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Home My WebLink AboutDERR-2024-011034 Voluntary Cleanup Program March 2024 Site Characterization Report Former PacifiCorp Carbon Power Plant Helper, Utah Prepared for: 1407 West North Temple (Suite 110) Salt Lake City, Utah 84116 Prepared by: 756 E Winchester Street Suite 400 Salt Lake City, UT 84107 AECOM Job Number: 60577967 March 2024 March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 i March 2024 TABLE OF CONTENTS 1.0 Introduction ......................................................................................................................... 1 2.0 Site Description:.................................................................................................................. 4 3.0 Screening Criteria ............................................................................................................. 10 4.0 2019, 2020, 2022, and 2023 Site Investigations ............................................................... 11 5.0 Comparison of VCP Sampling Results to Human Health Screening Criteria .................. 16 6.0 Summary and Conclusions ............................................................................................... 21 7.0 Limitations ........................................................................................................................ 24 8.0 References ......................................................................................................................... 25 FIGURES Figure 1 Site Location Map Figure 2 VCP Sampling Areas Figure 3 Emery County Parcel Map Figure 4 Background Soil Sampling Locations Figure 5 Power House Area Sample Locations Figure 6 Waste Water Pond Area Sample Locations Figure 7a 2023 XRF Screening for Lead Figure 7b 2023 Soil Sampling for Lead Figure 8a Power House Area Potentiometric Surface Map (July 3, 2019) Figure 8b Power House Area Potentiometric Surface Map (May 11, 2020) Figure 8c Power House Area Potentiometric Surface Map (November 29 & 30, 2022) Figure 9a Waste Water Pond Area Potentiometric Surface Map (July 3, 2019) Figure 9b Waste Water Pond Area Groundwater and Price River Elevations (May 11, 2020) March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 ii March 2024 TABLES Table 1 Soil Sampling Table 2 Groundwater Sampling APPENDICES Appendix A Field Forms and Logs A1 – Boring Logs A2 – Trench Logs and Shallow Soil Sampling Forms A3 – Groundwater Sampling Forms A4 – Depth to Groundwater and Surface Water Measurements A5 – Well Abandonment, Daily Field Summaries, Other Forms, and 2023 XRF Work Plan Appendix B Laboratory Reports B1 – 2019 Laboratory Reports B2 – 2020 Laboratory Reports B3 – 2022 Laboratory Reports B4 - 2023 Laboratory Reports B5 – 2016 Laboratory Reports for Clean Imported Backfill Appendix C Lab Data Validation C1 – 2019 Data Validation Reports C2 – 2020 Data Validation Reports C3 – 2022 Data Validation Reports C4 – 2023 Data Validation Report Appendix D Utah Site Specific Cleanup Level Calculations for DRO and GRO Fractionations Appendix E Topographic Survey Data Appendix F Background Threshold Values Appendix G Soil Leaching Calculations March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 iii March 2024 ACRONYMS AWAL American West Analytical Laboratory BTV background threshold value CL low plasticity clay CS Coal Storage CT Cooling Tower DERR Utah Division of Environmental Response and Remediation DO dissolved oxygen concentration DRO diesel range organics EPA United States Environmental Protection Agency FCS Former Coal Storage GRO gasoline range organics GW well graded gravel ISL Utah Initial Screening Level Concentration LUST Leaking Underground Storage Tank MCL USEPA maximum contaminant level mg/kg milligrams per kilogram mg/L milligrams per liter ML silt NTU nephelometric turbidity unit ORP oxidation reduction potential PCB polychlorinated biphenyl PH Power House PID photoionization detector ppm parts per million PVC Polyvinyl chloride RAP Remedial Action Plan RSL Regional Screening Levels SM silty sand SSL soil screening level SSCL site specific cleanup levels SVOC semivolatile organic compound SW well graded sand TOC top of casing TPH total petroleum hydrocarbons TRPH total recoverable petroleum hydrocarbons UDEQ Utah Department of Environmental Quality UDWQ Utah Division of Water Quality UPRR Union Pacific Railroad USCS Unified Soil Classification System USEPA United States Environmental Protection Agency USFWS United States Fish and Wildlife Service UTL upper tolerance limit VCP Utah Voluntary Cleanup Program VOC volatile organic compound WQSs Utah Water Quality Standards WWP Former Waste Water Treatment Pond March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 1 March 2024 1.0 INTRODUCTION In calendar years 2019, 2020, 2022, and 2023 site assessments were performed at PacifiCorp’s Former Carbon Power Plant located near Helper, Utah (see Figure 1). Site work completed between 2019 and 2022 was performed under the oversight of the Utah Voluntary Cleanup Program (VCP) and in accordance with three approved VCP Site Assessment Workplans (AECOM, 2019, AECOM, 2020, AECOM 2021). In 2023, a limited soil sampling effort guided by X-Ray Diffraction (XRF) field screening, was performed to further assess an isolated hot spot of lead detected in 2022 at boring CS-UPRR33. Field investigations were performed between June 10 and July 3, 2019; May 4 through 14, 2020; November 14 through 30, 2022; and October 30 through October 31, 2023. Between the Dec 3, 2021, VCP workplan approval and the November 2022 field investigation, PacifiCorp was also negotiating with Union Pacific Railroad (UPRR) on a scope of work required in order to terminate a lease agreement. Currently PacifiCorp leases a portion of the Coal Storage Area (CS Area) from UPRR but plans to terminate the lease after completing the required site investigation activities. The site investigation work completed in November 2022 addressed both the UPRR lease termination and VCP program requirements and all results of these parallel site investigations are presented herein. The 2022 site investigation in the CS Area reported a surface soil sample at boring CS- UPPRR33 with a lead concentration of 1340 mg/kg. This detection significantly exceeded all historical lead concentrations observed during prior VCP investigations. The 1340 mg/kg concentration also exceeded the United States Environmental Protection Agency (USEPA) Composite Worker Regional Screening Level of 800 mg/kg. To further assess this isolated hot spot, XRF field screening was performed on October 30 and 31, 2023 to guide delineation of the extent of lead impacts near boring CS-UPRR33. Based on the XRF results, fifteen soil samples surrounding boring CS-UPRR33 were collected and submitted to the lab for lead analyses. The 2023 XRF screening and laboratory analyses for lead in soil are present herein. Brief Site History - When in operation, the Carbon Power Plant consisted of two power generating units constructed between calendar years 1954 and 1957. Low sulfur coal from mines near the site was used as the source of power. The plant was shut down in April 2015 and decommissioning began in late 2016. No structures remain other than a perimeter fence surrounding the area where the two power generating units once stood. During the demolition, concrete pad(s), and foundations beneath the former Power House were excavated three to five feet below grade with the remainder being left in place and then the area backfilled with up to eight feet of imported fill. The CS Area was also excavated to depths of up to 25 feet during demolition to remove coal and shallow soils. Following the excavation, the CS Area was backfilled with imported fill. In the spring of 2018, sediments from the Plant’s Waste Water Pond Area (WWP Area) were excavated to depths of three to five feet below existing grade and then the sediments disposed of offsite. Because the VCP study area encompasses a March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 2 March 2024 large area (approximately 168 acres), it has been subdivided into areas referred to throughout this report as the CS Area, Former Coal Storage (FCS), Power House (PH), Cooling Tower (CT), and WWP Area as shown on Figure 2. Summary of the 2019 Site Investigation - During the 2019 VCP site investigation, a Boart Longyear LSTM250 Sonic drill rig was used to advance borings and collect most of the soil samples. A few soil samples in the FCS Area were collected by using a trackhoe to trench into a berm. Soil sampling of the FCS berm was then performed with a hand auger. Background soil sampling for the former power plant area as well as other required surface soil sampling was performed using a hand auger. When groundwater was encountered in a boring, temporary monitoring wells were installed using standard 0.01-inch slot, two-inch diameter, schedule 40, polyvinyl chloride (PVC) screen with 10/20 gradation sand pack. Groundwater was then sampled from the temporary monitoring wells using a peristaltic pump in accordance with the protocols described in the VCP Sampling and Analysis Plan (AECOM, May 2019). During the 2019 field effort, groundwater was encountered and sampled in nineteen borings (CS-1, CS-2, CS-3, CS-4, PH-3, PH-6, PH-11, PH-12, PH-13, PH-14, PH-15, PH-16, FCS-1, FCS-2, FCS-3, and WWP-1, WWP-2, WWP-Berm-2, and WWP-Berm-4). Figures 4, 5 and 6 show all VCP soil and groundwater sampling locations. All temporary VCP monitoring wells installed in 2019, except for CS-1, were abandoned on August 2, 2019. Field forms including boring logs, shallow soil sampling/trenching logs, groundwater sampling forms, depth to water measurements, and well abandonment details are provided in Appendix A. Laboratory reports, data validation reports, calculated site-specific cleanup levels for select diesel range fractionations, topographic survey coordinates, calculations of soil background threshold values (BTVs), and leaching estimates for the WWP Coal Ash Berm are provided in Appendices B, C, D, E, F, and G respectively. Summaries of the results of the laboratory analyses performed on soil and groundwater samples are provided in Tables 1 and 2, respectively. Summary of the 2020 Site Investigation - Between May 4 and 14, 2020, a Boart Longyear 100C MiniSonic drill rig was used to install four new monitoring wells (CS-201, FCS-201, PH-201, and WWP-201). These wells were constructed using standard 0.01-inch slot PVC screens and a finer 20-40 gradation sand pack. These wells were installed and sampled because previous temporary monitoring wells installed at the site in 2019 had high turbidity. Boring logs and groundwater sampling forms for the 2020 site investigation work are included in Appendix A and 2020 survey data are provided in Appendix E. The locations of all VCP monitoring wells are shown on Figures 4, 5 and 6. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 3 March 2024 The USEPA low stress protocol was used to purge and sample monitoring wells CS-201, FCS- 201, PH-201, and WWP-201 as described in AECOM’s 2020 VCP Workplan Addendum (AECOM 2020b). During the 2020 groundwater sampling event, laboratory analyses were limited to evaluating filtered and unfiltered groundwater samples from each of the four new wells for seventeen metals, radium 226, radium 228, and combined radium 226 & 228. Laboratory and data validation reports for the 2020 sampling are provided in Appendices B and C, respectively. Results of the 2020 groundwater sampling are also summarized in Table 2. Installation and sampling of the four new wells (CS-201, FCS-201, PH-201, and WWP-201) in 2020 was required due to the high turbidity encountered during the 2019 groundwater sampling event. Use of a finer sand pack (20-40 gradation) along with the use of USEPA’s Low Stress purge and sample method, successfully reduced the nephelometric turbidity unit (NTU) readings to acceptable levels. Summary of the November 2022 Site Investigation - Between November 14 and 31, 2022, a Boart Longyear 100C MiniSonic drill rig and hydrovac system were used in the CS Area to install two new monitoring wells (CS-UPRR32 and CS-UPRR34) and advance two shallow borings (CS-UPRR31 and CS-UPRR33). The new well/boring logs and soil/groundwater sampling forms are included in Appendix A, laboratory results for soil and groundwater sampling are summarized in Tables 1 (soil) and 2 (groundwater), detailed laboratory reports are provided in Appendix B, laboratory data validation reports are provided in Appendix C, and topographic survey data in Appendix E. The locations of all wells and borings installed during the VCP and UPRR subsurface investigations are shown on Figures 4, 5, and 6. Soil samples from the four new CS Area sampling locations were collected at the ground surface and then between the depths of one to five feet below ground surface. Soil samples from the boreholes of new monitoring wells CS-UPRR32 and CS-UPRR34 were also collected at the groundwater interface. The methods of laboratory analyses performed on each new soil sample are summarized in Table 1. New monitoring wells CS-UPRR32 and CS-UPRR34 were constructed using standard 0.01-inch slot PVC screens and 20-40 gradation sand pack and then developed to remove sediment from the casing. After development, the two new wells, along with existing wells CS-201, PH-201, and WWP-201; were purged and sampled using USEPA’s low stress method. The laboratory analyses run on each new groundwater sample and the reported concentrations are summarized in Table 2. Note that the original sampling plans for 2022 included collection of groundwater samples from wells CS-1 and FCS-201, however, in late November of 2022 there was insufficient groundwater present in these wells to collect samples. Summary of the Fall 2023 Investigation for Lead in Soil– On October 30 and 31, 2023, 53 surface soil locations in the CS Area were screened for lead concentrations surrounding boring CS-UPRR33 using a handheld Niton™ XL3t 700 XRF Analyzer. As shown on Figure 7a XRF March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 4 March 2024 readings were obtained in cardinal and intercardinal directions relative to boring CS-UPRR33. For example, points along XRF Line A, contained eleven screening points labeled A.01 through A.11. A similar numbering format was used to label the XRF points screened along Lines B, C, and D. The Work Plan for the 2023 XRF Screening is provided in Appendix A5. Based on the XRF field data and historical soil sampling results, AECOM selected the locations of fifteen soil samples (labeled S.01 through S.11 Figure 7b) to be analyzed at Chem Tech Ford Laboratory for lead (Method 6020A). Two soil samples were collected at soil sampling locations S-04, S.05, and S.07: one from the surface and a second composite soil sample from depths extending between 0.5’ and 1.5 feet below ground surface. For quality control purposes, one blind duplicate (sample S.901) was also collected and analyzed from location S.01. Daily logs comparing the XRF readings to known standards are provided in Appendix A5. A certification that the XRF was checked for calibration before being shipped to the site is also provided in Appendix A5. 2.0 SITE DESCRIPTION: The footprint of the VCP study area encompasses all or part of five Emery County parcels (UTCU 35, 36, 37, 77, and 78). Figure 3 delineates these properties and identifies the portions of parcels 77 and 78 that are excluded from this VCP investigation. Annotated photographs documenting the current site conditions are provided below and on the following page. View is Looking South from the Northern End of the Coal Storage Area March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 5 March 2024 View is Looking South from Former Waste Water Pond 1 Unconsolidated Soils - Unconsolidated soils were observed above shallow bedrock in all sampling locations. Soils typically consisted of well graded sand (SW), silty sand (SM), or silt (ML). Occasionally intervals of low plasticity clay (CL), well graded gravel (GW), and even natural deposits of coal were encountered. Samples were collected into five-foot long, three-inch diameter sonic core barrels or removed from the borehole using air knifing/hydrovacing/hand augering. During collection, soils were characterized using the Unified Soil Classification System (USCS)Visual-Manual method. The soils were field screened using a photoionization detector (PID) calibrated to 100 parts per million (ppm) isobutylene gas standard. During screening, soils were placed in zip lock baggies, allowed to equilibrate, and then evaluated by inserting the tip of the PID into the bag. Detailed boring logs containing the USCS descriptions, PID measurements, sample recovery lengths, and temporary well construction information are provided in Appendix A. