations, Reaction 4 is a more likely mechanism (Kolle et al., 1987; van Beek, 1999; Schlippers and Jorgensen, 2002): 2 2 3 2 2 4 3 2 6 4 3 4 2 ( ) 2FeS NO H O N SO Fe OH H -- ++ + = + + +(Reaction 4). By Reaction 4, two moles of pyrite reduce six moles of nitrate, yielding iron hydroxide, sulfate, acid, and nitrogen gas. Therefore, when nitrate concentrations exceed pyrite concentrations (Reaction 4), denitrification by pyrite is more efficient than when pyrite is in excess (Reaction 3). Additionally, Reaction 4 produces acid, while Reaction 3 consumes acid, indicating that the impact of denitrification by pyrite on aquifer geochemistry is controlled by the relative abundance of pyrite and nitrate. Reaction 4 is an overall reaction that combines Reaction 3 and a second step whereby ferrous iron is oxidized by nitrate. This second step is more likely to occur when excess nitrate is present and available to oxidize ferrous iron (Kolle et al., 1987; Rivett et al., 2008; Zhang 2012). Stoichiometric calculations were used to determine the weight percent of perched zone pyrite that would be required to reduce 43,700 lbs of nitrate via reaction mechanisms 3 and 4 (assuming each was the only denitrification reaction occurring). 43,700 lbs of nitrate is the baseline nitrate mass calculated as specified in the nitrate CAP (HGC, 2012a). 43,700 lbs of nitrate corresponds to 19,822 kg and 319,684 moles. Although noted in lithologic logs the organic matter content of the perched zone has not been quantified so calculations regarding nitrate degradation by reactions 1 and 2 are not presented, even though significant nitrate reduction via these mechanisms is likely to occur. Nitrate can either migrate towards Ruin Spring to the south-southwest or to Westwater Seep to the west. Assuming the entire nitrate plume migrated south towards Ruin Spring, the volume of the perched zone through which the nitrate plume would migrate was assumed to be on average 20 feet thick, 1,200 feet wide, and 10,000 feet long, representing a total saturated formation volume of 2.4 x 108 ft3 or 6.8 x 109 liters. Assuming the entire nitrate plume migrated west Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 57 toward Westwater Seep, the volume of the perched zone through which the nitrate plume would migrate was assumed to be on average 18 feet thick, 2,800 feet wide, and 4,950 feet long, representing a total saturated formation volume of 2.5 x 108 ft3 or 7 x 109 liters. To be conservative, the following calculations are based on the smaller volume of 6.8 x 109 liters. Using these estimates, reaction 3 would require 114,173 moles of pyrite to consume 43,700 lbs of nitrate, and would consume 91,338 moles of acid (1.34 x 10-5 moles H+ per liter of formation). Reaction 4 would require 106,561 moles of pyrite to degrade the nitrate, producing 106,561 moles of acid or 1.57 x 10-5 moles H+ per liter of formation. Assuming a conservatively large porosity of 0.2 for the perched zone (HGC, 2012c), the total volume of water is 1.36 x 109 liters; and assuming a solids density of 2.6 kg L-1, yields a total solid mass of 1.4 x 1010 kg. Using this solid mass, both Reactions 3 and 4 would require pyrite formation weight percents of 0.000098% (9.8 x 10-5 %) and 0.000091% (9.1 x 10-5 %), respectively, to degrade 43,700 lbs of nitrate. These calculated pyrite weight percents are orders of magnitude less than conservative estimates of pyrite content based on samples analyzed during the pyrite investigation (HGC, 2012c), which ranged from 0.0056% to 0.08% (5.6 x 10-3 % to 8 x 10-2 %). These results suggest that the available pyrite content in the path of the nitrate plume is two to three orders of magnitude greater than needed to degrade the total mass (43,700 lbs) of nitrate. These calculations are conservative in that they assume the degradation of the entire mass of nitrate and not just the mass needed to reduce concentrations below 10 mg/L. Whether or not pyrite oxidation by nitrate at the site is generating or consuming acid depends largely on whether oxidation of ferrous iron by nitrate is occurring (i.e. whether pyrite denitrification is occurring by Reaction 3 or Reaction 4; whether nitrate exists in excess). The preferred mechanism for denitrification by pyrite is likely to vary spatially. If pyrite is assumed to be relatively evenly distributed throughout the formation, while nitrate occurs in a discrete plume, Reaction 3 may dominate on the plume edges while Reaction 4 may dominate the core of the plume. 4.4.3 Chloroform Reduction As discussed in HGC (2007), the presence of chloroform daughter products indicates that chloroform is degrading naturally via reductive dechlorination. Calculations presented in HGC (2007) based on daughter product concentrations indicated that the entire chloroform plume Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 58 would be reduced to concentrations below 70 ug/L within approximately 190 years. Reductive dechlorination takes place under anaerobic conditions which were inferred to exist only locally within the perched zone. The low rates of degradation and the persistence of nitrate associated with the chloroform plume are consistent with primarily aerobic conditions. However, the presence of widespread pyrite in the perched zone is consistent with at least locally anaerobic conditions, and with the low calculated rates of chloroform degradation presented in HGC (2007). Continued reductive dechlorination is expected within locally anaerobic portions of the perched zone. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 59 5. SUMMARY OF INTERA WORK AND FINDINGS Background groundwater quality evaluations have been performed for each MW-series groundwater monitoring well. Groundwater compliance limits (GWCLs) have been established for each permit constituent on an intra-well basis. A Revised Background Groundwater Quality Report (INTERA, 2007a) evaluated groundwater analytical data collected since the initiation of groundwater sampling. The revisions included a Flow Sheet that was approved by the DRC and contained steps for analyzing data and setting GWCLs. INTERA (2007a) identified naturally occurring elevated, increasing, and decreasing concentrations of various constituents in monitoring wells located far upgradient, far downgradient, and in the vicinity of the Mill Site. This report also presented a thorough discussion and identification of the most appropriate indicator parameters (chloride, fluoride, sulfate, and uranium) based on constituents in tailings solutions and their behavior in groundwater. Analysis of the indicator parameters in monitoring wells, including monitoring wells that contained increasing trends in other constituents, provided no evidence of tailings cell seepage. Since INTERA (2007a), three additional Background Reports (INTERA 2007b, 2008, and 2014c) evaluate available data and determine GWCLs for each permit constituent in each well based on the DRC-approved Flow Sheet. Upon approval of the GWDP in 2010, constituents with two consecutive GWCL exceedances are subject to a Source Assessment Report (SAR) as defined in the GWDP. The initial SAR was submitted in October of 2012 (INTERA 2012a) and covered all of the constituents in wells with consecutive exceedances since the approval of the GWDP in 2010. The October 2012 SAR (INTERA 2012a) presented a geochemical analysis of parameters that exhibited exceedances as well as an analysis of the indicator parameters in each of those wells to determine if the exceedance could be related to potential tailings seepage or Mill-related activities. Since then, four additional SARs, (INTERA 2013a, 2013b, 2014a, qne 2014b) cover additional consecutive exceedances. In all cases the exceedances for which the SARs were performed were determined to result from naturally occurring conditions in the groundwater at the site or from other factors that are affecting groundwater but are unrelated to tailings cell operation. These other factors include the chloride and nitrate plume that is addressed by the nitrate CAP and a sitewide decline in pH that was identified at the time of the Background Report. At the time of the Background Report, an overall decline in pH across the site was observed. Background analysis and determination of GWCLs for pH were performed using laboratory pH measurements rather than using measurements that are collected in the field at the time of sampling by using a pH probe. Since the latter of these two methods of measuring pH is more Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 60 reliable, an additional pH analysis was performed in 2012 using only field data. GWCLs for pH were recalculated at this time using the field measurements. As discussed in Section 4.4.1, HGC (2012c) determined that pH decreases resulted from pyrite oxidation enhanced by oxygen delivery to the perched zone. Oxygen delivery mechanisms included advective transport to the perched zone dissolved in wildlife pond seepage, and diffusive transport to perched water in the vicinities of perched wells via perched well casings. pH decreases were therefore determined to be unrelated to tailings cell operation. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 61 6. SUMMARY AND CONCLUSIONS The Mill is is situated on White Mesa and is located within the Blanding Basin physiographic province. The Mill has an average elevation of approximately 5,600 feet above mean sea level (ft amsl) and is underlain by unconsolidated alluvium and indurated sedimentary rocks. Indurated rocks include those exposed within the Blanding Basin, and consist primarily of sandstone and shale. The indurated rocks are relatively flat lying with dips generally less than 3º. The alluvial materials overlying the indurated rocks consist primarily of aeolian silts and fine- grained aeolian sands with a thickness varying from a few feet to as much as 25 to 30 feet across the site. The alluvium is underlain by the Dakota Sandstone and Burro Canyon Formation, and where present, the Mancos Shale. The Dakota Sandstone and Burro Canyon Formation are sandstones having a total thickness ranging from approximately 55 to 140 feet. Beneath the Burro Canyon Formation lies the Morrison Formation, consisting, in descending order, of the Brushy Basin Member, the Westwater Canyon Member, the Recapture Member, and the Salt Wash Member. The Brushy Basin and Recapture Members of the Morrison Formation, classified as shales, are very fine-grained and have a very low permeability. The Brushy Basin Member is primarily composed of bentonitic mudstones, siltstones, and claystones. The Westwater Canyon and Salt Wash Members also have a low average vertical permeability due to the presence of interbedded shales. Beneath the Morrison Formation lie the Summerville Formation, an argillaceous sandstone with interbedded shales, and the Entrada Sandstone. Beneath the Entrada lies the Navajo Sandstone. The Navajo and Entrada Sandstones constitute the primary aquifer in the area of the site. The Entrada and Navajo Sandstones are separated from the Burro Canyon Formation (and the perched water system monitored at the site) by approximately 1,000 to 1,100 feet of materials having a low average vertical permeability. Groundwater within this system is under artesian pressure in the vicinity of the site, is of generally good quality, and is used as a secondary source of water at the site. Stratigraphic relationships beneath the site are summarized in Figure 3. The site and vicinity has a dry to arid continental climate, with an average annual precipitation of approximately 13.3 inches, and an average annual lake evaporation rate of approximately 47.6 inches. Recharge to major aquifers (such as the Entrada/Navajo) occurs primarily along the mountain fronts (for example, the Henry, Abajo, and La Sal Mountains), and along the flanks of folds such as Comb Ridge Monocline. Perched groundwater occurs in the Dakota Sandstone and Burro Canyon Formation beneath the site and is used on a limited basis to the north (upgradient) of the site because it is more easily Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 62 accessible than the Navajo/Entrada aquifer. Perched groundwater originates mainly from precipitation and local recharge sources such as unlined reservoirs (Kirby, 2008) and is supported within the Burro Canyon Formation by the underlying, fine-grained Brushy Basin Member, considered an aquiclude. Water quality of the Dakota Sandstone and Burro Canyon Formation is generally poor due to high total dissolved solids (TDS) in the range of approximately 1,100 to 7,900 milligrams per liter (mg/L) and is used primarily for stock watering and irrigation. Nitrate and chloroform plumes occur in site perched water as shown in Figure 1B. The nitrate plume extends from upgradient (north-northeast) of the tailings cells to beneath the cells. The chloroform plume is located primarily upgradient to cross-gradient of the cells. Sources of the nitrate plume are not well-defined but a historical pond shown on Figure 1B is considered a source of nitrate and chloride to the plume. The only potentially active source of nitrate to the plume is related to ammonium sulfate crystal handling near the ammonium sulfate crystal tanks located southeast of TWN-2 (Figure 1B) and is being addresses through implementation of Phase I of the nitrate CAP. Past sources of the chloroform plume are two abandoned sanitary leach fields (located near TW4-18 and TW4-19) that received laboratory wastes prior to tailings cells becoming operational circa 1980. Both plumes are under remediation by pumping. The saturated thickness of the perched water zone generally increases to the north of the site, increasing the yield of the perched zone to wells installed north of the site. The generally low permeability of the perched zones limits well yields. Although sustainable yields of as much as 4 gallons per minute (gpm) have been achieved in site wells penetrating higher transmissivity zones near wildlife ponds, yields are typically low (<1/2 gpm) due to the generally low permeability of the perched zone. Many of the perched monitoring wells purge dry and take several hours to more than a day to recover sufficiently for groundwater samples to be collected. During redevelopment (HGC, 2011b) many of the wells went dry during surging and bailing and required several sessions on subsequent days to remove the proper volumes of water. As shown in Figure 5 and Appendix D, perched water flow across the site is generally (and historically) from northeast to southwest. Beneath and south of the tailings cells, in the west central portion of the site, perched water flow is south-southwest to southwest. Flow on the western margin of White Mesa is also south, approximately parallel to the rim (where the Burro Canyon Formation is terminated by erosion). On the eastern side of the site perched water flow is also generally southerly. Hydraulic gradients at the site currently range from approximately 0.002 ft/ft in the northeastern corner of the site to approximately 0.075 ft/ft east of tailings cell 2 (in the vicinity of the chloroform plume). Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 63 Because of mounding near wildlife ponds, flow direction ranges locally from westerly (west of the ponds) to easterly (east of the ponds). The March 2012 cessation of water delivery to the northern ponds, which are generally upgradient of the nitrate and chloroform plumes at the site, has resulted in changing conditions that are expected to impact constituent concentrations and migration rates within these plumes. Specifically, past recharge from the ponds has helped limit many constituent concentrations within these plumes by dilution while the associated groundwater mounding has increased hydraulic gradients and contributed to plume migration. Since use of the northern wildlife ponds ceased in March 2012, the reduction in recharge and decay of the associated groundwater mound are expected to increase many constituent concentrations within the plumes while reducing hydraulic gradients and acting to reduce rates of plume migration. The impacts associated with cessation of water delivery to the northern ponds are expected to propagate downgradient (south and southwest) over time. Perched water discharges in seeps and springs located to the west, south, east, and southeast of the site (Figure 1B). Flow onto the site occurs as underflow from areas northeast of the millsite where perched zone saturated thicknesses are generally greater. Flow exits the Mill property in seeps and springs to the east, west, southwest and southeast. Any flow that does not discharge in seeps or springs presumably exits as underflow to the southeast. Darcy’s Law calculations of perched water flow to Ruin Spring and Westwater Seep yield reasonable results and suggest that local recharge contributes to seep/spring flow. Hydraulic testing of perched zone wells yields a hydraulic conductivity range of approximately 2 x 10-8 to 0.01 cm/s (Tables 1- 4). In general, the highest permeabilities and well yields are in the area of the site immediately northeast and east (upgradient to cross gradient) of the tailings cells. A relatively continuous, higher permeability zone associated with the chloroform plume and consisting of poorly indurated coarser-grained materials has been inferred to exist in this portion of the site (HGC, 2007). Permeabilities downgradient (southwest) of the tailings cells are generally low. The low permeabilities and shallow hydraulic gradients downgradient of the tailings cells result in average perched groundwater pore velocity estimates that are among the lowest on site. Furthermore, more than 30 years of groundwater monitoring indicate no impacts to perched water from tailings cell operation (based on various work by INTERA and Hurst and Solomon [2008]). As discussed above, perched groundwater discharges in seeps and springs located along the mesa margins. The relationships between seeps and springs and site geology/stratigraphy are provided Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 64 in Figure E.1 and Figure E.2_. Seep and spring investigation (HGC, 2010e) and investigation of the southwest portion of the site (HGC, 2012b) indicate the following: 1. Incorporating the seep and spring elevations in perched water elevation contour maps produces little change with regard to perched water flow directions except in the area west of the tailings cells and near Entrance Spring. West of the tailings cells, incorporation of Westwater Seep creates a more westerly hydraulic gradient. Westwater Seep appears to be nearly downgradient of the western portion of the cell complex (Figure 25). Ruin Spring is downgradient of the eastern portion of the cell complex (Figure 25). Westwater Seep is the closest apparent discharge point west of the tailings cells and Ruin Spring is the closest discharge point south-southwest of the tailings cells. Including the Entrance Spring elevation on the east side of the site creates a more easterly gradient in the perched water contours, and places Entrance Spring more directly downgradient of the northern wildlife ponds. Seeps and springs on the east side of the mesa are either cross-gradient of the tailings cells or are separated from the tailings cells by a groundwater divide 2. Ruin Spring and Westwater Seep are interpreted to occur at the contact between the Burro Canyon Formation and the Brushy Basin Member. Corral Canyon Seep, Entrance Spring, and Corral Springs are interpreted to occur at elevations within the Burro Canyon Formation at their respective locations but above the contact with the Brushy Basin Member. All seeps and springs (except Cottonwood Seep which is located near the Brushy Basin Member/Westwater Canyon Member contact) are associated with conglomeratic portions of the Burro Canyon Formation. Provided they are poorly indurated the more conglomeratic portions of the Burro Canyon Formation are likely to have higher permeabilities and the ability to transmit water more readily than finer- grained portions. This behavior is consistent with on-site drilling and hydraulic test data that associates higher permeability with the poorly indurated coarser-grained horizons detected east and northeast of the tailing cells associated with the chloroform plume. 