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HomeMy WebLinkAboutDRC-2012-002050 - 0901a068803141f5. f State of Utah GARY R. HERBERT Governor GREG BELL Lieutenant Governor Department of Environmental Quality Amanda Smith Executive Director DIVISION OF RADIATION CONTROL Rusty Lundberg Director DRC-/e|12-002050 September 20,2012 CERTIFIED MAIL (Return Receipt Requested) a DP IT m tr a o a a CO 1-^ cr a Jo Ann Tischler, Director, Compliance and Permittmg a Energy Fuels Resources (USA) Inc. ^ 225 Umon Boulevard, Suite 600 Lakewood,CO 80228 — U.S. Postal Service ri CERTIFIED MAILn, RECEIPT (Domestic Mail Only; No Insurance Coverage Provided) For delivery information visit our website at wwv/.usps.comoj OFFICIAL USE Postage Certified Fee Retum Receipt Fee (Endorsement Required) Restrtcted Delivery Fee (Endorsement Required) $ Postmark Here Postage Certified Fee Retum Receipt Fee (Endorsement Required) Restrtcted Delivery Fee (Endorsement Required) Postmark Here Postage Certified Fee Retum Receipt Fee (Endorsement Required) Restrtcted Delivery Fee (Endorsement Required) Postmark Here Postage Certified Fee Retum Receipt Fee (Endorsement Required) Restrtcted Delivery Fee (Endorsement Required) Postmark Here Postage Certified Fee Retum Receipt Fee (Endorsement Required) Restrtcted Delivery Fee (Endorsement Required) Postmark Here Sent To "Sfi^ei,'A'pt"i\ orPOBoxM City, State, 2 Jo Ann Tischler Energy Fuels Resources (USA) Inc 225 Union Boulevard, Suite 600 Lakewood, CO 80228 PS Form 3100, August 2006 See Reverse for Instructions Subject: Energy Fuels Resources (USA) Inc. ''''Revised Report on the Hydrogeology of the Perched Groundwater Zone in the Area Southwest of the Tailings Cells, White Mesa Uranium Mill Site'': DRC Review Summary, Request for Information and Conclusions Dear Ms. Tischler: The Utah Division of Radiation Control ("DRC") has reviewed the Energy Fuels Resources (USA) Inc. ("EFR") July 13,2012 Response to May 30, 2012 NOED and RFI Southwest Hydrogeology Investigation Report ("EFR Response Letter") and, the August 3,2012 EFR Cover Letter and attached Document titled "Revised Report on the Hydrogeology of the Perched Groundwater Zone in the Area Southwest of the Tailings Cells, White Mesa Uranium Mill Site" ("Revised Report") prepared by Hydro Geo Chem, Inc ("HOC"). Summarv The Report was revised from the January 12, 2012 Report on the Hydrogeology of the Perched Groundwater Zone in the Area Southwest of the Tailings Cells ("Onginal Report") based on telephone conferences between EFR and DRC staff on May 23,2012 and July 2,2012, as well as a DRC Notice of Enforcement Discretion and Request for Information Letter dated May 30, 2012 ("DRC Letter") Per these documents/discussions EFR responded to the identified issues (and modified the Report as applicable) as follows:' • In response to the May 30, 2012 DRC Letter regarding EFR abandonment of study bonngs with a saturated thickness greater than five feet [violation of the White Mesa 195 North 1950 West • Salt Lake City, UT Maihng Address P O Box 144850 • Salt Lake City, UT 84114-4850 Telephone (801) 536-4250 • Fax (801) 533-4097 'TDD (801) 536-4414 www deq Utah gov Printed on 100% recycled paper Jo Ann Tischler Page 2 Uranium Mill Ground Water Discharge Permit, UGW370004 (Permit) Part IH 6 a 2], EFR disagrees with the basis of the violation, specifically per the EFR Response Letter "At the outset, and as discussed with DRC staff, it should be noted that Denison disagrees that the abandonment of three borings, which had a saturated thickness of 5- feet or more, constitutes a violation of the Permit Part IH6a 2 The Permit does not specify how many borings are required or where the bonngs were to be located The Permit merely requires that the charactenzation/definition of the subsurface shall be based on either dry wells, to delineate dry areas, or wet wells to delineate areas that are not dry, in an effort to define the dry zones It further states that in order to qualify as a wet well, the well must have a saturated thickness of at least 5 feet The Permit does not state that all bonngs drilled need to be retained It merely states that enough dry and wet bonngs must be drilled in order