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 6 March 2024 Background Soil Sampling - In 2019, a total of nine surficial soil samples were collected by AECOM in the locations shown on Figure 4. Two of these samples (BG-2b and BG-3) were from natural outcrops of coal. All background soil samples were analyzed for total recoverable petroleum hydrocarbon (TRPH), semivolatile organic compounds (SVOCs), 17 metals, and combined radium 226 & 228. The results of the background soil sampling are included near the bottom of Table 1. The USEPA ProUCL v5.1 Statistical Software (USEPA, 2016) was used to calculate BTVs representative of local anthropogenic or natural background using the background dataset. The 95% upper tolerance limit (UTL) with 95% coverage (95/95 UTL) was selected to represent the BTV. The UTLs provide a reasonable upper limit of what is likely to be observed in local background soil. A 95/95 UTL is the value that will be exceeded by all values potentially originating from the background population less than 5% of the time with 95 percent confidence (i.e., a confidence coefficient of 0.95). The UTLs were calculated only for analytes in the background datasets with at least 50 percent detection frequency (i.e., 50 percent of sample concentrations reported above the laboratory reporting limit). The BTV and the range of background concentrations are presented in Table 1. Appendix F presents the ProUCL input table and output statistics, the latter including descriptive statistics and BTVs. Table F-1 in Appendix F summarizes the background statistics and the selected BTVs. Additional discussion of background concentrations is presented within the context of the following sections. Bedrock - The Quaternary alluvial and fluvial soils described above sit directly on top of the Cretaceous aged Blackhawk (Kbh) formation. As described on Utah Geologic Survey’s Geologic Map of the Price 30’ x 60’ Quadrangle, (UGS, 2003), the Blackhawk Formation typically consists of “thin to medium bedded, fine to medium grained quartzose sandstone interleaved with shaley siltstone, shale, carbonaceous shale, and coal.” Hydrogeology Observed During the Summer of 2019 - On July 3, 2019, shallow groundwater was encountered in seventeen boring locations with depths to the static water level ranging from 0.39’ (WWP- Berm 4) to 23.91’ (PH-6). A potentiometric map showing the apparent westward direction of flow within the shallow most aquifer beneath the CS, FCS, and PH Areas is shown as Figure 8a. The elevation of the static water level in the shallow most aquifer in this portion of the study area was found to be approximately nine feet below the elevation of surface water in Willow Creek. The elevation of surface water in Willow Creek at “Bridge 1” on July 3, 2019, is shown along with the groundwater potentiometric surface on Figure 8a. These measurements strongly suggest that on July 3, 2019, Willow Creek was a losing stream and likely remains so throughout the year. The United States Fish and Wildlife Service (USFWS) National Wetland Inventory (USFWS, 2019) indicates that the site-related reach of Willow Creek is a semi-permanent stream, with water present during the growing season most years. The creek generally stops flowing in late summer of each year and, during the fall and March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 7 March 2024 winter, flows only after significant rainfall or snow melt events. Therefore, rainfall or snow melt infiltrating into the CS, FCS, and PH Areas would generally be expected to move vertically to the saturated interval of the shallow aquifer and then westward where it eventually discharges into the Price River. The top of bedrock for the Blackhawk Formation would generally act as an aquitard forming the base of the shallow most aquifer. No significant groundwater discharge to Willow Creek is anticipated within the immediate study area. The apparent direction of groundwater flow in the WWP Area on July 3, 2019, differed from that observed in the CS, FCS, and PH Areas. In this portion of the study area, groundwater generally flowed toward the southeast as shown on Figure 8a. Based on the July 3, 2019, surface water and the groundwater measurements, the Price River was likely a gaining stream in the WWP Area. Note that the eastern most berm (see borings WWP-Berm 1, 2, and 3) was not excavated during the demolition of the waste water ponds. This was because it helps control the Price River during flood stages. The decision to leave this berm in place was made by PacifiCorp in consultation with the United States Army Corps of Engineers. Hydrogeology Observed During the Spring of 2020 - On May 11, 2020, groundwater elevations were measured in new monitoring wells CS-201, FCS-201, PH-201, and WWP-201. Surface water elevations were also measured in Willow Creek (Bridge 1 see Figure 8b) and the Price River (Bridge 2 see Figure 8b). The groundwater and surface water elevations reinforce the 2019 VCP findings that Willow Creek is generally a losing stream and that the Price River is typically a gaining stream in the former WWP Area. Potentiometric surface maps prepared for the Power House Area for July 3, 2019 (Figure 8a), May 11, 2020 (Figure8b), and late November 2023 (Figure 8c) all suggest shallow groundwater flows westward towards the Price River. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 8 March 2024 Coal Ash Observed in 2019 Within WWP Berm - During the 2019 VCP site investigation, six to eight feet of coal ash was observed in berms WWP-Berm1, 2, and 3 (Appendix A1). The log for WWP Berm 2 (shown to the right) documents the presence of coal ash extending from one to nine feet below ground surface. Leaching Evaluation - To evaluate the potential for leaching of coal ash metals from the WWP berm to underlying groundwater and ultimately into the Price River, a leaching model was prepared, and the modeling results provided in Appendix G. Within the model, site-specific soil screening levels (SSLs) were developed that are protective of the regulated beneficial uses of the Price River. Calculations were performed in accordance with USEPA guidance (USEPA (1996, 2002) and use chemical- specific input parameters, and site-specific aquifer, and soil input values. Beneficial uses specified in the Utah Water Quality Standards (WQSs) stream classifications (Utah Department of Environmental Quality [UDEQ], 2019) include the following:  Class 2B Recreation (infrequent recreation/contact - wading, hunting, fishing);  Class 3A Aquatic life - protected for non-game fish and other aquatic life;  Class 3A HH Aquatic life - protected for non-game fish and other aquatic life for human consumption; and  Class 4 Agriculture - protected for agricultural use including crop irrigation and stock watering. As directed on page 7 of the VCP Agreement, Price River water quality rather than drinking water standards were used when assessing the results of the leaching evaluation. The first paragraph on page 7 of the VCP Agreement states that PacifiCorp is to assume the following: “For the entire site, groundwater will not be accessed via wells, pits or sump for drinking water, bathing, and/or irrigation purposes.” March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 9 March 2024 The leaching SSLs for all soil types occurring in the WWP Area (i.e., silt, silty/loamy sand, and sand) are shown in Appendix G Table G 5-1. The applicable SSLs are listed under the section of Table G 5-1 titled “WWP Berm Area – Sand”. Within this section of Table G 5-1, the appropriate remediation goals for metals and radionuclides are listed under the column labeled “Leaching to Groundwater SSL_dilution”. Concentrations listed in this column are considered protective of the applicable Price River water quality standards. Calculations used in this column account for leaching to groundwater from the WWP berms and then mixing of this groundwater with surface water in the Price River. Sand was selected as the soil type for the calculations because it returns the most conservative (lowest) “Leaching to Groundwater SSL _dilution” concentrations. As indicated in Table 1 of the VCP Report, no metal or radionuclide detected within the WWP berm exceeded any of the “Leaching to Groundwater SSL_dilution” concentrations. Coal Observed Within FCS Area Berm - During the VCP site investigation, significant intervals of unburned coal were observed when trenching into the berm located west of Willow Creek at the FCS Area. Sampling logs document that coal represents between 1 and 10 percent of the soil/rock in this berm. The most significant concentration of unburned coal was found in trench FCS-6 between the depths of 1.5 and 5.5 feet (see Appendix A2). Potential regulatory and/or remedial options to address the coal remaining in the FCS Area berm will be evaluated with in the VCP RAP. It is anticipated however, that the berms at both the FCS and WWP Areas will be left in place and that a site management plan will be prepared to inspect the berms annually to ensure that the vegetative cover remains intact, and erosion is not occurring. Isolated Lead Hotspot Observed Within the CS Area – One surface soil sample collected during the 2022 VCP investigation from boring CS-UPRR33 reported lead at 1340 mg/kg (Table 1 page 7 of 9). This detection exceeded the USEPA Composite Worker Regional Screening Level of 800 mg/kg and so, between October 30 and October 31, 2023, an additional XRF and soil sampling assessment was performed to further evaluate lead concentrations surrounding boring CS-UPRR33. Of the 53 XRF screening locations and fifteen soil samples shown on Figures 7a and 7b, respectively, only one (soil sample S.07, 1030 mg/kg) reported lead at a concentration exceeding the 800 mg/kg USEPA Composite Worker RSL. The S.07 hot spot sample was collected between the depths of 0.5 and 1.5 feet bgs. Note that the locations of samples S.07 and boring CS-UPPRR 33 are within a two foot diameter of each other. The 2022 and 2023 lead sampling results found elevated lead only at boring CS-UPRR33 / sample point S.07. A targeted over excavation immediately surrounding boring CS-UPRR33 will be considered as a remedial option during preparation of the VCP Remedial Action Plan. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 10 March 2024 3.0 SCREENING CRITERIA Factors effecting the selection of regulatory screening levels for the former Carbon Power Plant are:  The former PH Area is expected to be redeveloped for commercial/industrial purposes.  The WWP Area sits adjacent to the Price River. An emergent wetland is present at the southern extent of the southernmost waste water pond.  The CS Area historically contained an underground storage tank and therefore impacts in this area will be regulated by the Utah Leaking Underground Storage Tank (LUST) Program rather than the VCP. Given these expected future uses and site conditions, the following are the primary screening criteria considered when interpreting the results from a Human Health perspective: Human Health Screening – Soil:  USEPA Regional Screening Levels (RSLs) for the Composite (Industrial) Worker (USEPA, 2023a). The exposure scenario for this indoor/outdoor worker is defined in Section 4.2.1 of the USEPA RSL Users Guide (USEPA, 2023b).  Polychlorinated biphenyl (PCB) Screening Criteria for High Occupancy Areas as defined in the Code of Federal Regulations Chapter 40 Section 761 Part 61.  Utah Site Specific Cleanup Levels for six Diesel Range Organic (DRO) fractions (UDEQ, 2012). The Utah Risk-Based Corrective Action Site Specific Calculator (version 1.2) was used to calculate these values for groundwater at the CS-1 boring and for soil at the PH-6 boring. The calculations are provided in Appendix D.  Utah Initial Screening Level (ISL) and Tier 1 Screening Levels per Guidelines for Utah's Corrective Action Process for Leaking Underground Storage Tank Sites (UDEQ 2015). These regulatory screening levels apply primarily to the groundwater and soil sampling results observed for boring CS-1. Impacts in this area will be addressed under the regulatory oversight of the Utah LUST Program rather than the Utah VCP.  Combined (total) radium 226 & 228 per Code of Federal Regulations 40 CFR §192.12 Subpart B (Standards for Cleanup of Land and Buildings Contaminated with Residual Radioactive Materials from Inactive Uranium Processing Sites). Human Health Screening – Groundwater:  Utah Division of Water Quality (UDWQ) Groundwater Quality Standards - These standards are as defined in Utah Administrative Code Rule 317-6 Table 1. The screening standards likely to be applicable to the site are those listed for Class II Drinking Water Aquifer with total dissolved solids greater than 500 but less than 3000 milligrams per liter (mg/L). No adjustments to the Table 1 Groundwater Quality Standards have been made at this time due to the absence of background data for groundwater. Potential adjustments to March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 11 March 2024 the Class II Drinking Water Standards are as described in Rule 317-6 Chapter 4.5 Sections B1, B2, and B3.  USEPA Maximum Contaminant Levels (MCLs) - These promulgated regulatory levels per USEPA (USEPA, 2023a) have been provided in Table 2, however, the property is not expected to be redeveloped for residential use nor is the shallow groundwater expected to be used for drinking water purposes.  Tap water RSLs per USEPA (2023a). As indicated, shallow groundwater is not used or expected to be used for drinking water purposes.  As requested by the Utah VCP, the USEPA tap water RSL for 1,4 Dioxane was included. A summary of laboratory analytical results, including a comparison to the screening criteria, follows in Sections 4.0 and 5.0. Leaching Calculations to Price River:  UDEQ Beneficial Use Standards for the Price River were used to evaluate leaching of metals from the coal ash berm in the WWP Area. As documented in Appendix G, the USEPA Soil Screening Guidance (USEPA, 1996; USEPA 202) approach was used to perform the leaching calculations. Beneficial use thresholds for the segment of the Price River extending between the Price City Water Plant Intake and the Price-Wellington Canal Diversions were used as the target surface water thresholds. The beneficial use thresholds are published in Utah Administrative Code Rule R317-2. In addition to leaching to groundwater, the calculations provided in Appendix G also account for the dilution of the groundwater plume as it transitions through the bed substate of the Price River and then mixes with overlying river surface water. Select Analytes without Screening Levels:  Note that a few analytes which were evaluated in soils and groundwater do not have applicable regulatory screening levels under the VCP program. Some analytes have no published USEPA RSL or other applicable thresholds, nor do they have beneficial use concentrations published in Utah Administrative Code Rule R317-2. 4.0 2019, 2020, 2022, AND 2023 SITE INVESTIGATIONS VCP Soil Sampling in 2019 - Between June 10 and July 3, 2019, AECOM collected a combined total of 78 soil samples from 45 locations in the CS, FCS, PH, CT, and WWP Areas. Samples were submitted to American West Analytical Laboratory (AWAL) in Salt Lake City, Utah for analysis of TRPH, gasoline range organics (GRO), DRO, fractionations of DRO, volatile organic compounds (VOCs), SVOCs, nine PCBs (as aroclors), radium 226 & 228, and seventeen metals. AWAL subcontracted with ACZ Laboratory of Steamboat Springs, Colorado to provide hexavalent chromium and radionuclides analyses. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 12 March 2024 All analyses by both labs were performed in accordance with the VCP approved Sampling and Analysis / Quality Assurance Quality Control Plan (AECOM, May 2019). Validation of these laboratory analyses was performed by an AECOM chemist and documented in Appendix C1. Two soil samples (WWP-3 00-04 and CS-1 2023) had a limited number of analytes which were “rejected” by the project chemist because the matrix spike recoveries were below quality control limits. The results of the laboratory analyses of site soils are summarized in Table 1. The depth at which each sample was collected is provided within the sample ID. For example, CS-1-2023 was collected from boring CS-1 and a depth below ground surface of 20 to 23 feet. Regulatory screening levels and background summary statistics are provided at the top of Table 1. If a concentration of an analyte exceeds a regulatory screening level, it has been color coded with a definition provided in the key at the bottom of the table. For example, a box with red fill and a red boarder (see below) indicates that a concentration or radioactivity exceeds a potentially applicable human health standard. Concentration or radioactivity exceeds potentially applicable human health regulatory standard. VCP Soil Sampling in 2022 - On November 14 and 15, 2022, AECOM collected a combined total of thirteen soil samples from four locations (CS-UPRR31, 32, 33, and 34) in the CS Area. Depending on the location and depth of the sample, Chem Tech Ford Laboratory in Salt Lake City, Utah performed analysis for all or part of the following list: TRPH, GRO, DRO, fractionations of DRO, VOCs, SVOCs, radium 226 & 228, and eight RCRA metals. Chem Tech Ford Laboratory subcontracted with Pace Analytical National Laboratory of Mount Juliet, Tennessee to provide the required radionuclides analyses. The results of the 2022 laboratory analyses for soils are summarized in Table 1. Laboratory and data validation reports are provided in Appendices B and C, respectively. XRF Screening and Soil Sampling in 2023 – On October 30 and 31, 2023, a hand held Niton Model XL3 XRF analyzer was used to screen surface soils at 54 points for elevated lead concentrations as shown on Figure 7a. The highest concentration detected by the XRF was 38 mg/kg at point B.02. Based on these results, fifteen soil samples were collected for method 6020A lead analyses at Chem Tech Ford Laboratory. The results of the XRF field screening are presented on Figure 7a. The results of the 2023 laboratory analyses for lead in CS-Area soils are summarized in Table 1 and presented on Figure 7b. Laboratory and data validation reports are provided in Appendices B and C, respectively. The XRF screening results for lead were generally lower than the analytical results provided by the lab. When considering the reason for the differences, it is important to recognize that the XRF was used as a rough screening tool without:  Formal sample preparation/homogenization,  Evaluation of spectral or chemical matrix interference; or March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 13 March 2024  Formal analysis of moisture content. A Niton XL3 XRF analyzer cannot be calibrated in the field. It must be shipped to the manufacturer for recalibration. However, two standards and a blank were provided by Premier Safety which allowed the field team to check the readings of the XRF during use at the former Carbon Power Plant. The field checks to the standards are included in Appendix A5 and shown to the right. Also, the XRF screening points and subsequent soil sampling locations differ slightly even though they may be plotted in the same location on Figures 7a and 7b. The XRF screening points measured on October 30 and soil samples collected on October 31 which appear as the “same location” should not be considered split samples that have been homogenized in a stainless steel bowl and then separated for analysis. XRF and soil sample points shown as the same location can realistically be interpreted as having been collected one day apart and within a two foot diameter of each other. Significant variability in soil geochemistry commonly exists within a two diameter of native soils and as shown in the photograph below, one possible source of elevated lead (isolated paint chips) might also cause considerable variation within a two foot diameter on the ground. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 14 March 2024 2019 Groundwater Sampling - Between June 18 and 27, 2019, AECOM collected a combined total of 21 groundwater samples from 19 locations in the CS, FCS, PH, CT, and WWP Areas. Prior to sampling, the VCP workplan required each well to be purged for two minutes, allowed to settle un-pumped for a few minutes, and then pumped again to collect the sample. Alternate strategies to achieve low turbidity were to be used on a well-by-well basis as needed. Appendix A3 documents the purge parameters recorded during the June 2019 groundwater sampling. Due to the presence of a significant fraction of fines in the soils within the saturated intervals, the site geologist was not able to control turbidity during sample collection. As a result, there is a large difference between reported dissolved and total metals concentrations. Radium 226 & 228 concentrations in groundwater were also reported based on analysis of unfiltered groundwater samples with high turbidity. Groundwater samples were submitted to AWAL in Salt Lake City, Utah for analysis of TRPH, GRO, DRO, fractionations of DRO, VOCs, SVOCs, nine PCBs (as aroclors), hardness, nitrate, radium 226 & 228, and seventeen metals. Separate groundwater samples were collected for dissolved and total metals analyses and the dissolved analysis field filtered immediately after collection. AWAL subcontracted with ACZ Laboratory of Steamboat Springs, Colorado to provide hexavalent chromium and radionuclides analyses. Results of laboratory analyses run on site groundwater samples are summarized in Table 2. Laboratory and data validation reports are provided in Appendices B and C, respectively. While in the field, a modification to the VCP workplan was required when boring PH-1 could not safely be installed. This location was originally selected to evaluate whether impacts were present from a former sewer leach field. A combination of overhead power lines, underground utilities, and highway US191 DOT restrictions, however, made it unsafe to drill this boring. To fill this data gap, AECOM sampled wells located down (PH-15) and side gradient (PH-16) of the historical sewer leach field for nitrate, E-coli, and total coliform. These additional samples were analyzed by AWAL and Chem Tech Ford and have also been included in Table 2. 2020 Groundwater Sampling - Between May 4 and 14, 2020, a Boart Longyear 100C MiniSonic drill rig was used to install four new monitoring wells (CS-201, FCS-201, PH-201, and WWP-201). Standard 0.01-inch slot PVC screens were used along with 20-40 gradation sand pack in these new wells. Field logs are provided in Appendix A1, and the locations of the wells installed in 2020 are shown on Figures 7b and 8b. Once installed, three well casing volumes were purged from wells CS-201, FCS-201, PH-201, and WWP-201 using disposable bailers. Over the next two days, AECOM used USEPA Low Stress Sampling Procedures (USEPA, 2017) and a flow through cell to purge and sample wells CS-201, FCS-201, PH-201, and WWP-201. Filtered and unfiltered groundwater samples were collected at each well. Filtering was performed in the field using 0.45-micron filters. Because the depth to groundwater exceeded the lifting capacity of a peristaltic pump, wells CS-201, FCS-201, and PH-201 were sampled using a variable speed Redi Flo II pump. This March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 15 March 2024 pump was decontaminated between each well using alconox (soapy water) and a potable water rinse. Due to the shallow depth to groundwater in the WWP Area, AECOM was able to use a peristaltic pump to complete the Low Stress groundwater sampling at well WWP-201. Appendix A3 documents the purge parameters recorded during the May 2020 groundwater sampling. Prior to collection of the blank, the pump was decontaminated and then deionized water poured over the pump intake mesh. Water dripping from the mesh was collected into the appropriate sample vials. Analysis of the equipment blank reported all analytes below the laboratory reporting limits thus indicating adequate field decontamination procedures were implemented. The results of the analysis of the duplicate groundwater samples for well WWP- 201 met the quality assurance / quality control requirements as presented in the data validation report in Appendix C. Filtered and unfiltered groundwater samples were analyzed for seventeen metals, radium 226, radium 228, and combined radium 226 & 228. The analytical methods used, and results of the 2020 groundwater sampling are summarized in Table 2. Lab and data validation reports are provided in Appendices B and C, respectively. The 2020 additional investigation work did not require analyses for volatile or semivolatile organic compounds. 2022 Groundwater Sampling – On November 14 and 15, 2022, a Boart Longyear 100C MiniSonic drill rig was used to drill and install two new monitoring wells (CS-UPRR32 and CS- UPRR34). Standard 0.01-inch slot PVC screens were used along with 20-40 gradation sand pack in these new wells. On November 14 and 15, borings CS-UPRR31 and CS-UPRR33 were also advanced and sampled to a depth of five feet below ground surface using a combination of hydrovac and hand auger. Well and boring logs are provided in Appendices A1 and A2, respectively. The locations of the new wells and borings shown on Figure 5. Once installed, disposable bailers were used to remove three well casing volumes from the two new wells. On November 29 and 30, AECOM used USEPA’s Low Stress Sampling Procedures (USEPA, 2017) and a flow through cell to purge and sample wells CS-201, CS-UPRR32, CS- UPRR34, PH-201, and WWP-201. Appendix A3 documents the purge parameters recorded during the November 2022 groundwater sampling. Filtered and unfiltered groundwater samples were collected at each well. Field filtering was performed using 0.45-micron filters. Sampling of VCP wells CS-1 and FCS-201 could not be performed as planned because these two wells did not intercept the static water level. Groundwater elevations at the site in late November of 2022 were deeper than what had been observed during prior VCP groundwater sampling rounds. Filtered and unfiltered groundwater samples were analyzed for seventeen metals, radium 226, radium 228, and combined radium 226 & 228. Depending on the location of the monitoring well and the project quality control sampling requirements, select groundwater and quality control samples were also analyzed for VOCs, SVOCs, PAHs, GRO, DRO, TRPH, and PCB aroclors. The specific analytical methods used, and results of the 2022 groundwater sampling are March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 16 March 2024 summarized in Table 2. Lab and data validation reports are provided in Appendices B and C, respectively. Topographic Surveying and Ground Water Elevations - After each of the 2019, 2020 and 2022 soil and groundwater sampling events, CIVCO Engineering mobilized to the site to survey the elevations of the top of the PVC casings (TOCs) and horizontal positions of each new sample location. CIVCO also surveyed two reference points on Bridges 1 and 2 as shown on Figures 5, 6, 7a, 7b, 8a, and 8b. Vertical survey points have an accuracy of +/- 0.01 feet and are tied to the North American Vertical Datum of 1988. Horizontal coordinates are provided in state plane coordinate system and have an accuracy of approximately +/- 0.1 feet. All Survey data are provided in Appendix E. On July 3, 2019, and May 11, 2020, depths to groundwater were measured from the TOCs in key site monitoring wells. Depths to the top of surface water in Willow Creek and Price River were also measured from Bridges 1 and 2, respectively, on these two dates. Interpretation of these groundwater elevation data indicate that the apparent direction of groundwater flow beneath the CS, FCS, and PH Areas (Figures 8a and 8b) is westward toward the Price River. The data also indicates that on July 3, 2019, surface water in Willow Creek was perched approximately seven to nine feet above the static water level in the shallow unconfined aquifer. In the WWP Area on July 3, 2019, (Figure 9a) the apparent direction of groundwater flow was toward the southeast and the Price River was very likely a gaining stream. On May 11, 2020 (Figure 9b), again the groundwater and surface water elevation data suggested that the Price River in the WWP Area was a gaining stream. 5.0 COMPARISON OF VCP SAMPLING RESULTS TO HUMAN HEALTH SCREENING CRITERIA Comparison of the 2019 Soil Sampling Results to Regulatory Screening Levels Soil Sample PH-6 1314 (Table 1 Page 2 of 9) – This sample reported a DRO concentration at 505 milligrams per kilogram (mg/kg) as compared to the Utah ISL concentration of 500 mg/kg. As a result of this exceedance, the sample was further analyzed using Utah’s total petroleum hydrocarbons (TPH) fractionation protocol (UDEQ, 2012). Utah site-specific cleanup levels (SSCLs) for six hydrocarbon ranges including C11-13 (alkyl naphthalenes), C-12-22 (PAHs), C11-12 (aliphatics), C13-16 (aliphatics), C17-21 (aliphatics), and C22-35 (aliphatics) were then calculated and included in Appendix D. Although the DRO concentration was slightly above the ISL, none of the six fractionated intervals exceeded the SSCLs. Soil Sample FCS-6 1.5-3 Berm (Table 1 Page 6 of 9) - The 15.3 mg/kg naphthalene concentration reported in the sample collected between the depths of 1.5 and 3 feet in the FCS-6 trench exceeds USEPA’s Composite Worker RSL of 8.6 mg/kg. As required by the Utah VCP, a discussion of the significance of this finding will be presented in the VCP RAP. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 17 March 2024 Soil Sample BG-3 (Table 1 Page 6 of 9) - This background sample was collected from a naturally occurring coal outcrop in the study area and contained naphthalene at a concentration of 25 mg/kg. This concentration exceeds the USEPA RSL (Composite Worker) of 8.6 mg/kg for naphthalene. Arsenic Exceedances (Table 1 Pages 7, 8 & 9 of 9) – Forty seven out of seventy VCP soil samples analyzed for arsenic exceed the USEPA RSL (Composite Worker) threshold of 3 mg/kg. Note that five of the nine background soil samples also exceeded USEPA’s RSL for arsenic. As requested by the Utah VCP, discussion of BTVs for arsenic relative to site concentrations will be presented within the VCP RAP. Comparison of the 2022 Soil Sampling Results to Regulatory Screening Levels Soil Sample CS-UPRR33-Surface (Table 1 Page 7 of 8) – An isolated hot spot of lead (1340 mg/kg) was detected in the CS-UPRR33-Surface soil sample. The source for this lead hot spot is unknown. Surface soils described on the sampling log (Appendix A) for boring CS-UPRR33 include Silty SAND (SM) with angular to subangular gravel, cobbles, concrete, and minor amounts of coal. This along with verbal reports on the excavation which occurred in the CS Area during the demolition phase suggest that surficial soils at boring CS-UPRR33 represents a mix of imported fill, concrete, and minor amounts of either native or locally mined coal. Soil Sample CS-UPRR32-0105 (Table 1 Page 7 of 9) – Consistent with historical VCP soil sampling, the arsenic concentration (3.24 mg/kg) in this sample slightly exceeded USEPA’s Composite Worker RSL threshold of 3 mg/kg. Note that five of the nine background soil samples also exceeded USEPA’s RSL for arsenic and the calculated BTV (7.36 mg/kg) was more than twice the concentration detected in the CS-UPRR32-0105 soil sample. As requested by the Utah VCP, discussion of BTVs for arsenic relative to site concentrations will be presented in greater detail within the VCP RAP. Soil Sample CS-UPRR32-2025 (Table 1 Page 7 of 9) – Consistent with historical VCP soil sampling, the arsenic concentration (3.33 mg/kg) in the duplicate soil sample collected at this location slightly exceeded USEPA’s Composite Worker RSL threshold of 3 mg/kg. However, five of the nine background soil samples also exceeded USEPA’s arsenic Composite Worker RSL as well as the calculated BTV (7.36 mg/kg) for arsenic is more than twice the concentration detected in the CS-UPRR32-2025 soil sample. As requested by the Utah VCP, BTVs for arsenic relative to site concentrations will be discussed in greater detail within the VCP RAP. Comparison of the 2023 Soil Sampling Results to Regulatory Screening Levels Soil Sample S.07 0.5 -1.5 (Table 1 Page 7 of 9) - Of the fifteen soil samples evaluated in 2023, only one reported lead at a concentration exceeding the 800 mg/kg USEPA Composite Worker RSL. The isolated hot spot (soil sample S.07, 1030 mg/kg) was collected in surficial soil between the depths of 0.5 and 1.5 feet bgs. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 18 March 2024 Discussion of 2019 Groundwater Concentrations and Human Health Based Screening Levels Groundwater concentrations which exceed potentially applicable regulatory screening levels are described below. Groundwater Sample CS-1 (Table 2 Page 1 of 5) - This groundwater sample was collected within the portion of the CS Area being regulated under the Utah LUST Program. Concentrations of TRPH, TPH DRO, benzo(a)pyrene, total arsenic, total barium, total cadmium, total chromium, and total lead were reported above potentially applicable health-based screening levels. TPH DRO fraction (C13-16 aliphatic hydrocarbons) was also detected at a concentration above the calculated Utah SSCL (See Appendix D). The DRO concentration (99.4 mg/L) was one order of magnitude above the 10 mg/L Utah LUST Tier 1 standard. Bis(2-ethylhexyl) phthalate was also detected at a concentration of (0.0102 mg/L) exceeding the USEPA MCL (0.006 mg/L). Bis(2-ethylhexyl) phthalate is a common lab contaminant and is very unlikely to be present at concentrations of regulatory concern. PacifiCorp will coordinate future requirements for the CS Area with the Utah LUST Program. Currently the Coal Storage Area is “closed with contamination remaining in place” under the LUST Program (UDEQ 1998). Groundwater from downgradient well CS-201 was sampled and analyzed for diesel range organics in November of 2022 and found to be below the laboratory reporting limit of 0.001 mg/L. This data coupled with the fact that this plume was closed by the Utah LUST Program 26 years ago, suggests that this diesel range organic plume is stable and does not impact the PacifiCorp/UPRR lease area. Groundwater Sample CS-3 (Table 2 Page 3 of 5) - This groundwater sample was collected in the northern most portion of the CS Area and reported bis(2-ethylhexyl) phthalate at a concentration (0.032 mg/L) exceeding the MCL (0.006 mg/L). Based on the use of the area for coal storage, it is likely that this detection is due to plasticizer materials being present in sampling gloves, plastic bottles, or is a lab contaminant. No further site assessment is recommended to address this exceedance of the USEPA drinking water standard. Groundwater Sample PH-16 (Table 2 Page 1 of 5) – This groundwater sample reported GRO at a concentration (1.13 mg/L), slightly above the Utah ISL threshold of 1 mg/L. Laboratory analyses were then performed to fractionate the gasoline range organics within this sample. Site specific cleanup levels for gasoline range fractionations were calculated based on the 2019 hydrogeologic conditions at well PH-16. As shown on Table 2 page 1, all TPH GRO fraction concentrations were reported well below the calculated SSCLs. Therefore, this 1.13 mg/L detection is below levels of regulatory concern. Groundwater Sample FCS-3 (Table 2 Page 3 of 5) - Bis(2-ethylhexyl) phthalate was detected in the FCS Area at a concentration of 0.0341 mg/L, exceeding the USEPA MCL (0.006 mg/L). Because this constituent is a common laboratory contaminant and because the VCP agreement states that PacifiCorp is to assume that groundwater at the site will not be used for drinking water purposes, the bis(2-ethylhexyl) phthalate detection in well FCS-3 is not considered a site contaminant of concern. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 19 March 2024 Groundwater Sample WWP-2 (Table 2 Page 5 of 5) – The groundwater sample collected in 2019 from well WWP-2 had low turbidity (4.2 NTUs) but a combined radium 226 and 228 activity of 7.7 pCi/L. This activity exceeds the USEPA MCL, Utah Groundwater Quality threshold, and Utah Surface Water Quality threshold of 5 pCi/L. The USEPA and Utah Groundwater Quality thresholds are both based on the use of groundwater for drinking water purposes. Because the VCP Agreement excludes the use of groundwater for drinking water purposes, exceedance of the USEPA and Utah Groundwater Quality standards do not trigger the need for corrective action. The surface water within the Price River adjacent to the WWP Area, however, carries beneficial use classifications 2B (infrequent recreation), 3A (protection of nongame fish and other aquatic life), 3A HH (protection of nongame fish and other aquatic life for human consumption), and 4 (agricultural use), and a 5 pCi/L water quality threshold. As described in Appendix G, groundwater seeping into the Price River in the WWP Area has an estimated minimum dilution factor of 221 at base flow (10 cfs). Meaning that, the applicable combined radium 226 and 228 regulatory threshold for groundwater beneath the WWP Area should be 221 x 5 pCi/L or 1105 pCi/L. For this reason, the 7.7 pCi/L detection for combined radium 226 and 228 in monitoring well WWP-2 does not trigger the need for corrective action under the VCP. All Remaining 2019 Groundwater Samples Except PH-14 and PH-16 (Table 2 Pages 4 & 5 of 5) - All groundwater samples except PH-14 and PH-16 reported one or more total metals concentrations above USEPA MCLs and/or Utah Groundwater Quality Standards. These elevated concentrations are due to high turbidity encountered during sampling. Dissolved metals in contrast were all orders of magnitude lower in concentration. Turbidity values observed during the purging process for each groundwater sample are shown in the far-right section of Table 2. To verify that the elevated total metals concentrations observed in groundwater were the result of high turbidity, wells CS-201, FCS-201, PH-201, and WWP-201 were installed and sampled in calendar year 2020. FCS and WWP Area Groundwater Samples Collected in 2019 (Table 2 Page 5 of 5) - With the exception of well WWP-2, groundwater samples collected in 2019 had high turbidity. In addition, all of the 2019 groundwater samples had combined radium 226 & 228 activities exceeding the USEPA MCL, Utah Groundwater Quality, and Utah Surface Water Quality threshold of 5 pCi/L. Radium 226 and 228 exceedances are generally attributed to the high sample turbidities. As previous described, the USEPA and Utah Groundwater Quality thresholds for combined radium 226 & 228, are based on the use of groundwater for drinking water purposes. Because the VCP Agreement excludes the use of groundwater for drinking water purposes, exceedance of the USEPA and Utah Groundwater Quality standards do not trigger the need for corrective action. The surface water within the Price River adjacent to the Carbon Power Plant, however, carries beneficial use classifications 2B (infrequent recreation), 3A (protection of nongame fish and other aquatic life), 3A HH (protection of nongame fish and other aquatic life for human consumption), and 4 (agricultural use), and a 5 pCi/L water quality threshold. As described in Appendix G, groundwater seeping into the Price River in the WWP Area has an estimated minimum dilution factor of 221. Meaning that, the applicable combined radium 226 and 228 groundwater regulatory threshold for the WWP Area should be 221 x 5 pCi/L or 1105 pCi/L. If radium were to be leaching to groundwater in the FCS Area, dispersion of this plume would be much greater than that modeled for the WWP Area due to a larger March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 20 March 2024 distance to the Price River. For this reason, none of the radium 226 & 228 activities reported in 2019 trigger the need for corrective action under the VCP. It should also be noted that the low turbidity groundwater sample collected in 2020 from well FCS-201 reported a combined radium 226 and 228 activity of 0 pCi/L (Table 2 Page 5 of 5). This low turbidity result is considered more representative of the actual aquifer conditions than the high turbidity samples collected in 2019 (Table 2 Page 5 of 5). Discussion of 2020 Groundwater Concentrations and Human Health Based Screening Levels All Groundwater Sampling Results Collected in 2020 (Table 2 Pages 4 and 5 of 5) - In calendar year 2020, filtered and unfiltered groundwater samples from wells CS-201, FCS-201, PH-201, and WWP-201 were analyzed for seventeen metals and radium. The turbidity observed during low stress groundwater sampling of these four wells ranged from 3.1 to 12.8 NTUs and laboratory analyses reported concentrations for all metals and radium below levels of regulatory concern. The 2020 groundwater sampling program was implemented to assess metals and radionuclides only. No additional analyses for volatile organics, semivolatile organics, polychlorinated bisphenols, or other compounds were required. Groundwater Sample WWP-201 (Table 2 Page 4 of 5) - In November of 2020, a groundwater sample collected from well WWP-201 reported dissolved (filtered) arsenic at a concentration of 0.0106 mg/L exceeding the USEPA MCL of 0.01. However, dissolved arsenic is not considered a contaminant of concern for the WWP Area because the highest reported concentration in the WWP Area (i.e., WWP-201 at 0.0106 mg/L) is one order of magnitude below the Utah Division of Water Quality’s 0.1 mg/L water quality standard (protective of Agricultural Beneficial Use), and because the VCP Agreement states that PacifiCorp is to assume that groundwater beneath the Former Carbon Plant will not be used in the future for drinking water purposes. Discussion of 2022 Groundwater Concentrations and Human Health Based Screening Levels Groundwater Sample PH-201 (Table 2 Page 4 of 5) - Results from the November 2022 groundwater sampling reported total lead in monitoring well PH-201 at 0.0846 mg/L (Table 2 Page 4 of 5) which exceeds the Utah Groundwater Quality Standard of 0.015 mg/L. This elevated lead concentration is likely due to the elevated turbidity of the unfiltered November 2022 PH-201 sample. Despite the use of the USEPA low stress / low flow sampling protocol, the unfiltered groundwater sample from PH-201 had a turbidity of 156 NTUs (Table 2 Page 5 of 5). Elevated turbidity in this well was surprising given that AECOM sampled the same well in May of 2020 with a turbidity of 10.8 NTUs (Table 2 Page 5 of 5). Note that on both sampling events (May 2020 and November 2022) the lab reported the dissolved (filtered) lead concentration in well PH-201 orders of magnitude below the 0.015 mg/L Utah Groundwater Quality Standard. A correlation between elevated sample turbidity and elevated total metals has often been seen during the VCP groundwater sampling events. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 21 March 2024 Upon receipt of laboratory reports, the PacifiCorp/AECOM team discussed with Chris Howell (VCP PM), the elevated lead result for the PH-201 groundwater sample and it was decided that re-development/re-purging/re-sampling of the PH-201 well would not be required. This decision by the VCP personnel was based on the low total lead concentration reported in the 2020 groundwater sample from well PH-201, the general correlation between elevated turbidity and elevated total metals in many of the VCP groundwater samples, and the very low metals concentrations reported for the filtered PH-201 and other groundwater samples collected in 2020 and 2022. 6.0 SUMMARY AND CONCLUSIONS Between June 10, 2019, and November 1, 2023, AECOM collected a combined total of 104 soil and 33 groundwater samples from the Former Carbon Power Plant. Samples were collected from the CS, FCS, PH, CT, and WWP Areas as well as nearby “background” locations in the immediate vicinity of the former power plant. The total sample number presented above do not include trip blanks or samples of investigatively derived waste but do include groundwater and soil duplicates. Depending on their location, samples were analyzed for one or more of the following: TRPH, GRO, DRO, fractionations of DRO, VOCs, SVOCs, nine PCBs (as aroclors), radium 226 & 228, nitrate, E-coli, total coliform and seventeen metals. Results of the soil and groundwater sampling are compared with Human Health screening criteria in Chapter 5 above and summarized in Tables 1 and 2, respectively. Laboratory reports and data validation reports are provided in Appendices B and C, respectively. Maps showing the sampling locations and apparent direction of groundwater flow are provided on page 4 (above) and Figures 4 through 8a (below). Summary of VCP Soil Sampling and Leachate Modeling Results Summary of Soil Sampling Results for the Power House Area - Soil Sample ‘PH-6 1314’(Table 1 Page 1 of 1), collected in 2019 from a depth of 13 to 14 feet below ground surface at boring PH- 13, reported a DRO concentration of 505 mg/kg as compared to the Utah ISL concentration of 500 mg/kg. As a result of this exceedance, the sample was further analyzed using Utah’s TPH fractionation protocol (UDEQ, 2012). As discussed in Chapter 5 above and Appendix D herein, none of the six fractionated intervals exceeded the SSCLs. So, this detected DRO concentration is below levels of VCP regulatory concern. Summary of Soil Sampling Results for the Former Coal Storage Area – A soil sample collected between the depths of 1.5 and 3 feet below ground surface at FCS Area trench FCS-6 reported naphthalene at 15.3 mg/kg (Table 1 page 6 of 9), exceeding the USEPA threshold of 8.6 mg/kg. This detected concentration, however, is less than the site-specific ambient background threshold value for naphthalene. At Utah VCP’s request, further discussion of background concentrations have been deferred and will be presented in the RAP. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 22 March 2024 Summary of Soil Sampling Results for the Coal Storage Area - In November of 2022, lead was detected above the USEPA Composite Worker RSL in one surface soil sample collected at boring CS-UPRR33 (1340 mg/kg Table 1 Page 7 of 9) in the CS Area. During the same sampling event, a soil sample collected between the depths of 1 and 5 feet below ground surface at boring CS-UPRR33, reported lead at only 11.4 mg/kg (Table 1 page 7 of 9). One year later (November of 2023) lead was reported at 1030 mg/kg (Table 1 page 7 of 9)in a soil sample collected from a depth of 0.5 to 1.5 feet below ground surface at point S.07. Note that point S.07 and boring CS- UPPRR33 represent the same sample location. Adjacent sample locations collected in November of 2023 delineated lead impacts horizontally from CS-UPRR-33, with all concentrations well below the USEPA Composite Worker RSL. Based on these data, the regulatory significant hot spot for lead appears to be isolated to shallow soils at boring CS-UPRR33. Summary of VCP Soil Sampling Results for the Cooling Tower and Waste Water Pond Areas – With the exception of the arsenic detections described in the following section, there were no other constituents detected above levels of regulatory concern during VCP soil sampling in the CT and WWP Areas. Discussion of Arsenic in Soil Throughout the Former Carbon Power Plant Areas - Forty seven out of seventy VCP soil samples in the PH, FCS, CS, CT, and WWP Areas that were analyzed for arsenic, exceeded the USEPA Composite Worker RSL threshold of 3 mg/kg (Table 1 Pages 7 & 8 of 8). Note that five of the nine background soil samples also exceeded USEPA’s arsenic Composite Worker RSL. A background threshold value of 7.36 mg/kg was calculated for arsenic at the Former Cabon Power Plant, As requested by the Utah VCP, further discussion of BTVs for arsenic will be presented within the VCP RAP. Summary of Modeling Results Evaluating the Potential for Metals to Leach From Coal Combustion Residual Materials in the Berm at the Waste Water Pond Area - In addition to the soil sampling summarized above, the PacifiCorp/AECOM team used a USEPA numerical model to evaluate the potential for the WWP Berm running parallel and adjacent to the Price River to leach coal ash metals to groundwater and then through the riverbed into the Price River. This leaching evaluation is included herein as Appendix G. The modeling results indicate that metals potentially leaching from coal ash in the WWP Area berm are not of concern and would not raise Price River water concentrations above applicable Utah / Price River Beneficial Use water quality standards. Summary of VCP Groundwater Sampling Results Summary of Groundwater Sampling Results for the Power House Area – As described in Chapter 5 above, elevated total metals and radionuclides reported during the 2019 VCP groundwater sampling are attributed to high turbidity of the samples. Excluding these high turbidity results, the only other VCP groundwater sample collected in the PH Area potentially above a level of regulatory concern is the June 2019 GRO sample result for well PH-16 (Table 2 page 1 of 5). A GRO concentration of 1.13 mg/L was detected in this sample which exceeded the Utah DERR March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 23 March 2024 ISL of 1 mg/l. Because this GRO concentration exceeded the ISL threshold it was further evaluated in June of 2019 to report fractionations of GRO. All GRO TPH fractionations including C7 & C8 Aliphatics, C9 and C10 Aliphatics, and C9 & C10 Alkyl Benzenes for this sample were reported below laboratory reporting limits. Based on the results of the VCP groundwater sampling, there are no dissolved analytes in the PH Area which require corrective action. Summary of Groundwater Sampling Results for the Former Coal Storage Area – As described above, elevated total metals and radionuclides reported during the 2019 VCP groundwater sampling are attributed to high turbidity of the samples. Excluding these high turbidity results, the only other VCP groundwater sample collected in the Former Coal Storage Area which was potentially above levels of regulatory concern was the July 3, 2019, groundwater sample from well FCS-3. This sample reported Bis(2-ethylhexyl phthalate) at 0.0341 mg/L (Table 2 page 3 of 5), which exceeded the USEPA MCL of 0.006 mg/L. Because this constituent is a common laboratory contaminant and because the VCP agreement states that PacifiCorp is to assume that groundwater at the site will not be used for drinking water purposes, bis(2-ethylhexyl) phthalate is not considered a site contaminant of concern. Summary of Groundwater Sampling Results for the Coal Storage Area - As described above, elevated total metals and radionuclides reported during the 2019 VCP groundwater sampling are attributed to high turbidity of the samples. These high turbidity results have been excluded when summarizing the potential constituents of concern detected in the CS Area. Laboratory analyses of the groundwater sample collected from monitoring well CS-1 in July of 2019, reported concentrations of TRPH, TPH DRO, and benzo(a)pyrene, (Table 2 Pages 1 and 3) above potentially applicable health-based screening levels. TPH DRO fraction (C13-16 aliphatic hydrocarbons) was also detected at a concentration above the calculated Utah SSCL (See Appendix D). The DRO concentration (99.4 mg/L Table 2 page 1 of 5) was one order of magnitude above the 10 mg/L Utah LUST Tier 1 standard. For the past 32 years, this hydrocarbon plume has been regulated by the Utah Department of Environmental Quality – Division of Environmental Response (DERR) as underground storage tank release identification designation EFMU (UDEQ 1998). In 1997, remediation efforts for release EFMU were