3. Cottonwood Seep is located more than 1,500 feet west of the mesa rim in an area where the Dakota Sandstone and Burro Canyon Formation (which hosts the perched water system) are absent due to erosion (Figures E.1 and E.2). Cottonwood Seep occurs near a transition from slope-forming to bench-forming morphology (indicating a change in lithology). Cottonwood Seep (and 2nd Seep located immediately to the north [Figure 8]) is interpreted to originate from coarser-grained materials within the lower portion of the Brushy Basin Member (or upper portion of the Westwater Canyon Member). Alternatively, Cottonwood Seep may originate from coarser-grained materials of the Westwater Canyon (sandstone) Member intertongueing with the overlying Brushy Basin Member at the transition between the two Members. The presence of coarser-grained materials similar to the Salt Wash (sandstone) Member within the lower portion of the Brushy Basin member is discussed in Shawe (2005). The intertongueing of the Westwater Canyon and Brushy Basin Members is discussed in Craig et al. (1955) and Flesch (1974). Based on lithologic cross sections provided in TITAN (1994), the elevation of Cottonwood Seep (5234 ft amsl) is within 5 to 15 feet of the elevation of the contact between the Brushy Basin Member and the underlying Westwater Canyon Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 65 Member (5220 to 5230 ft amsl). This is also shown in Figure 3. Cottonwood Seep is therefore not (directly) connected to the perched water system at the site. 4. Only Ruin Spring appears to receive a predominant and relatively consistent proportion of its flow from perched water. Ruin Spring originates from conglomeratic Burro Canyon Formation sandstone where it contacts the underlying Brushy Basin Member, at an elevation above the alluvium in the associated drainage. Westwater Seep, which also originates at the contact between the Burro Canyon Formation and the Brushy Basin Member, likely receives a significant contribution from perched water. All seeps and springs other than Ruin Spring (and 2nd Seep just north of Cottonwood Seep) are located within alluvium occupying the basal portions of small drainages and canyons. The relative contribution of flow to these features from bedrock and from alluvium is indeterminate. 5. All seeps and springs are reported to have enhanced flow during wet periods. For seeps and springs associated with alluvium, this behavior is consistent with an alluvial contribution to flow. Enhanced flow during wet periods at Ruin Spring, which originates from bedrock above the level of the alluvium, likely results from direct recharge of Burro Canyon Formation and Dakota Sandstone exposed near the mesa margin in the vicinity of Ruin Spring. This recharge would be expected to temporarily increase the flow at Ruin Spring (as well as other seeps and springs where associated bedrock is directly recharged) after precipitation events. As discussed previously, local recharge is consistent with Darcy’s law calculations of perched water flow to Ruin Spring and Westwater Seep. The assumption that the seep or spring elevation is representative of the perched water elevation is likely to be correct only where the feature receives most or all of its flow from perched water and where the supply is relatively continuous (for example at Ruin Spring). The perched water elevation at the location of a seep or spring that receives a significant proportion of water from a source other than perched water may be different from the elevation of the seep or spring. The elevations of seeps that are dry for at least part of the year will not be representative of the perched water elevation when dry. The uncertainty that results from including seeps and springs in the contouring of perched water levels must be considered. The rate of flow in the perched water zone in the southwest area of the site (downgradient of the tailings cells) is small and contributions from local recharge are needed to explain many areas of higher saturated thickness near sinks such as Westwater Seep and Ruin Spring that are downgradient of areas of low saturated thickness (HGC, 2012b). The presence of local recharge is expected to affect the water quality of seeps and springs and has the potential to dilute any dissolved constituents that may migrate from upgradient areas. As discussed in HGC (2012c), samples of selected archived drill core and drill cuttings were analyzed visually and quantitatively by a contract analytical laboratory. Table 13 and Figure 32 summarize the occurrence of pyrite in site borings based on lithologic logs and laboratory analyses. The results verify the site-wide, apparently ubiquitous existence of pyrite in the Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 66 perched zone at the site. The existence of pyrite is confirmed at locations upgradient, cross- gradient, and downgradient of the millsite and tailings cells. The results are consistent with Shawe’s (1976) description of the Dakota Sandstone and Burro Canyon Formations as “altered- facies” rocks within which pyrite formed as a result of invasion by pore waters originating from compaction of the overlying Mancos Shale. A large portion of the perched water system at the site is in a transient state, manifested in long- term changes in saturated thicknesses and rates of groundwater flow. This condition is expected to result in trends in pH and concentrations of many dissolved constituents that are unrelated to site operations. Changes in saturated thicknesses and rates of groundwater flow can result in changes in concentrations of dissolved constituents (or pH) for many reasons. For example, as discussed in HGC (2012c), groundwater rising into a vadose zone having a different chemistry than the saturated zone can result in changes in pH and groundwater constituent concentrations. If the rise in groundwater represents a long-term trend, long-term changes in groundwater constituent concentrations (or pH) may result. Under conditions where vadose zone chemistry is not markedly different from saturated zone chemistry, changing groundwater flow rates may result in changing constituent concentrations due to changes in dilution. For example, relatively constant flux of a particular solute into the groundwater zone that results in a relatively constant groundwater concentration under conditions of steady groundwater flow, will likely result in changing concentrations should groundwater flow become unsteady. If the change in flow rate is in one direction over a long period of time, a long-term trend in the solute concentration is expected to result. Examples include oxygen dissolved in recharge or a constituent present in vadose zone materials overlying perched groundwater that dissolves in recharge and leaches into perched water at a steady rate. An increase in perched flow may cause an increase in dilution and a reduction in constituent concentration and vice-versa. For example, a decrease in dilution related to cessation of water delivery to the northern wildlife ponds is expected to result in increases in dissolved constituent concentrations within chloroform and nitrate plumes. Furthermore, the mere presence of the lined tailings cells as barriers to natural recharge and exchange of gas with the atmosphere may result in changes in perched water chemistry. Any such changes are likely to be relatively slow and in one direction, potentially yielding long term trends in parameter values. The perched groundwater chemistry at the Mill is also expected to be impacted by the following factors: Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 67 1. The relatively low permeability of the perched zone. This condition increases groundwater residence times and the time available for groundwater to react with the formation. 2. The location of the perched system between two shales, the underlying Brushy Basin Member of the Morrison Formation and the overlying Mancos Shale. Both are potential sources of numerous dissolved constituents. 3. The rate of interaction between the shales and the perched water. Interaction with the Mancos Shale at any particular location will depend on the presence, thickness, and composition of the Mancos, the rate of recharge through the Mancos into the perched zone, and the saturated thickness and rate of groundwater flow in the perched zone. Interaction with the Brushy Basin Member at any particular location will depend on the composition of the Brushy Basin, and the saturated thickness and rate of flow in the perched zone. Oxygen introduced into site monitoring wells may also react with the Brushy Basin and affect overlying perched water chemistry. 4. The rate of oxygen introduction into the perched zone via recharge or via site groundwater monitoring wells. Introduced oxygen is available to oxidize constituents such as pyrite, which impacts the local groundwater chemistry near each recharge source and near each well by releasing acid and sulfate. The resulting increased acidity can also destabilize various mineral phases in the aquifer matrix. The degree of impact on groundwater chemistry will depend on the amount of pyrite, the rate of oxygen transfer, the neutralization capacity and saturated thickness of the perched zone, and the rate of groundwater flow. 5. Elements other than iron and sulfur as contaminants in pyrite. Pyrite reacting with oxygen introduced into the formation will release these elements, potentially altering both the vadose zone and the groundwater chemistry. The potential for pyrite to have significant contaminants (such as selenium) is enhanced by it’s origin from fluids expelled from the Mancos. Changes in perched zone constituent concentrations and pH are therefore expected to result from the introduction of oxygen into the subsurface, the oxidation of pyrite and other constituents, changes in recharge rates, and past and current recharge passing through the Mancos Shale. Decreasing trends in pH accompanied by increasing sulfate concentrations in MW-series wells that were OOC for pH were determined to result from oxidation of pyrite based on screening- level calculations and geochemical modeling presented in HGC (2012c). The calculations also indicated that pyrite existed in sufficient quantity to maintain these trends provided sufficient oxygen was available. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 68 6.1 Perched Water Pore Velocities in the Nitrate Plume Area Perched water pore velocities and travel times calculated within the nitrate plume along Path 1 (Figure 27) yield an estimated average pore velocity of approximately 21 ft/yr and a travel time of approximately 60 years, based on a first quarter, 2014 hydraulic gradient of 0.028 ft/ft. Historic hydraulic gradients within the area of the nitrate plume were likely much larger than 0.028 ft/ft during the time prior to Mill construction when the historical pond was active (Figure 1B). Based on historic water levels in the vicinities of MW-30 and MW-31, located along the downgradient margin of tailings cell 2 (Appendix D), and at the downgradient margin of the nitrate plume, an historic hydraulic gradient is estimated as approximately 0.048 ft/ft. This is more than four times the overall average site hydraulic gradient of approximately 0.011 ft/ft (calculated between TWN-19 and Ruin Spring). Using the historic hydraulic gradient of 0.048 ft/ft, the estimated historic pore velocity downgradient of the historical pond is approximately 35 ft/yr, implying that nitrate originating from the historical pond could have migrated to the downgradient edge of cell 2 within 63 years. Assuming the historical pond was active by 1920, that nitrate was conservative, and ignoring hydrodynamic dispersion, nitrate originating from the historical pond could have reached the vicinities of MW-30 and MW-31 by 1983. 6.2 Perched Water Pore Velocities in the Chloroform Plume Area Perched water pore velocities and travel times within the chloroform plume area along Paths 2A and 2B (Figure 27) were calculated based on first quarter, 2014 hydraulic gradients of 0.0275 ft/ft and 0.0262 ft/ft, respectively. The estimated average pore velocity along Path 2A is approximately 76 ft/yr, implying that approximately 16 years would be required to traverse Path 2A. The estimated average pore velocity along Path 2B is approximately 38 ft/yr, implying that approximately 38 years would be required to traverse Path 2B. Historic hydraulic gradients within the northern (upgradient) areas of the eastern portion of the chloroform plume (prior to about 1990) were likely larger and contributed to relatively rapid movement of chloroform from the abandoned scale house leach field (located immediately north of TW4-18) to MW-4 where chloroform was detected in 1999. Based on historic water levels (Appendix D) the hydraulic gradient between the abandoned scale house leach field and MW-4 is estimated as approximately 0.048 ft/ft in 1990 and approximately 0.029 ft/ft in 1999, averaging 0.038 ft/ft. This is more than three times the overall average site hydraulic gradient of approximately 0.011 ft/ft (calculated between TWN-19 and Ruin Spring) and is approximately Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 69 the same as current hydraulic gradients at the leading edge of the southeastern portion of the chloroform plume. The historic hydraulic gradient implies an average pore velocity prior to 1999 of approximately 84 ft/yr, sufficient for chloroform to have migrated from the abandoned scale house leach field to MW-4 between 1978 and 1999. This calculation implies that chloroform could have migrated nearly to TW4-4 by 1999. 6.3 Hydrogeology and Perched Water Pore Velocities in the Southwest Area Investigation of the southwest area of the site, including seeps and springs (HGC, 2012b), indicates that permeabilities in the southwest portion of the site are on average lower than previously estimated (as for example in HGC, 2009), and that perched water discharges to Westwater Seep and Ruin Spring, but there is no evidence for a direct hydraulic connection between the perched water zone and Cottonwood Seep. The hydraulic test and water level data also demonstrate that the perched zone southwest of cell 4B is inadequate as a primary supply to Cottonwood Seep by several orders of magnitude and that that the primary source of Cottonwood Seep lies elsewhere. However, a hypothetical connection between the perched zone near piezometer DR-8 and Cottonwood Seep is postulated for the purposes of calculating perched water travel times and to allow for the possibility that an as yet unidentified connection may exist Important results of the southwest area investigation are: 1. The Brushy Basin Member erosional paleosurface in the southwest area of the Mill site is dominated by a paleoridge extending from beneath Cell 4B to abandoned boring DR-18 (Figure 8). The paleoridge is flanked to the west by a north-south trending paleovalley oriented roughly parallel to the western mesa rim (Figure 8). 2. The southwest area of the Mill site is characterized by generally low saturated thicknesses, low permeabilities, and relatively shallow hydraulic gradients. This is illustrated in Table 1 and Figure 14. Hydraulic gradients in the southwest portion of the site are typically close to 0.1 ft/ft, but are less than approximately 0.005 ft/ft west/southwest of tailings Cell 4B, between Cell 4B and DR-8. 3. The paleotopography of the Brushy Basin Member erosional surface has a greater influence on perched water flow in the southwest portion of the site than other areas because of the low saturated thicknesses and dry areas associated with the paleoridge extending south-southwest from the tailings cells (Figures 8, 14, 18, and 19). 4. The low transmissivities implied by the low permeabilities and low saturated thicknesses combined with the shallow hydraulic gradients imply low rates of perched water flow in the southwest portion of the site. Calculated average pore velocities along Pathlines 3, 5, Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 70 and 6 (Figure 27) from tailings cells to known discharge points Westwater Seep and Ruin Spring range from 0.60 ft/yr to 0.91 ft/yr, and travel times from 3,230 to 19,650 years based on first quarter, 2014 water level data. If vadose zone travel times from the base of the tailings cells to the perched water are included, the range of calculated travel times is 3,470 to 19,900 years. 5. The estimated travel time from the tailings cells to the vicinity of DR-8 (Path 4) is approximately 15,850 years based on first quarter, 2014 water level data and a calculated pore velocity of 0.26 ft/yr. Including the vadose travel time of approximately 250 years yields a total travel time of 16,100 years. Assuming a hypothetical pathway to Cottonwood Seep, the time to travel along Path 4 and thence along the potential pathway from the edge of Path 4 to Cottonwood Seep (which adds approximately 2,150 horizontal feet) is expected to be significantly greater than 16,100 years. 6. Brushy Basin Member paleotopography influences the locations of Westwater Seep and Ruin Spring; both are located in paleovalleys within the Brushy Basin Member paleosurface (Figure 8). 7. Local recharge is needed to explain areas of relatively large saturated thickness that supply Westwater Seep and Ruin Spring, because lateral flow into these areas from upgradient low saturated thickness portions of the perched zone is inadequate. The calculated perched zone recharge rate in the approximate 175 acre area southwest of Westwater Seep (near DR-2 [abandoned] and DR-5) is approximately 0.0011 in/yr. 8. The perched water system in the southwestern portion of the site is inadequate as the primary supply to Cottonwood Seep by several orders of magnitude. Therefore the primary source(s) of Cottonwood Seep must lie elsewhere. 6.4 Fate of Chloroform and Nitrate Natural attenuation of nitrate and chloroform in the perched water is expected to result from physical processes that include dilution by recharge and hydrodynamic dispersion. Volatilization is another physical process that is expected to lower chloroform concentrations in perched water. Mass reduction processes expected to lower both nitrate and chloroform concentrations include chemical and biologically-mediated processes. These processes include reduction of nitrate by pyrite, and anaerobic reductive dechlorination of chloroform. Both nitrate and chloroform plumes are under remediation by pumping. Pumping acts to reduce nitrate and chloroform mass as rapidly as is practical, allowing natural attenuation to be more effective. The nearest potential discharge points for nitrate originating from the nitrate plume are Westwater Seep and Ruin Spring, both located downgradient of the tailings cell complex at the site. The nearest potential discharge points for chloroform are Ruin Spring and ultimately Corral Springs for the southeastern portion of the plume. Corral Springs is located downgradient of the Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 71 eastern portion of the chloroform plume and cross-gradient of the tailings cell complex. Calculations of perched water flow rates indicate that thousands of years will be required for perched water at the downgradient margins of the tailings cells to reach a discharge point. Because both chloroform and nitrate plumes are more distant from discharge points than the tailings cell complex, even more time would be required for chloroform or nitrate to reach a discharge point. This is more than sufficient time for any residual chloroform or nitrate within the respective plumes to be attenuated through physical, chemical, and/or biological processes. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 72 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 73 7. REFERENCES Aubrey, W. M. 1992. Stratigraphy and Sedimentology of Latest Jurassic to Mid-Cretaceous Rocks, Four Corners Area, in Semken, S. C., ed., Field Guide to a Geologic Excursion in the Northeastern Navajo Nation: Shiprock, New Mexico, Navajo Community College, p. 33-40. Avery, C. 1986. Bedrock Aquifers of Eastern San Juan County, Utah: Utah Department of Natural Resources Technical Publication no. 86, 114 p. Baker. 2007. Passive Treatment of Selenium-Contaminated Groundwater. Colorado NPS Connection, Summer, 2007. Colorado Department of Public Health and Environment, Water Quality Control Division. January 2011. Total Maximum Daily Load Assessment, Gunnison River and Tributaries, Uncompahgre River and Tributaries, Delta/Mesa/Montrose Counties, Colorado. Craig et al. 1955. Stratigraphy of the Morrison and Related Formations, Colorado Plateau Region. A Preliminary Report. U. S. Geological Survey Bulletin 1009-E. Cross, C. W., and Purington, C. W. 1899. Description of the Telluride Quadrangle (Colorado): U.S. Geological Survey Geological Atlas, Folio 57, 19 p. Deditius, Artur P., Satoshi Utsunomiya, Martin Reich, Stephen E. Kesler, Rodney C. Ewing, Robert Hough, and John Walsh. 2011. Trace Metal Nonoparticles in Pyrite. Ore Geology reviews 42 (2011) p. 32-46. Doelling, H. H. 2004. Geologic Map of the La Sal 30 x 60’ Quadrangle, San Juan, Wayne, and Garfield Counties, Utah, and Montrose and San Miguel Counties, Colorado: Utah Geological Survey Map 205, scale 1:100,000. Dames and Moore. 1978. White Mesa Uranium Project, San Juan County, Utah. For Energy Fuels Nuclear, Inc. January 30, 1978. Energy Fuels Resources, Inc. (EFRI). 