to define the dry area Denison and its experts determined that the three borings in question were not required in order to define the dry area, so they were abandoned." DRC Response: DRC disagrees that the only intention of the Permit requurement was to define dry areas Per the Permit Part I H.6. "The purpose of this investigation is to define, demonstrate, and characterize 1) Hydraulic connection and local groundwater flow directions between the area near Tailings Cell 4B, and the western margin of White Mesa, including Westwater, Cottonwood Seeps, and Ruin Spnng, and 2) the full physical extent of unsaturated area between former well MW'16, MW-33 and the western margin of White Mesa, as defined above " Part I H.6.a of the Permit requnes that bonngs and/or momtonng wells are installed to achieve both of these goals, not just the delineation of area unsaturated ("dry") zones. In preparation of the groundwater level and groundwater contour maps included with the Report, water level data at wells, with at least 5 feet of saturated thickness, are the cntical tool to develop the contours and groundwater flow directions. In particular, the decision to abandon well DR-02 and to discount the water levels at that well and not perform hydraulic tests biased the data west of the tailmgs cells by eliminating important information relevant to the study Per the DRC Letter request for information item one "the Report data shows relatively significant saturated thickness, >10 ft, measured at piezometer DR-05 and boring DR-02 (pnor to abandonment), but does not provide field data to determine how far west the zone of saturation extends or to provide hydraulic evaluation of that zone." Information relevant to abandoned well DR-02 was needed to help charactenze the flow directions m that area, additionally; the information for all **wet wells" was needed m order to define and support the Report ground water elevation contours and anticipated flow paths. It is the DRC contention tiiat the abandonment of the 'Vet wells" was m violation of the Permit Part IH 6.a.2 which requires EFR to completely enclose and define the shallow aquifer and to complete piezometers that encounter a saturated thickness of five feet or more as specified, m order to achieve the purposes of the study Jo Ann Tischler Page 3 • In response to the DRC Letter request for information item number one, EFR has included a potential flow path fi"om the tailings cells to Cottonwood Seep, and included travel tune calculations This action is required based on the lack of field data and study to predict flow directions west of the tailings cells in the area piezometer DR-05 and abandoned bonng DR-02. The HGC conclusion in the Onginal Report that a flow divide is present m this area is not supported by the current field data. EFR has mcluded figures m the Revised Report to depict a potential flow path fi-om the tailmgs cells to Cottonwood Seep. DRC and EFR agreed that Cottonwood Seep may be recharged m part by the Dakota/Burro Canyon aquifer (Perched Aquifer) • In response to the DRC Letter request for information item number two, EFR has committed to repeat slug tests at piezometer DR-08 and recalculate average hydraulic properties (K and Ss) as discussed m the request for information section of this letter below. • In response to the DRC Letter request for information item number three, EFR has removed language and figures in the Revised Report which related to a hydrauhc corinection between Westwater Creek and Cottonwood Seep. The statements that such a connection is "likely** are not supported by the investigation data & were not withm the scope of the mvestigation Request for Information Per the DRC Letter, the request for mformation item number two specifically requested* "The Report, Table 3, lists slug test results (K and Ss) for the investigation completed piezometers DRC notes that the slug test results for piezometer DR-08 differ by an order of magnitude between the automatically logged data and the hand collected data DRC additionally notes that Table 3 lists, "Not Interpretable " as the K value at DR-08 by the Bouwer-Rice Method using the Hand Collected data Slug tests at piezometer DR-08 