terminated and in January of 1998, the DERR closed the site with contamination remaining in place. The DERR has requested that the PacifiCorp / AECOM Team negotiate all future response actions (if any) associated with release EFMU with the DERR rather than the VCP. It is significant to note that groundwater from well CS-201 in the CS Area was sampled and analyzed for DRO in November of 2022 and found to be below the laboratory reporting limit of 0.001 mg/L (Table 2 Page 1 of 5). This data coupled with the remediation history and age of release EFMU, suggests that the DRO plume surrounding well CS-1 is stable and will not impact the property leased by PacifiCorp from UPRR (see Figures 5, 7a, 7b, and 7c). March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 24 March 2024 As shown in Table 2, bis(2-ethylhexyl) phthalate was also detected in July of 2019 in the CS Area wells CS-1 and CS-3 at concentrations of 0.0102 and 0.032 mg/L, respectively (Table 2 page 3 of 5). Bis(2-ethylhexyl) phthalate is a common lab contaminant and is therefore not considered a contaminant of concern for the CS Area. Summary of Groundwater Sampling Results for the Waste Water Pond Area - As described above, elevated total metals and radionuclides reported during the 2019 VCP groundwater sampling are attributed to high turbidity of the samples. These high turbidity results have been excluded when summarizing the potential constituents of concern detected in the WWP Area. In November of 2020, a groundwater sample collected from well WWP-201 reported dissolve (filtered) arsenic at a concentration of 0.0106 mg/L (Table 2 page 4 of 5) exceeding the USEPA MCL of 0.01. Dissolved arsenic is not considered a contaminant of concern for the WWP Area because:  The highest reported dissolved arsenic concentration in the WWP Area is one order of magnitude below the Utah Division of Water Quality Beneficial Use threshold for this segment of the Price River; and  The VCP Agreement states that PacifiCorp is to assume that groundwater beneath the Former Carbon Plant will not be used in the future for drinking water purposes. Based on the results of the VCP groundwater sampling, there are no dissolved analytes in the WWP Area which require corrective action. Cooling Tower Area – Groundwater was not encountered in the CT Area. 7.0 LIMITATIONS AECOM completed these site characterizations in a reasonable and prudent manner in accordance with the customary standards of care and diligence practiced by firms that conduct services of a similar nature. As with any characterization, this report represents a snapshot in time of soil conditions at the site and does not include representation of conditions that may occur in areas not assessed. This report was prepared for the sole use of PacifiCorp. The scope of services during the site characterization may not be appropriate to satisfy the needs of other users. Any use or re-use of this document or of the findings, conclusions or recommendations presented herein is at the sole risk of said user. Historical information and other data have been furnished to AECOM by PacifiCorp, which AECOM has used in preparing this report. AECOM has relied on this information as furnished and is neither responsible for nor has confirmed the accuracy of this information. March 2024 VCP Site Characterization Report Former PacifiCorp Carbon Power Plant Project Number 60577967 25 March 2024 8.0 REFERENCES AECOM, 2019. Site Characterization Work Plan Utah Voluntary Cleanup Program Former Carbon Power Plant. May 2019. AECOM, 2020a. Carbon Plant - VCP Work Plan Addendum. April 2020. AECOM, 2020b. VCP Work Plan Addendum Letter – October 2021 UDEQ, 1998. Release Site EFMU, Carbon Steam Plant, Junction of Highways 6 & 191, Helper, Utah Facility Identification No. 5000225. January 23, 1998. UDEQ, 2012. Guidelines for TPH Fractionation at Leaking Underground Storage Tank Sites. Final Draft. December. UDEQ DERR. UDEQ, 2015. Guidelines for Utah's Corrective Action Process for Leaking Underground Storage Tank Sites. Third Edition Final Draft. Leaking Underground Storage Tank Program. Division of Environmental Response and Remediation. Utah Department of Environmental Quality. October 30. 2005, Updated March 2015. UDEQ, 2019. R 317 Environmental Quality, Water Quality, Rule R317-2. Standards of Quality for Waters of the State. Effective October 1, 2019. UGS, 2003. Geologic Map of the Price 30’ x 60’ Quadrangle, Carbon, Duchesne, Uintah, Utah, and Washington Counties, Utah, Weiss, Witkind, Cashion. USFWS, 2019. National Wetlands Inventory, Wetland Mapper. Available online at: https://www.fws.gov/wetlands/data/mapper.html USEPA, 1996. Soil Screening Guidance: Technical Background Document. Office of Emergency and Remedial Response, Washington, D.C. EPA/540/R-95/128, May 1996. USEPA, 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites. Office of Solid Waste and Emergency Response, Washington, D.C. OSWER 9355.4-24. December 2002. USEPA, 2016. ProUCL Version 5.1. Office of Research and Development. June 2016. USEPA, 2017. USEPA, 2017. Low Stress (low flow) Purging and Sampling Procedure for the Collection of Groundwater Samples From Monitoring Wells. September 2017. USEPA 2023a. Regional Screening Levels (RSLs) for Chemical Contaminants at Superfund Sites - Generic Tables. TR-1E-06 and THQ=1). May 2023. Accessed online at: https://www.epa.gov/risk/regional-screening-levels-rsls USEPA, 2023b. Regional Screening Levels (RSLs) for Chemical Contaminants at Superfund Sites – Users Guide. May 2023. Accessed online at: https://www.epa.gov/risk/regional- screening-levels-rsls Former CarbonPower Plant Helper Price £¤191 £¤6 £¤6 Do c u m e n t P a t h : Q : \ P r o j e c t s \ P a c i f i c o r p \ 2 0 1 8 a n d 2 0 1 9 C a r b o n P o w e r P l a n t \ 6 0 5 7 7 9 6 7 a n d 6 0 6 0 3 3 8 9 \ 9 0 0 - C A D , G I S \ C a r b o n P l a n t V C P \ V C P _ S I _ R e p o r t _ F i g u r e s \ F i g 1 _ S i t e _ L o c a t i o n _ M a p . m x d Map Extent Figure 1PacifiCorp Former Carbon Power PlantSite Location Map 0 0.5 10.25 Miles µ WastewaterPond Area Cooling Tower Area Power HouseArea Coal Storage Area Former CoalStorage Area Do c u m e n t P a t h : Q : \ P r o j e c t s \ P a c i f i c o r p \ 2 0 1 8 a n d 2 0 1 9 C a r b o n P o w e r P l a n t \ 6 0 5 7 7 9 6 7 a n d 6 0 6 0 3 3 8 9 \ 9 0 0 - C A D , G I S \ C a r b o n P l a n t V C P \ V C P _ S I _ R e p o r t _ F i g u r e s \ F i g 2 _ V C P _ S a m p l i n g _ A r e a s ( L a n d s c a p e ) . m x d Figure 2 PacifiCorp Former Carbon Power Plant VCP Sampling Areas 0 300 600150Feet µ UTCU-0035 (1.06 acres) County: 2-15-003 UTCU-0078 (1.45 acres) County: 2-15-003 UTCU-0036 (19.82 acres) County: 2-15-001 UTCU-0037 (39.87 acres) County: 2-15-001 UTCU-0077 (9.63 acres) County: 2-15-003 UTCU-0040 (3.40 acres) County: 2-15-002 UTCU-0038 (12.55 acres) County: 2-40-001 UTCU-0043 (39.92 acres) County: 2-37-002 UTCU-0043 (72.01 acres) County: 2-37-002 Area north of Willow Creek in PacifiCorp parcels UTCU-0036 and 0037 is excluded from the VCP Program Parcel UTCU-0040 is excluded from the VCP program Parcel UTCU-0038 is excluded from the VCP program Parcel UTCU-0043 is excluded from the VCP program Parcel UTCU-0043 is excluded from the VCP program Approximately 38.27 of the 39.87 acres in parcel UTCU-0037 is in- cluded in the VCP program Parcels UTCU-0035 and 0078 are included in the VCP program The area south of Willow Creek in parcel UTCU-0036 is included in the VCP program Parcel UTCU-0077 is included in the VCP program £¤191 £¤6 £¤6 T13S R9E 1 T13S R9E 12 T13S R10E 7 T13S R10E 6 T13S R9E 13 T13S R9E 2 T13S R9E 11 T13S R10E 18 T12S R9E 36 T12S R10E 31 T13S R9E 14 T12S R9E 35 µ Do c u m e n t P a t h : Q : \ P r o j e c t s \ P a c i f i c o r p \ 2 0 1 8 a n d 2 0 1 9 C a r b o n P o w e r P l a n t \ 6 0 5 7 7 9 6 7 a n d 6 0 6 0 3 3 8 9 \ 9 0 0 - C A D , G I S \ C a r b o n P l a n t V C P \ V C P _ S I _ R e p o r t _ F i g u r e s \ F i g 8 _ P a r c e l _ m a p . m x d Figure 3 PacifiCorp Former Carbon Power Plant Emery County Parcel Map 0 1,400 2,800700Feet Pacificorp owned parcels !( !( !( !( !(!( !( !( !( Willow Creek £¤191 £¤6 P r i c e R i v e r Former Carbon Power PlantPower House Area BG-3 BG-1 BG-6 BG-4 BG-7 BG-8 BG-5 BG-2A BG-2B µ Q: \ P r o j e c t s \ P a c i f i c o r p \ 2 0 1 8 a n d 2 0 1 9 C a r b o n P o w e r P l a n t \ 6 0 5 7 7 9 6 7 a n d 6 0 6 0 3 3 8 9 \ 9 0 0 - C A D , G I S \ C a r b o n P l a n t V C P \ V C P _ S I _ R e p o r t _ F i g u r e s _ S u m m e r 2 0 2 0 \ F i g 4 _ B a c k g r o u n d _ S a m p l e _ L o c a t i o n s ( L a n d s c a p e ) . m x d Figure 4PacifiCorp Former Carbon Power PlantBackground Soil Sampling Locations 0 350 700175Feet Background Soil Sampling Location Aerial imagery flown 11/3/2018 !( !< !< !< !< !< !< !< !< !< !< !< !< @A @A @A @A @A @A @A @A @A @A @A@A @A@A@A @A !<!< !< !< @A @A !< !< W i l l o w C r e e k £¤191 Bridge 1CS-201 FCS-201 PH-201 CS-UPRR31 CS-UPRR34 CS-UPRR33 CS-UPRR32 PH-13 PH-6 PH-3 FCS-3 CS-2 CS-1 PH-15 PH-14 PH-11 FCS-2 FCS-1 PH-9 PH-8 PH-7 PH-5 PH-4 PH-2 CS-4 CS-3 CT-3 CT-2 CT-1 PH-16 PH-10 FCS-6 FCS-5 FCS-4 PH-12 µ \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\VCP_SI_Report_Figures_Summer2020\Fig5_Powerhouse_Sample_Locations(Landscape).mxd Figure 5PacifiCorp Former Carbon Power PlantPower House AreaSample Locations 0 150 30075Feet Aerial imagery flown 11/3/2018 !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well UPRR/PacifiCorp Lea se Area !< !< !< !< @A @A @A @A @A !< !< P r i c e R i v e r £¤6 WWP-201 WWP-2 WWP-1 Bridge 2 WWP-Berm4 WWP-Berm2 WWP-4 WWP-3 WWP-Sed1 WWP-Berm3 WWP-Berm1 µ \\ u r s s a l t l a k e c i t y . u s . i e . u r s \ S a l t L a k e C i t y \ P r o j e c t s \ P a c i f i c o r p \ 2 0 1 8 a n d 2 0 1 9 C a r b o n P o w e r P l a n t \ 6 0 5 7 7 9 6 7 a n d 6 0 6 0 3 3 8 9 \ 9 0 0 - C A D , G I S \ C a r b o n P l a n t V C P \ V C P _ S I _ R e p o r t _ F i g u r e s _ S u m m e r 2 0 2 0 \ F i g 6 _ W W P _ S a m p l i n g _ L o c a t i o n s ( L a n d s c a p e ) . m x d Figure 6PacifiCorp Former Carbon Power Plant Waste Water Pond AreaSample Locations 0 100 20050Feet Aerial imagery flown 11/3/2018 !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well @A @A !< !< #*#*#*#*#*#*#*#*#*#*#* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* #* A.0123 A.0225 A.030.0 A.040.0 A.050.0 A.060.0 A.070.0 A.080.0 A.090.0 A.100.0 A.110.0 B.010.0 B.0238 B.030.0 B.040.0 B.050.0 B.060.0 B.070.0 B.080.0 B.090.0 B.100.0 C.020.0 C.030.0 C.040.0 C.050.0 C.060.0 C.070.0 C.080.0 C.090.0 C.1019 C.110.0 C.120.0C.130.0 C.1426 C.1546 C.160.0 C.170.0 C.180.0 C.190.0 C.200.0 C.210.0 C.220.0 C.230.0 D.010.0 D.020.0 D.030.0 D.040.0 D.050.0 D.0619 D.0721 D.080.0 D.090.0 D.100.0 C.010.0 CS-4 CS-UPRR33 CS-UPRR34 CS-UPRR32 µ Document Path: \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig7a_XREF Screening Results for Lead.mxd Figure 7aPacifiCorp Former Carbon Power Plant2023 XRF Screening Results For Lead 0 30 6015Feet Legend B.0238 2023 XRF Surface Soil Screening Point Pb screening concentration (mg/kg) UPRR/PacificCorp Lease Area !<Monitoring Well @A Soil Boring/Soil Sample Location !<Tem porary Monitoring Well #* @A @A !< !< ")" ")" ")" ")" ")" ")" ")" ")" ")"")" ")" S.017.28 S.02353 S.038.00 S.06149 S.0812.3 S.0915.0 S.109.31 S.117.74 S.0412.727.2 S.0521.991.5 S.0721.51030 CS-4 CS-UPRR33 CS-UPRR34 CS-UPRR32 µ Document Path: \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig7b_Soil Sampling Results for Lead.mxd Figure 7bPacifiCorp Former Carbon Power Plant2023 Soil Sampling Results For Lead 0 30 6015Feet LegendS.0721.51030 ")"2023 Soil Sample Location Pb concentration (mg/kg) in surface sample Pb concentration (mg/kg) in 0.5' to 1.5' sample UPRR/PacificCorp Lease Area !<Monitoring Well @A Soil Boring/Soil Sample Location !<Tem porary Monitoring Well !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< !< @A @A @A @A @A @A @A @A @A @A @A@A @A@A@A @A !< @A @A !< !< W i l l o w C r e e k £¤191 CS-UPRR31 CS-UPRR32 CS-UPRR33 CS-UPRR34 PH-136067.4 PH-66070.66 PH-36071.23 FCS-36079.6 CS-26071.13 CS-16070.89 PH-156068.03 PH-146067.58 PH-116066.86 FCS-26074.77 FCS-16073.08 Bridge 1*Willow Creek Surface Water Elevation = 6080.68 PH-9 PH-8 PH-7 PH-5 PH-4 PH-2 CS-4 CS-3 CT-3 CT-2 CT-1 PH-16 PH-10 FCS-6 FCS-5 FCS-4 PH-126067.77 6 0 7 1 6 0 7 2 6 0 7 1 . 5 6070 6 0 7 0 . 5 60736072.5 6074 6 0 6 9 6 0 6 9 . 5 6073.5 60756074.5 6076 6 0 6 8 . 5 6068 6075.5 60776076.5 6078 6077.5 6 0 6 7 . 5 6078.5 6079 6 0 6 7 6079.5 µ \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig8a_Potentiometric_Powerhouse_area(lLandscape).mxd 0 150 30075Feet Aerial imagery flown 11/3/2018 Notes: * - Well was not used in potentiometric surface generation Figure 8aPacifiCorp Former Carbon Power PlantPower House AreaPotentiometric Surface MapJuly 3, 2019Potentiometric Contour (ft amsl)(Da shed where Inferred) !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well Groundwater Flow Dire ction 6070.89 July 3 , 2019 Groundwater Elevation (ft amsl) UPRR/PacifiCorp Lease Area !< !< !< !< !< !< !< !< !< !< !< !< @A @A @A @A @A @A @A @A @A @A @A@A @A@A@A @A !<!< !< !< @A @A !< !< W i l l o w C r e e k £¤191 CS-UPRR31 CS-UPRR32 CS-UPRR33 CS-UPRR34 PH-2016064.94 CS-2016066.87 FCS-2016071.13PH-9 PH-8 PH-7 PH-5 PH-4 PH-2 CS-4 CS-3 CT-3 CT-2 CT-1 PH-6 PH-3 CS-2 CS-1 PH-16 PH-10 FCS-6 FCS-5 FCS-4 PH-15 PH-14 PH-13 PH-12 PH-11 FCS-3 FCS-2 FCS-1 Bridge 1Willow Creek Surface Water Elevation = 6080.90 6 0 6 7 6068 6 0 6 6 . 5 6 0 6 7 . 56 0 6 6 6069 6068.5 6069.5 6 0 6 5 . 5 6070 µ \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig8b_Potentiometric_Powerhouse_area(lLandscape).mxd 0 150 30075Feet Aerial imagery flown 11/3/2018 Notes: * - Well was not used in potentiometric surface generation Figure 8bPacifiCorp Former Carbon Power PlantPower House AreaPotentiometric Surface MapMay 11, 2020Potentiometric Contour (ft amsl)(Da shed where Inferred) !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well Groundwater Flow Dire ction 6070.89 May 11, 202 0 Groundwater Elevation (ft amsl) UPRR/PacifiCorp Lease Area ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !< !< !< !< !< !< !< !< !< !< !< !< @A @A @A @A @A @A @A @A @A @A @A@A @A@A@A @A !<!< !< !< @A @A !< !< W i l l o w C r e e k £¤191 CS-UPRR31 CS-UPRR326060.74 CS-UPRR33 CS-UPRR346060.62 6 0 6 1 . 5 0 6 0 6 1 . 0 0 PH-2016060.96 CS-2016061.42 FCS-201PH-9 PH-8 PH-7 PH-5 PH-4 PH-2 CS-4 CS-3 CT-3 CT-2 CT-1 PH-6 PH-3 CS-2 CS-1 PH-16 PH-10 FCS-6 FCS-5 FCS-4 PH-15 PH-14 PH-13 PH-12 PH-11 FCS-3 FCS-2 FCS-1 Bridge 1 µ \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig8c_Potentiometric_Powerhouse_area(lLandscape).mxd 0 150 30075Feet Aerial imagery flown 11/3/2018 Notes: * - Well was not used in potentiometric surface generation Figure 8cPacifiCorp Former Carbon Power PlantPower House AreaPotentiometric Surface MapNovember 19 & 20, 2022Potentiometric Contour (ft amsl)(Da shed where Inferred) !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well Groundwater Flow Dire ction 6060.89 November 20, 202 2 Groundwater Elevation (ft amsl) UPRR/PacifiCorp Lease Area !< !< !< !< !< !< !< !< !< !< !< !< !< !< @A @A @A @A @A !< P rice River £¤6 WWP-26044.37 WWP-16046.82 Bridge 2*Price River Surface Water Elevation = 6045.16 WWP-Berm46042.05 WWP-Berm26040.69 WWP-4 WWP-3 WWP-Sed1 WWP-Berm3 WWP-Berm1 6043 6 0 4 4 6043.5 6042 6042.5 6 0 4 5 6 0 4 4 .5 6041.5 6041 6046 6 0 4 5 .5 6046.5 6040.5 µ \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig9a_Potentiometric_WWP_area(Landscape).mxd 0 100 20050Feet Aerial imagery flown 11/3/2018 Figure 9aPacifiCorp Former Carbon Power PlantWWP AreaPotentiometric Surface MapJuly 3, 2019 Notes: * - Well was not used in potentiometric surface generation - Ponds have been drained after aerial was acquired Potentiometric Contour (ft amsl)(Da shed where Inferred) !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well Groundwater Flow Dire ction 6070.89 July 3 , 2019 Groundwater Elevation (ft amsl) !< !< !< !< @A @A @A @A @A !< !< P rice River £¤6 WWP-2016046.16 WWP-4 WWP-3 WWP-2 WWP-1 Bridge 2Price River Surface Water Elevation = 6044.69 WWP-Sed1 WWP-Berm3 WWP-Berm1 WWP-Berm4 WWP-Berm2 µ \\na.aecomnet.com\lfs\AMER\SaltLakeCity-USSLC2\DCS\Projects\Pacificorp\2018 and 2019 Carbon Power Plant\60577967 and 60603389\900 - CAD, GIS\Carbon Plant VCP\XREF\Fig9b_Potentiometric_WWP_area(Landscape).mxd 0 100 20050Feet Aerial imagery flown 11/3/2018 Figure 9bPacifiCorp Former Carbon Power PlantWWP AreaPotentiometric Surface MapMay 11, 2020 Notes: * - Well was not used in potentiometric surface generation - Ponds have been drained after aerial was acquired !<Monitoring Well @A Soil Boring/Soil Sample Location !