2013. Proposal for Remediation of Nitrate Contaminated Soils. Phase I of Final Nitrate Corrective Action Plan, May 7, 2012 and Stipulation and Consent Order of December 12, 2012 Docket UGW-12-04. Submitted to R. Lundberg, Utah Division of Radiation Control, December 12, 2013. EFRI. 2014a. White Mesa Uranium Mill. Nitrate Monitoring Report, State of Utah Stipulated Consent Agreement, January 2009, Docket No. UGW09-03, 1st Quarter (January through March) 2014. EFRI. 2014b. White Mesa Uranium Mill. Chloroform Monitoring Report, State of Utah Notice of Violation and Groundwater Corrective Action Order UDEQ Docket No. UGW-20-01 1st Quarter (January through March) 2014. Elder, W. P., and Kirkland, J. I. 1994. Cretaceous Paleogeography of the Southern Western Interior Region, in Caputo, M.V., Peterson, J. A., and Franczyk, K. J. editors, Mesozoic Systems of the Rocky Mountain Region, USA: Denver, Colorado, Rocky Mountain Section, SEPM (Society for Sedimentary Geology), p. 415- 440. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 74 Fenner, C. N. 1933. Pneumatolytic Processes in the Formation of Minerals and Ores, in Ore Deposits of the Western States (Lindgren Volume): American Institute Mining & Metallurgical Engineers, p. 58-106 Flesch. 1974. Stratigraphy and Sedimentology of the Morrison Formation (Jurassic), Ojito Spring Quadrangle, Sandoval County, New Mexico: A Preliminary Discussion. New Mexico Geological Society Guidebook, 25th Field Conference, Ghost Ranch (Central- Northern New Mexico), 1974. Goodknight, C. S., and Smith, G. M. 1996. Influences of Geologic and Hydrogeologic Conditions on the Uranium Mill Tailings Repository Design, Monticello, Utah, in Huffman, A. C., Jr., Lund, W.R., and Godwin, L.H., editors, Geology and Resources of the Paradox Basin: Utah Geological Association Guidebook 25, p. 377-388 Hartog, N., Griffionen, J., Van Bergen, P., and Van Der Weidjen, C. 2001. Determining The Reactivity of Reduced Components in Dutch Aquifer Sediments. Proceedings of a Symposium Held During the Sixth IAHS Scientific Assembly at Maastricht, the Netherlands, July 2001). Hartog, N., P.F. Van Bergen, J.W. De Leeuw, and J. Griffioen. 2004. Reactivity of organic matter in aquifer sediments: Geological and geochemical controls. Geochimica Cosmochimica Acta 2004, 68 (6), 1281-1292. Haynes, D. D., Vogel, J. D., and Wyant, D. G. 1972. Geology, Structure, and Uranium Deposits of the Cortez [1° x 2°] Quadrangle, Colorado and Utah: U.S. Geological Survey Miscellaneous Investigations Series Map I-629, 2 sheets, scale 1:250,000. Hedberg, H. D. 1936. Gravitational Compaction of Clays and Shales: American Association of Petroleum Geologists Bulletin v. 10, no. 11, p. 241-287. Huff, L.C., and Lesure, F. G. 1965. Geology and Uranium Deposits of Montezuma Canyon area, San Juan County, Utah: U.S. Geological Survey Bulletin 1190, 102 p. Hurst and Solomon. 2008. Utah Division of Radiation Control. Summary of Work Completed, Data Results, Interpretations and Recommendations for the July 2007 Sampling Event at the Denison Mines, USA, White Mesa Uranium Mill Near Blanding, Utah. Prepared by T. Grant Hurst and D. Kip Solomon, Department of Geology and Geophysics, University of Utah. Submitted May 2008. Hydro Geo Chem, Inc (HGC). 1988. WHIP. Well Hydraulics Interpretation Program, Version 3.22, User’s Manual. July, 1988 HGC. 2002. Hydraulic Testing at the White Mesa Uranium Mill Near Blanding, Utah During July, 2002. August 22, 2002. HGC. 2004. Final Report. Long Term Pumping at MW-4, TW4-10, and TW4-15. White Mesa Uranium Mill Near Blanding, Utah. May 26, 2004. HGC. 2005. Perched Monitoring Well Installation and Testing at the White Mesa Uranium Mill, April through June 2005. August 3, 2005. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 75 HGC. 2007. Preliminary Contamination Investigation Report. White Mesa Uranium Mill Site Near Blanding, Utah. November 20, 2007. HGC. 2009. Site Hydrogeology and Estimation of Groundwater Travel Times in the Perched Zone. White Mesa Uranium Mill Near Blanding, Utah. August 27, 2009. HGC. 2010a. Perched Monitoring Well Installation and Hydraulic Testing. White Mesa Uranium Mill, October 2009. March 10, 2010. HGC. 2010b. Letter Report to David Frydenlund, Esq. March 10, 2010. HGC. 2010c. Hydraulic Testing of TW4-4, TW4-6, and TW4-26. White Mesa Uranium Mill. July 2010. September 20, 2010. HGC. 2010d. Installation and Hydraulic Testing of Perched Monitoring Wells MW-33, MW-34, and MW-35 at the White Mesa Uranium Mill Near Blanding Utah. October 11, 2010. HGC. 2010e. Hydrogeology of the Perched Groundwater Zone and Associated Seeps and Springs Near the White Mesa Uranium Mill Site, Blanding, Utah. November 12, 2010. HGC. 2011a. Installation and Hydraulic Testing of Perched Monitoring Wells MW-36 and MW- 37 at the White Mesa Uranium Mill Near Blanding Utah. June 28, 2011. HGC. 2011b. Redevelopment of Existing Perched Monitoring Wells. White Mesa Uranium Mill Near Blanding, Utah. September 30, 2011 HGC. 2011c. Installation, Hydraulic Testing, and Perched Zone Hydrogeology of Perched Monitoring Well TW4-27. White Mesa Uranium Mill Near Blanding Utah. November 28, 2011. HGC. 2012a. Corrective Action Plan for Nitrate. White Mesa Uranium Mill Near Blanding, Utah. May 7, 2012 HGC. 2012b. Revised Report on the Hydrogeology of the Perched Groundwater Zone in the Area Southwest of the Tailings Cells. White Mesa Uranium Mill Site. Blanding, Utah. August 3, 2012. HGC. 2012c, Investigation of Pyrite in the Perched Zone. White Mesa Uranium Mill Site. Blanding, Utah. December 7, 2012. HGC. 2013a. Installation and Hydraulic Testing of Perched Monitoring Wells TW4-28 through TW4-31. White Mesa Uranium Mill Near Blanding Utah. April 30, 2013. HGC. 2013b. Installation and Hydraulic Testing of Perched Monitoring Wells TW4-32 through TW4-34. White Mesa Uranium Mill Near Blanding Utah.As Built Report. October 30, 2013. HGC. 2014. Contamination Investigation Report. TW4-12 and TW4-27 Areas. White Mesa Uranium Mill Near Blanding, Utah. January 23, 2014. HydroSOLVE, Inc. 2000. AQTESOLVE for Windows. User=s Guide. INTERA. 2007a. Revised Background Groundwater Quality Report: Existing Wells for Denison Mines (USA) Corp.’s Mill Site, San Juan County, Utah. October 2007. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 76 INTERA. 2007b. Revised Addendum: Evaluation of Available Pre-Operational and Regional Background Data, Background Groundwater Quality Report: Existing Wells for Denison Mines (USA) Corp.’s Mill Site, San Juan County, Utah.November 16, 2007. INTERA. 2008. Revised Addendum: Background Groundwater Quality Report: New Wells for Denison Mines (USA) Corp.’s Mill Site, San Juan County, Utah. April 30, 2008. INTERA. 2009. Nitrate Contamination Investigation Report White Mesa Uranium Mill Site, Blanding, Utah. INTERA. 2010. Background Groundwater Quality Report for Wells MW-20 and MW-22 for Denison Mines (USA) Corp.’s White Mesa Mill Site, San Juan County, Utah. June1, 2010. INTERA. 2012a. Source Assessment Report, White Mesa Uranium Mill. Blanding, Utah October 10, 2012. INTERA. 2012b. PH Report White Mesa Uranium Mill, Blanding, Utah. November 9, 2012,. INTERA. 2013a. Source Assessment Report for TDS in MW-29 White Mesa Uranium Mill, Blanding Utah May 7 2013. INTERA. 2013b. Source Assessment Report for Selenium in MW-31, White Mesa Uranium Mill. August 30, 2013. INTERA. 2014a. Source Assessment Report for Gross Alpha in MW-32, White Mesa Uranium Mill. January 13, 2014. INTERA. 2014b. Source Assessment Report for Sulfate in MW-01 and TDS in MW-03A, White Mesa Uranium Mill. March 18, 2014. INTERA. 2014c. Background groundwater quality Report for Monitoring Wells MW-35, MW- 36, and MW-37. White Mesa Uranium Mill, Blanding, Utah. May 1, 2014. International Uranium (USA) Corporation and Hydro Geo Chem. 2000. Investigation of Elevated Chloroform Concentrations in Perched Groundwater at the White Mesa Uranium Mill near Blanding, Utah. International Uranium (USA) Corporation and Hydro Geo Chem. 2001. Update to report “Investigation of Elevated Chloroform Concentrations in Perched Groundwater at the White Mesa Uranium Mill near Blanding, Utah” Kirby. 2008. Geologic and Hydrologic Characterization of the Dakota-Burro Canyon Aquifer Near Blanding, San Juan County, Utah. Utah Geological Survey Special Study 123. Knight-Piésold. 1998. Evaluation of Potential for Tailings Cell Discharge – White Mesa Mill. Attachment 5, Groundwater Information Report, White Mesa Uranium Mill, Blanding, Utah. Submitted to UDEQ. Kolle, W., P. Werner, O. Strebel, and J. Bottcher. 1983. Denitrification in a reducing aquifer. Vom Wasser 1983, 61, 125-147. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 77 Kolle, W., O. Strebel, and J. Bottcher. 1985. Formation of sulphate by microbial denitrification in a reducing aquifer. Water Supply 1985, 3, 35-40. Kolle, W., O. Strebel, and J. Bottcher. 1987. Reduced sulphur compounds in sandy aquifers and their interactions with groundwater. Proceedings of the Dresden Symposium of Groundwater Monitoring and Management, March, 1987. Korom, S.F. 1992. Natural denitrification in the saturated zone: A review. Water Resources Research, 1992, 28, 1657-1668. McFarland, Michael J. (Utah State University), M. Schmitz (Utah Division of Water Quality), R. B. Brobst (EPA), D. Desai (Utah State University), and H. R. Hall (Utah State University). 2006. Use of Disturbed Western Rangelands as Dedicated Biosolids Beneficial Use Sites. Proceedings of the Water Environment Federation, WEFTEC 2006: Session 21 through Session 30, pp. 2044-2059 (16). October, 2006. Meek, F. B., and Hayden, F. V. 1862. Descriptions of New Cretaceous Fossils from Nebraska Territory: Acad. National Science, Philadelphia Proc., p. 21-28. MWH Americas. 2010.Revised Infiltration and Contaminant Transport Modeling Report, White Mesa Mill Site, Blanding Utah, Denison Mines (USA) Corp. March, 2010. O'Sullivan, R. B., Repenning, C. A., Beaumont, E. C., and Page, Fl. G. 1972. Stratigraphy of the Cretaceous Rocks and the Tertiary Ojo Alamo Sandstone, Navajo and Hopi Indian Reservations, Arizona, New Mexico and Utah: U.S. Geological Society Professional Paper 521-E, 61 p. Parkhurst, D. L., and C. A. J. Appelo. 1999. User’s Guide to PHREEQC (Version 2) - A Computer Program for Speciation, Batch Reaction, One-Dimensional Transport, and Inverse Geochemical Calculations. US Department of the Interior, USGS, Water- Resources Investigations Report 99-4259, 1999. Pauwels, H., W. Kloppmann, J.C. Foucher, A. Martelat, and V. Fritsche. 1998. Field tracer test for denitrification in a pyrite-bearing schist aquifer. Applied Geochemistry, 1998, 13 (6), 767-778. Peterson, Fred, and Turner-Peterson, C. E. 1987. The Morrison Formation of the Colorado Plateau-Recent Advances in Sedimentology, Stratigraphy, and Paleotectonics: North American Paleontological Conference, 4th, Proceedings, Hunteria, v. 2, no. 1, p. 1–18. Postma, D., C. Boesen, H. Kristiansen, and F. Larsen. 1991. Nitrate reduction in an unconfined sandy aquifer - water chemistry, reduction processes, and geochemical modeling. Water Resource Research, 1991, 27 (8), 2027-2045. Potoroff, Edward J., Matthew P. Wickham, Jacob S. Waples, and Bruce Bertram. 2005. Case Study of Selenium Mobilization From Mancos Shale: Relationship to Nitrate Contamination. Geological Society of America Abstracts with Programs, Vol 37, No. 6, p 45. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 78 Rivett, M.O., S.R. Buss, P. Morgan, J.W.N. Smith, and C.D. Bemment. 2008. Nitrate attenuation in groundwater: A review of biogeochemical controlling processes. Water Research, 2008, 42, 4215-4232. Robertson, W.D., B.M. Russel, and J.A. Cherry. 1996. Attenuation of nitrate in aquitard sediments of southern Ontario. Journal of Hydrology, 1996, 180 (1), 267-281 Schippers, A., and B.B. Jorgensen. 2002. Biogeochemistry of pyrite and iron sulfide oxidation in marine sediments. Geochimica et Cosmochimica Acta, 2002, 66 (1), 85-92. Shawe, D. R. 1968. Petrography of Sedimentary Rocks in the Slick Rock District, San Miguel and Dolores Counties, Colorado. U.S. Geological Survey Professional Paper 576-B., 34 p. Shawe, D. R. 1976. Sedimentary Rock Alteration in the Slick Rock District, San Miguel and Dolores Counties, Colorado. U.S. Geological Survey Professional Paper 576-D., 51 p. Shawe. 2005. U S Geological Survey Professional Paper 576-F. Geologic Investigations in the Slick Rock District, San Miguel and Dolores Counties, Colorado. Spiteri, C., C.P. Slomp, K. Tuncay, and C. Meile. 2008. Modeling biogeochemical processes in subterranean estuaries: Effect of flow dynamics and redox conditions on submarine groundwater discharge of nutrients. Water Resources Research, 2008, 44, W02430. Stokes, W. L. and Phoenix, D. A. 1948. Geology of the Egnar-Gypsum Valley Area, San Miguel and Montrose Counties, Colorado: U.S. Geological Survey Oil and Gas Preliminary Map 93. Tesoriero, A.J. and L.J. Puckett. 2011. O2 reduction and denitrification rates in shallow aquifers. Water Resources Research, 2011, 37, W12522. TITAN. 1994. Hydrogeological Evaluation of White Mesa Uranium Mill. Submitted to Energy Fuels Nuclear. Tschudy, R.H., Tschudy, B.D., and Craig, L.C. 1984. Palynological Evaluation of Cedar Mountain and Burro Canyon Formation, Colorado Plateau: U.S. Geological Survey Professional Paper 1281, 24 p. Turner, C. E., and Fishman, N. S. 1991. Jurassic Lake T’oo’dichi’ - A Large Alkaline, Saline Lake, Morrison Formation, Eastern Colorado Plateau: Geological Society of America Bulletin, v. 103, p. 538–558. Tuttle, M. L. W., 2005. Salt and Selenium in Mancos Shale, Terrane on the Gunnison Gorge National Conservation Area, Western Colorado, USA. Geological Society of America Abstracts with Programs, Vol 37, No. 6, p 45. UMETCO. 1993. Groundwater Study, White Mesa Facility, Blanding Utah. Prepared by UMETCO Minerals Corporation and Peel Environmental Services. January, 1993. UMETCO. 1994. Groundwater Study 1994 Update, White Mesa Facility, Blanding Utah. Prepared by UMETCO Minerals Corporation. June, 1994. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 79 van Beek, C.G.E.M. 1999. Redox Processes Active in Denitrification. Chapter in: Redox Fundamentals, Processes, and Applications, J. Schuring, H.D. Schulz, W.R. Fischer, J. Bottcher, and W.H.M. Duijnisveld, eds. Springer-Verlag New York, 1999. Yoder, H. S., Jr. 1955. Role of Water in Metamorphism, in Poldevaart, Arie, Crust of the Earth: Geological Society of America Special Paper 62, p. 505-523. Young, R. G. 1960. Dakota Group of Colorado Plateau: American Association of Petroleum Geologists Bulletin, v. 44, no. 2, p. 156-194. Young, R. G. 1973. Depositional Environments of Basal Cretaceous Rocks of Colorado Plateau. Geological Society Memorandum. Zhang, Y. 2012. Coupled biogeochemical dynamics of nitrogen and sulfur in a sandy aquifer and implications for groundwater quality. Thesis presented at Utrecht University, Netherlands, November 19, 2012. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 80 Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 81 8. LIMITATIONS STATEMENT The opinions and recommendations presented in this report are based upon the scope of services and information obtained through the performance of the services, as agreed upon by HGC and the party for whom this report was originally prepared. Results of any investigations, tests, or findings presented in this report apply solely to conditions existing at the time HGC’s investigative work was performed and are inherently based on and limited to the available data and the extent of the investigation activities. No representation, warranty, or guarantee, express or implied, is intended or given. HGC makes no representation as to the accuracy or completeness of any information provided by other parties not under contract to HGC to the extent that HGC relied upon that information. This report is expressly for the sole and exclusive use of the party for whom this report was originally prepared and for the particular purpose that it was intended. Reuse of this report, or any portion thereof, for other than its intended purpose, or if modified, or if used by third parties, shall be at the sole risk of the user. Hydrogeology of the White Mesa Uranium Mill H:\718000\hydrpt14\report\EFRI_hydrorpt14__060614.doc June 6. 2014 82 TABLES TABLE 1 Results of Slug test Analyses Using KGS and Bouwer-Rice Solutions Bouwer-Rice Bouwer-Rice Test Saturated Thickness K (cm/s) Ss (1/ft) K (cm/s) K (cm/s) Ss (1/ft) K (cm/s) TWN-1 54 1.70E-04 2.22E-03 NI 1.97E-04 1.25E-03 1.36E-04 TWN-2 74 1.49E-05 3.20E-04 2.25E-05 2.04E-05 1.16E-04 2.73E-05 TWN-3 60 8.56E-06 8.73E-06 8.97E-06 7.75E-06 1.53E-05 8.89E-06 TWN-4 85 1.76E-03 3.43E-04 2.79E-05 1.25E-03 1.84E-06 NI TWN-5 77 4.88E-04 3.88E-07 4.06E-04 4.88E-04 3.88E-07 3.70E-04 TWN-6 79 1.74E-04 2.22E-03 NI 3.50E-04 2.22E-12 3.36E-04 TWN-7 11 3.57E-07 2.22E-03 4.59E-07 3.57E-07 2.21E-03 NI TWN-8 80 1.51E-04 3.66E-04 7.55E-05 4.73E-04 1.41E-06 2.48E-04 TWN-9 29 2.99E-05 6.92E-03 2.86E-05 6.02E-05 5.59E-03 7.93E-05 TWN-10 20 3.83E-05 0.1 2.31E-05 8.71E-05 8.12E-03 1.10E-04 TWN-11 68 1.18E-04 1.08E-05 9.83E-05 9.34E-05 7.18E-05 9.78E-05 TWN-12 67 8.05E-05 4.65E-05 7.69E-05 1.28E-04 1.27E-07 7.39E-05 TWN-13 68 2.62E-06 0.1 4.77E-06 2.09E-06 0.1 6.93E-06 TWN-14 57 3.61E-06 6.39E-03 2.74E-06 3.98E-06 3.17E-03 7.93E-06 TWN-15 58 4.75E-05 1.04E-03 2.61E-05 5.86E-05 3.49E-04 6.42E-05 TWN-16 41 0.0142 8.02E-04 6.47E-03 NI NI NI TWN-17 69 3.73E-06 0.033 6.18E-06 1.41E-06 0.061 1.96E-06 TWN-18 83 2.27E-03 2.44E-06 1.14E-03 2.67E-03 2.22E-12 NI TWN-19 50 2.69E-05 2.49E-03 1.81E-05 3.83E-05 3.34E-03 NI MW-03 (mlt; pssc) 5.2 4.00E-07 1.92E-02 1.50E-05 -- -- -- MW-05 (lt; pssc)3.90E-06 4.30E-06 MW-05 (et; pssc)2.40E-05 1.80E-05 MW-17 18 2.60E-05 1.71E-04 2.70E-05 2.20E-05 -- 3.00E-05 MW-18 58 2.90E-04 4.60E-07 2.40E-04 3.20E-04 -- 2.50E-04 MW-19 80 1.70E-05 1.44E-06 1.30E-05 1.20E-05 -- 1.50E-05 MW-19, confined 47 1.60E-05 3.24E-06 1.20E-05 -- -- -- MW-20 (mlt; pssc)9.30E-06 -- MW-20 (mlt)5.90E-06 2.50E-06 MW-22 (pscc)7.90E-06 -- MW-22 4.40E-06 3.40E-06 MW-23 12 3.20E-08 0.1 1.60E-06 NI NI NI MW-23b 12 2.30E-07 2.30E-03 2.50E-07 NI NI 2.00E-07 MW-24 3.4 4.16E-05 5.20E-03 3.15E-05 3.03E-05 0.0152 3.03E-05 MW-25 33 1.10E-04 3.00E-04 7.40E-05 1.70E-04 2.00E-04 1.00E-04 MW-27 36 8.20E-05 5.30E-04 3.60E-05 1.40E-04 8.70E-05 3.10E-05 MW-28 23 1.70E-06 0.02 1.70E-06 1.70E-06 0.02 2.00E-06 MW-29 18 1.10E-04 1.90E-04 9.30E-05 1.30E-04 2.10E-04 1.00E-04 MW-30 24 1.00E-04 2.90E-04 6.40E-05 1.10E-04 1.40E-04 5.10E-05 MW-31 53 7.10E-05 2.50E-05 6.90E-05 7.40E-05 7.20E-06 6.90E-05 MW-32 46 3.00E-05 8.80E-05 2.60E-05 2.80E-05 2.50E-04 3.00E-05 MW-35 12 3.48E-04 1.95E-05 2.18E-04 2.59E-04 1.78E-05 1.65E-04 MW-36 6.2 4.51E-04 4.29E-04 NA 7.73E-04 2.66E-04 6.52E-04 MW-36 (lt)6.2 NA NA 1.84E-04 NA NA NA MW-36 (et)6.2 NA NA 5.07E-04 NA NA NA MW-37 2.9 1.28E-05 2.22E-12 1.21E-05 NA NA NA TW4-4 (et) 22 NA NA 1.26E-03 NA NA NA TW4-4 (lt) 22 1.66E-03 6.21E-05 2.89E-04 1.63E-03 3.01E-04 7.91E-04 TW4-6 24 1.15E-05 3.67E-05 1.00E-05 1.19E-05 1.49E-04 1.32E-05 TW4-20 43 5.90E-05 1.60E-05 4.20E-05 7.00E-05 1.20E-05 5.30E-05 TW4-21 63 1.90E-04 1.10E-04 3.20E-05 1.90E-04 3.20E-05 9.40E-06 TW4-22 55 1.30E-04 6.80E-06 1.10E-04 1.30E-04 4.50E-06 1.10E-04 TW4-23 43 3.80E-05 7.40E-03 2.90E-05 3.40E-01 6.40E-04 7.90E-05 TW4-24 53 1.60E-04 1.10E-03 1.00E-04 1.20E-04 1.70E-03 5.20E-05 TW4-25 89 5.80E-05 0.001 3.70E-05 7.40E-05 1.10E-03 5.00E-05 TW4-26 18 2.40E-05 3.23E-04 2.16E-05 2.28E-05 3.13E-04 2.55E-05 TW4-27 (uncorrected) NA NA NA 2.13E-06 1.51E-03 1.59E-06 TW4-27 (100% correction) 7.01E-07 2.22E-03 1.99E-06 NA NA NA TW4-27(60% correction) 1.35E-06 1.27E-03 1.15E-06 NA NA NA TW4-28 67.9 3.52E-04 1.22E-06 3.92E-04 3.29E-04 7.49E-06 4.07E-04 TW4-29 17.7 4.24E-05 1.19E-03 5.24E-05 4.52E-05 9.62E-04 5.66E-05 TW4-29 (lt) 17.7 NA NA 2.00E-05 NA NA 3.80E-05 TW4-30 9.6 1.44E-04 1.00E-02 6.22E-05 1.34E-04 1.00E-02 1.38E-04 TW4-30 (et) 9.6 NA NA 1.63E-04 NA NA 2.91E-04 TW4-30 (lt) 9.6 NA NA 1.12E-05 NA NA 1.41E-05 TW4-31 18.1 4.18E-05 2.54E-05 3.87E-05 3.24E-05 9.65E-05 4.01E-05 TW4-32 64.8 9.53E-05 1.15E-04 NA 5.34E-05 7.97E-04 5.86E-05 TW4-32(et) 64.8 NA NA 1.09E-04 NA NA 1.34E-04 TW4-32(lt) 64.8 NA NA 2.51E-05 NA NA 1.17E-05 TW4-33 13.1 5.51E-05 3.73E-04 5.78E-05 5.25E-05 5.32E-04 5.76E-05 TW4-34 25.2 9.98E-05 1.13E-03 1.54E-04 9.39E-05 1.54E-03 1.25E-04 TW4-34 (lt) 25.2 NA NA 1.17E-04 NA NA NA DR-5 12.3 2.95E-05 4.21E-05 3.80E-05 2.86E-05 2.65E-03 3.76E-05 DR-8, Oct 2012 7.8 2.46E-08 1.00E-02 3.56E-07 4.46E-08 1.00E-02 4.45E-07 DR-8, Oct 2011 7.7 3.40E-08 0.01 NA 1.07E-07 0.0011 NA DR-9 24.5 4.49E-04 4.30E-06 3.41E-04 4.73E-04 1.21E-05 4.73E-04 DR-10 3 2.92E-06 6.54E-03 5.56E-06 9.71E-06 8.41E-04 9.71E-06 DR-11 8.9 8.88E-06 8.88E-04 1.54E-05 5.83E-06 2.22E-03 1.11E-05 DR-13 11.2 5.90E-06 7.33E-05 5.38E-06 4.93E-06 1.57E-04 1.49E-06 DR-13(et) 11.2 NA NA NA NA NA 6.81E-06 DR-14 18.8 1.26E-05 7.34E-05 1.66E-05 7.78E-06 4.84E-04 6.18E-06 DR-14(et) 18.8 NA NA NA NA NA 1.23E-05 DR-17 6.5 1.24E-05 1.53E-04 1.43E-05 3.17E-06 5.00E-03 2.19E-06 DR-17(et) 6.5 NA NA NA NA NA 8.35E-06 DR-19 3.5 3.29E-05 2.54E-03 3.78E-05 3.39E-05 1.86E-03 