need to be repeated in order to validate the reported hydraulic conductivity values, and to substantiate the inclusion of these results in the hydraulic conductivity averages." In the EFR Response Letter regarding this request EFR "agrees to repeat slug tests at piezometer DR-08 as requested." DRC noted that no timelme was included m the EFR Response Letter regardmg when EFR will conduct/complete the pump test and recalculate the average hydraulic conductivity used m the Revised Report. Per a telephone conversation between EFR Representative (Jo Ann Tischler) and DRC Staff (Tom Rushmg) on September 18,2012 (2.15 P M.), EFR will submit the results of the repeated slug tests, as well as the recalculated hydrauhc parameters and travel time calculations (if necessary) on or before November 9,2012 DRC appreciates that any calculated travel times in the Revised Report are estimations only and have been represented as such These calculations mclude a potentially large margin of Jo Ann Tischler Page 4 error based on the hydraulic testmg method used (fallmg head slug tests). Per literature review it IS noted that such aquifer tests cannot account for formation amsotropy, may underestimate hydraulic conductivity due to the development of a low permeable well skin, and provide a weighted average for the entire wetted length of the boring/well screen (does not account for formation heterogeneities).^ The calculations submitted with the Revised Report provide usefiil information as an estimate of travel times for the anticipated ground water paths in this context, and comphes with the Permit Parts I H.6.a.2 and IH 6 e.6 Conclusions Based on review of the Report, DRC agrees with the Report Section 2 4, Part 3 and Conclusions that "an as yet unidentified connection may exist" between the Burro Canyon perched zone and Cottonwood Seep. Per discussions between DRC and EFR, the contmued investigation of preferred ground water flow path lines and potential hydraulic connections between the Burro Canyon Member and the Brushy Basin Member will not be reqmred at this time due to the EFR recogmtion that Cottonwood Seep may be recharged m part by the Dakota/Burro Canyon Aquifer (Perched Zone). Additionally, DRC recogmzes that Report language and figures (postulated source area) of the Ongmal Report which inferred that the "the likely source" of water discharged at Cottonwood Seep is Westwater Creek, via coarser gramed materials in the Brushy Basin Member and Westwater Canyon Member, has been removed smce such claims are unsubstantiated (see the DRC May 30, 2012 Letter for additional detail). DRC appreciates that HGC has better reflected the available ground water head data by removmg suspect ground water path Imes from the Ongmal Report which were based on an assumed hydrauhc divide in the area of piezometer DR-05. Per the DRC Letter, the postulated hydraulic divide on which those path lines were based is not supported by the field data. DRC acknowledges that additional study to charactenze the saturated zone and flow west of DR-05 and DR-02, in order to substantiate or refiite the claims m the Onginal Report, will not be required at this time based on the EFR acknowledgement that Cottonwood Seep may be recharged in part by the Dakota/Burro Canyon Aqmfer (Perched Zone) Therefore, per DRC mterpretation of the Revised Report, contmued ground water momtonng and analysis from Westwater Seep, Cottonwood Seep and Rum Spnng is warranted since they are potential pomts of exposure for discharges from the White Mesa Uramum Mill Tailings Impoundments. DRC appreciates the effort by EFR to prepare the Report and Revised Report This information is valuable regardmg mterpretation of ground water momtonng results from the White Mesa Mill momtonng network, a better understandmg of local geology/hydrogeology, as well as identification of long term momtonng needs. ' Binkhorst, Gordon K and Robbins, Gary A, February, 1994, A Review and Assessment of Factors Affecting Hydraulic Conductivity Values Determined from Slug Tests, EPA/600/R-93/202 Jo Ann Tischler Pages If you have any questions regardme th,^ I.H. I Rusty Lundber^Director ^ RL:TR.tr ""•^ ^es..«a.™yAug„,. 3.20.2 Revse. HOC R M™.