<Temporary Monitoring Well 6070.89 May 11, 202 0 Groundwater and Surface Water Elevation (ft amsl) Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted SG T ‐HE M / N o n ‐Po l a r Ma t e r i a l SG T ‐ Di e s e l Ra n g e Or g a n i c s (D R O ) (C 1 0 ‐C2 8 ) C1 1 ‐C1 2 Al i p h a t i c hy d r o c a r b o n s C1 1 ‐C1 3 Al k y l Na p h t h a l e n e s C1 2 ‐C2 2 Po l y a r o m a t i c hy d r o c a r b o n s C1 3 ‐C1 6 Al i p h a t i c hy d r o c a r b o n s C1 7 ‐C2 1 Al i p h a t i c hy d r o c a r b o n s C2 2 ‐C3 5 Al i p h a t i c hy d r o c a r b o n s TP H C6 ‐C1 0 (G R O ) Me t h y l te r t ‐bu t y l et h e r be n z e n e to l u e n e et h y l b e n z e n e xy l e n e s , to t a l na p h t h a l e n e (b a s e d on 82 7 0 E ) Te t r a c h l o r o e t h e n e Tr i c h l o r o e t h e n e ci s ‐1, 2 ‐Di c h l o r o e t h e n e tr a n s ‐1, 2 ‐Di c h l o r o e t h e n e 1, 1 ‐Di c h l o r o e t h e n e vi n y l ch l o r i d e 1, 4 ‐Di o x a n e (s a m e as p‐Di o x a n e ) Ac e t o n e Ca r b o n di s u l f i d e Cy c l o h e x a n e Me t h y l c y c l o h e x a n e m, p ‐Xy l e n e o‐Xy l e n e 1000 / 10000 500 / 5000 150 / 1500 0.3/ 0.3 0.2 / 0.9 9 / 25 5 / 23 142 / 142 51 / 51 210 5.1 47000 25 2500 8.6 100 6 370 300 1,000 1.7 24 1.1E+06 3,500 27,000 2,400 2800 321 98.7 657 5,770 133,000 133,000 Min (mg/kg)0.00899 Max (mg/kg)25 Background Threshold Value 2 (mg/kg or pCi/g)58.2 95%UCL 9 684 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CS‐1‐2023 (June 19, 2019)COC 1906561 7070323.116 1819202.117 < 174 104 <0.00569 <0.00569 <0.00569 <0.00569 0.021 CS‐2‐2022 (June 19, 2019)COC 1906561 7070520.955 1819210.376 < 178 <0.0599 <0.00599 <0.00599 <0.00599 <0.00599 <0.00599 <0.00778 CS‐3‐1819 (June 18, 2019)COC 1906473 7070684.457 1819000.500 < 181 CS‐4‐1820 (June 18, 2019)COC 1906473 7070271.158 1818959.311 < 184 CS‐UPRR31‐Surface (Nov 15, 2022) 22K1233 7070675.300 1818916.900 <0.40 CS‐UPRR31‐0105 (Nov 15, 2022)22K1233 7070675.300 1818916.900 <8.00 CS‐UPRR32‐Surface (Nov 15, 2022)22K1233 7070531.400 1818951.400 <8.00 CS‐UPRR32‐0105 (Nov 15, 2022)22K1233 7070531.400 1818951.400 <2.00 CS‐UPRR32‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 <266 <53 <0.253 <0.01 <0.01 <0.03 <0.03 <0.03 <0.43 CS‐UPRR932‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 <268 <54 <0.246 <0.01 <0.01 <0.02 <0.02 <0.02 <0.43 CS‐UPRR33‐Surface (Nov 15, 2022)22K1233 7070367.300 1818979.800 <2.00 CS‐UPRR33‐0105 (Nov 15, 2022)22K1233 7070367.300 1818979.800 <2.00 CS‐UPRR34‐Surface (Nov 14, 2022)22K1233 7070273.500 1818983.500 <0.40 CS‐UPRR34‐0105 (Nov 14, 2022)22K1233 7070273.500 1818983.500 <1.70 CS‐UPRR34‐2022 (Nov 14, 2022)22K1233 7070273.500 1818983.500 <278 <56 <0.219 <0.009 <0.009 <0.02 <0.02 <0.02 <0.45 S.01 Surface (Oct 31, 2023)23J2567 S.901 Surface (Oct 31, 2023)23J2567 S.02 Surface (Oct 31, 2023)23J2567 S.03 Surface (Oct 31, 2023)23J2567 S.04 Surface (Oct 31, 2023)23J2567 S.04 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 S.05 Surface (Oct 31, 2023)23J2567 S.05 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 S.06 Surface (Oct 31, 2023)23J2567 S.07 Surface (Oct 31, 2023)23J2567 S.07 1.0‐1.5 (Oct 31, 2023)23J2567 S.08 Surface (Oct 31, 2023)23J2567 S.09 Surface (Oct 31, 2023)23J2567 S.10 Surface (Oct 31, 2023)23J2567 S.11 Surface (Oct 31, 2023)23J2567 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) DRO Fractionation Coal Storage Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted SG T ‐HE M / N o n ‐Po l a r Ma t e r i a l SG T ‐ Di e s e l Ra n g e Or g a n i c s (D R O ) (C 1 0 ‐C2 8 ) C1 1 ‐C1 2 Al i p h a t i c hy d r o c a r b o n s C1 1 ‐C1 3 Al k y l Na p h t h a l e n e s C1 2 ‐C2 2 Po l y a r o m a t i c hy d r o c a r b o n s C1 3 ‐C1 6 Al i p h a t i c hy d r o c a r b o n s C1 7 ‐C2 1 Al i p h a t i c hy d r o c a r b o n s C2 2 ‐C3 5 Al i p h a t i c hy d r o c a r b o n s TP H C6 ‐C1 0 (G R O ) Me t h y l te r t ‐bu t y l et h e r be n z e n e to l u e n e et h y l b e n z e n e xy l e n e s , to t a l na p h t h a l e n e (b a s e d on 82 7 0 E ) Te t r a c h l o r o e t h e n e Tr i c h l o r o e t h e n e ci s ‐1, 2 ‐Di c h l o r o e t h e n e tr a n s ‐1, 2 ‐Di c h l o r o e t h e n e 1, 1 ‐Di c h l o r o e t h e n e vi n y l ch l o r i d e 1, 4 ‐Di o x a n e (s a m e as p‐Di o x a n e ) Ac e t o n e Ca r b o n di s u l f i d e Cy c l o h e x a n e Me t h y l c y c l o h e x a n e m, p ‐Xy l e n e o‐Xy l e n e 1000 / 10000 500 / 5000 150 / 1500 0.3/ 0.3 0.2 / 0.9 9 / 25 5 / 23 142 / 142 51 / 51 210 5.1 47000 25 2500 8.6 100 6 370 300 1,000 1.7 24 1.1E+06 3,500 27,000 2,400 2800 321 98.7 657 5,770 133,000 133,000 Min (mg/kg)0.00899 Max (mg/kg)25 Background Threshold Value 2 (mg/kg or pCi/g)58.2 95%UCL 9 684 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting PH‐2‐0203 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐2‐0607 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐2‐1011 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐3‐0203 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐3‐0607 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐3‐1112 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐4‐0203 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐4‐0607 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐4‐1112 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐5‐0203 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐5‐0607 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐5‐1012 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐6‐1314 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 < 164 UJ 505 J 8.47 10.1 2.99 45.1 25.3 78.2 0.0398 J 0.199 J 0.0203 J <0.1383 2.92 <0.00545 <0.00545 <0.00545 <0.00545 <0.00545 <0.00272 <0.136 0.185 0.0246 0.00553 0.04 0.0893 0.049 PH‐6‐2122 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 < 180 UJ 43.4 <0.00563 UJ <0.00563 UJ <0.00563 UJ <0.01255 0.0356 J <0.00563 <0.00563 <0.00563 <0.00563 <0.00563 <0.00281 <0.141 <0.0281 <0.00563 <0.00563 <0.00563 0.00692 <0.00563 PH‐7‐0910 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 < 154 UJ <0.00488 UJ <0.00488 UJ <0.00488 UJ <0.00976 0.0115 J <0.00488 <0.00488 <0.00488 <0.00488 <0.00488 <0.00244 <0.122 <0.0244 <0.00488 <0.00488 <0.00488 <0.00488 <0.00488 PH‐7‐1516 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 < 154 UJ <0.00504 UJ 0.0277 J0.01 J <0.0372 1.04 J <0.00504 <0.00504 <0.00504 <0.00504 <0.00504 <0.00252 <0.126 <0.0252 0.0102 <0.00504 0.0101 0.0279 0.0093 PH‐8‐1112 (June 27, 2019)1906750 7069917.254 1819200.329 < 153 0.0039 J 0.0336 0.00678 0.0272 1.12 <0.00204 <0.00204 <0.00204 <0.00204 <0.00204 <0.00102 <0.051 0.0141 0.00293 <0.00204 0.00235 0.02 0.0072 PH‐8‐1516 (June 27, 2019)1906750 7069917.254 1819200.329 < 155 0.0104 0.0229 0.00334 0.01436 1.26 <0.00206 <0.00206 <0.00206 <0.00206 <0.00206 <0.00103 <0.0515 <0.0103 <0.00206 <0.00206 0.00291 0.0107 0.00366 PH‐9‐0405 (June 28, 2019)1906750 7069924.775 1819114.989 < 169 <0.00226 0.00534 <0.00226 <0.0052 0.133 <0.00226 <0.00226 <0.00226 <0.00226 <0.00226 <0.00113 <0.0565 0.0394 <0.00226 <0.00226 <0.00226 <0.00226 <0.00226 PH‐9‐1112 (June 28, 2019)1906750 7069924.775 1819114.989 < 158 0.00335 0.0186 0.00491 0.02834 0.106 <0.0021 <0.0021 <0.0021 <0.0021 <0.0021 <0.00105 <0.0525 <0.0105 <0.0021 <0.0021 <0.0021 0.0217 0.00664 PH‐10‐1213 (June 26, 2019 1906718 / 1906719 7069907.863 1818897.646 PH‐10‐1516 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 PH‐10‐1920 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 PH‐11‐1011 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐11‐1314 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐11‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐911‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐12‐2425 (June 26, 2019)1906718 / 1906719 7069973.231 1818969.332 < 177 <0.0223 <0.0223 <0.0223 <0.0446 <0.00781 <0.0223 <0.0223 <0.0223 <0.0223 <0.0223 <0.0112 <0.558 <0.112 0.0258 <0.0223 <0.0223 <0.0223 <0.0223 PH‐13‐1819 (June 25, 2019)1906718 / 1906719 7069940.699 1818927.749 < 206 0.00326 0.0119 <0.00274 <0.00579 <0.00904 <0.00274 <0.00274 <0.00274 <0.00274 <0.00274 <0.00137 <0.0686 <0.0137 <0.00274 <0.00274 <0.00274 0.00442 <0.00274 PH‐14‐1920 (June 25, 2019)1906718 / 1906719 7069998.380 1818939.247 < 170 UJ <0.00227 0.00362 <0.00227 <0.00454 <0.00751 <0.00227 <0.00227 <0.00227 <0.00227 <0.00227 <0.00113 <0.0566 0.0117 <0.00227 <0.00227 <0.00227 <0.00227 <0.00227 PH‐15‐1920 (June 24, 2019)1906634/1906628 7070035.968 1818961.838 < 188 <0.00613 <0.00613 <0.00613 <0.01226 0.0349 <0.00613 <0.00613 <0.00613 <0.00613 <0.00613 <0.00307 <0.153 <0.0307 <0.00613 <0.00613 <0.00613 <0.00613 <0.00613 PH‐16‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 445 <0.111 <0.111 3.04 <0.465 1.37 <0.111 <0.111 <0.111 <0.111 <0.111 <0.0557 <2.78 <0.557 <0.111 0.123 4.11 0.354 <0.111 PH‐916‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 295 <0.112 <0.112 3.67 <0.485 1.51 <0.112 <0.112 <0.112 <0.112 <0.112 <0.0558 <2.79 <0.558 <0.112 0.128 4.5 0.373 <0.112 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) Former AST Pipeline Release Area Central Power House Area 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Power House Area Power Units 1 &2 Trans‐former Areas 1 Western Switch Yard Trans‐ former Area DRO Fractionation Chem Unload & Plant Drain Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted SG T ‐HE M / N o n ‐Po l a r Ma t e r i a l SG T ‐ Di e s e l Ra n g e Or g a n i c s (D R O ) (C 1 0 ‐C2 8 ) C1 1 ‐C1 2 Al i p h a t i c hy d r o c a r b o n s C1 1 ‐C1 3 Al k y l Na p h t h a l e n e s C1 2 ‐C2 2 Po l y a r o m a t i c hy d r o c a r b o n s C1 3 ‐C1 6 Al i p h a t i c hy d r o c a r b o n s C1 7 ‐C2 1 Al i p h a t i c hy d r o c a r b o n s C2 2 ‐C3 5 Al i p h a t i c hy d r o c a r b o n s TP H C6 ‐C1 0 (G R O ) Me t h y l te r t ‐bu t y l et h e r be n z e n e to l u e n e et h y l b e n z e n e xy l e n e s , to t a l na p h t h a l e n e (b a s e d on 82 7 0 E ) Te t r a c h l o r o e t h e n e Tr i c h l o r o e t h e n e ci s ‐1, 2 ‐Di c h l o r o e t h e n e tr a n s ‐1, 2 ‐Di c h l o r o e t h e n e 1, 1 ‐Di c h l o r o e t h e n e vi n y l ch l o r i d e 1, 4 ‐Di o x a n e (s a m e as p‐Di o x a n e ) Ac e t o n e Ca r b o n di s u l f i d e Cy c l o h e x a n e Me t h y l c y c l o h e x a n e m, p ‐Xy l e n e o‐Xy l e n e 1000 / 10000 500 / 5000 150 / 1500 0.3/ 0.3 0.2 / 0.9 9 / 25 5 / 23 142 / 142 51 / 51 210 5.1 47000 25 2500 8.6 100 6 370 300 1,000 1.7 24 1.1E+06 3,500 27,000 2,400 2800 321 98.7 657 5,770 133,000 133,000 Min (mg/kg)0.00899 Max (mg/kg)25 Background Threshold Value 2 (mg/kg or pCi/g)58.2 95%UCL 9 684 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CT‐1‐Surface (June 10, 2019)COC 1906405 7069603.505 1818981.732 CT‐2‐Surface (June 10, 2019)COC 1906405 7069742.697 1819071.901 CT‐3‐Y‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 CT‐3‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 FCS‐1‐Surface (June 12, 2019)COC 1906405 7070122.062 1819458.168 < 189 FCS‐1‐0709 (June 19, 2019)COC 1906561 7070122.062 1819458.168 < 167 FCS‐2‐Surface (June 12, 2019)COC 1906405 7069977.823 1819565.309 < 181 FCS‐2‐0708 (June 19, 2019)COC 1906561 7069977.823 1819565.309 < 176 FCS‐3‐Surface (June 12, 2019)COC 1906405 7069740.284 1819744.758 < 203 FCS‐3‐0607 (June 20, 2019)COC 1906561 7069740.284 1819744.758 < 157 FCS‐4‐Berm‐Surface (June 12, 2019)COC 1906405 7070154.651 1819491.097 < 177 FCS‐4 02‐03' Berm (July 9, 2019)COC 1907225 7070154.651 1819491.097 < 150 FCS‐4 08‐09' Native (July 9, 2019)COC 1907225 7070154.651 1819491.097 < 164 FCS‐5‐Berm‐Surface (June 12, 2019)COC 1906405 7070074.177 1819567.860 241 FCS‐5 02‐03' Berm (July 9, 2019)COC 1907225 7070074.177 1819567.860 < 155 FCS‐5 12‐12.5' Native (July 9, 2019)COC 1907225 7070074.177 1819567.860 < 184 FCS‐6‐Berm‐Surface (June 12, 2019)COC 1906405 7069838.042 1819740.929 < 202 FCS‐6 1.5‐3' Berm (July 9, 2019)COC 1907225 7069838.042 1819740.929 577 FCS‐6 10‐11' Native (July 9, 2019)COC 1907225 7069838.042 1819740.929 < 165 WWP‐1‐0506 (June 20, 2019)COC 1906561 7069160.561 1818679.345 < 168 WWP‐2‐0405 (June 20, 2019)COC 1906561 7069032.709 1818762.723 < 170 WWP‐3 00"‐04" (July 9, 2019)COC 1907225 7068958.464 1818864.099 < 168 WWP‐4‐0203 (July 3, 2019)COC 1907131 7068797.899 1818932.898 < 161 UJ WWP‐Berm 1‐Surface (June 11, 2019)COC 1906405 7069006.864 1818962.203 205 WWP‐Berm 1‐0307 (June 21, 2019)COC 1906561 7069006.864 1818962.203 < 201 WWP‐Berm 2‐Surface(June 11, 2019)COC 1906405 7068919.329 1819003.919 < 200 WWP‐Berm 2‐0305 (June 20, 2019)COC 1906561 7068919.329 1819003.919 < 198 WWP‐Berm 2‐1012 (June 20, 2019)COC 1906561 7068919.329 1819003.919 < 182 WWP‐Berm 3‐Surface (June 11, 2019)COC 1906405 7068824.973 1819049.196 < 192 WWP‐Berm 3‐0307 (June 20, 2019)COC 1906561 7068824.973 1819049.196 < 192 WWP‐Berm‐4‐0102 (July 3, 2019)COC 1907131 7068905.213 1818779.369 < 172 WWP‐Sed‐1 (June 13, 2019)COC 1906405 7068685.890 1819030.435 < 233 BG‐1 Soil (June 11, 2019)COC 1906405 7070870.893 1818952.498 < 194 BG‐2a (June 12, 2019)COC 1907131 7070068.657 1821186.156 < 190 BG‐2b (June 12, 2019)COC 1907131 7070393.754 1818321.563 159 BG‐3‐Soil (Coal) (June 13, 2019)COC 1906405 7070178.722 1821404.205 < 214 BG‐4‐Soil (June 13, 2019)COC 1906405 7069599.224 1819723.307 < 203 BG‐5‐Soil (June 14, 2019)COC 1906405 7068616.982 1819399.171 < 159 BG‐6 (July 3, 2019)COC 1907131 7070406.164 1818217.233 < 155 BG‐7 (July 3, 2019)COC 1907131 7069927.666 1818402.678 222 BG‐8 (July 3, 2019)COC 1907131 7069235.086 1818981.155 275 1664 with SGT SW‐846 8015D Notes:Qualifiers U ‐ The analyte was analyzed for, but was not detected J/UJ ‐ The associated result is estimated GP ‐ Geoprobe Rig bgs ‐ below ground surface TPH‐GRO ‐ Total Petroleum Hydrocarbons ‐ Gasoline Range Organics Laboratory reporting limit exceeds potentially applicable regulatory standard. Sonic ‐ Sonic Rig TPH‐DRO ‐ Total Petroleum Hydrocarbons ‐ Diesel Range Organics HA ‐ Hand Auger Concentration or radioactivity exceeds potentially applicable human health regulatory standard. HV ‐Hydrovac SW ‐ Surface Water pCi/g ‐ picocuries of radioactivity per gram R Laboratory result was rejected during AECOM data validation process SWL ‐ Static Water Level mg/kg ‐ milligram per kilogram PCBs ‐ Polychlorinated Biphenols For sum of Ra226/228: For the sum of the radiums, the benchmark is identified as the Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings (40 CFR §192.12). While these regulations are only applicable to the control of residual radioactive material at designated Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) Cooling Tower Basin Waste Water Pond Area SW‐846 8260D SW‐846 8260D 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) DRO Fractionation Background Former Coal Storage Area Analytical Method SW846‐8270E FS and appropriate at other CERCLA sites. The regulations identify a standard of 5 pCi/g above background for use of assessing the combined levels of Ra‐226 and Ra‐228. For Ra 226 and Ra 228: USEPA, 2018a. Preliminary Remediation Goals for Radionuclides . PRG Calculator, default mode. Value for composite worker soil, adjusted to a cancer risk level of 1E‐5. Accessed March. https://epa‐prgs.ornl.gov/radionuclides/ processing or depository (Title I) sites under Section 108 of UMTRCA , USEPA has provided guidance that these criteria should be considered relevant USGS ‐ United States Geological Survey HMW PAHs ‐ High Molecular Weight PAHs 1 ‐ Interval sampled is shown as last 4 digits of the sample ID. EXAMPLE: CS‐1‐2023 means the soil sample was collected between the depths of 20' and 23' below ground surface.. RSLs ‐ Regional Screening Levels PAHs ‐ Polycyclic Aromatic Hydrocarbons EPA ‐ Environmental Protection Agency LMW PAHs ‐ Low Molecular Weight PAHs 2 ‐ Background threshold values were only calculated for analytes that had six or more concentrations reported above the laboratory reporting limits. Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted Ar o c l o r 10 1 6 Ar o c l o r 12 6 0 Ar o c l o r 12 2 1 Ar o c l o r 12 3 2 Ar o c l o r 12 4 2 Ar o c l o r 12 4 8 Ar o c l o r 12 5 4 Ar o c l o r 12 6 8 Ar o c l o r 12 6 2 27 0.99 0.83 0.72 0.95 0.94 0.97 Min (mg/kg) Max (mg/kg) Background Threshold Value 2 (mg/kg or pCi/g) 95%UCL Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CS‐1‐2023 (June 19, 2019)COC 1906561 7070323.116 1819202.117 CS‐2‐2022 (June 19, 2019)COC 1906561 7070520.955 1819210.376 CS‐3‐1819 (June 18, 2019)COC 1906473 7070684.457 1819000.500 CS‐4‐1820 (June 18, 2019)COC 1906473 7070271.158 1818959.311 CS‐UPRR31‐Surface (Nov 15, 2022) 22K1233 7070675.300 1818916.900 CS‐UPRR31‐0105 (Nov 15, 2022)22K1233 7070675.300 1818916.900 CS‐UPRR32‐Surface (Nov 15, 2022)22K1233 7070531.400 1818951.400 CS‐UPRR32‐0105 (Nov 15, 2022)22K1233 7070531.400 1818951.400 CS‐UPRR32‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 CS‐UPRR932‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 CS‐UPRR33‐Surface (Nov 15, 2022)22K1233 7070367.300 1818979.800 CS‐UPRR33‐0105 (Nov 15, 2022)22K1233 7070367.300 1818979.800 CS‐UPRR34‐Surface (Nov 14, 2022)22K1233 7070273.500 1818983.500 CS‐UPRR34‐0105 (Nov 14, 2022)22K1233 7070273.500 1818983.500 CS‐UPRR34‐2022 (Nov 14, 2022)22K1233 7070273.500 1818983.500 Trip Blank (Nov 2022)22K1233 ‐‐ S.01 Surface (Oct 31, 2023)23J2567 S.901 Surface (Oct 31, 2023)23J2567 S.02 Surface (Oct 31, 2023)23J2567 S.03 Surface (Oct 31, 2023)23J2567 S.04 Surface (Oct 31, 2023)23J2567 S.04 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 S.05 Surface (Oct 31, 2023)23J2567 S.05 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 S.06 Surface (Oct 31, 2023)23J2567 S.07 Surface (Oct 31, 2023)23J2567 S.07 1.0‐1.5 (Oct 31, 2023)23J2567 S.08 Surface (Oct 31, 2023)23J2567 S.09 Surface (Oct 31, 2023)23J2567 S.10 Surface (Oct 31, 2023)23J2567 S.11 Surface (Oct 31, 2023)23J2567 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) combined total aroclors < 1 mg/kg Coal Storage Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted Ar o c l o r 10 1 6 Ar o c l o r 12 6 0 Ar o c l o r 12 2 1 Ar o c l o r 12 3 2 Ar o c l o r 12 4 2 Ar o c l o r 12 4 8 Ar o c l o r 12 5 4 Ar o c l o r 12 6 8 Ar o c l o r 12 6 2 27 0.99 0.83 0.72 0.95 0.94 0.97 Min (mg/kg) Max (mg/kg) Background Threshold Value 2 (mg/kg or pCi/g) 95%UCL Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting PH‐2‐0203 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 <0.0256 <0.0256 <0.0256 <0.0256 <0.0256 <0.0256 <0.0256 <0.0256 <0.0256 PH‐2‐0607 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 <0.0273 <0.0273 <0.0273 <0.0273 <0.0273 <0.0273 <0.0273 <0.0273 <0.0273 PH‐2‐1011 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 PH‐3‐0203 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 <0.0302 <0.0302 <0.0302 <0.0302 <0.0302 <0.0302 <0.0302 <0.0302 <0.0302 PH‐3‐0607 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 <0.0279 <0.0279 <0.0279 <0.0279 <0.0279 <0.0279 <0.0279 <0.0279 <0.0279 PH‐3‐1112 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 0.219 0.0704 <0.0267 <0.0267 <0.0267 <0.0267 <0.0267 <0.0267 <0.0267 PH‐4‐0203 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 <0.0287 <0.0287 <0.0287 <0.0287 <0.0287 <0.0287 <0.0287 <0.0287 <0.0287 PH‐4‐0607 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 PH‐4‐1112 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 <0.0257 PH‐5‐0203 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 <0.0261 <0.0261 <0.0261 <0.0261 <0.0261 <0.0261 <0.0261 <0.0261 <0.0261 PH‐5‐0607 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 <0.026 <0.026 <0.026 <0.026 <0.026 <0.026 <0.026 <0.026 <0.026 PH‐5‐1012 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 <0.0269 PH‐6‐1314 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 PH‐6‐2122 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 PH‐7‐0910 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 PH‐7‐1516 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 PH‐8‐1112 (June 27, 2019)1906750 7069917.254 1819200.329 PH‐8‐1516 (June 27, 2019)1906750 7069917.254 1819200.329 PH‐9‐0405 (June 28, 2019)1906750 7069924.775 1819114.989 PH‐9‐1112 (June 28, 2019)1906750 7069924.775 1819114.989 PH‐10‐1213 (June 26, 2019 1906718 / 1906719 7069907.863 1818897.646 <0.0263 <0.0263 <0.0263 <0.0263 <0.0263 <0.0263 <0.0263 <0.0263 <0.0263 PH‐10‐1516 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 <0.0303 <0.0303 <0.0303 <0.0303 <0.0303 <0.0303 <0.0303 <0.0303 <0.0303 PH‐10‐1920 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 <0.033 <0.033 <0.033 <0.033 <0.033 <0.033 <0.033 <0.033 <0.033 PH‐11‐1011 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 <0.0266 <0.0266 <0.0266 <0.0266 <0.0266 <0.0266 <0.0266 <0.0266 <0.0266 PH‐11‐1314 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 <0.0316 <0.0316 <0.0316 <0.0316 <0.0316 <0.0316 <0.0316 <0.0316 <0.0316 PH‐11‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 PH‐911‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 <0.0296 PH‐12‐2425 (June 26, 2019)1906718 / 1906719 7069973.231 1818969.332 PH‐13‐1819 (June 25, 2019)1906718 / 1906719 7069940.699 1818927.749 PH‐14‐1920 (June 25, 2019)1906718 / 1906719 7069998.380 1818939.247 PH‐15‐1920 (June 24, 2019)1906634/1906628 7070035.968 1818961.838 PH‐16‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 PH‐916‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Former AST Pipeline Release Area Central Power House AreaPower House Area Power Units 1 &2 Trans‐former Areas 1 Western Switch Yard Trans‐ former Area combined total aroclors < 1 mg/kg Chem Unload & Plant Drain Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted Ar o c l o r 10 1 6 Ar o c l o r 12 6 0 Ar o c l o r 12 2 1 Ar o c l o r 12 3 2 Ar o c l o r 12 4 2 Ar o c l o r 12 4 8 Ar o c l o r 12 5 4 Ar o c l o r 12 6 8 Ar o c l o r 12 6 2 27 0.99 0.83 0.72 0.95 0.94 0.97 Min (mg/kg) Max (mg/kg) Background Threshold Value 2 (mg/kg or pCi/g) 95%UCL Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CT‐1‐Surface (June 10, 2019)COC 1906405 7069603.505 1818981.732 CT‐2‐Surface (June 10, 2019)COC 1906405 7069742.697 1819071.901 CT‐3‐Y‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 CT‐3‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 FCS‐1‐Surface (June 12, 2019)COC 1906405 7070122.062 1819458.168 FCS‐1‐0709 (June 19, 2019)COC 1906561 7070122.062 1819458.168 FCS‐2‐Surface (June 12, 2019)COC 1906405 7069977.823 1819565.309 FCS‐2‐0708 (June 19, 2019)COC 1906561 7069977.823 1819565.309 FCS‐3‐Surface (June 12, 2019)COC 1906405 7069740.284 1819744.758 FCS‐3‐0607 (June 20, 2019)COC 1906561 7069740.284 1819744.758 FCS‐4‐Berm‐Surface (June 12, 2019)COC 1906405 7070154.651 1819491.097 FCS‐4 02‐03' Berm (July 9, 2019)COC 1907225 7070154.651 1819491.097 FCS‐4 08‐09' Native (July 9, 2019)COC 1907225 7070154.651 1819491.097 FCS‐5‐Berm‐Surface (June 12, 2019)COC 1906405 7070074.177 1819567.860 FCS‐5 02‐03' Berm (July 9, 2019)COC 1907225 7070074.177 1819567.860 FCS‐5 12‐12.5' Native (July 9, 2019)COC 1907225 7070074.177 1819567.860 FCS‐6‐Berm‐Surface (June 12, 2019)COC 1906405 7069838.042 1819740.929 FCS‐6 1.5‐3' Berm (July 9, 2019)COC 1907225 7069838.042 1819740.929 FCS‐6 10‐11' Native (July 9, 2019)COC 1907225 7069838.042 1819740.929 WWP‐1‐0506 (June 20, 2019)COC 1906561 7069160.561 1818679.345 WWP‐2‐0405 (June 20, 2019)COC 1906561 7069032.709 1818762.723 WWP‐3 00"‐04" (July 9, 2019)COC 1907225 7068958.464 1818864.099 WWP‐4‐0203 (July 3, 2019)COC 1907131 7068797.899 1818932.898 WWP‐Berm 1‐Surface (June 11, 2019)COC 1906405 7069006.864 1818962.203 WWP‐Berm 1‐0307 (June 21, 2019)COC 1906561 7069006.864 1818962.203 WWP‐Berm 2‐Surface(June 11, 2019)COC 1906405 7068919.329 1819003.919 WWP‐Berm 2‐0305 (June 20, 2019)COC 1906561 7068919.329 1819003.919 WWP‐Berm 2‐1012 (June 20, 2019)COC 1906561 7068919.329 1819003.919 WWP‐Berm 3‐Surface (June 11, 2019)COC 1906405 7068824.973 1819049.196 WWP‐Berm 3‐0307 (June 20, 2019)COC 1906561 7068824.973 1819049.196 WWP‐Berm‐4‐0102 (July 3, 2019)COC 1907131 7068905.213 1818779.369 WWP‐Sed‐1 (June 13, 2019)COC 1906405 7068685.890 1819030.435 BG‐1 Soil (June 11, 2019)COC 1906405 7070870.893 1818952.498 BG‐2a (June 12, 2019)COC 1907131 7070068.657 1821186.156 BG‐2b (June 12, 2019)COC 1907131 7070393.754 1818321.563 BG‐3‐Soil (Coal) (June 13, 2019)COC 1906405 7070178.722 1821404.205 BG‐4‐Soil (June 13, 2019)COC 1906405 7069599.224 1819723.307 BG‐5‐Soil (June 14, 2019)COC 1906405 7068616.982 1819399.171 BG‐6 (July 3, 2019)COC 1907131 7070406.164 1818217.233 BG‐7 (July 3, 2019)COC 1907131 7069927.666 1818402.678 BG‐8 (July 3, 2019)COC 1907131 7069235.086 1818981.155 Notes:Qualifiers U ‐ The analyte was analyzed for, but was not detected J/UJ ‐ The associated result is estimated GP ‐ Geoprobe Rig bgs ‐ below ground surface TPH‐GRO ‐ Total Petroleum Hydrocarbons ‐ Gasoline Range Organics Sonic ‐ Sonic Rig TPH‐DRO ‐ Total Petroleum Hydrocarbons ‐ Diesel Range Organics HA ‐ Hand Auger HV ‐Hydrovac SW ‐ Surface Water pCi/g ‐ picocuries of radioactivity per gram R Laboratory result was rejected during AECOM data validation process SWL ‐ Static Water Level mg/kg ‐ milligram per kilogram PCBs ‐ Polychlorinated Biphenols For sum of Ra226/228: For the sum of the radiums, the benchmark is identified as the Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings (40 CFR §192.12). While these regulations are only applicable to the control of residual radioactive material at designated Laboratory reporting limit exceeds potentially applicable regulatory standard. Concentration or radioactivity exceeds potentially applicable human health regulatory standard. Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Cooling Tower Basin Waste Water Pond Area 1 ‐ Interval sampled is shown as last 4 digits of the sample ID. EXAMPLE: CS‐1‐2023 means the soil sample was collected between the depths of 20' and 23' below ground surface.. combined total aroclors < 1 mg/kg Background Former Coal Storage Area SW‐846‐8082AAnalytical Method and appropriate at other CERCLA sites. The regulations identify a standard of 5 pCi/g above background for use of assessing the combined levels of Ra‐226 and Ra‐228. For Ra 226 and Ra 228: USEPA, 2018a. Preliminary Remediation Goals for Radionuclides . PRG Calculator, default mode. Value for composite worker soil, adjusted to a cancer risk level of 1E‐5. Accessed March. https://epa‐prgs.ornl.gov/radionuclides/ processing or depository (Title I) sites under Section 108 of UMTRCA , USEPA has provided guidance that these criteria should be considered relevant USGS ‐ United States Geological Survey HMW PAHs ‐ High Molecular Weight PAHs RSLs ‐ Regional Screening Levels PAHs ‐ Polycyclic Aromatic Hydrocarbons EPA ‐ Environmental Protection Agency LMW PAHs ‐ Low Molecular Weight PAHs 2 ‐ Background threshold values were only calculated for analytes that had six or more concentrations reported above the laboratory reporting limits. Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted In d e n e 1‐Me t h y l n a p h t h a l e n e 2‐Me t h y l n a p h t h a l e n e Na p h t h a l e n e (b a s e d on 82 7 0 E ) Ac e n a p h t h y l e n e Ac e n a p h t h e n e Fl u o r e n e Ph e n a n t h r e n e An t h r a c e n e Fl u o r a n t h e n e Py r e n e Be n z ( a ) a n t h r a c e n e Ch r y s e n e Be n z o ( b ) f l u o r a n t h e n e Be n z o ( k ) f l u o r a n t h e n e Be n z o ( a ) p y r e n e In d e n o ( 1 , 2 , 3 ‐cd ) p y r e n e Di b e n z ( a , h ) a n t h r a c e n e Be n z o ( g , h , i ) p e r y l e n e 2, 4 ‐Di m e t h y l p h e n o l 2, 4 ‐Di n i t r o p h e n o l 3& 4 ‐Me t h y l p h e n o l Di e t h y l ph t h a l a t e 51 / 51 73 3,000 8.6 45,000 30,000 230,000 30,000 23,000 21 2,100 21 210 2.1 21 2.1 16,000 1,600 41,000 660,000 Min (mg/kg) 0.0143 0.00901 0.00899 <0.00703 <0.00703 <0.00703 <0.017 <0.00851 <0.00851 <0.00851 <0.017 <0.00851 0.00962 <0.00703 <0.00703 Max (mg/kg) 22 26.4 25 0.329 0.14 0.228 3.86 0.513 0.612 0.778 0.629 0.61 0.296 0.263 0.054 Background Threshold Value 2 (mg/kg or pCi/g)31.0 61.6 58.2 4.44 0.734 0.781 0.942 0.76 0.352 95%UCL 11 8 10 4 9 684 1 719 0 298 0 338 0 391 0 322 0 143 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CS‐1‐2023 (June 19, 2019)COC 1906561 7070323.116 1819202.117 0.0527 0.0278 0.021 <0.00758 <0.00758 <0.00758 <0.0152 <0.00758 <0.00758 <0.00758 <0.0152 <0.00758 <0.00758 <0.00758 <0.00758 <0.00758 <0.00758 <0.00758 <0.385 <0.758 <0.385 <0.385 CS‐2‐2022 (June 19, 2019)COC 1906561 7070520.955 1819210.376 <0.00778 <0.00778 <0.00778 <0.00778 <0.00778 <0.00778 <0.0156 <0.00778 <0.00778 <0.00778 <0.0156 <0.00778 <0.00778 <0.00778 <0.00778 <0.00778 <0.00778 <0.00778 <0.395 <0.778 <0.395 <0.395 CS‐3‐1819 (June 18, 2019)COC 1906473 7070684.457 1819000.500 <0.00803 <0.00803 <0.00803 <0.00803 <0.00803 <0.00803 <0.0161 <0.00803 <0.00803 <0.00803 <0.0161 <0.00803 <0.00803 <0.00803 <0.00803 <0.00803 <0.00803 <0.00803 <0.406 <0.8 <0.406 <0.406 CS‐4‐1820 (June 18, 2019)COC 1906473 7070271.158 1818959.311 0.0742 0.0497 0.0235 <0.00813 <0.00813 <0.00813 <0.0163 <0.00813 <0.00813 <0.00813 <0.0163 <0.00813 <0.00813 <0.00813 <0.00813 <0.00813 <0.00813 <0.00813 <0.412 <0.813 <0.412 <0.412 CS‐UPRR31‐Surface (Nov 15, 2022) 22K1233 7070675.300 1818916.900 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 R <0.40 <0.40 CS‐UPRR31‐0105 (Nov 15, 2022)22K1233 7070675.300 1818916.900 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 R <8.00 <8.00 CS‐UPRR32‐Surface (Nov 15, 2022)22K1233 7070531.400 1818951.400 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 <8.00 R <8.00 <8.00 CS‐UPRR32‐0105 (Nov 15, 2022)22K1233 7070531.400 1818951.400 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 R <2.00 <2.00 CS‐UPRR32‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 R <0.43 <0.43 CS‐UPRR932‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 <0.43 R <0.43 <0.43 CS‐UPRR33‐Surface (Nov 15, 2022)22K1233 7070367.300 1818979.800 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 R <2.00 <2.00 CS‐UPRR33‐0105 (Nov 15, 2022)22K1233 7070367.300 1818979.800 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 <2.00 R <2.00 <2.00 CS‐UPRR34‐Surface (Nov 14, 2022)22K1233 7070273.500 1818983.500 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 R <0.40 <0.40 CS‐UPRR34‐0105 (Nov 14, 2022)22K1233 7070273.500 1818983.500 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 <1.70 R <1.70 <1.70 CS‐UPRR34‐2022 (Nov 14, 2022)22K1233 7070273.500 1818983.500 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 R <0.45 <0.45 Trip Blank (Nov 2022)22K1233 ‐‐ S.01 Surface (Oct 31, 2023)23J2567 S.901 Surface (Oct 31, 2023)23J2567 S.02 Surface (Oct 31, 2023)23J2567 S.03 Surface (Oct 31, 2023)23J2567 S.04 Surface (Oct 31, 2023)23J2567 S.04 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 S.05 Surface (Oct 31, 2023)23J2567 S.05 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 S.06 Surface (Oct 31, 2023)23J2567 S.07 Surface (Oct 31, 2023)23J2567 S.07 1.0‐1.5 (Oct 31, 2023)23J2567 S.08 Surface (Oct 31, 2023)23J2567 S.09 Surface (Oct 31, 2023)23J2567 S.10 Surface (Oct 31, 2023)23J2567 S.11 Surface (Oct 31, 2023)23J2567 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Coal Storage Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted In d e n e 1‐Me t h y l n a p h t h a l e n e 2‐Me t h y l n a p h t h a l e n e Na p h t h a l e n e (b a s e d on 82 7 0 E ) Ac e n a p h t h y l e n e Ac e n a p h t h e n e Fl u o r e n e Ph e n a n t h r e n e An t h r a c e n e Fl u o r a n t h e n e Py r e n e Be n z ( a ) a n t h r a c e n e Ch r y s e n e Be n z o ( b ) f l u o r a n t h e n e Be n z o ( k ) f l u o r a n t h e n e Be n z o ( a ) p y r e n e In d e n o ( 1 , 2 , 3 ‐cd ) p y r e n e Di b e n z ( a , h ) a n t h r a c e n e Be n z o ( g , h , i ) p e r y l e n e 2, 4 ‐Di m e t h y l p h e n o l 2, 4 ‐Di n i t r o p h e n o l 3& 4 ‐Me t h y l p h e n o l Di e t h y l ph t h a l a t e 51 / 51 73 3,000 8.6 45,000 30,000 230,000 30,000 23,000 21 2,100 21 210 2.1 21 2.1 16,000 1,600 41,000 660,000 Min (mg/kg) 0.0143 0.00901 0.00899 <0.00703 <0.00703 <0.00703 <0.017 <0.00851 <0.00851 <0.00851 <0.017 <0.00851 0.00962 <0.00703 <0.00703 Max (mg/kg) 22 26.4 25 0.329 0.14 0.228 3.86 0.513 0.612 0.778 0.629 0.61 0.296 0.263 0.054 Background Threshold Value 2 (mg/kg or pCi/g)31.0 61.6 58.2 4.44 0.734 0.781 0.942 0.76 0.352 95%UCL 11 8 10 4 9 684 1 719 0 298 0 338 0 391 0 322 0 143 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting PH‐2‐0203 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐2‐0607 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐2‐1011 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐3‐0203 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐3‐0607 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐3‐1112 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐4‐0203 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐4‐0607 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐4‐1112 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐5‐0203 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐5‐0607 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐5‐1012 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐6‐1314 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 <0.00729 UJ 5.64 J4.65 J 2.92 0.132 J 0.102 J 0.177 J1.38 J 0.406 J 0.465 J 0.457 J 0.343 J 0.287 J 0.265 J 0.0467 J0.12 J 0.162 J <0.00729 UJ <0.00729 UJ 0.634 J <0.729 UJ 0.487 J <0.37 UJ PH‐6‐2122 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 <0.008 UJ 0.0635 J 0.0303 J 0.0356 J <0.008 UJ <0.008 UJ <0.008 UJ <0.016 UJ <0.008 UJ <0.008 UJ <0.008 UJ <0.016 UJ <0.008 UJ <0.008 UJ <0.008 UJ <0.008 UJ <0.008 UJ <0.008 UJ <0.008 UJ <0.406 UJ <0.8 UJ <0.406 UJ <0.406 UJ PH‐7‐0910 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 <0.00685 UJ 0.0138 J 0.011 J 0.0115 J <0.00685 UJ <0.00685 UJ <0.00685 UJ 0.0277 J <0.00685 UJ <0.00685 UJ <0.00685 UJ <0.0137 UJ 0.00756 J 0.00987 J <0.00685 UJ <0.00685 UJ <0.00685 UJ <0.00685 UJ 0.0082 J <0.348 UJ <0.685 UJ <0.348 UJ <0.348 UJ PH‐7‐1516 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 <0.00683 UJ 0.949 J1.45 J1.04 J 0.0109 J 0.0241 J 0.0535 J 0.373 J <0.00683 UJ 0.0537 J 0.0489 J 0.0351 J 0.0487 J <0.346 UJ 0.0128 J 0.0361 J 0.0192 J 0.00818 J 0.0516 J <0.346 UJ <0.683 UJ <0.346 UJ <0.346 UJ PH‐8‐1112 (June 27, 2019)1906750 7069917.254 1819200.329 <0.00679 1.23 1.16 1.12 0.0137 0.0343 J 0.0808 0.298 <0.00679 0.0496 0.0459 0.0391 0.0437 0.0381 0.0111 0.0317 0.0177 0.00836 0.0516 <0.345 <0.679 <0.345 <0.345 PH‐8‐1516 (June 27, 2019)1906750 7069917.254 1819200.329 <0.00689 2.36 1.88 1.26 0.013 0.0318 0.0604 0.371 <0.00689 0.0288 0.0421 0.0242 0.0238 0.038 0.00783 0.0507 0.0183 0.00869 0.0403 R R R <0.35 PH‐9‐0405 (June 28, 2019)1906750 7069924.775 1819114.989 <0.00751 0.284 0.178 0.133 0.00884 0.0217 0.0223 0.237 0.054 0.185 0.174 0.109 0.113 0.104 0.039 0.0818 0.0586 0.0239 0.0855 <0.381 <0.751 <0.381 <0.381 PH‐9‐1112 (June 28, 2019)1906750 7069924.775 1819114.989 <0.00702 