4.08E-05 DR-20 17.9 2.14E-06 1.91E-05 2.69E-06 1.43E-06 1.90E-05 1.89E-06 DR-21 13.5 3.29E-05 7.17E-06 3.60E-05 2.21E-05 1.87E-04 3.49E-05 DR-23 7.5 1.96E-05 3.85E-04 2.35E-05 7.49E-06 5.00E-03 4.51E-06 DR-23(et) 7.5 NA NA NA NA NA 2.16E-05 DR-24 17.4 1.64E-05 7.49E-05 1.43E-05 1.64E-05 7.49E-05 8.23E-06 DR-24(et) 17.4 NA NA NA NA NA 1.97E-05 Notes: Bouwer-Rice = Unconfined Bouwer-Rice solution method in Aqtesolv™ unless otherwise noted cm/s = centimeters per second ft = feet K = hydraulic conductivity KGS = Unconfined KGS solution method in Aqtesolv™ unless otherwise noted Ss= specific storage NI= Not Interpretable . et= early time data mlt=middle to late time data lt=late time data pssc=partially submerged screen correction used for Bouwer-Rice solution NA=not applicable 9 Automatically Logged Data 12 -- -- 51 1.00E-06 2.00E-03 Hand Collected Data KGS KGS 10 3.50E-06 4.40E-03 9.00E-07 -- 3.20E-06 -- -- -- H:\718000\hydrpt14\Hydraulic_props.xls: T1-KGS and B-R slug test K data TABLE 2 Results of Recovery and Slug Test Analyses Using Moench Solution Hand Data Well ID Interpretation Method Type Hydraulic Conductivity (cm/sec) Storativity Saturated Thickness (feet) Skin Hydraulic Conductivity (cm/sec) WHIP pump/recovery 7.70E-07 0.0082 20 none 7.70E-07 AQTESOLV (Moench, Leaky)pump/recovery 7.70E-07 0.0082 20 none 7.70E-07 AQTESOLV (Moench, Unconfined)pump/recovery 8.90E-07 0.01 40 none -- MW-03 WHIP slug 4.30E-05 0.01 5.2 none -- MW-05 WHIP slug 1.10E-05 0.1 10 none -- MW-17 WHIP slug 2.90E-05 0.01 18 none -- WHIP slug 4.40E-04 2.20E-05 45 none -- WHIP slug 5.30E-04 0.02 45 6.54 -- WHIP slug 7.10E-06 0.032 47 none -- WHIP slug 1.70E-05 0.027 47 2.24 -- AQTESOLV (Moench, Leaky)slug 1.70E-05 0.027 47 2.24 -- MW-20 WHIP slug 8.20E-06 0.02 12 none -- MW-22 WHIP slug 4.20E-06 0.014 51 none -- Notes: cm/sec = Centimeters per second WHIP analyses via modfied Moench Leaky Solution MW-01 MW-19 Automatically-Logged Data MW-18 H:\718000\hydrpt14\Hydrauic_props.xls: T2-Moench and WHIP data 5/15/2014 TABLE 3 Estimated Perched Zone Hydraulic Properties Based on Analysis of Observation Wells Near MW-4 and TW4-19 During Long Term Pumping of MW-4 and TW4-19 Observation Well Theis Solution (Confined or Unconfined) Transmissivity (ft2/day) Storage Coefficient Water Bearing Zone Thickness (feet) Average Hydraulic Conductivity (ft/day) Average Hydraulic Conductivity (cm/sec) Unconfined 8.9 0.023 39 0.23 8.20E-05 Confined 8.4 0.023 24 0.35 1.30E-04 Unconfined 4.6 0.0065 39 0.12 4.30E-05 Confined 3.8 0.0063 24 0.16 5.70E-05 Unconfined 4.7 0.011 39 0.12 4.30E-05 Confined 3.3 0.011 24 0.14 5.00E-05 Unconfined 4.5 0.010 39 0.12 4.30E-05 Confined 3.9 0.010 24 0.16 5.70E-05 Unconfined 5.8 0.019 39 0.15 5.40E-05 Confined 3.5 0.019 24 0.15 5.40E-05 Unconfined 12.4 0.0029 39 0.32 1.10E-04 Confined 9.1 0.0031 24 0.38 1.40E-04 Unconfined 89 0.0043 67 1.3 4.60E-04 Confined 87 0.0043 31 2.8 1.00E-03 Unconfined 72 0.0043 67 1.1 3.90E-04 Confined 71 0.0043 31 2.3 8.20E-04 Unconfined 48 0.0077 67 0.72 2.60E-04 Confined 46 0.0076 31 1.5 5.40E-04 Unconfined 15 0.0037 67 0.22 7.90E-05 Confined 12 0.0037 31 0.39 1.40E-04 Unconfined 19 0.0036 67 0.28 1.00E-04 Confined 18 0.0035 31 0.58 2.10E-04 TW4-16 TW4-5 TW4-9 TW4-10 TW4-15 MW-4A (early time) TW4-1 TW4-2 TW4-7 TW4-8 MW-4A H:\718000\hydrpt14\Hydrauic_props.xls: T3-Pump Test Obs Wells Page 1 of 2 5/15/2014 TABLE 3 Estimated Perched Zone Hydraulic Properties Based on Analysis of Observation Wells Near MW-4 and TW4-19 During Long Term Pumping of MW-4 and TW4-19 Observation Well Theis Solution (Confined or Unconfined) Transmissivity (ft2/day) Storage Coefficient Water Bearing Zone Thickness (feet) Average Hydraulic Conductivity (ft/day) Average Hydraulic Conductivity (cm/sec) Unconfined 76 0.0046 67 1.1 3.90E-04 Confined 74 0.0046 31 2.4 8.60E-04 Unconfined 44 0.12 67 0.66 2.40E-04 Confined 39 0.12 31 1.3 4.60E-04 Notes: cm/sec = Centimeters per second ft/day = Feet per day ft 2 /day = Feet squared per day TW4-18 TW4-19 H:\718000\hydrpt14\Hydrauic_props.xls: T3-Pump Test Obs Wells Page 2 of 2 5/15/2014 TABLE 4 Summary of Hydraulic Properties White Mesa Uranium Mill from TITAN (1994) Soils 6 Laboratory Test 9 D&M 1.20E+01 1.20E-05 7 Laboratory Test 4.5 D&M 1.00E+01 1.00E-05 10 Laboratory Test 4 D&M 1.20E+01 1.20E-05 12 Laboratory Test 9 D&M 1.40E+02 1.40E-04 16 Laboratory Test 4.5 D&M 2.20E+01 2.10E-05 17 Laboratory Test 4.5 D&M 9.30E+01 9.00E-05 19 Laboratory Test 4 D&M 7.00E+01 6.80E-05 22 Laboratory Test 4 D&M 3.90E+00 3.80E-06 Geometric Mean 2.45E+01 2.37E-05 Dakota Sandstone No. 3 Injection Test 28-33 D&M (1) 5.68E+02 5.49E-04 No. 3 Injection Test 33-42.5 D&M 2.80E+00 2.71E-06 No. 12 Injection Test 16-22.5 D&M 5.10E+00 4.93E-06 No. 12 Injection Test 22.5-37.5 D&M 7.92E+01 7.66E-05 No. 19 Injection Test 26-37.5 D&M 7.00E+00 6.77E-06 No. 19 Injection Test 37.5-52.5 D&M 9.44E+02 9.12E-04 Geometric Mean 4.03E+01 3.89E-05 Burro Canyon Formation No. 3 Injection Test 42.5-52.5 D&M 5.80E+00 5.61E-06 No. 3 Injection Test 52.5-63 D&M 1.62E+01 1.57E-05 No. 3 Injection Test 63-72.5 D&M 5.30E+00 5.13E-06 No. 3 Injection Test 72.5-92.5 D&M 3.20E+00 3.09E-06 No. 3 Injection Test 92.5-107.5 D&M 4.90E+00 4.74E-06 No. 3 Injection Test 122.5-142 D&M 6.00E-01 5.80E-07 No. 9 Injection Test 27.5-42.5 D&M 2.70E+00 2.61E-06 No. 9 Injection Test 42.5-59 D&M 2.00E+00 1.93E-06 No. 9 Injection Test 59-82.5 D&M 7.00E-01 6.77E-07 No. 9 Injection Test 82.5-107.5 D&M 1.10E+00 1.06E-06 No. 9 Injection Test 107.5-132 D&M 3.00E-01 2.90E-07 No. 12 Injection Test 37.5-57.5 D&M 9.01E-01 8.70E-07 No. 12 Injection Test 57.5-82.5 D&M 1.40E+00 1.35E-06 No. 12 Injection Test 82.5-102.5 D&M 1.07E+01 1.03E-05 No. 28 Injection Test 76-87.5 D&M 4.30E+00 4.16E-06 No. 28 Injection Test 87.5-107.5 D&M 3.00E-01 2.90E-06 No. 28 Injection Test 107.5-132.5 D&M 2.00E-01 1.93E-07 WMMW1 (7) Recovery 92-112 Peel (2) 3.00E+00 2.90E-06 WMMW3 (7) Recovery 67-87 Peel 2.97E+00 2.87E-06 WMMW5 (7) Recovery 95.5-133.5 H-E 1.31E+01 1.27E-05 WMMW5 (7) Recovery 95.5-133.5 Peel 2.10E+01 2.03E-05 WMMW11 (7) Recovery 90.7-130.4 H-E (3)1.23E+03 1.19E-03 WMMW11 (7) Single Well Drawdown 90.7-130.4 Peel 1.63E+03 1.58E-03 WMMW12 (7) Recovery 84-124 H-E 6.84E+01 6.61E-05 WMMW12 (7) Recovery 84-124 Peel 6.84E+01 6.61E-05 WMMW14 Single Well Drawdown 90-120 (5) H-E 1.21E+03 1.16E-03 WMMW14 Single Well Drawdown 90-120 (6) H-E 4.02E+02 3.88E-04 WMMW15 Single Well Drawdown 99-129 H-E 3.65E+01 3.53E-05 WMMW15 (7) Recovery 99-129 Peel 2.58E+01 2.49E-05 WMMW16 Injection Test 28.5-31.5 Peel 9.42E+02 9.10E-04 WMMW16 Injection Test 45.5-51.5 Peel 5.28E+01 5.10E-05 WMMW16 Injection Test 65.5-71.5 Peel 8.07E+01 7.80E-05 WMMW16 Injection Test 85.5-91.5 Peel 3.00E+01 2.90E-05 WMMW17 Injection Test 45-50 Peel 3.10E+00 3.00E-06 WMMW17 Injection Test 90-95 Peel 3.62E+00 3.50E-06 WMMW17 Injection Test 100-105 Peel 5.69E+00 5.50E-06 WMMW18 Injection Test 27-32 Peel 1.14E+02 1.10E-04 WMMW18 Injection Test 85-90 Peel 2.59E+01 2.50E-05 WMMW18 Injection Test 85-90 Peel 2.69E+01 2.60E-05 WMMW18 Injection Test 120-125 Peel 4.66E+00 4.50E-06 WMMW19 Injection Test 55-60 Peel 8.69E+00 8.40E-06 WMMW19 Injection Test 95-100 Peel 1.45E+00 1.40E-06 Geometric Mean 1.05E+01 1.01E-05 Entrada/Navajo Sandstones WW-1 Recovery D'Appolonia (4) 3.80E+02 3.67E-04 WW-1 Multi-well drawdown D'Appolonia 4.66E+02 4.50E-04 WW-1,2,3 Multi-well drawdown D'Appolonia 4.24E+02 4.10E-04 Geometric Mean 4.22E+02 4.08E-04 Notes (1) D&M = Dames & Moore, Environmental Report, White Mesa Uranium Project, January 1978. (2) Peel = Peel Environmental Services, UMETCO Minerals Corp., Ground Water Study, White Mesa Facility, June 1994. (3) H-E = Hydro-Engineering, Ground-Water Hydrology at the White Mesa Tailings Facility, July 1991. (4) D'Appolonia, Assessment of the Water Supply System, White Mesa Project, Feb. 1981. (5) Early test data. (6) Late test data. (7) Test data reanalyzed by TEC. Hydraulic Conductivity (ft/yr) Hydraulic Conductivity (cm/sec) Boring/ Well Location Test Type Interval (ft-ft) Document Referenced H:\718000\hydrpt14\Titan_material_props.xls TABLE 5 Properties of the Dakota/Burro Canyon Formation White Mesa Uranium Mill from TITAN (1994) Dakota WMMW-16 26.4' - 38.4' 1.50 3.30 135.20 17.90 2.64 18.20 5.10 -- -- -- Sandstone WMMW-16 37.8' - 38.4' 0.40 0.80 127.40 22.40 2.63 3.70 6.30 -- -- -- Sandstone WMMW-17 27.0' - 27.5' 0.30 0.60 138.80 13.40 2.57 4.80 5.10 -- -- -- Sandstone WMMW-17 49.0' - 49.5' 3.60 7.10 121.90 26.00 2.64 27.20 9.60 -- -- -- Sandstone Burro Canyon WMMW-16 45.0' - 45.5' 5.60 12.60 140.90 16.40 2.70 77.20 --29.60 15.40 14.20 Sandy Mudstone WMMW-16 47.5' - 48.0' 2.60 5.90 142.80 12.00 2.60 48.90 4.40 -- -- -- Sandstone WMMW-16 53.5' - 54.1' 0.70 1.40 129.00 19.90 2.58 7.10 6.40 -- -- -- Sandstone WMMW-16 60.5' - 61.0' 0.10 0.20 117.90 27.30 2.61 0.80 9.90 -- -- -- Sandstone WMMW-16 65.5' - 66.0' 2.60 5.50 131.50 19.30 2.62 28.20 7.10 -- -- -- Sandstone WMMW-16 73.0' - 73.5' 0.10 0.30 130.30 20.60 2.63 1.30 5.50 -- -- -- Sandstone WMMW-16 82.0' - 82.4' 0.10 0.10 134.30 18.50 2.64 0.60 4.80 -- -- -- Sandstone WMMW-16 90.0' - 90.7' 0.10 0.30 161.50 2.00 2.64 12.80 0.90 -- -- -- Sandstone WMMW-16 91.1' - 91.4' 5.20 9.80 118.10 29.10 2.67 33.80 -- 33.70 16.20 17.50 Claystone WMMW-17 104.0' - 104.5' *0.20 0.40 161.40 1.70 2.67 26.60 0.80 -- -- -- Sandstone* Note: *Data from this interval is actually from the Brushy Basin and is not included in the averages. 18.34 2.63 23.41 5.57Formation Average: 1.90 4.01 134.03 19.93 2.62 13.48 6.53Formation Average: 1.45 % Plasticity Index Rock TypeWell No. and Sample Interval % Moisture Content 2.95 130.83 % Saturation % Retained Moisture % Liquid Limit % Plastic Limit Moisture Content, Volumetric Dry Unit Weight (lbs/cu ft) % Porosity Particle Specific Gravity Formation H:\718000\hydrpt14\Titan_material_props.xls: T5-TITAN Formation Properties 5/15/2014 TABLE 6 Hydraulic Conductivity Estimates For Spring Flow Calculations location k (cm/s) location k (cm/s) location k (cm/s) DR-21 3.29E-05 DR-5 2.95E-05 DR-5 2.95E-05 DR-23 1.96E-05 DR-8 2.46E-08 MW-23 2.30E-07 DR-24 1.64E-05 DR-9 4.49E-04 MW-24 4.16E-05 DR-10 2.92E-06 MW-35 3.48E-04 DR-11 8.88E-06 MW-12 2.20E-05 MW-23 2.30E-07 MW-24 4.16E-05 MW-36 4.51E-04 geomean:2.19E-05 geomean:9.76E-06 geomean:1.77E-05 Notes: k = hydraulic conductivity cm/s = centimeters per second Ruin Spring Westwater Seep Westwater Seep (2) H:\718000\hydrpt14\Hydrauic_props.xls: T6-Springs 5/15/2014 TABLE 7 Hydraulic Conductivity Estimates For Travel Time Calculations Paths 1, 2A, and 2B location k (cm/s) location k (cm/s) location k (cm/s) TWN-2 1.49E-05 TW4-5 u 4.60E-04 TW4-2 u 4.30E-05 TWN-3 8.56E-06 TW4-5 c 1.00E-03 TW4-2 c 5.70E-05 TWN-18 2.27E-03 TW4-9 u 3.90E-04 MW-4A u 1.10E-04 TW4-21 1.90E-04 TW4-9 c 8.20E-04 MW-4A c 1.40E-04 TW4-22 1.30E-04 TW4-10 u 2.60E-04 TW4-5 u 4.60E-04 TW4-24 1.60E-04 TW4-10 c 5.40E-04 TW4-5 c 1.00E-03 MW-11 1.40E-03 TW4-18 u 3.90E-04 TW4-9 u 3.90E-04 MW-30 1.00E-04 TW4-18 c 8.60E-04 TW4-9 c 8.20E-04 MW-31 7.10E-05 TW4-19 u 2.40E-04 TW4-10 u 2.60E-04 TW4-19 c 4.60E-04 TW4-10 c 5.40E-04 TW4-28 3.52E-04 geomean:1.31E-04 geomean:4.88E-04 geomean:2.53E-04 Notes: k = hydraulic conductivity cm/s = centimeters per second c = confined solution u = unconfined solution PATH 1 PATH 2A PATH 2B H:\718000\hydrpt14\PATHCALCS.xls: T7-paths 1, 2a, 2b 5/15/2014 TABLE 8 Hydraulic Conductivity Estimates for Travel Time Calculations Paths 3-6 location k (cm/s) location k (cm/s) location k (cm/s) DR-5 2.95E-05 DR-5 2.95E-05 DR-11 8.88E-06 DR-8 2.46E-08 DR-8 2.46E-08 DR-13 5.89E-06 DR-9 4.49E-04 DR-9 4.49E-04 DR-21 3.29E-05 DR-10 2.92E-06 DR-10 2.92E-06 DR-23 1.54E-05 DR-11 8.88E-06 DR-11 8.88E-06 MW-3 4.00E-07 MW-12 2.20E-05 DR-14 1.26E-05 MW-14 7.50E-04 MW-23 2.30E-07 DR-17 1.24E-05 MW-15 1.90E-05 MW-24 4.16E-05 DR-19 3.29E-05 MW-20 9.30E-06 MW-36 4.51E-04 DR-20 2.14E-06 MW-37 1.28E-05 DR-21 3.29E-05 DR-23 1.96E-05 DR-24 1.64E-05 MW-23 2.30E-07 MW-24 4.16E-05 MW-36 4.51E-04 geomean:9.76E-06 geomean:1.10E-05 geomean:1.38E-05 Notes: k = hydraulic conductivity cm/s = centimeters per second PATHS 3 and 4 PATH 5 PATH 6 H:\718000\hydrpt14\PATHCALCS.xls: T8-paths 4-6 5/15/2014 TABLE 9 Estimated Perched Zone Pore Velocities Along Path Lines Path Length Head Change Hydraulic Gradient Pore Velocity (cm/s) (ft/yr) (ft) (ft) ft/ft ft/yr 1 1.31E-04 134 1,250 35 0.0280 21 2A 4.88E-04 499 1,200 33 0.0275 76 2B 2.53E-04 259 1,450 38 0.0262 38 3 9.76E-06 10.0 2,200 27 0.0123 0.68 4 9.76E-06 10.0 4,125 19 0.0046 0.26 5 1.10E-05 11.3 11,800 113 0.0096 0.60 6 1.38E-05 14.1 9,685 112 0.0116 0.91 Notes: aGeometric average (from Tables 7 and 8) Assumes effective porosity of 0.18 cm/s = centimeters per second ft/ft = feet per foot ft/yr = feet per year Path Hydraulic Conductivitya H:\718000\hydrpt14\PATHCALCS.xls: T9-pore velocities 5/15/2014 TABLE 10 Results of XRD and Sulfur Analysis in Weight Percent Mineral Formula MW-3A MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 (TW4-17)SS-26* 89.5 108 118.5 65 - 67.5 90 - 92.5 80 - 82.5 88.5 102 65 - 67.5 95 - 97.5 105-107.5 NA quartz SiO2 79.7 96.2 88.4 90 86.9 95.4 90.1 95.8 87 91.7 94.1 39.2 K-feldspar KAlSi3O8 ND 0.2 0.6 2.4 2.4 0.7 1.5 0.5 1.4 2 0.8 21.6 plagioclase (Na,Ca)(Si,Al)4O8 ND ND ND 1.4 1.6 1.5 1.8 1.5 1.5 0.5 0.2 29 mica KAl2(Si3Al)O10(OH)2 0.3 1.2 4.5 2.2 2 0.2 3 0.2 5.9 3.1 1.2 5.2 kaolinite Al2Si2O5(OH)4 1.1 1 4.3 3.2 2.5 1.4 2.9 1.7 3.6 2.4 1.6 0.8 calcite CaCO3 14 ND ND ND 3.9 ND ND ND ND ND 1.2 0.6 dolomite CaMg(CO3)2 4.1 ND ND ND ND ND ND ND ND ND ND ND anhydrite CaSO4 0.4 0.8 0.4 0.4 ND ND ND ND ND ND ND ND gypsum CaSO4·2H2O ND 0.2 0.8 ND ND ND 0.3 ND 0.3 ND ND ND iron Fe 0.3 0.4 0.2 0.4 0.4 0.4 0.2 0.3 0.3 0.3 0.4 0.2 pyrite FeS2 0.1 ND 0.8 ND 0.3 0.4 0.2 ND ND ND 0.5 ND hematite Fe2O3 ND ND ND ND ND ND ND ND ND ND ND 1.4 magnetite Fe3O4 ND ND ND ND ND ND ND ND ND ND ND 2 Total S S 0.14 0.14 0.63 0.05 0.13 0.15 0.04 0.03 0.02 0.02 0.26 0.02 equivalent FeS2 FeS2 0.3 0.3 1.2 0.1 0.2 0.3 0.1 0.1 <0.1 <0.1 0.5 <0.1 Notes: NA = Not applicable: quality control sample ND = Not Detected * = 'play sand' Sulfur Determination Depth (feet) H:\718000\hydrpt14\ Pyrite_results_tables.xls: Table 10 5/23/2014 TABLE 11 Tabulation of Presence of Pyrite, Iron Oxide, and Carbonaceous Fragments in Drill Logs Well Pyrite C Fragments Iron Oxide MW-3A X aMW-16 X aMW-17 X aMW-18 X aMW-19 X aMW-20 X aMW-21 X X aMW-22 X MW-23 X MW-24 X MW-25 X X MW-26 X X MW-27 X X MW-28 X MW-29 X MW-30 X X MW-31 X X MW-32 X X MW-33 X MW-34 X X X MW-35 X X X MW-36 X X MW-37 X X Piez-2 X Piez-4 X X Piez-5 X X DR-2 X X DR-5 X X DR-6 X X DR-7 X DR-8 X DR-9 X X DR-10 X DR-11 X X DR-12 X X DR-13 X DR-14 X X DR-15 X X DR-16 X X DR-17 DR-18 X X DR-19 X DR-20 X X DR-21 X DR-22 DR-23 X X DR-24 X X DR-25 X X TW4-1 X TW4-2 X X TW4-3 X X X TW4-4 TW4-5 X X TW4-6 X X X H:\718000\hydrpt14\ Pyrite_results_tables.xls: Table 11 Page 1 of 2 5/23/2014 TABLE 11 Tabulation of Presence of Pyrite, Iron Oxide, and Carbonaceous Fragments in Drill Logs Well Pyrite C Fragments Iron Oxide TW4-7 X X X TW4-8 X TW4-9 X X X TW4-10 X X TW4-11 X TW4-12 X X X TW4-13 X X X TW4-14 X TW4-15 X X TW4-16 X X TW4-17 X X TW4-18 X X TW4-19 X TW4-20 X TW4-21 X X TW4-22 X TW4-23 X X X TW4-24 X TW4-25 X X TW4-26 X TW4-27 X X TW4-28 X X TW4-29 X X X TW4-30 X X X TW4-31 X X X TW4-32 X X X TW4-33 X X TW4-34 X X TWN-1 X TWN-2 X X TWN-3 X X TWN-4 X TWN-5 X X TWN-6 X X TWN-7 X TWN-8 X X TWN-9 X TWN-10 X TWN-11 X X TWN-12 X X TWN-13 X X TWN-14 X X TWN-15 X X TWN-16 X X TWN-17 X TWN-18 X X TWN-19 X X Notes: C Fragments = particles of carbonaceous material (plant remains, etc) a = only moderately detailed log available H:\718000\hydrpt14\ Pyrite_results_tables.xls: Table 11 Page 2 of 2 5/23/2014 TABLE 12 Sulfide Analysis by Optical Microscopy Grain size (micrometers) Sample Depth (feet) Mineral Volume% Minimum Maximum Mean MW-26 (TW4-15)1 92.5’ - 97.5' pyrite 4.30 5.6 44.4 128.9 MW-34 67.5’ - 70' pyrite 0.30 1.1 177.8 71.1 MW-36 87.5’ - 90' pyrite 5.20 5.6 88.9 52.2 MW-36 87.5’ - 90' marcasite 0.50 22.2 488.8 121.2 MW-36 112.5’ - 115' pyrite 2.20 16.7 577.7 188.9 MW-36 112.5’ - 115' marcasite 0.20 22.2 333.3 177.8 MW-37 110’ - 112.5' pyrite 9.80 11.1 1666.5 131.1 TW4-162 92.5’ - 95' pyrite 0.10 11.1 105.5 47.8 TW4-22 90’ - 92.5' pyrite 0.30 5.6 66.7 26.7 TWN-5 110’ - 112.5' pyrite 15.80 5.6 1377.6 208.9 TWN-5 112.5’ - 115' pyrite 0.50 5.6 266.6 70 TWN-5 112.5’ - 115' marcasite 0.50 22.2 55.6 36.7 TWN-5 112.5’ - 115' chalcopyrite 0.02 ND ND 6 TWN-8 117.5’ - 120' pyrite 12.00 5.6 455.1 137.8 TWN-8 117.5’ - 120' marcasite 0.60 66.6 288.9 155.5 AWN-X23 87.5’ - 90' pyrite 2.40 5.6 33.3 17.8 AWN-X23 87.5’ - 90' marcasite 0.60 66.6 288.9 155.5 TWN-164 82.5’ - 85' pyrite 0.10 1.1 11.1 6.1 TWN-164 87.5' - 90' pyrite 0.16 7 168 35.5 TWN-164 87.5' - 90' marcasite 0.05 ND 129.5 ND TWN-195 82.5 ' - 85' pyrite 1.18 3.5 434 42.1 TWN-195 82.5 ' - 85' marcasite 0.06 21 42 36.4 DR-9 105’ - 107.5' pyrite 17.00 2.2 677.7 136.7 DR-12 87.5’ - 90' pyrite 0.30 11.1 111.1 52.2 DR-12 87.5’ - 90' marcasite 0.10 22.2 111.1 72.2 DR-16 97.5’ - 100' pyrite 2.40 5.6 33.3 17.8 DR-16 97.5’ - 100' marcasite 0.60 66.6 288.9 155.5 DR-25 75’ - 77.5' pyrite 25.00 1.1 1955 22 DR-25 75’ - 77.5' marcasite 2.50 55.6 621.6 265.5 SS-31*NA chalcopyrite 0.01 ND ND 10 SS-37*NA pyrite 0.02 7 14 11.7 Notes: 1 Samples from 92.5' - 95' and 95' - 97.5' combined due to small sample volume 2 Sample from 92.5' - 95' submitted instead of sample from 95' - 97.5' because no sample material available 3 Originally TWN-16 4 Originally TWN-19 5 Originally TWN-22 NA = Not applicable: quality control sample ND = Not determined * = 'play sand' H:\718000\hydrpt14\ Pyrite_results_tables.xls: Table 12 5/23/2014 TABLE 13 Summary of Pyrite in Drill Cuttings and Core Well Pyrite Noted in Drill Logs Pyrite Detected by Laboratory MW-3A X (Q) aMW-16 NA aMW-17 NA aMW-18 NA aMW-19 NA aMW-20 NA aMW-21 X NA aMW-22 NA MW-23 possibleb (Q) MW-24 X (Q) MW-25 X possibleb (Q) MW-26 X X (Q) MW-27 X X (Q) MW-28 X (Q) MW-29 possibleb (Q) MW-30 X ND (Q) MW-31 X ND (Q) MW-32 X X (Q) MW-33 NA MW-34 X X (V) MW-35 X NA MW-36 X X (V) MW-37 X X (V) Piez-2 NA Piez-4 X NA Piez-5 X NA DR-2 X NA DR-5 X NA DR-6 X NA DR-7 NA DR-8 NA DR-9 X X (V) DR-10 NA DR-11 X NA DR-12 X X (V) DR-13 NA DR-14 X NA DR-15 X NA DR-16 X X (V) DR-17 NA DR-18 X NA DR-19 NA DR-20 X NA DR-21 NA DR-22 NA DR-23 X NA DR-24 X NA DR-25 X X (V) TW4-1 NA TW4-2 X NA TW4-3 X NA TW4-4 NA TW4-5 X NA TW4-6 X NA TW4-7 X NA TW4-8 NA TW4-9 X NA TW4-10 X NA TW4-11 NA H:\718000\hydrpt14\ Pyrite_results_tables.xls: Table 13 Page 1 of 2 5/23/2014 TABLE 13 Summary of Pyrite in Drill Cuttings and Core Well Pyrite Noted in Drill Logs Pyrite Detected by Laboratory TW4-12 X NA TW4-13 X NA TW4-14 NA TW4-15 X NA TW4-16 X X (V) TW4-17 X NA TW4-18 NA TW4-19 NA TW4-20 NA TW4-21 X NA TW4-22 X X (V) TW4-23 X NA TW4-24 NA TW4-25 X NA TW4-26 NA TW4-27 NA TW4-28 X NA TW4-29 X NA TW4-30 X NA TW4-31 X NA TW4-32 X NA TW4-33 X NA TW4-34 NA TWN-1 NA TWN-2 X NA TWN-3 X NA TWN-4 NA TWN-5 X X (V) TWN-6 X NA TWN-7 NA TWN-8 X X (V) TWN-9 NA TWN-10 NA TWN-11 X NA TWN-12 X NA TWN-13 X NA TWN-14 X NA TWN-15 X NA TWN-16 X X (V) TWN-17 NA TWN-18 X NA TWN-19 X X (V) AWN-X1 NA AWN-X2 X X (V) AWN-X3 NA Notes: a = only moderately detailed log available b = detected iron and sulfur may indicate the presence of pyrite Q = quantiative analysis by XRD V = visual (microscopic) analysis ND = not detected by laboratory NA = not analyzed by laboratory H:\718000\hydrpt14\ Pyrite_results_tables.xls: Table 13 Page 2 of 2 5/23/2014 FIGURES HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile Mill Site CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TW4-34 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 abandoned abandoned abandoned abandoned abandoned abandoned abandoned abandoned abandoned DR-02 DR-16 DR-18 DR-25 abandoned abandoned abandoned abandoned MW-16abandoned W E W2 E2 S N SW NE SW2 NE2 NW SE wildlife pond wildlife pond wildlife pond TW4-35 TW4-36 EXPLANATION perched monitoring well perched piezometer seep or spring WHITE MESA SITE PLAN SHOWING LOCATIONS OF PERCHED WELLS, PIEZOMETERS, AND LITHOLOGIC CROSS-SECTIONS H:/718000/hydrpt14/maps/Uwellocxs14.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 TW4-32 temporary perched monitoring well temporary perched nitrate monitoring well TW4-12 TWN-7 TW4-19 perched chloroform or nitrate pumping well TW4-35 approximate extent of historical pond 1 A proposed temporary perched monitoring well HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile Mill Site CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TW4-34 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 abandoned abandoned abandoned abandoned abandoned abandoned abandoned abandoned abandoned DR-02 DR-16 DR-18 DR-25 abandoned abandoned abandoned abandoned MW-16abandoned wildlife pond wildlife pond wildlife pond TW4-35 TW4-36 WW-3 EXPLANATION perched monitoring well perched piezometer seep or spring WHITE MESA SITE PLAN SHOWING LOCATIONS OF PERCHED WELLS, PIEZOMETERS, AND KRIGED NITRATE AND CHLOROFORM PLUME BOUNDARIES H:/718000/hydrpt14/maps/UwellocNchl.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 TW4-32 temporary perched monitoring well temporary perched nitrate monitoring well TW4-12 TWN-7 TW4-19 perched chloroform or nitrate pumping well TW4-35 proposed temporary perched monitoring well approximate extent of historical pond kriged nitrate >10 mg/L within area addressed by nitrate CAP kriged chloroform > 70 ug/L 1 B WW-3 water supply well WW-3 (completed in Navajo Sandstone) H:\718000\hydrpt14\report\Figures.xls: F2 litho clmn LITHOLOGIC COLUMNHYDRO GEO CHEM, INC.Approved FigureDateAuthorDate File Name SJS 11/9/12 2F2 litho clmn11/9/12SJS B ur ro Canyon Fo rma t ion Brushy Basin Member Highway 95 Reference Outcrop Just North of White Mesa Uranium Mill APPROVED DATE REFERENCE FIGURE HYDRO GEO CHEM, INC. 4 PHOTOGRAPH OF THE CONTACT BETWEEN THE BURRO CANYON FORMATION AND THE BRUSHY BASIN MEMBER H:/718000/ hydrpt14/maps/contact2.srfSJS HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5584 5503 5472 5503 5524 5501 54955494 5503 5587 5597 5455 dry 5451 5495 5508 5539 5575 5545 5514 5540 5549 dry 5492 5494 5493 5486 55755557 5551 55695560 5585 5592 5595 5593 5539 5535 5590 5598 5598 5592 abandoned 5589 5563 abandoned abandoned abandoned abandoned abandoned abandoned 5588 abandoned 5606 abandoned 5587 5609 5580 5544 5556 5582 5573 5529 5562 5576 5563 5534 5553 5559 5579 5579 55655561 55795565 5542 5539 5540 5580 5526 5522 5534 5528 5536 5483 5485 5492 5474 5480 5483 5487 5490 5487 5467 5466 5454 5455 5444 5421 dry 5426 5418 5624 5383 5234 5560 5380 5468 (not included) EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring showing elevation in feet amsl KRIGED 1st QUARTER, 2014 WATER LEVELS WHITE MESA SITE H:/718000/hydrpt4/maps/Uwl0314det.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5503 5582 5562 5592 5564 5380 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet 53 9 0 kriged perched water level contour and label 5 APPROVED DATE REFERENCE FIGURE "Dry Seep""2nd Seep" (5240 ft amsl)Cottonwood Seep (5234 ft amsl) Kdbc Kdbc Jmbb ss (within Jmw) sh (Jmr) (contact approx. 5465 ft amsl) Approximate Location of DR-8 EXPLANATION Dakota Sandstone/ Burro Canyon Formation Brushy Basin (Shale) Member Approximate Location of Geologic Contact Kdbc Jmbb sandstone (within Westwater Canyon Member) ss (within Jmw) shale (Recapture Member)sh (Jmr) H:/718000/hydrpt14/maps/cottonwood2.srf ANNOTATED PHOTOGRAPH SHOWING EAST SIDE OF COTTONWOOD CANYON (looking east toward White Mesa from west side of Cottonwood Canyon) NOTES: adapted from HGC (2010); "2nd Seep" and "Dry Seep" are described in HGC (2010) Approximate Change From Slope-Former to Bench-Former Jmbb Jmbb WHITE MESA (slope-former) (cliff-former) (cliff-former)(cliff-former) (slope-former)(slope-former) COTTONWOOD CANYON lower Jmbb/upper Jmw (bench former) lower Jmbb/upper Jmw (bench former) (slope-former) SJS 6 H:\718000\hydrpt14\report\Figures.xls: F7 west int sea EXTENT OF THE WESTERN INTERIOR SEA (CRETACEOUS) HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5536 5492 5466 5491 5479 5494 54775473 5470 5518 5511 5449 5470 5396 5483 5502 5499 5537 5515 5491 5508 5489 5494 5491 5475 5487 5481 55265506 5497 55165513 5511 5552 5536 5558 5501 5477 5544 5534 5542 5519 5507 5536 5545 5507 5552 5562 5543 5560 5518 5528 5525 5561 5536 5502 5555 5534 5522 5517 5521 5517 5520 5525 5521 5499 5509 5515 5518 5536 5532 55365481 55025509 5494 5517 5512 5511 5513 5500 5515 5515 5470 5483 5489 5466 5455 5479 5478 5487 5473 5447 5461 5447 5451 5425 5407 5425 5418 5400 5624 5383 5234 5560 5380 5468 (not included) (not included) (not included) (not included) MW-16 DR-02 DR-16 DR-18 DR-25 5495 5464 5451 5467 5386 EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring showing elevation in feet amsl KRIGED TOP OF BRUSHY BASIN WHITE MESA SITE H:/718000/fhydrpt14/Ubbel14rv.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5491 5521 5545 5551 5499 5380 abandoned boring showing elevation in feet amsl DR-25 5386 approximate axis of Brushy Basin paleoridge approximate axis of Brushy Basin paleovalley 5 3 8 0 kriged top of Brushy Basin elevation contour and label 8 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5641 5583 5545 5579 5579 5586 55655570 5570 5651 5649 5527 5543 5505 5589 5608 5607 5602 5597 5601 5606 5603 5592 5568 5600 5600 5573 56255609 5608 56135611 5638 5640 5622 5615 5585 5563 5634 5616 5630 5629 5644 5661 5637 5644 5641 5660 5677 5662 5628 5643 5663 5649 5635 5634 5655 5626 5602 5610 5602 5606 5601 5621 5636 5601 5597 5608 5618 5629 5624 56195612 56325625 5601 5598 5600 5603 5594 5596 5595 5600 5601 5547 5561 5574 5576 5521 5551 5554 5580 5574 5550 5539 5552 5545 5512 5519 5511 5492 5513 5478 5493 5455 5461 DR-02 DR-16 DR-18 DR-25 EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring KRIGED TOP OF BEDROCK WHITE MESA SITE H:/718000/hydrpt4/bedrock/Ubdrkel14.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5579 5619 5637 5640 5601 NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells 5 3 90 kriged bedrock elevation contour and label 9 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5636 5583 5545 5579 5579 5586 55655570 5570 5645 5649 5527 5543 5505 5589 5608 5570 5602 5597 5594 5591 5579 5581 5563 5577 5579 5568 55925596 5581 56085608 5615 5640 5622 5615 5576 5563 5620 5610 5625 5621 5626 5636 5625 5644 5641 5635 5662 5662 5628 5643 5641 5649 5635 5634 5655 5594 5595 5592 5591 5588 5593 5607 5611 5593 5574 5588 5585 5601 5598 55875589 56005609 5575 5587 5585 5586 5568 5581 5575 5594 5594 5547 5561 5572 5576 5520 5551 5554 5572 5566 5550 5536 5546 5541 5512 5519 5507 5492 5497 5478 5488 5453 5461 DR-02 DR-16 DR-18 DR-25 EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring KRIGED TOP OF DAKOTA SANDSTONE WHITE MESA SITE H:/718000/hydrpt4/bedrock/Udakotael14.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5579 5619 5637 5640 5601 NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells 5 3 90 kriged bedrock elevation contour and label 10 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5641 5583 5545 5579 5579 5586 55655570 5570 5651 5649 5527 5543 5505 5589 5608 5607 5602 5597 5601 5606 5603 5592 5568 5600 5600 5573 56255609 5608 56135611 5638 5640 5622 5615 5585 5563 5634 5616 5630 5629 5644 5661 5637 5644 5641 5660 5677 5662 5628 5643 5663 5649 5635 5634 5655 5626 5602 5610 5602 5606 5601 5621 5636 5601 5597 5608 5618 5629 5624 56195612 56325625 5601 5598 5600 5603 5594 5596 5595 5600 5601 5547 5561 5574 5576 5521 5551 5554 5580 5574 5550 5539 5552 5545 5512 5519 5511 5492 5513 5478 5493 5455 5461 DR-02 DR-16 DR-18 DR-25 EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring KRIGED TOP OF BEDROCK AND MANCOS SHALE THICKNESS WHITE MESA SITE H:/718000/hydrpt4/bedrock/Ubdrkmanc.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5579 5619 5637 5640 5601 NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells 5 3 90 kriged bedrock elevation contour and label 2.5 5 10 20 30 approximate Mancos thickness (ft) 11 APPROVED DATE REFERENCE FIGURE P1A-01 P2A-01 P3A-N01 P4A-01 P5A-01 P1A-08 P2A-08 P3A-08 P4A-10 P5A-10 P6A-01 P6A-04 100 feet EXPLANATION APPROXIMATE GEOPROBE BORING AND CROSS-SECTION LOCATIONS WHITE MESA SITE H:/718000/hydrpt14/ xsection/soilxs/soilxsloc_rev.srf 12 approximate 1st sampling event geoprobe boring location approximate 2nd sampling event geoprobe boring location approximate 3rd sampling event geoprobe boring location ammonium sulfate crystal tank north-south (N-S) cross-section northeast - southwest (NE-SW) cross-section APPROVED DATE REFERENCE FIGURE SOIL CROSS SECTIONS EAST OF AMMONIUM SULFATE CRYSTAL TANKS WHITE MESA SITE S N EXPLANATION weathered mancos shale competent bedrock asphalt primarily sand primarily clay primarily silt vertical exaggeration = 2:1 Note: NH3 xtal tanks 60 feet west of section 0 50 100 150 200 250 300 distance along cross section (feet) 5610 5615 5620 5625 5630 5635 5640 5645 ap p r o x i m a t e e l e v a t i o n ( f t a m s l ) NH 3 x t a l t a n k s P1 7 C - 0 1 P1 6 C - 0 1 P1 4 C - 0 1 P1 3 C - 0 1 P1 2 C - 0 1 P1 A - 0 8 P1 A - 0 7 P1 A - 0 6 P1 A - 0 5 P1 A - 0 4 P1 A - 0 3 P1 A - 0 2 P2 A - 0 1 P3 A - N 0 1 P4 A - 0 1 P5 A - 0 1 P1 1 C - 0 4 P1 1 C - 0 3 P1 1 C - 0 2 silt/clay 0 50 100 distance along cross-section (feet) 5605 5610 5615 5620 5625 5630 5635 5640 5645 ep p r o x i m a t e e l e v a t i o n ( f t a m s l ) P1 A - 0 3 P2 A - 0 3 P3 A - 0 3 P4 A - 0 5 P5 A - 0 5 P6 A - 0 2 P8 C - 0 1 P9 C - 0 1 P1 0 C - 0 1 SW NE H:/718000/hydrpt14/ xsection/soilxs/soilxs.srf 13 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 48 11 6 12 46 7 1821 33 69 86 6 dry 55 13 6 41 38 30 23 31 60 dry 2 12 6 5 4951 54 5347 74 40 59 35 39 58 46 64 56 73 abandoned 52 18 abandoned abandoned abandoned abandoned abandoned abandoned 60 abandoned 45 abandoned 85 54 46 22 39 60 56 9 38 55 64 25 39 41 43 47 2980 7857 48 22 27 69 1322 20 12 13 13 2 2 8 25 3 9 3 14 19 4 7 4 19 14 dry 8 17 EXPLANATION perched monitoring well showing saturated thickness in feet perched piezometer showing saturated thickness in feet seep or spring 1st QUARTER, 2014 PERCHED ZONE SATURATED THICKNESSES AND BRUSHY BASIN PALEORIDGES AND PALEOVALLEYS WHITE MESA SITE H:/718000/hydrpt14/maps/Usat0314rv.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing saturated thickness in feet TW4-32 temporary perched monitoring well showing saturated thickness in feet temporary perched nitrate monitoring well showing saturated thickness in feet TW4-12 TWN-7 12 29 18 40 64 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet approximate axis of Brushy Basin paleoridge approximate axis of Brushy Basin paleovalley 14 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 64 110 83 106 86 108 103106 72 71 58 86 dry 67 117 114 73 53 76 101 75 67 dry 108 112 111 114 5969 74 6066 60 63 34 45 52 50 58 29 37 50 abandoned 76 86 abandoned abandoned abandoned abandoned abandoned abandoned 62 abandoned 47 abandoned 59 52 53 69 65 43 47 84 67 63 49 69 65 66 61 59 5963 6266 65 63 69 37 7782 72 80 70 83 94 92 51 86 78 98 90 70 76 93 65 63 55 101 dry 70 44 EXPLANATION perched monitoring well showing depth to water in feet perched piezometer showing depth to water in feet seep or spring 1st QUARTER, 2014 DEPTHS TO PERCHED WATER WHITE MESA SITE H:/718000/hydrpt14/maps/Udtw0314.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing depth to water in feet TW4-32 temporary perched monitoring well showing depth to water in feet temporary perched nitrate monitoring well showing depth to water in feet TW4-12 TWN-7 106 43 86 63 49 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet 15 APPROVED DATE REFERENCE FIGURE EXPLANATION Qaf Km Kdbc Jmbb Alluvium/Fill Mancos Shale Dakota Sandstone/ Burro Canyon Formation Brushy Basin Member of Morrison Formation Shale/claystone in Dakota / Burro Canyon Formation Conglomerate in Dakota / Burro Canyon Formation SW NE INTERPRETIVE NORTHEAST-SOUTHWEST CROSS SECTION (NE-SW) WHITE MESA SITE Piezometric Surface vertical exaggeration = 20 : 1 SJS 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 distance along cross-section (feet) 5420 5440 5460 5480 5500 5520 5540 5560 5580 5600 5620 5640 5660 5680 5700 5720 el e v a t i o n ( f e e t a m s l ) MW - 0 3 MW - 1 4 MW - 1 1 MW - 3 1 TW 4 - 2 4 MW - 2 7 TW N - 2 TW N - 3 TW N - 1 8 TW N - 8 * TW N - 6 TW N - 1 0 * TW N - 1 5 * TW N - 1 6 TW N - 1 2 * Cell # 4A Cell # 3 Cell # 2 Cell # 1 Fl y A s h P o n d Ce l l 1 L e a c h F i e l d CC D / S X L e a c h F i e l d Hi s t o r i c a l P o n d La w z y L a k e Kdbc Kdbc Kdbc Km Km Km Jmbb Jmbb Jmbb Qaf Qaf Note: waterl levels from TWN-8, TWN-10, TWN-12, and TWN-15 are from Q2, 2013 * denotes abandoned boring 16 AH:/718000/hydrpt14/xsection/nsxsne/nsxsneb.srf APPROVED DATE REFERENCE FIGURE SW2 NE2 INTERPRETIVE NORTHEAST-SOUTHWEST CROSS SECTION (NE2-SW2) WHITE MESA SITE EXPLANATION Qaf Kdbc Jmbb Alluvium/Fill Dakota Sandstone/ Burro Canyon Formation Brushy Basin Member of Morrison Formation Shale/claystone in Dakota / Burro Canyon Formation Conglomerate or Conglomeratic Sandstone in Dakota / Burro Canyon Formation Piezometric Surface TW N - 1 8 MW - 1 9 PI E Z - 1 TW N - 9 * TW N - 1 4 TW N - 1 7 * TW N - 1 9 5450 5470 5490 5510 5530 5550 5570 5590 5610 5630 5650 5670 5690 5710 5730 5750 el e v a t i o n ( f e e t a m s l ) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 distance along cross section (feet) Notes: (1) approximately 200 feet north of cross section (2) approximately 200 feet south of cross section vertical exaggeration = 8 : 1 SJS Note: water levels from TWN-9 and TWN-17 are from Q2, 2013 * denotes abandoned boring H:/718000/hydrpt14/ xsection/nsxs2ne/nsxs2neb.srf 16 B APPROVED DATE REFERENCE FIGURE 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 distance along cross-section (feet) 5460 5480 5500 5520 5540 5560 5580 5600 5620 5640 5660 5680 5700 5720 5740 5760 el e v a t i o n ( f e e t a m s l ) TW N - 7 TW N - 2 TW 4 - 2 5 TW 4 - 2 1 TW N - 1 PI E Z - 3 Hi s t o r i c a l P o n d La w z y S u m p SA G L e a c h F i e l d Am m o n i u m S u l f a t e T a n k s ( 1 ) Am m o n i a T a n k s ( 2 ) Fo r m e r O f f i c e L e a c h F i e l d ( 3 ) Ma i n L e a c h F i e l d ( 4 ) QafKm Km Km Kdbc Kdbc Kdbc Jmbb Jmbb Notes: (1) approximately 115 feet southwest of cross-section (2) approximately 150 feet southwest of cross-section (3) approximately 300 feet south of cross-section (4) immediately south of cross-section EXPLANATION Qaf Km Kdbc Jmbb Alluvium/Fill Mancos Shale Dakota Sandstone/ Burro Canyon Formation Brushy Basin Member of Morrison Formation Shale/claystone in Dakota / Burro Canyon Formation Conglomerate or Conglomeratic Sandstone in Dakota / Burro Canyon Formation Piezometric Surface INTERPRETIVE NORTHWEST-SOUTHEAST CROSS SECTION (NW-SE) WHITE MESA SITE NW SE vertical exaggeration = 3 : 1 SJS H:/718000/hydrpt14/ xsection/ewxsne/ewxsneb.srf 17 APPROVED DATE REFERENCE FIGURE EXPLANATION Qal Km Kdbc Jmbb Alluvium/Fill Mancos Shale Dakota Sandstone/ Burro Canyon Formation Brushy Basin Member of Morrison Formation Piezometric surface vertical exaggeration = 5:1 Shale/claystone within Dakota/Burro Canyon Conglomerate within Dakota/Burro Canyon INTERPRETIVE EAST-WEST CROSS SECTIONS (W-E and W2-E2) SOUTHWEST INVESTIGATION AREA 0 500 1000 1500 2000 2500 3000 3500 distance along cross section (feet) 5450 5475 5500 5525 5550 5575 5600 5625 5650 el e v a t i o n ( f e e t a m s l ) DR - 2 ( a b n d ) DR - 5 DR - 6 DR - 7 MW - 3 5 W E Qal Km Kdbc Kdbc Jmbb Jmbb 0 500 1000 1500 2000 2500 3000 3500 4000 4500 distance along cross section (feet) 5450 5475 5500 5525 5550 5575 5600 5625 el e v a t i o n ( f e e t a m s l ) DR - 8 DR - 9 DR - 1 0 DR - 1 1 DR - 1 2 DR - 1 3 Qal Km Km Kdbc Kdbc Jmbb Jmbb W2 E2 18 H:/718000/hydrpt14/ xsection/ewxssw/ewxsswb.srf APPROVED DATE REFERENCE FIGURE EXPLANATION Qal Km Kdbc Jmbb Alluvium/Fill Mancos Shale Dakota Sandstone/ Burro Canyon Formation Brushy Basin Member of Morrison Formation Piezometric surface INTERPRETIVE NORTH-SOUTH CROSS SECTION (S-N) SOUTHWEST INVESTIGATION AREA vertical exaggeration = 20:1 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 distance along cross section (feet) 5375 5400 5425 5450 5475 5500 5525 5550 5575 5600 5625 el e v a t i o n ( f e e t ) Ru i n S p r i n g DR - 2 5 ( a b n d ) DR - 2 1 MW - 2 0 DR - 1 6 ( a b n d ) MW - 3 A DR - 1 3 MW - 3 7 Qal Km Km Km Kdbc Kdbc Jmbb Jmbb S N Shale/claystone within Dakota/Burro Canyon Conglomerate within Dakota/Burro Canyon H:/718000/hydrpt14/xsection/nsxssw/nsxsswb.srf 19 H:\718000\hydrpt14\DR_ Hydrographs.xls: DR Piez Hydrographs 0 20 40 60 80 100 120 12/18/2010 7/16/2011 2/11/2012 9/8/2012 4/6/2013 11/2/2013 5/31/2014 Measurement Date St a t i c W a t e r L e v e l ( f e e t b g s ) DR-5 DR-6 DR-7 DR-8 DR-9 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-23 DR-24 DR SERIES PIEZOMETER DEPTHS TO WATER 2Q 2011 TO 1Q 2014 HYDRO GEO CHEM, INC.Approved FigureDateAuthorDate File Name SJS 5/12/14 20DR Piez Hydrograph5/12/14SJS (not included) 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 EXPLANATION perched monitoring well perched piezometer seep or spring KRIGED 1st QUARTER, 2014 WATER LEVELS SHOWING INFERRED PERCHED WATER PATHLINES AND KRIGED NITRATE AND CHLOROFORM PLUMES H:/718000/hydrpt4/maps/UflowNchl.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 TW4-32 temporary perched monitoring well temporary perched nitrate monitoring well TW4-12 TWN-7 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet 5 3 90 kriged perched water level contour and label estimated perched water flow path estimated capture zone resulting from chloroform and nitrate pumping kriged nitrate > 10 mg/L within area addressed by nitrate CAP kriged chloroform > 10 ug/L 21 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1000 feet MW-25 MW-27 MW-31 TW4-01 TW4-02 TW4-03 TW4-04 TW4-05 TW4-06 TW4-09 TW4-10 TW4-11 TW4-12 TW4-13 TW4-14 MW-26 TW4-16 MW-32 TW4-18TW4-19 TW4-20 TW4-21 TW4-22 TW4-23 TW4-24 TW4-25 TW4-26 TW4-32 TW4-33 TW4-34 PIEZ-02 PIEZ-03 PIEZ-04 TWN-01 TWN-02 TWN-03 TWN-04 TW4-07 TW4-08 MW-04 TW4-27 TW4-29 TW4-32 TW4-33 TW4-34 TW4-28 TW4-30 TW4-31 5540 5574 5549 5554 5559 5580 5543 5581 5540 5580 5576 5566 5582 5573 5528 5559 5562 5551 55805565 5559 5578 5570 5543 5564 5561 5539 5595 5593 5541 5590 5595 5598 5592 5556 5557 5553 5527 5534 5564 5537 5534 5580 5526 5522 EXPLANATION estimated chloroform capture zone boundary stream tubes resulting from pumping perched monitoring well showing elevation in feet amsl temporary perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl temporary perched monitoring well installed September, 2013 showing elevation in feet amsl MW-4 TW4-1 PIEZ-2 TW4-32 KRIGED 1st QUARTER, 2014 WATER LEVELS AND ESTIMATED CAPTURE ZONES WHITE MESA SITE (detail map) H:/718000/hydrpt14/ maps/Ucap0314.srf 5551 5553 5595 5563 NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated nitrate capture zone boundary stream tubes resulting from pumping 22 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TW4-23 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-02 TW4-05 TW4-06 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-27 TW4-19 TW4-26 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-03 TW4-08 MW-04 DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5581 5503 5471 5503 5523 5501 54945494 5500 5588 5603 5453 dry 5451 5495 5507 5539 5577 5544 5513 5538 5548 dry 5494 5493 5484 55795549 5550 55765571 5598 5594 5610 5598 5544 5542 5597 5610 5602 5603 5586 5591 5561 5590 5587 5586 5615 5639 5588 5587 5584 5605 5608 5588 5609 5583 5544 5539 5555 5584 5574 5526 5559 5586 5538 5518 5555 5558 5585 5584 55675563 55855571 5543 5493548354845492 5474 5480 5482 5487 5492 5487 5466 5465 5454 5455 5443 5420 dry 5425 5418 5624 5383 5234 5560 5380 5468 (not included) EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring showing elevation in feet amsl KRIGED 4th QUARTER, 2011 WATER LEVELS WHITE MESA SITE H:/718000/hydrpt14/maps/Uwl1211b.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed October, 2011 showing elevation in feet amsl TW4-27 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-10 5503 5584 5586 5594 5518 5380 Estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are pumping wells 23 H:\718000\may14\wltrend_q114.xls: wltrend plot 5530 5535 5540 5545 5550 5555 Q4 07 Q1 08 Q2 08 Q3 08 Q4 08 Q1 09 Q2 09 Q3 09 Q4 09 Q1 10 Q2 10 Q3 10 Q4 10 Q1 11 Q2 11 Q3 11 Q4 11 Q1 12 Q2 12 Q3 12 Q4 12 Q1 13 Q2 13 Q3 13 Q4 13 Q1 14 Quarter Wa t e r L e v e l ( f t a m s l ) TW4-4 TW4-6 TW4-4 AND TW4-6 WATER LEVELSHYDRO GEO CHEM, INC.Approved FigureDateAuthorDateFile Name SJS 24wltrend plotSJS HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5584 5503 5472 5503 5524 5501 54955494 5503 5587 5597 5455 dry 5451 5495 5508 5539 5575 5545 5514 5540 5549 dry 5492 5494 5493 5486 55755557 5551 55695560 5585 5592 5595 5593 5539 5535 5590 5598 5598 5592 abandoned 5589 5563 abandoned abandoned abandoned abandoned abandoned abandoned 5588 abandoned 5606 abandoned 5587 5609 5580 5544 5556 5582 5573 5529 5562 5576 5563 5534 5553 5559 5579 5579 55655561 55795565 5542 5539 5540 5580 5526 5522 5534 5528 5536 5483 5485 5492 5474 5480 5483 5487 5490 5487 5467 5466 5454 5455 5444 5421 dry 5426 5418 5624 5383 5234 5560 5380 5468 (not included) EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring showing elevation in feet amsl KRIGED 1st QUARTER, 2014 WATER LEVELS SHOWING INFERRED PERCHED WATER PATHLINES DOWNGRADIENT OF THE TAILINGS CELLS WHITE MESA SITE H:/718000/hydrpt4/maps/Uflowsw14.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5503 5582 5562 5592 5564 5380 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet estimated perched water flow path downgradient of tailings cells 5390 kriged perched water level contour and label 25 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5584 5503 5472 5503 5524 5501 54955494 5503 5587 5597 5455 dry 5451 5495 5508 5539 5575 5545 5514 5540 5549 dry 5492 5494 5493 5486 55755557 5551 55695560 5585 5592 5595 5593 5539 5535 5590 5598 5598 5592 abandoned 5589 5563 abandoned abandoned abandoned abandoned abandoned abandoned 5588 abandoned 5606 abandoned 5587 5609 5580 5544 5556 5582 5573 5529 5562 5576 5563 5534 5553 5559 5579 5579 55655561 55795565 5542 5539 5540 5580 5526 5522 5534 5528 5536 5483 5485 5492 5474 5480 5483 5487 5490 5487 5467 5466 5454 5455 5444 5421 dry 5426 5418 5624 5383 5234 5560 5380 5468 (not included) 12151615141312111111111314 1415 15 161719 20 22 232426 27 29 30 31 8 6 4 3 3 3 4 4 5 5 5 6 EXPLANATION perched monitoring well showing elevation in feet amsl perched piezometer showing elevation in feet amsl seep or spring showing elevation in feet amsl H:/718000/ hydrpt4/springs/Uspgfl14.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 showing elevation in feet amsl TW4-32 temporary perched monitoring well showing elevation in feet amsl temporary perched nitrate monitoring well showing elevation in feet amsl TW4-12 TWN-7 5503 5582 5563 5592 5563 5380 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet KRIGED 1st QUARTER, 2014 WATER LEVELS SHOWING INFERRED PERCHED WATER FLOW PATHLINES NEAR RUIN SPRING AND WESTWATER SEEP estimated perched flow path line 16 estimated saturated thickness in feet 26 HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 5624 5383 5234 5560 5380 5468 (not included) 5552 5493 5557 5495 5492 5560 5474 EXPLANATION perched monitoring well perched piezometer seep or spring KRIGED 1st QUARTER, 2014 WATER LEVELS SHOWING INFERRED PERCHED WATER FLOW PATHS USED FOR TRAVEL TIME ESTIMATES AND KRIGED NITRATE AND CHLOROFORM PLUMES H:/718000/hydrpt4/maps/UpathNchl.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 TW4-32 temporary perched monitoring well temporary perched nitrate monitoring well TW4-12 TWN-7 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet 5 3 9 0 kriged perched water level contour and label kriged nitrate > 10 mg/L within area addressed by nitrate CAP kriged chloroform > 10 ug/L inferred perched water pathline potential perched flow pathline (assuming hypothetical connection to Cottonwood Seep) 27 B ur ro Canyon Fo rma t ion Brushy Basin Member APPROVED DATE REFERENCE FIGURE HYDRO GEO CHEM, INC. 28 PHOTOGRAPH OF THE WESTWATER SEEP SAMPLING LOCATION JULY, 2010 H:/718000/ hydrpt14/maps/westsmpl2.srfSJS Westwater Seep (sampling location) B ur ro Canyon Fo rma t ion Brushy Basin Member APPROVED DATE REFERENCE FIGURE HYDRO GEO CHEM, INC. 29 PHOTOGRAPH OF THE CONTACT BETWEEN THE BURRO CANYON FORMATION AND THE BRUSHY BASIN MEMBER AT WESTWATER SEEP H:/718000/ hydrpt14/maps/westcontact2.srfSJS Westwater Seep (immediately downgradient from sampling location) Burro Canyon Formation Brushy Basin Member HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27TW4-06 TW4-23 TW4-28 TW4-29 TW4-30 TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 (not included) EXPLANATION perched monitoring well perched piezometer seep or spring KRIGED 1st QUARTER, 2014 WATER LEVELS SHOWING KRIGED NITRATE AND CHLOROFORM PLUMES AND GENERAL FLOW DIRECTIONS WHITE MESA SITE H:/718000/hydrpt4/maps/UflowNchlnp.srf MW-5 PIEZ-1 RUIN SPRING temporary perched monitoring well installed September, 2013 TW4-32 temporary perched monitoring well temporary perched nitrate monitoring well TW4-12 TWN-7 estimated dry area NOTE: MW-4, MW-26, TW4-4, TW4-19, and TW4-20 are chloroform pumping wells; TW4-22, TW4-24, TW4-25, and TWN-2 are nitrate pumping wells estimated area having saturated thickness less than 5 feet 539 0 kriged perched water level contour and label approximate perched water flow direction kriged nitrate > 10 mg/L within area addressed by nitrate CAP kriged chloroform > 10 ug/L 30 H:\718000\hydrpt14\TW27area_wl2.xls: plot F30 5510 5520 5530 5540 5550 5560 5570 5580 5590 5600 12/31/1999 12/30/2001 12/30/2003 12/29/2005 12/29/2007 12/28/2009 12/28/2011 date el e v a t i o n ( f t a m s l ) TW4-6 TW4-12 TW4-13 TW4-14 TW4-26 TW4-27 WATER LEVELS IN WELLS NEAR TW4-12 AND TW4-27HYDRO GEO CHEM, INC.Approved FigureDateAuthorDateFile Name SJS 31plot F30SJS HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile Mill Site Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B MW-01 MW-02 MW-03 MW-05 MW-11 MW-12 MW-14MW-15 MW-17 MW-18 MW-19 MW-20 MW-21 MW-22 MW-23 MW-24 MW-25 MW-26 MW-27 MW-28 MW-29 MW-30 MW-31 MW-32 MW-33 MW-34 MW-35 MW-36 MW-37 TW4-01 TW4-10 TW4-20TW4-22 TWN-01 TWN-02 TWN-03 TWN-04 TWN-05 TWN-06 TWN-07 TWN-08 TWN-09 TWN-10 TWN-11 TWN-12 TWN-13 TWN-14 TWN-15 TWN-16 TWN-17 TWN-18 TWN-19 PIEZ-01 PIEZ-02 PIEZ-03 PIEZ-04 PIEZ-05 TW4-03 TW4-05 TW4-09 TW4-11 TW4-12 TW4-13 TW4-14 TW4-16 TW4-18 TW4-31 TW4-32 TW4-34 TW4-19 TW4-04 TW4-07 TW4-21 TW4-24 TW4-25 TW4-26 TW4-02 TW4-08 MW-04 TW4-27 TW4-06 TW4-23 TW4-28 TW4-29 TW4-30TW4-33DR-05 DR-06 DR-07 DR-08 DR-09 DR-10 DR-11 DR-12 DR-13 DR-14 DR-15 DR-17 DR-19 DR-20 DR-21 DR-22 DR-23 DR-24 AWN-X1 AWN-X2 AWN-X3 DR-02 DR-16 DR-18 DR-25 EXPLANATION H:/718000/hydrpt14/ maps/pyrite_occurrence_rev2.srf MW-5 MW-24 MW-29 MW-33 MW-25 WHITE MESA SITE PLAN SHOWING PYRITE OCCURRENCE IN PERCHED BORINGS perched boring (pyrite status unknown) perched boring having detailed log showing no pyrite perched boring showing pyrite in log and having a laboratory detection (if analyzed) perched boring having pyrite detected via laboratory analysis only (not shown in log) perched boring having a possible pyrite detection via laboratory analysis (but not in log) MW-30 perched boring showing pyrite in log and having no laboratory detection 32 APPENDIX A LITHOLOGIC LOGS APPENDIX A.1 DR - SERIES APPENDIX A.2 MW - SERIES APPENDIX A.3 PIEZ - SERIES APPENDIX A.4 TW4 - SERIES APPENDIX A.5 TWN - SERIES APPENDIX B WELL CONSTRUCTION SCHEMATICS APPENDIX B.1 DR - SERIES APPENDIX B.2 MW - SERIES APPENDIX B.3 TW4 - SERIES 2 TW4-27 AS-BUILT WELL CONSTRUCTION SCHEMATIC SJS 10/25/11 K:\7180272A Well Construction DiagramCHEM, INC. GEO HYDRO Approved Date FigureReference 2 APPENDIX B.4 TWN - SERIES APPENDIX C INTERA SOIL BORING LOGS H:\718000\hydrpt14\AppC_INTERA_logs\INTERA soil boring logs summary.doc C-1 APPENDIX C INTERA SOIL BORING LOGS SUMMARY In May and June 2011, INTERA, Inc. installed 75 soil borings in the vicinity of the mill site. Borings GP-01A1 through GP-02A1 and GP-01C through GP-07C were installed to the north and south of the mill site and tailings cells; GP-01B through GP-48B were completed within and immediately outside the area of the mill site. Borings were drilled by Earth Worx using the Geoprobe push probe method. Soil samples for lithologic logging were collected using the continuous dual tube method. Locations of soil borings are provided on Figures C.1 and C.2; copies of the boring logs are provided in Appendix C.1. Soil samples from the GP-A1 and GP-B series borings showed a consistent lithology. Depths of refusal ranged from 2.7 ft bgs to 9.7 ft bgs. Yellowish-red, silty, fine sand predominated from the ground surface to about four to six ft bgs, generally transitioning to pink, silty, fine sand or pink sandstone to the depth of refusal. Roots were occasionally present in the top several feet of the borings. Soil samples from the GP-C series borings within or near the mill site showed more variable lithology. Depths to refusal were deeper overall than in the GP-A1 and GP-B series borings, and ranged from 1.7 to 24.5 ft bgs. Yellowish-red silty sand predominated in the upper portion of the GP-C borings, from approximately four to 10 ft bgs, and was typically underlain by interbedded reddish clay or clayey silt, and pinkish silt or silty sand to the depth of refusal. Gypsum precipitate was commonly seen in the lower portions of the GP-C series borings, and fine gravel was present in low proportions in multiple borings. FIGURES HYDRO GEO CHEM, INC. APPROVED DATE REFERENCE FIGURE 1 mile Mill Site CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING RUIN SPRING WESTWATER Cell 1 Cell 2 Cell 3 Cell 4A Cell 4B GP-01A GP-02A GP-03A GP-04A GP-05A GP-06A GP-07A GP-08A GP-09A GP-10A GP-11A GP-12A GP-13A GP-14A GP-15A GP-16A GP-17A GP-18A GP-19A GP-20A GP-01C GP-02C GP-03C GP-04C GP-05C GP-06C GP-07C EXPLANATION off-site Intera soil borings GP-01A through GP-20A seep or spring GP-01A RUIN SPRING off-site Intera soil borings GP-01C through GP-07C GP-01C GP-01B on-site Intera soil borings GP-01B through GP-48B INTERA SOIL BORING LOCATIONS WHITE MESA SITE See Inset Map Detail Figure C.2 H:/718000/hydrpt14/Intera_logs/interaloc.srf C.1 Cell 1 Cell 2 Cell 3 Cell 4A GP-07B GP-35B GP-25B GP-39B GP-08B GP-36B GP-44B GP-26B GP-40B GP-11BGP-12B GP-31B GP-32B GP-33B GP-46B GP-47B GP-42B GP-43B GP-21BGP-22B GP-23B GP-24B GP-16B GP-37B GP-03B GP-05B GP-10B GP-34B GP-45B GP-48B GP-41B GP-15B GP-38B GP-04B GP-01B GP-02B GP-09B HYDRO GEO CHEM, INC.APPROVED DATE REFERENCE FIGURE EXPLANATION GP-01B INTERA BORING LOCATIONS GP-1B THROUGH GP-48B (DETAIL MAP) WHITE MESA SITEon-site Intera soil borings GP-01B through GP-48B GP-06B GP-13B GP-14B GP-30BGP-28BGP-27B GP-29B GP-20B GP-19B GP-17B GP-18B H:/718000/hydrpt14/ Intera_logs/intera_loc_det_rev.srf C.2 APPENDIX C.1 INTERA BORING LOGS 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 1 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-01A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.95 0.5/0.65 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.7' Silty SAND, reddish brown (5YR 4/4), very fine-grained sand, silt, poorly graded, very loose, dry, little white mottling, HCl strong 3.7-4.5' Silty SAND, pink (5YR 6/4), very fine-grained sand, silt, poorly graded, medium dense, dry, HCl strong Total depth of boring 4.5' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 2 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-02A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 3.1/3.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.7' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl weak to moderate, little white mottling w/ HCl strong 4.7-7.1' Silty SAND, pink (5YR 7/3), very fine-grained sand, silt, poorly graded, dense, dry, HCl strong, trace fine sand Total depth of boring 7.1' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 3 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate additional sample volume required by the analytical laboratory. Log of Soil Boring GP-03A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 2.8/3.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis (1) 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose, dry, root at top, HCl strong 4.0-6.8' Silty SAND, reddish yellow (6/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl strong, trace fine sand Total depth of boring 6.8' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 4 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-04A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.7' Silty SAND, reddish brown (5YR 4/4), very fine-grained sand, silt, poorly graded, very loose, dry, little white mottling, HCl strong 3.7-4.0' Silty SAND, pink (5YR 6/4), very fine-grained sand, silt, poorly graded, medium dense, dry, HCl strong Total depth of boring 4.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 5 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-05A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Duel Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.7 3.6/3.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-6.4' Silty SAND, yellow red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose, roots at top, HCl moderate 6.4-7.6' Silty SAND, light brown gray (10YR 6/2), very fine-grained sand, silt, poorly graded, dense, dry, HCl strong, trace fine sand Total depth of boring 7.6' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 6 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-06A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.1 4.0/3.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis (1) 0-5.9' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl moderate, trace roots at top, little white mottling w/ HCl strong 5.9-8.0' Silty SAND, very pale brown (10YR 8/4), very fine-grained sand, silt, poorly graded, dense, dry, HCl strong, trace fine sand Total depth of boring 8.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 7 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-07A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 4.0/3.3 1.7/1.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.9' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl strong, little white mottling, HCl strong 4 to 4.9' bgs 4.9-7.5' Silty SAND, pink (7.5YR 7/4), very fine-grained sand, silt, poorly graded, medium dense to dense, dry, HCl strong, trace loose fine sand 7 to 7.5' 7.5-9.7' Silty SAND, pink (7.5YR 7/3), very fine-grained sand, silt, poorly graded, loose to dense, dry, HCl strong, trace fine sand Total depth of boring 9.7' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 8 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-08A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose, dry, trace gravel, roots at top, HCl none 3.5-4.0' Silty SAND, pink (7.5YR 8/4), very fine-grained sand, silt, poorly graded, dense, dry, HCl strong Total depth of boring 4.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 0 9 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Duplicate sample collected. Sample interval was increased to 2 feet to accommodate additional sample volume required by the analytical laboratory. Log of Soil Boring GP-09A1 (Page 1 of 1) Date/Time Started : 05/17/11 Date/Time Completed : 05/17/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.95 4.0/3.75 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose, dry, HCl none, trace roots 4.0-8.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand trace fine-grained sand, silt, poorly graded, loose, HCl none, trace mica, trace white mottled w/ HCl strong Total depth of boring 8.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 0 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-10A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 2.66/1.25 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none to weak 2.0-2.7' Sand/Silty Sand, very pale brown (10YR 8/3), very fine-grained sand, trace silt, poorly graded, loose, dry, subangular to subrounded, HCl none, little very fine sand Total depth of boring 2.7' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 1 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Duplicate sample collected. Sample interval was increased to 2 feet to accommodate additional sample volume required by the analytical laboratory. Log of Soil Boring GP-11A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 1.0/1.2 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none 3.0-5.0' Silty SAND, yellowish red (5YR 5/8 & very pale brown 10YR 8/2), fine-grained sand, silt, poorly graded, loose to medium dense, dry, some white mottling w/ HCl strong, mottled but little red or very pale brown, HCl weak to medium, trace fine sand Total depth of boring 5.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 2 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-12A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none 2.0-4.0' Silty SAND, pink (5YR 7/4), very fine-grained sand, silt, poorly graded, medium dense loose to medium dense, trace fine sand, dry, some white mottling w/ HCl strong Total depth of boring 4.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 3 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-13A1 (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.1 0.7/0.7 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, trace white mottling w/ HCl strong 4.0-4.7' Silty SAND, pink (5YR 7/4), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl strong, trace fine sand Total depth of boring 4.7' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 4 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-14A1 (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.9 2.9/1.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-5.8' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, trace white mottling w/ HCl strong, HCl none to weak 5.8-6.9' Silty SAND, pink (5YR 7/4 & yellowish red 5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, some what mottling w/ HCl strong, trace fine sand Total depth of boring 6.9' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 5 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-15A1 (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 3.6/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-5.1' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, trace white mottling w/ HCl strong, HCl none to weak 5.1-7.6' Silty SAND, pink (5YR 7/4), very fine-grained sand, silt, poorly graded, medium dense, dry, trace fine sand, HCl strong, some white mottling w/ HCl strong Total depth of boring 7.6' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 6 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Duplicate sample collected. Sample interval was increased to 2 feet to accommodate additional sample volume required by the analytical laboratory. Log of Soil Boring GP-16A1 (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.7 3.1/3.3 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.1' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none 3.1-7.1' Silty SAND, pink (5YR 7/4), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl strong, trace fine sand Total depth of boring 7.1' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 7 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Notes: Log of Soil Boring GP-17A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 3.2/2.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl weak 2.5-3.2' Silty SAND, pink (5YR 7/4), very fine-grainded sand, silt, loose to medium dense, dry, HCl strong, trace fine sand, little white mottling w/ HCl strong Total depth of boring 3.2' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 8 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Notes: Log of Soil Boring GP-18A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 3.3/3.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-6.9' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl strong, trace white mottling w/ HCl strong, trace roots at top 6.9-7.3' Silty SAND, pink (5YR 7/4), very fine-grainded sand, silt, poorly graded, loose to medium dense, dry, HCl strong, trace fine sand Total depth of boring 7.3' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 1 9 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Duplicate sample collected. Sample interval was increased to 2 feet to accommodate additional sample volume required by the analytical laboratory. Log of Soil Boring GP-19A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v l Pe n . / R e c . ( f e e t ) 4.0/3.9 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-6.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none to weak, little white mottling w/ HCl strong 6.0-8.0' Silty SAND, pink (5YR 7/4), very fine-grainded sand, silt, poorly graded, loose to medium dense, dry, HCl strong, trace fine sand, sand & fine gravel 7.9-8.0' bgs Total depth of boring 8.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o re L o g s \ D e n i s o n \ G P - 2 0 A 1 . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Notes: Log of Soil Boring GP-20A1 (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 1.1/1.3 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.1' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none 3.1-5.1' Silty SAND, pink (5YR 7/4), very fine-grainded sand, silt, loose to medium dense, dry, HCl weak to strong, little white mottling w/ HCl strong, trace fine sand Total depth of boring 5.1' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 1 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-01B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.15 0.4/0.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.1' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, loose to dense, dry, HCl strong, mottling common 3.1-4.4' Silty Gravelly SAND, pinkish gray (5YR 7/2), very fine- to coarse-grained sand (~60%), gravel to 0.1" diameter (~30%), well graded, angular to subrounded, very loose, non-plastic, dry, no HCl Total depth of boring 4.4' bgs (refusal) US C S SM SW/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 2 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-02B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/1.5 4.0/3.8 3.8/3.5 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~65%), poorly graded, subangular to subrounded, loose, dry, HCl strong, roots abundant top 0.5' 3.0-7.0' Lean CLAY, light reddish brown (5YR 6/3), very fine-grained sand (~25%), subangular to subrounded, soft, medium plastic, moist, HCl moderate 7.0-11.8' Clayey SAND, light reddish brown (5YR 6/3), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose to dense, medium plastic, moist, HCl strong Total depth of boring 11.8' bgs (refusal) US C S SM CL SC GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 3 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-03B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 4.0/4.0 1.6/2.2 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, dry, HCl strong, mottling common 4.0-8.6' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, moist, HCl strong, mottling common 8.6-9.6' Lean CLAY, pink (5YR 7/4), very fine-grained sand (~25%), subangular to subrounded, soft, moderately plastic, moist, HCl strong Total depth of boring 9.6' bgs (refusal) US C S SM CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 4 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-04B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 0.8/1.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, dry, HCl weak, mottling common, roots in top 0.3' 4.0-4.6' SILT, red (2.5YR 5/6), very fine-grained sand (~25%), loose, non-plastic, non-cohesive, dry, HCl strong Total depth of boring 4.8' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 5 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-05B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 4.0/3.4 4.0/3.9 1.3/1.3 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-6.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common, roots in top 1.3' 6.5-13.3' Clayey SILT, yellowish brown (10YR 5/4), loose to dense, non- to slightly plastic, dry to moist, HCl slight, gypsum stringers and precipitate common Total depth of boring 13.3' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 6 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-06B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 4.0/4.0 4.0/4.0 1.8/1.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~80%), poorly graded, angular to subrounded, very loose, dry, no HCl 1-4' HCl strong and 5YR 4/4 4.0-8.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~80%), poorly graded, angular to subrounded, very loose, dry, HCl 8.0-12' Clayey SILT, yellowish brown (10YR 5/4), poorly graded, loose, non-plastic, dry to moist, HCl slight 12-13.8' Clayey SILT, yellowish brown (10YR 5/4), poorly graded, loose, non-plastic, dry, HCl slight, laminated Total depth of boring 13.8' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 7 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-07B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.5 4.0/3.5 2.8/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common 4.0-8.0' Silty SAND, reddish brown (5YR 5/4), very fine-grainded sand (~80%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common 8.0-10.2' Silty SAND, reddish brown (5YR 5/4), very fine-grainded sand (~60%), poorly graded, subangular to subrounded, slightly dense, dry, HCl strong, white mottling common 10.2-10.8' SILT, pink (5YR 7/4), very dense to hard, non-plastic, dry, HCl strong Total depth of boring 10.8' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 8 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-08B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 4.0/3.9 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis Road base 0.8-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, dense, dry, HCl strong, white mottling throughout 4.0-8.0' SILT, pink (5YR 7/4), trace very fine-grained sand, loose, non-plastic, dry, HCl strong 8.0-11.3' Silty SAND, pink (5YR 7/4), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose to dense, dry, HCl strong 11.3-12' SILT, pink (5YR 7/4), very dense, hard, non-plastic, dry, HCl strong Total depth of boring 12' bgs (refusal) US C S SM ML SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 9 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-09B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.2 4.0/3.75 3.4/3.4 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, reddish brown (5YR 5/4), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common 4.0-8.0' Silty SAND, reddish brown (5YR 5/4), very fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common 8.0-10.8' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, slightly dense, dry to moist, HCl strong, white mottling common 10.8-11.4' SILT, pink (5YR 7/4), very dense, hard, non-plastic, dry, HCl strong Total depth of boring 11.4' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 0 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-10B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 4.0/4.0 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common 4.0-8.0' Silty SAND, reddish brown (5YR 5/4), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common 8.0-11.5' Silty SAND, reddish brown (5YR 5/4), very fine-grained sand (~60%), poorly graded, loose to dense, dry, HCl strong, white mottling common 11.5- 12' SILT, pink (5YR 7/4), very dense, hard, dry, HCl strong Total depth of boring 12' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 1 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-11B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 4.0/3.2 4.0/3.2 0.1/0.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2.0' Silty SAND, reddish brown (5YR 4/4), very fine-grained sand (~60%), poorly graded, subangular to subrounded, very loose, dry, HCl slight, roots 2.0-4.0' Silty SAND, light reddish brown (5YR 6/3), very fine-grained sand (~60%), poorly graded, subangular to subrounded, very loose, dry, HCl strong 4.0-7.0' Silty SAND, light reddish brown (5YR 6/3), very fine-grained sand (~60%), poorly graded, subangular to subrounded, very loose, dry, HCl strong 7.0-12.1' Clayey SILT, pinkish gray (7.5YR 6/2), loose to dense, non-plastic, dry, HCl strong, white mottling common, laminated Total depth of boring 12.1' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 2 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-12B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.5 4.0/3.1 4.0/3.4 0.4/0.4 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.5' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, poorly graded, subangular to subrounded, very loose, dry, no HCl 0-1.5' bgs, HCl slight 1.5-8.0' Silty SAND, reddish brown (5YR 5/4), very fine-grained sand, poorly graded, subangular to subrounded, very loose, dry, HCl slight, laminated 8.0-12.4' Clayey SILT, light olive brown (2.5YR 4/3), poorly graded, loose, non-plastic, dry, HCl, laminated, gypsum precipitate throughout 10.5-12' 5-10mm gypsum stringers Total depth of boring 12.4' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 3 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-13B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 4.0/4.0 4.0/4.0 1.8/1.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.5' Silty SAND, yellowish red brown (5YR 4/6), very fine-grained sand, poorly graded, subangular to subrounded, very loose, dry, HCl slight 1.5-6.2' Silty SAND, light reddish brown (5YR 6/3), very fine-grained sand, poorly graded, subangular to subrounded, very loose, dry, HCl slight 6.2-8.0' Clayey SILT, reddish brown (5YR 5/4), trace very fine-grained sand, loose to dense, non-plastic, dry to moist, HCl strong, white mottling throughout 8.0-12' Clayey SILT, dark grayish brown (10YR 4/2), dense, slightly plastic, dry, HCl weak, thin bedding 12-13.8' Clayey SILT, light yellowish brown (10YR 6/4), loose, non-plastic, dry, HCl slight, thin bedding Total depth of boring 13.8' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 4 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-14B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 4.0/3.0 4.0/3.5 2.0/2.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand, poorly graded, subangular to subrounded, very loose, dry, no HCl quartz fragments 4.0-4.7' bgs 4.7-8.0' Silty SAND, reddish yellow (2.5YR 6/6), very fine-grained sand, poorly graded, loose to dense, dry, HCl moderate, white mottling throughout 8.0-12' Clayey SILT, brown (7.5YR 5/2), poorly graded, loose to dense, non-plastic, dry, HCl slight 12-14' Clayey SILT, yellowish brown (10YR 5/6), poorly graded, loose to dense, non-plastic, dry, HCl slight Total depth of boring 14' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 5 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-15B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.4 4.0/3.4 4.0/2.8 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.5' Silty SAND, yellowish red (5YR 4/6), very fine- to medium-grained sand (~80%), well graded, angular to subrounded, loose, dry to moist, HCl moderate, minor white mottling 3.5-4.0' Clayey SILT, light reddish brown (5YR 6/4), poorly graded, dense, slightly plastic, moist, HCl moderate 4.0-10' Silty SAND, yellowish red (5YR 4/6), very fine-grainded sand (~75%), poorly graded, subangular to subrounded, loose, dry to moist, HCl strong, white mottling throughout 10-12' CLAY, yellowish red (5YR 4/6), dense, low to medium plastic, cohesive, moist, HCl slight 12-16' CLAY, pale brown (10YR 6/3), very dense, low plastic, slightly cohesive, dry, HCL moderate, minor FeO staining Total depth of boring 16' bgs (refusal) US C S SM ML/CL SM CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 6 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-16B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 4.0/3.2 4.0/3.1 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-5.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~75%), poorly graded, subangular to subrounded, loose, dry to moist, no HCl 5.5-8.0' Silty SAND, reddish yellow (5YR 6/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling throughout 8.0-11.3' CLAY, reddish yellow (5YR 6/6), hard, medium plastic, cohesive, dry to moist w/ increasing moisture towards base of interval, HCl strong 11.3-16' CLAY, pale brown (10YR 6/3), very hard, slightly plastic, slightly cohesive, moist, HCl strong Total depth of boring 16' bgs (refusal) US C S SM CL ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 7 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-17B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 4.0/3.85 4.0/3.65 4.0/3.4 2.6/2.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.4' FILL 1.4-12' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~75%), poorly graded, subangular to subrounded, loose, dry, HCl moderate, white mottling common 12-15.6' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, moist, HCl strong, white mottling common 15.6-16' SILT, very pale brown (10YR 7/4), hard, non-plastic, non-cohesive, dry, HCl moderate 16-18' Lean CLAY, yellowish red (5YR 5/6), very fine-grained sand (~30%), subrounded, soft, slightly plastic, slightly cohesive, moist, HCl slight 18-18.6' SILT, very pale brown (10YR 7/4), hard, non-plastic, non-cohesive, dry, HCl moderate Total Depth of Boring 18.6' bgs (refusal) US C S SM ML ML/CL ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 8 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-18B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/4.0 4.0/3.8 4.0/3.8 4.0/3.25 2.5/2.85 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.5' FILL 1.5-12' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~75%), poorly graded, subangular to subrounded, loose, dry, HCl strong, white mottling common, caliche rich 10-10.5' bgs 12-16' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~75%), poorly graded, subangular to subrounded, loose, slightly moist with moisture increasing w/ depth, HCl strong, occasional white mottling 16-17.9' Sandy Silty CLAY, yellowish red (5YR 5/6), very fine-grained sand (~30%), soft, slightly plastic, slightly cohesive, moist, HCl slight 17.9-18.5' SILT, very pale brown (10YR 7/4), hard, non-plastic, non-cohesive, dry, HCl strong, shale Total depth of boring 18.5' bgs (refusal) US C S SM ML/CL ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 1 9 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-19B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.85 4.0/3.85 4.0/3.95 4.0/3.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2.5' FILL 2.5-12' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~75%), poorly graded, subangular to subrounded, loose, dry, HCl moderate, occasional white mottling 12-17.1' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose to dense, slightly moist to moist increasing w/ depth, HCl strong, occasional white mottling 17.1-17.9' SILT, very pale brown (10YR 7/4), very dense, hard, non-plastic, dry, HCl strong, weathered shale Total depth of boring 17.9' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 0 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-20B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/4.0 4.0/3.9 4.0/3.5 4.0/3.2 1.4/1.4 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.0' FILL 1.0-12' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, dry, HCl moderate, occasional white mottling 12-16' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, moist, HCl moderate, occasional white mottling 16-16.7' Sandy Lean CLAY, very fine-grained sand (~15%), yellowish red (5YR 5/6), soft, medium plastic, medium cohesive, very moist, HCl slight 16.7-17.4' SILT, very pale brown (10YR 7/4), hard, non-plastic, dry, HCl strong, shale Total depth of boring 17.4' bgs (refusal) US C S SM CL ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 1 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-21B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.3 2.7/2.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.5' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, moist, HCl weak, gravel from 3.8-4.0' 4.5-5.5' Silty SAND, pink (5YR 7/3), very fine-grained sand (~60%), poorly graded, subrounded, loose, slightly cohesive, wet, HCl moderate 5.5-6.7' Sandy SILT, light yellowish brown (10YR 6/4), very fine-grained sand (~15%), poorly graded, subrounded, loose, dry, thin bedding, HCl strong Total depth of boring 6.7' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 2 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-22B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 4.0/2.9 0.9/1.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~75%), poorly graded, subrounded, loose, dry to slightly moist, HCl no to weak 4.0-7.6' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, moist to very moist, HCl weak 7.6-8.0' SILT, pink (5YR 8/3), very fine-grained sand (~25%), poorly graded, subrounded, dense, slightly cohesive, moist, HCl strong8.0-8.9' SILT, brownish yellow (10YR 6/6), very fine-grained sand (~25%), poorly graded, subrounded, loose, slightly moist, HCl weak, thin bedding Total depth of boring 8.9' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 3 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-23B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 4.0/2.5 4.0/2.0 3.3/2.3 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2.0' Silty SAND, reddish gray (5YR 5/2), very fine- to coarse-grained sand, well graded, angular to subrounded, loose, non-plastic, dry, HCl moderate 2.0-4.0' Lean CLAY w/ Sand, brownish yellow (10YR 6/6), fine- to coarse-grained sand (~20%), well graded, angular to subrounded, hard, slightly plastic, moist, HCl slight, burned (ash?) layer from 2.0-2.2' bgs 4.0-15.3' Sandy Lean CLAY, reddish brown (5YR 5/4), fine- to coarse-grained sand (~30%), up to 0.05' diameter gravel (<10%), well graded, angular to subrounded, soft, low to moderate plastic, moist, HCl weak Total depth of boring 15.3' bgs (refusal) US C S SW/SM CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 4 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-24B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.7 4.0/2.7 4.0/2.5 0.8/0.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-8.0' Clayey Gravelly SAND, dark yellowish brown, (10YR 4/4), very fine- to coarse-grained sand (~75%), up to 0.04' diameter gravel (~15%), soft, slightly plastic, moist, HCl weak 8.0-11.3' Sandy Gravelly SILT, brown (10YR 5/3), fine- to coarse-grained sand (~30%), up to 0.02' diameter gravel (~10%), soft, slightly plastic, moist, HCl weak 11.3-12.5' Silty SAND, brownish yellow (10YR 6/6), very fine- to fine-grained sand (~70%), well graded, subangular to subrounded, dense, dry, no HCl, gypsum precipitate throughout 12.5-12.8' Silty SAND, yellowish red (5YR 4/6), very fine- to fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, wet, HCl weak Total depth of boring 12.8' bgs (refusal) US C S SW/SC ML SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 5 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-25B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.1 4.0/3.6 4.0/3.8 4.0/4.0 3.4/3.4 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-0.75' Road base gravel 0.75-11.7' Silty SAND, reddish yellow (5YR 6/6), very fine-grained sand (~65%), poorly graded, subangular to subrounded, loose to dense, dry to 10.9' bgs, moist to 11.7' bgs, HCl strong, occasional white mottling 11.7-13.3' CLAY, reddish yellow (5YR 6/6), dense, plastic to very plastic, cohesive, slightly moist, HCl strong 13.3-19.4' CLAY, pale brown (10YR 6/3), dense, slightly plastic, slightly cohesive, dry, HCl slight, weathered shale, platy shale fragments increasing w/ depth, weathered shale w/ shale fragments Total depth of boring 19.4' bgs (refusal) US C S SM CL/CH ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 6 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-26B (Page 1 of 1) Date/Time Started : 06/09/11 Date/Time Completed : 06/09/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 4.0/3.3 4.0/3.6 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-0.3' Road base gravel 0.3-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, dense, moist, HCl strong, white mottling common 4.0-10.1' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, dense, dry to moist, HCl moderate, white mottling common 10.1-13' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, dense, moist, HCl moderate 13-16' SILT, yellowish brown (10YR 5/4), very dense, hard, dry, HCl strong Total depth of boring 16' bgs (refusal) US C S SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 7 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-27B (Page 1 of 1) Date/Time Started : 06/10/11 Date/Time Completed : 06/10/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 4.0/3.3 4.0/3.6 2.6/2.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, dry, HCl moderate, mottling common 4.0-11.8' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, moist, HCl weak, mottling rare 11.8-13' Clayey SAND, yellowish red (5YR 4/6), very fine-grained sand, subrounded, loose, slightly plastic, moist, HCl strong, mottling throughout 13-14.6' Sandy SILT, yellowish brown (10YR 5/6), very fine-grained sand (~25%), subrounded, loose, non-plastic, non-cohesive, dry, HCl strong Total depth of boring 14.6' bgs (refusal) US C S SM SC ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 8 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-28B (Page 1 of 1) Date/Time Started : 06/10/11 Date/Time Completed : 06/10/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 4.0/3.0 4.3/3.4 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-7.4' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, moist, HCl weak to strong 7.4-7.7' Lean CLAY w/ Sand, very dark gray (5YR 3/1), very fine-grained sand (~15%), soft, plastic, moist, HCl weak 7.7-12' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, moist, HCl weak, occasional mottling 12-12.3' Clayey SAND, very pale brown (10YR 7/3), very fine-grained sand w/ plastic fines, poorly graded, subangular to subrounded, loose, slightly plastic, moist, HCl strong Total depth of boring 12.3' bgs (refusal) US C S SM CL SM SC GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 2 9 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-29B (Page 1 of 1) Date/Time Started : 06/10/11 Date/Time Completed : 06/10/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.95 4.0/3.0 4.0/3.25 2.4/2.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.3' Road base 1.3-3.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, dry, HCl moderate, white mottling throughout 3.0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, loose, moist, gravel and wood fragments common, HCl moderate, 4.0-12' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, dry to moist, HCl weak, occasional mottling 12-13.2' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, moist, HCl moderate 13.2-14.4' Silty SAND, yellowish brown (10YR 5/4), very fine-grained sand (~60%), poorly graded, subangular to subrounded, dense, moist, HCl moderate Total depth of boring 14.4' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 0 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-30B (Page 1 of 1) Date/Time Started : 06/10/11 Date/Time Completed : 06/10/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 4.0/3.15 4.0/3.3 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-7.1' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, loose, dry to moist, HCl weak, occasional mottling 7.1-7.2' Clayey SAND w/ low plastic fines, dark reddish brown (5YR 3/4), very fine-grained sand, poorly graded, subrounded, soft, slightly plastic, moist, HCl moderate 7.2-12' Silty SAND, Yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, moist, HCl none to weak 12-13.1' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, wet, HCl moderate Total depth of boring 13.1' bgs (refusal) US C S SM SC SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 1 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-31B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.1 1.6/1.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.7' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~65%), poorly graded, subangular to subrounded, very loose, dry, HCl moderate, white mottling throughout 4.7-5.6' SAND w/ minor Silt, pinkish gray (7.5YR 6/2), very fine- to fine-grained sand, poorly to well graded, subangular to subrounded, very loose, moist, HCl strong Total depth of boring 5.6' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 2 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-32B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subangular to subrounded, very loose, dry to moist increasing w/ depth, HCl moderate Total depth of boring 4.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 3 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-33B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 1 2 3 4 5 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 1.7/1.7 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.2' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~75%), poorly graded, subangular to subrounded, very loose, dry, HCl moderate, minor white mottling 1.2-1.7' SAND w/ minor Silt, pinkish gray (5YR 6/2), very fine- to fine-grained sand, poorly to well graded, subangular to subrounded, very loose, dry, HCl strong Total depth of boring 1.7' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 4 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-34B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 3.8/2.7 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~65%), poorly graded, subangular to subrounded, loose, dry to moist, HCl slight, minor roots 0-0.8' bgs 3.0-3.8' SAND w/ minor silt, pinkish gray (5YR 6/2), very fine- to fine-grained sand, poorly to well graded, subangular to subrounded, very loose, moist, HCl strong Total depth of boring 3.8' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 5 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-35B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.5 4.0/1.8 4.0/2.7 4.0/3.7 2.9/2.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' SAND w/ gravel FILL, dark reddish brown (5YR 3/3), fine- to coarse-grained sand, gravel to 0.06' diameter, well graded, angular to subrounded, loose, dry, HCl moderate 4.0-11' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~75%), poorly graded, subrounded, loose, moist, HCl moderate, mottling common 11-12' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~75%), poorly graded, subrounded, dense, moist, HCl weak 12-17.4' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~75%), poorly graded, subrounded, loose, moist to wet near bottom of interval. HCl weak 17.4-18.9' Clayey SILT, yellowish brown (10YR 5/4), dense, slightly plastic, moist, HCl strong Total depth of boring 18.9' bgs (refusal) US C S SW SM ML/CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 6 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-36B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.5 4.0/2.6 4.0/2.8 4.0/3.4 9.3/3.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, loose, dry, HCl moderate, mottling common 2.5-11' Clayey Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, soft, slightly plastic, moist, HCl moderate 11- 13' Clayey Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, dense, slightly plastic, moist, no HCl 13-18.3' Silty SAND, reddish yellow ( 5YR 6/8), very fine-grained sand (~70%), poorly graded, subrounded, loose, dry to moist increasing with depth, HCl strong, mottling common 18.3-19.3' SILT, light gray (10YR 7/2), very fine-grained sand (~30%), subrounded, dense, non-plastic, dry, HCl strong, FeO staining Total depth of boring 19.3' bgs (refusal) US C S SM SM/SC SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 7 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-37B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 4.0/3.2 4.0/4.0 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, dry, HCl strong, mottling throughout 4.0-9.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subrounded, loose, moist, HCl slight, occasional mottling 9.0'-13.2' Clayey SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subrounded, soft, slightly plastic, moist, HCl strong, ~30% motttling 13.2-16' Clayey SILT, yellowish brown (10YR 5/6), soft to hard, slightly plastic, moist, HCl strong, ~5% mottling Total depth of boring 16' bgs (refusal) US C S SM SC ML/CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 8 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-38B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 4.0/3.3 4.0/3.1 4.0/4.0 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-5.0' Silty SAND, yellowish red (5YR 5/8), very fine-grained sand (~70%), poorly graded, subrounded, loose, dry, HCL strong, mottling common 5.0-11.9' Silty SAND, yellowish red (5YR 5/8), very fine-grained sand (~60%), poorly graded, subrounded, dense, moist, HCl weak 11.9-16' Clayey SILT, yellowish brown (10YR 5/6), soft to hard, slightly plastic, moist, massive-transitions to platy structure near bottom of interval, HCl slight Total depth of boring 16' bgs (refusal) US C S SM ML/CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 3 9 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-39B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 4.0/4.0 4.0/4.0 2.2/3.4 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-6.6' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~70%), poorly graded, subrounded, loose, dry to moist, HCL none 0-4' bgs & strong 4-6.6' bgs, mottling common 4-6.6' bgs 6.6-11' Lean CLAY, reddish brown (5YR 5/3), very fine-grained sand (~15%), poorly graded, subrounded soft, slightly plastic to plastic, moist, HCl strong 11-12.8' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, moist w/ moisture increasing with depth, HCl weak 12.8-14.2' Sandy SILT, gray (10YR 5/1), very fine-grained sand (~30%), poorly graded, subrounded, dense, dry, HCl weak, thin bedding to platy, FeO common 12.8-13.6' bgs Total depth of boring 14.2' bgs (refusal) US C S SM CL SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 0 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-40B (Page 1 of 1) Date/Time Started : 06/12/11 Date/Time Completed : 06/12/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 4.0/4.0 4.0/3.9 1.6/1.8 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subrounded, loose, dry to moist, HCL moderate 4.0-8.0' Sandy Silty Lean CLAY, yellowish red (5YR 5/6), very fine-grained sand (~20%), poorly graded, subrounded, soft, slightly plastic, moist, HCl moderate, occasional mottling 8.0-13' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, moist, HCl moderate, occasional mottling 13-13.6' Sandy SILT, yellowish brown (10YR 5/4), very fine-grained sand (~30%), poorly graded, subrounded, soft, slightly plastic, moist, HCl moderate Total depth of boring 13.6' bgs (refusal) US C S SM ML/CL SM ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 1 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-41B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 25 30 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.4 4.0/2.8 4.0/3.0 4.0/2.8 4.0/2.7 4.0/3.8 0.5/0.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-6.5' SAND, pale yellow (5Y 8/2), very fine- to fine-grained sand (~85%), poorly graded, subangular to subrounded, dense, dry, HCl none 6.5-19' Silty SAND, light brown (7.5YR 6/3) to pinkish gray (7.5YR 7/2), very fine-grained sand (~60%), poorly graded, subangular to subrounded, loose, dry, HCl none, thin bedded, occasional sandstone fragments, occasional FeO stains 19-24.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, loose, dry, HCl strong, mottling common Total depth of boring 24.5' bgs (refusal) US C S SP SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 2 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-42B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.4 4.0/3.8 0.5/1.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-5.5' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~65%), poorly graded, subangular to subrounded, loose, dry to moist, HCl strong, mottling common 5.5-8.0' Clayey Silty SAND, reddish brown (5YR 5/4), very fine-grained sand, poorly graded, subrounded, dense, slightly plastic, moist, HCl strong, mottling common 8.0-8.5' Silty CLAY, dark reddish brown (5YR 3/2), soft, slightly plastic to plastic, non-cohesive, dry, HCl strong, weathered shale, thin bedding Total depth of boring 8.5' bgs (refusal) US C S SM SM/SC ML/CL GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 3 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-43B (Page 1 of 1) Date/Time Started : 06/11/11 Date/Time Completed : 06/11/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.5 4.0/4.0 1.7/1.9 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-1.8' Fill 1.8-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~65%), poorly graded, subrounded, loose, dry, HCl moderate 4.0-5.8' Well Graded GRAVEL, very pale brown (10YR 2/3), fine- to medium-grained sand (~10%), gravel (~40%), well graded, subangular to subrounded, very loose, non-plastic, dry, HCl moderate 5.8-8.4' Clayey SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, dense, plastic, moist, HCl strong 8.4-9.7' SILT, light yellowish brown (10YR 6/4), soft, non-plastic, non-cohesive, moist, HCl strong Total depth of boring 9.7' bgs (refusal) US C S SM GW/GM SC ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 4 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-44B (Page 1 of 1) Date/Time Started : 06/10/11 Date/Time Completed : 06/10/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 15 20 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.3 4.0/2.8 4.0/3.7 4.0/3.5 2.4/3.1 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, pale brown (10YR 6/3), very fine- to medium-grained sand (~80%), well graded, subrounded, loose, dry, HCl moderate, fine crystals precipitate throughout 4.0-6.0' Clayey Sitly SAND, very pale brown (10YR 7/4), very fine-grained sand (~60%), poorly graded, subrounded, loose, slightly plastic, dry, HCL none, small rocks, wood scattered throughout 6.0-8.0' Clayey Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~60%), poorly graded, subrounded, slightly plastic, moist, HCl weak 8.0-12' Lean CLAY, dark reddish brown (5YR 3/2), silt, soft, slightly plastic, moist, HCl weak 12-14.3' Sandy Lean CLAY, dark reddish brown (5YR 3/2), very fine-grained sand (~20%), poorly graded, subrounded, very soft, plastic to very plastic, very cohesive, moist, HCl weak 14.3-16' Lean CLAY, gray to blueish gray (2 6/1), hard, plastic, non-cohesive, moist, HCl none, laminate bedding, weathered shale 16-18' Lean CLAY, blueish gray to gray (2 6/1), loose, plastic, moist, HCl none, thin bedding, FeO staining throughout, weathered shale 18-18.4' SILT, blueish gray to gray (2 5/1), hard, laminate bedding, shale fragments Total depth of boring 18.4' bgs (refusal) US C S SW/SM SM/SC CL CL/CH CL ML GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 5 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Duplicate sample collected. Sample interval was increased to 2 feet to accommodate for additional sample volume required by the analytical laboratory. Log of Soil Boring GP-45B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.0 0.6/0.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, dark reddish brown (5YR 3/4), fine- to very fine-grained sand, poorly graded, subangular to subrounded, very loose, moist to wet, HCl none, roots 0-2' bgs 4.0-4.6' SAND w/ minor silt, pinkish gray (5YR 6/2), very fine- to fine-grained sand, poorly graded, subangular to subrounded, very loose, moist, HCl none Total depth of boring 4.6' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 6 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-46B (Page 1 of 1) Date/Time Started : 06/07/11 Date/Time Completed : 06/07/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.8 0.3/0.6 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-3.7' Silty SAND, dark reddish brown (5YR 3/4), very fine-grained sand (~70%), poorly graded, subangular to subrounded, very loose, moist to wet, HCl slight 3.7-4.3' SAND w/ minor silt, yellowish red (5YR 5/6), very fine- to fine-grained sand, poorly graded, subangular to subrounded, very loose, moist, HCl none Total depth of boring 4.3' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 7 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-47B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.6 0.7/0.7 DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.7' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand (~80%), poorly graded, subangular to subrounded, very loose to loose, moist to wet, HCl none, roots 0-2.5' bgs Total depth of boring 4.7' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 4 8 B . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): Log of Soil Boring GP-48B (Page 1 of 1) Date/Time Started : 06/08/11 Date/Time Completed : 06/08/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : E. Muller Depth in Feet 0 1 2 3 4 5 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 2.3/ DESCRIPTION Sample Interval Description Soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-2.0' Silty SAND, yellowish red (5YR 5/6), very fine-grained sand (~70%), poorly graded, subangular to subrounded, very loose, dry, HCl none, roots 0-1.4' bgs 2.0-2.3' SAND w/ minor Silt, light gray (10YR 7/2), very fine- to fine-grained sand, poorly graded, subangular to subrounded, very loose, dry, HCl strong Total depth of boring 2.3' bgs (refusal) US C S SM SP/SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 1 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-01C (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 3.5/2.8 DESCRIPTION Sample Field test sample collected; not submitted to lab (1) Field test sample submitted for laboratory analysis Duplicate soil sample not submitted for laboratory analysis 0-3.1' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none, trace white mottled HCl strong 3.1-3.5' Sandstone, pink (5YR 7/3), very fine- to fine-grained sand, dense, dry, HCl medium to strong Total depth of boring 3.5' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 2 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-02C (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 2.7/2.7 DESCRIPTION Sample Interval Description Field test soil sample collected; not submitted to lab (1) Field test soil sample submitted for laboratory analysis Duplicate soil sample not submitted for laboratory analysis 0-2.3' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl strong 2.3-2.7' Sandstone, brownish yellow (10YR 6/6), very fine- to fine-grained sand, poorly graded, loose to dense, dry, subangular to subrounded, HCl none Total depth of boring 2.7' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 3 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-03C (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/2.8 2.6/2.7 DESCRIPTION Sample Interval Description Field test soil sample collected; not submitted to lab (1) Field test soil sample submitted for laboratory analysis Duplicate soil sample submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none 4.0-5.4' Silty SAND, pink (5YR 7/4), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, trace fine sand, HCl medium to strong, white mottling w/ HCl strong 5.4-6.6' Sandstone, light brown gray (10YR 6/2), very fine- to fine-grained sand, loose to dense, dry, HCl none to weak, subangular to subrounded Total depth of boring 6.6' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 4 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-04C (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.3 1.5/1.7 DESCRIPTION Sample Interval Description Field test soil sample collected; not submitted to lab (1) Field test soil sample submitted for laboratory analysis Duplicate soil sample not submitted for laboratory analysis 0-5.1' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none, trace white mottling w/ HCl strong, roots at top Total depth of boring 5.1' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 5 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-05C (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.6 DESCRIPTION Sample Interval Description Field test soil sample collected; not submitted to lab (1) Field test soil sample submitted for laboratory analysis Duplicate soil sample not submitted for laboratory analysis 0-4.0' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose, dry, HCl none, trace white mottling w/ HCl strong Total depth of boring 4.0' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 6 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-06C (Page 1 of 1) Date/Time Started : 05/19/11 Date/Time Completed : 05/19/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.4 1.6/1.7 DESCRIPTION Sample Interval Description Field test soil sample collected; not submitted to lab (1) Field test soil sample submitted for laboratory analysis Duplicate soil sample not submitted for laboratory analysis 0-4.4' Silty SAND, yellowish red (5YR 4/6), very fine-grained sand, silt, poorly graded, loose to medium dense, dry, HCl none to strong, some white mottling w/ HCl strong 3.2-4.4' bgs 4.4-4.9' Silty SAND, pink (5YR 7/4), very fine-grained sand, silt, poorly graded, loose to medium dense, HCl strong, trace fine sand 4.9-5.6' Rock fragments, white, HCl none, very fine grained Total depth of boring 5.6' bgs (refusal) US C S SM GR A P H I C 07 - 2 8 - 2 0 1 1 S : \ P r o j e c t s \ B o r e L o g s \ D e n i s o n \ G P - 0 7 C . b o r White Mesa Mill, Blanding, Utah Denison Nitrate Investigation Project Name: Project #: DENMC.C002.000 Note(s): 1. Field test soil sample not submitted to laboratory due to no detectable results during test kit analysis. Log of Soil Boring GP-07C (Page 1 of 1) Date/Time Started : 05/18/11 Date/Time Completed : 05/18/11 Drilling Method : Geoprobe Sampling Method : Continuous Dual Tube Drilling Co./Driller : Earth Worx Driller : L. Trujillo Depth to Water : NA Logged by : J. Reed Depth in Feet 0 5 10 Sa m p l e I n t e r v a l Pe n . / R e c . ( f e e t ) 4.0/3.2 2.1/2.1 DESCRIPTION Sample Interval Description Field test soil sample collected; not submitted to lab (1) Field test soil sample submitted for laboratory analysis Duplicate soil sample not submitted for laboratory analysis 0-1.5' Sandy Clayey SILT, reddish brown (5YR 4/4), very fine-grained sand, medium stiff, dry to moist, cohesive, HCl none 1.5-1.7' CLAY, dark red brown (5YR 3/4), stiff, moist, medium plastic 1.7-4.9' Sandy SILT/Silty SAND, reddish brown (5YR 4/4), very fine-grained sand, silt, medium stiff/medium dense, slightly moist to moist, trace clay (cohesive), trace fine sand, HCl none to weak, trace white mottling at 2.5' bgs, little more sand or more silt 4.9-6.1' Silty SAND/SAND, brownish yellow (10YR 6/4), very fine- to fine-grained sand, silt (varying amounts), medium dense, slightly moist, trace medium sand, slightly cohesive, HCl none, little iron stained Total depth of boring 6.1' bgs (refusal) US C S ML CL ML/SM SM/SP GR A P H I C APPENDIX D HISTORIC WATER LEVEL MAPS D.1 D.2 D.3 APPENDIX E TOPOGRAPHIC AND GEOLOGIC MAPS ! ! ! ! ! ! ! CORRAL CANYON 5624 CORRAL SPRINGS 5383 COTTONWOOD 5234 ENTRANCE SPRING 5560 FROG POND 5590 RUIN SPRING 5380 WESTWATER 5468 Approved Date Author Date File Name Figure HYDRO GEO CHEM, INC. SEEPS AND SPRINGS ON USGS TOPOGRAPHIC BASE WHITE MESA 7180002G09/17/10SJS 707/16/10DRS 0.5 0 0.5 10.25 Mile Cell No. 1 Cell No. 3 Cell No. 2 Cell No. 4A NK:\718000\GIS\7180002G.mxd: Friday, September 17, 2010 1:02:59 PM Cell No. 4B WESTWATER 5468 Seep or Spring Elevation (feet) above mean sea level 0.5 10 Mile E E E E E E E Cell No. 1 Cell No. 2 Cell No. 3 Cell No. 4A Qh Qlbb Qlbb Qlbb Kdb Kdb Kdb Kdb Kdb Kdb Jmb Jmb Jmb Jmb Jmb Jmb Qea Qea Qea Qea Qa Qa Qa Qa Qa Kdb Kdb Jmb Qa Cell No. 4B Jmw Jmr Qh Qea Jmr Jmw Kdb Jmb Kdb Kdb CORRAL CANYON CORRAL SPRINGS COTTONWOOD ENTRANCE SPRING FROG POND RUIN SPRING WESTWATER GEOLOGIC MAP WHITE MESA, UTAH SJSÒApproved Date File Figure HYDRO GEO CHEM, INC.12/28/11 Geological Map of the Blanding Area, San Juan County, Utah (modified from Haynes et al., 1962; Dames & Moore, 1978 and Kirby, 2008) Base Map Prepared from Portions of the Blanding South, Black Mesa Butte, Big Bench and No Mans Land U.S.G.S. 7.5' Quadrangles. K:\718000\GIS\Geology E.2 Contact - dashed where uncertain E Seep or Spring EXPLANATION Tailing Cell Artificial cut and fill Stream alluvium Slumps and landslides, Brushy Basin Mixed eolian and alluvial deposits Dakota and Burro Canyon Formations (undivided) Brushy Basin Member of the Morrison Formation Westwater Canyon Member of the Morrison Formation Recapture Member of the Morrison Formation QhQhQhQh QaQaQaQa QlbbQlbbQlbbQlbb QeaQeaQeaQea KdbKdbKdbKdb JmbJmbJmbJmb JmwJmwJmwJmw JmrJmrJmrJmr