0.0687 0.0529 0.106 <0.00702 <0.00702 <0.00702 0.137 <0.00702 0.0155 0.0128 <0.014 0.0197 0.0262 <0.00702 <0.00702 0.0101 <0.00702 0.0254 <0.356 <0.702 <0.356 <0.356 PH‐10‐1213 (June 26, 2019 1906718 / 1906719 7069907.863 1818897.646 PH‐10‐1516 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 PH‐10‐1920 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 PH‐11‐1011 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐11‐1314 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐11‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐911‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐12‐2425 (June 26, 2019)1906718 / 1906719 7069973.231 1818969.332 <0.00781 0.0205 <0.00781 <0.00781 <0.00781 <0.00781 <0.00781 <0.0156 <0.00781 0.0177 0.052 <0.0156 0.0159 <0.00781 <0.00781 <0.00781 <0.00781 <0.00781 <0.00781 <0.396 <0.781 <0.396 <0.396 PH‐13‐1819 (June 25, 2019)1906718 / 1906719 7069940.699 1818927.749 <0.00904 0.0104 <0.00904 <0.00904 <0.00904 <0.00904 <0.00904 <0.0181 <0.00904 <0.00904 <0.00904 <0.0181 <0.00904 <0.00904 <0.00904 <0.00904 <0.00904 <0.00904 <0.00904 <0.459 <0.904 <0.459 <0.459 PH‐14‐1920 (June 25, 2019)1906718 / 1906719 7069998.380 1818939.247 <0.00751 <0.00751 <0.00751 <0.00751 <0.00751 <0.00751 <0.00751 <0.015 <0.00751 <0.00751 <0.00751 <0.015 <0.00751 <0.00751 <0.00751 <0.00751 <0.00751 <0.00751 <0.00751 <0.381 UJ <0.751 <0.381 <0.381 PH‐15‐1920 (June 24, 2019)1906634/1906628 7070035.968 1818961.838 0.0111 0.17 0.0568 0.0349 <0.00827 <0.00827 0.0203 0.0439 0.0105 0.0103 0.0257 <0.0165 0.0128 <0.00827 <0.00827 <0.00827 <0.00827 <0.00827 <0.00827 <0.42 <0.827 <0.42 <0.42 PH‐16‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 <0.00735 13.1 7.32 1.37 <0.00735 1.09 2.09 4.9 0.2 <0.00735 0.359 0.0232 0.0459 <0.00735 <0.00735 <0.00735 <0.00735 <0.00735 <0.00735 <0.373 <0.735 <0.373 <0.373 PH‐916‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 <0.00744 11.9 6.44 1.51 <0.00744 1.08 1.31 4.38 0.215 0.0758 0.262 0.0231 0.048 <0.00744 <0.00744 <0.377 <0.00744 <0.00744 <0.00744 <0.377 <0.744 <0.377 <0.377 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Former AST Pipeline Release Area Central Power House AreaPower House Area Power Units 1 &2 Trans‐former Areas 1 Western Switch Yard Trans‐ former Area Chem Unload & Plant Drain Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted In d e n e 1‐Me t h y l n a p h t h a l e n e 2‐Me t h y l n a p h t h a l e n e Na p h t h a l e n e (b a s e d on 82 7 0 E ) Ac e n a p h t h y l e n e Ac e n a p h t h e n e Fl u o r e n e Ph e n a n t h r e n e An t h r a c e n e Fl u o r a n t h e n e Py r e n e Be n z ( a ) a n t h r a c e n e Ch r y s e n e Be n z o ( b ) f l u o r a n t h e n e Be n z o ( k ) f l u o r a n t h e n e Be n z o ( a ) p y r e n e In d e n o ( 1 , 2 , 3 ‐cd ) p y r e n e Di b e n z ( a , h ) a n t h r a c e n e Be n z o ( g , h , i ) p e r y l e n e 2, 4 ‐Di m e t h y l p h e n o l 2, 4 ‐Di n i t r o p h e n o l 3& 4 ‐Me t h y l p h e n o l Di e t h y l ph t h a l a t e 51 / 51 73 3,000 8.6 45,000 30,000 230,000 30,000 23,000 21 2,100 21 210 2.1 21 2.1 16,000 1,600 41,000 660,000 Min (mg/kg) 0.0143 0.00901 0.00899 <0.00703 <0.00703 <0.00703 <0.017 <0.00851 <0.00851 <0.00851 <0.017 <0.00851 0.00962 <0.00703 <0.00703 Max (mg/kg) 22 26.4 25 0.329 0.14 0.228 3.86 0.513 0.612 0.778 0.629 0.61 0.296 0.263 0.054 Background Threshold Value 2 (mg/kg or pCi/g)31.0 61.6 58.2 4.44 0.734 0.781 0.942 0.76 0.352 95%UCL 11 8 10 4 9 684 1 719 0 298 0 338 0 391 0 322 0 143 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CT‐1‐Surface (June 10, 2019)COC 1906405 7069603.505 1818981.732 CT‐2‐Surface (June 10, 2019)COC 1906405 7069742.697 1819071.901 CT‐3‐Y‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 CT‐3‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 FCS‐1‐Surface (June 12, 2019)COC 1906405 7070122.062 1819458.168 <0.00832 0.367 0.191 0.112 <0.00832 <0.00832 <0.00832 0.0531 0.0155 0.0437 0.0443 0.0293 0.0355 0.0294 <0.00832 0.0145 0.0113 <0.00832 0.00935 <0.422 <0.832 <0.422 <0.422 FCS‐1‐0709 (June 19, 2019)COC 1906561 7070122.062 1819458.168 <0.00737 <0.00737 <0.00737 <0.00737 <0.00737 <0.00737 <0.00737 <0.0147 <0.00737 <0.00737 <0.00737 <0.0147 <0.00737 <0.00737 <0.00737 <0.00737 <0.00737 <0.00737 <0.00737 <0.374 <0.737 <0.374 <0.374 FCS‐2‐Surface (June 12, 2019)COC 1906405 7069977.823 1819565.309 <0.00791 0.298 0.174 0.107 <0.00791 <0.00791 <0.00791 0.0464 0.0111 0.0233 0.0207 <0.0158 0.0186 0.023 <0.00791 <0.00791 <0.00791 <0.00791 0.0115 <0.401 <0.791 <0.401 <0.401 FCS‐2‐0708 (June 19, 2019)COC 1906561 7069977.823 1819565.309 <0.00773 <0.00773 <0.00773 <0.00773 <0.00773 <0.00773 <0.00773 <0.0155 <0.00773 <0.00773 <0.00773 <0.0155 <0.00773 <0.00773 <0.00773 <0.00773 <0.00773 <0.00773 <0.00773 <0.392 <0.773 <0.392 <0.392 FCS‐3‐Surface (June 12, 2019)COC 1906405 7069740.284 1819744.758 <0.00894 0.0193 0.0118 0.00953 <0.00894 <0.00894 <0.00894 <0.0179 <0.00894 <0.00894 <0.00894 <0.0179 <0.00894 <0.00894 <0.00894 <0.00894 <0.00894 <0.00894 <0.00894 <0.454 <0.894 <0.454 <0.454 FCS‐3‐0607 (June 20, 2019)COC 1906561 7069740.284 1819744.758 <0.0069 0.488 0.595 0.434 0.013 <0.0069 <0.0069 0.166 0.0268 0.0482 0.0381 0.0314 0.0315 0.025 <0.0069 0.0137 0.0106 0.0076 0.0105 <0.35 <0.69 <0.35 <0.35 FCS‐4‐Berm‐Surface (June 12, 2019)COC 1906405 7070154.651 1819491.097 <0.0787 3.69 2.03 1.75 <0.0787 <0.0787 <0.0787 0.625 0.115 0.228 0.226 0.161 0.211 0.154 <0.0787 0.0794 <0.0787 <0.0787 <0.0787 <3.99 <7.87 <3.99 <3.99 FCS‐4 02‐03' Berm (July 9, 2019)COC 1907225 7070154.651 1819491.097 <0.0335 9.38 J 5.3 4.38 0.167 <0.0335 0.126 1.85 0.234 0.363 0.309 0.216 0.265 0.167 <0.0335 0.0962 <0.0335 <0.0335 <0.0335 <1.7 <3.35 <1.7 <1.7 FCS‐4 08‐09' Native (July 9, 2019)COC 1907225 7070154.651 1819491.097 <0.0073 0.242 0.126 0.103 <0.0073 <0.0073 <0.0073 0.04 0.00966 0.023 0.0277 0.0223 0.0261 0.0245 0.00945 0.0206 0.0131 <0.0073 0.0134 <0.37 <0.73 <0.37 <0.37 FCS‐5‐Berm‐Surface (June 12, 2019)COC 1906405 7070074.177 1819567.860 <0.0754 0.441 0.238 0.131 <0.0754 <0.0754 <0.0754 <0.151 <0.0754 <0.0754 <0.0754 <0.151 <0.0754 <0.0754 <0.0754 <0.0754 <0.0754 <0.0754 <0.0754 <3.83 <7.54 <3.83 <3.83 FCS‐5 02‐03' Berm (July 9, 2019)COC 1907225 7070074.177 1819567.860 <0.0344 6.19 J 5.05 4.23 0.112 <0.0344 <0.0344 1.01 0.14 0.39 0.303 0.13 0.182 0.11 <0.0344 0.0479 <0.0344 <0.0344 <0.0344 <1.75 <3.44 <1.75 <1.75 FCS‐5 12‐12.5' Native (July 9, 2019)COC 1907225 7070074.177 1819567.860 <0.00818 0.141 0.0728 0.0733 <0.00818 <0.00818 <0.00818 0.0306 <0.00818 0.0103 0.0107 <0.0164 0.0101 0.00908 <0.00818 <0.00818 <0.00818 <0.00818 <0.00818 <0.415 <0.818 <0.415 <0.415 FCS‐6‐Berm‐Surface (June 12, 2019)COC 1906405 7069838.042 1819740.929 <0.00886 0.02 0.0124 0.00963 <0.00886 <0.00886 <0.00886 <0.0177 <0.00886 <0.00886 <0.00886 <0.0177 <0.00886 <0.00886 <0.00886 <0.00886 <0.00886 <0.00886 <0.00886 <0.45 <0.886 <0.45 <0.45 FCS‐6 1.5‐3' Berm (July 9, 2019)COC 1907225 7069838.042 1819740.929 <0.104 29.1 J 18.9 15.3 0.502 <0.104 0.458 7.77 0.516 0.837 0.667 0.541 0.515 0.295 <0.104 <0.104 <0.104 0.167 <0.104 <5.28 <10.4 <5.28 <5.28 FCS‐6 10‐11' Native (July 9, 2019)COC 1907225 7069838.042 1819740.929 <0.00734 0.215 0.108 0.0786 <0.00734 <0.00734 <0.00734 0.04 0.00838 0.0114 0.0108 <0.0147 0.00867 0.00755 <0.00734 <0.00734 <0.00734 <0.00734 <0.00734 <0.373 <0.734 <0.373 <0.373 WWP‐1‐0506 (June 20, 2019)COC 1906561 7069160.561 1818679.345 <0.037 0.895 0.5 0.366 <0.037 <0.037 <0.037 0.227 <0.037 0.0765 0.0672 <0.0739 0.0668 0.0468 <0.037 <0.037 0.0387 <0.037 <0.037 <1.88 <3.7 <1.88 <1.88 WWP‐2‐0405 (June 20, 2019)COC 1906561 7069032.709 1818762.723 <0.00747 0.311 0.17 0.137 <0.00747 <0.00747 <0.00747 0.0946 <0.00747 0.0216 0.0157 <0.0149 0.0212 0.0213 <0.00747 0.00922 <0.00747 <0.00747 0.0148 <0.379 <0.747 <0.379 <0.379 WWP‐3 00"‐04" (July 9, 2019)COC 1907225 7068958.464 1818864.099 <0.00751 0.292 0.14 0.132 <0.00751 <0.00751 <0.00751 0.0649 <0.00751 0.0173 0.00949 <0.015 0.0094 0.00785 <0.00751 <0.00751 <0.00751 <0.00751 0.0122 <0.381 R <0.381 <0.381 WWP‐4‐0203 (July 3, 2019)COC 1907131 7068797.899 1818932.898 <0.00701 0.647 0.315 0.202 <0.00701 0.00881 0.0106 0.289 0.0114 0.0564 0.0403 0.0234 0.0463 0.0311 <0.00701 0.0156 0.01 <0.00701 0.024 <0.356 <0.701 <0.356 <0.356 WWP‐Berm 1‐Surface (June 11, 2019)COC 1906405 7069006.864 1818962.203 <0.0075 0.015 0.0111 0.00909 <0.0075 <0.0075 <0.0075 <0.015 <0.0075 <0.0075 <0.0075 <0.015 <0.0075 <0.0075 <0.0075 <0.0075 <0.0075 <0.0075 <0.0075 <0.38 <0.749 <0.38 <0.38 WWP‐Berm 1‐0307 (June 21, 2019)COC 1906561 7069006.864 1818962.203 <0.00884 0.147 0.115 0.0143 <0.00884 <0.00884 <0.00884 <0.0177 <0.00884 <0.00884 <0.00884 <0.0177 <0.00884 <0.00884 <0.00884 <0.00884 <0.00884 <0.00884 <0.00884 <0.448 <0.884 <0.448 <0.448 WWP‐Berm 2‐Surface(June 11, 2019)COC 1906405 7068919.329 1819003.919 <0.00886 0.0107 <0.00886 0.00916 <0.00886 <0.00886 <0.00886 0.0213 <0.00886 0.0123 <0.00886 <0.0177 <0.00886 <0.00886 <0.00886 <0.00886 <0.00886 <0.00886 <0.00886 <0.449 <0.886 <0.449 <0.449 WWP‐Berm 2‐0305 (June 20, 2019)COC 1906561 7068919.329 1819003.919 <0.00867 0.0423 0.0236 0.0172 <0.00867 <0.00867 <0.00867 <0.0173 <0.00867 <0.00867 <0.00867 <0.0173 <0.00867 <0.00867 <0.00867 <0.00867 <0.00867 <0.00867 <0.00867 <0.44 <0.867 <0.44 <0.44 WWP‐Berm 2‐1012 (June 20, 2019)COC 1906561 7068919.329 1819003.919 <0.008 0.254 0.153 0.147 <0.008 <0.008 <0.008 0.0606 0.0117 0.0252 0.021 <0.016 0.0127 0.0131 <0.008 <0.008 <0.008 <0.008 0.00844 <0.406 <0.8 <0.406 <0.406 WWP‐Berm 3‐Surface (June 11, 2019)COC 1906405 7068824.973 1819049.196 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.0169 <0.00844 <0.00844 <0.00844 <0.0169 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.428 <0.844 <0.428 <0.428 WWP‐Berm 3‐0307 (June 20, 2019)COC 1906561 7068824.973 1819049.196 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.0169 <0.00844 <0.00844 <0.00844 <0.0169 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 <0.00844 R R R <0.433 WWP‐Berm‐4‐0102 (July 3, 2019)COC 1907131 7068905.213 1818779.369 <0.00757 0.779 0.44 0.34 0.0123 <0.00757 0.0136 0.123 0.0135 0.0321 0.0455 0.0224 0.0268 0.0179 <0.00757 0.014 0.00903 <0.00757 0.0164 <0.384 <0.757 UJ <0.384 <0.384 WWP‐Sed‐1 (June 13, 2019)COC 1906405 7068685.890 1819030.435 <0.0103 0.304 0.24 0.092 <0.0103 <0.0103 <0.0103 0.0423 <0.0103 0.0226 0.0226 <0.0205 0.0166 <0.0103 <0.0103 <0.0103 <0.0103 <0.0103 <0.0103 <0.521 <1.03 <0.521 <0.521 BG‐1 Soil (June 11, 2019)COC 1906405 7070870.893 1818952.498 <0.00851 0.0143 0.00901 0.00899 <0.00851 <0.00851 <0.00851 <0.017 <0.00851 <0.00851 <0.00851 <0.017 <0.00851 0.011 <0.00851 <0.00851 <0.00851 <0.00851 <0.00851 <0.432 <0.851 <0.432 <0.432 BG‐2a (June 12, 2019)COC 1907131 7070068.657 1821186.156 <0.0839 2.05 1.17 0.69 <0.0839 <0.0839 <0.0839 0.328 <0.0839 0.125 0.0955 <0.168 0.104 <0.0839 <0.0839 <0.0839 <0.0839 <0.0839 <0.0839 <4.26 <8.39 <4.26 <4.26 BG‐2b (June 12, 2019)COC 1907131 7070393.754 1818321.563 <0.0343 14.6 J 6.57 6.12 0.187 <0.0343 0.195 1.64 0.418 0.293 0.368 0.249 0.306 0.104 <0.0343 0.122 0.054 <0.0343 <0.0343 <1.74 <3.43 <1.74 <1.74 BG‐3‐Soil (Coal) (June 13, 2019)COC 1906405 7070178.722 1821404.205 <0.0937 22 26.4 25 0.329 0.14 0.228 3.86 0.513 0.612 0.778 0.629 0.61 0.296 <0.0937 0.263 <0.0937 <0.0937 <0.0937 <4.76 <9.37 <4.76 <4.76 BG‐4‐Soil (June 13, 2019)COC 1906405 7069599.224 1819723.307 <0.00896 0.377 0.218 0.122 <0.00896 <0.00896 <0.00896 0.0542 0.0115 0.0216 0.0242 <0.0179 0.0223 0.00962 <0.00896 <0.00896 <0.00896 <0.00896 <0.00896 <0.454 <0.896 <0.454 <0.454 BG‐5‐Soil (June 14, 2019)COC 1906405 7068616.982 1819399.171 <0.00703 0.132 0.0807 0.0513 <0.00703 <0.00703 <0.00703 0.0464 0.0103 0.0291 0.0283 0.0145 0.0169 0.0124 <0.00703 <0.00703 <0.00703 <0.00703 <0.00703 <0.357 <0.703 <0.357 <0.357 BG‐6 (July 3, 2019)COC 1907131 7070406.164 1818217.233 <0.0344 13.7 J 7.32 6.85 0.178 <0.0344 0.168 0.992 0.304 0.247 0.314 0.258 0.259 0.0972 <0.0344 0.103 <0.0344 <0.0344 <0.0344 <1.75 <3.44 <1.75 <1.75 BG‐7 (July 3, 2019)COC 1907131 7069927.666 1818402.678 <0.0336 5.12 J 2.46 2.06 0.106 <0.0336 0.0979 1 0.206 0.38 0.326 0.229 0.31 0.139 0.0394 0.0842 <0.0336 <0.0336 <0.0336 <1.7 <3.36 <1.7 <1.7 BG‐8 (July 3, 2019)COC 1907131 7069235.086 1818981.155 <0.0343 3.46 2.14 1.39 0.0516 <0.0343 0.047 0.672 0.0891 0.208 0.192 0.122 0.159 0.0844 <0.0343 0.0585 0.0421 <0.0343 0.0518 <1.74 <3.43 <1.74 <1.74 Notes:Qualifiers U ‐ The analyte was analyzed for, but was not detected J/UJ ‐ The associated result is estimated GP ‐ Geoprobe Rig bgs ‐ below ground surface TPH‐GRO ‐ Total Petroleum Hydrocarbons ‐ Gasoline Range Organics Laboratory reporting limit exceeds potentially applicable regulatory standard. Sonic ‐ Sonic Rig TPH‐DRO ‐ Total Petroleum Hydrocarbons ‐ Diesel Range Organics HA ‐ Hand Auger Concentration or radioactivity exceeds potentially applicable human health regulatory standard. HV ‐Hydrovac SW ‐ Surface Water pCi/g ‐ picocuries of radioactivity per gram R Laboratory result was rejected during AECOM data validation process SWL ‐ Static Water Level mg/kg ‐ milligram per kilogram PCBs ‐ Polychlorinated Biphenols For sum of Ra226/228: For the sum of the radiums, the benchmark is identified as the Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings (40 CFR §192.12). While these regulations are only applicable to the control of residual radioactive material at designated Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Cooling Tower Basin Waste Water Pond Area 1 ‐ Interval sampled is shown as last 4 digits of the sample ID. EXAMPLE: CS‐1‐2023 means the soil sample was collected between the depths of 20' and 23' below ground surface.. Background Former Coal Storage Area SW‐846 8270E SIM / 8270E FS SW‐846 8270E SIM / 8270E FSAnalytical Method and appropriate at other CERCLA sites. The regulations identify a standard of 5 pCi/g above background for use of assessing the combined levels of Ra‐226 and Ra‐228. For Ra 226 and Ra 228: USEPA, 2018a. Preliminary Remediation Goals for Radionuclides . PRG Calculator, default mode. Value for composite worker soil, adjusted to a cancer risk level of 1E‐5. Accessed March. https://epa‐prgs.ornl.gov/radionuclides/ processing or depository (Title I) sites under Section 108 of UMTRCA , USEPA has provided guidance that these criteria should be considered relevant USGS ‐ United States Geological Survey HMW PAHs ‐ High Molecular Weight PAHs RSLs ‐ Regional Screening Levels PAHs ‐ Polycyclic Aromatic Hydrocarbons EPA ‐ Environmental Protection Agency LMW PAHs ‐ Low Molecular Weight PAHs 2 ‐ Background threshold values were only calculated for analytes that had six or more concentrations reported above the laboratory reporting limits. Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted An t i m o n y Ar s e n i c Ba r i u m Be r y l l i u m Bo r o n Ca d m i u m Ca l c i u m Ch r o m i u m , He x a v a l e n t (3 0 6 0 ) Ch r o m i u m Ch r o m i u m +I I I Co b a l t Le a d Li t h i u m Me r c u r y Mo l y b d e n u m Se l e n i u m Si l v e r Ti t a n i u m Va n a d i u m Ra d i u m 22 6 & 2 2 8 (p i C / g ) 470 3 220,000 2,300 230,000 100 6.3 1.8E+06 350 800 2300 46 5800 5800 5800 5800 7.91 848,858 91,400 212,062 66,988 1,266,486 41,330 1.27E+10 2,650,860 71.0 2,714 3,288 10,370 152 Min (mg/kg) 1.25 43.2 0.436 < 18.2 < 0.364 < 8,970 <1 < 10.4 < 11.4 < 1.20 5.33 < 9.11 < 0.0353 <1.46 26.1 8.89 ‐‐ Max (mg/kg) 5.54 219 1.24 94.5 0.518 74,000 1 28.3 27.8 7.03 21.1 15 0.122 2.7 312 47.2 2.64 Background Threshold Value 2 (mg/kg or pCi/g)7.36 280.1 1.59 96,832 34.0 33.0 8.1 28.6 312 57.9 2.91 95%UCL 4 251 139 40 092 55822 22 04 20 51 472 14 6 199 30 4 126 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CS‐1‐2023 (June 19, 2019)COC 1906561 7070323.116 1819202.117 3.53 147 < 0.418 <1 21.3 ≤21.3 13 < 0.0463 < 1.67 < 0.251 CS‐2‐2022 (June 19, 2019)COC 1906561 7070520.955 1819210.376 3.13 86.4 J< 0.486 24.2 6.36 < 0.0455 < 1.94 < 0.292 CS‐3‐1819 (June 18, 2019)COC 1906473 7070684.457 1819000.500 2.06 66.3 < 0.549 14.5 5.43 < 0.0448 < 2.19 < 0.329 CS‐4‐1820 (June 18, 2019)COC 1906473 7070271.158 1818959.311 6.12 136 < 0.632 14.4 7.32 < 0.0408 < 2.53 < 0.379 CS‐UPRR31‐Surface (Nov 15, 2022) 22K1233 7070675.300 1818916.900 2.66 76.6 0.185 4.90 6.10 0.022 J 1.39 0.068 J1.80 CS‐UPRR31‐0105 (Nov 15, 2022)22K1233 7070675.300 1818916.900 2.86 105 0.333 4.30 11.1 0.024 J 1.38 0.104 J1.50 CS‐UPRR32‐Surface (Nov 15, 2022)22K1233 7070531.400 1818951.400 2.73 85.9 0.229 J 5.01 9.07 0.027 J 1.39 0.092 J1.40 CS‐UPRR32‐0105 (Nov 15, 2022)22K1233 7070531.400 1818951.400 3.24 88.4 0.339 4.97 10.0 0.036 J 1.52 0.088 J1.50 CS‐UPRR32‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 2.95 151 0.233 3.28 4.48 0.012 J 0.872 0.033 J0.93 CS‐UPRR932‐2025 (Nov 15, 2022)22K1233 7070531.400 1818951.400 3.33 135 0.219 3.06 3.90 0.012 J 0.816 0.029 J0.89 CS‐UPRR33‐Surface (Nov 15, 2022)22K1233 7070367.300 1818979.800 2.58 89.3 0.470 64.0 1340 0.069 1.41 0.126 J1.10 CS‐UPRR33‐0105 (Nov 15, 2022)22K1233 7070367.300 1818979.800 1.52 71.1 0.290 5.39 11.4 0.023 J 1.13 0.086 J1.50 CS‐UPRR34‐Surface (Nov 14, 2022)22K1233 7070273.500 1818983.500 2.54 81.0 0.212 5.28 13.4 0.020 1.39 0.071 J1.60 CS‐UPRR34‐0105 (Nov 14, 2022)22K1233 7070273.500 1818983.500 1.54 101 0.347 4.27 11.1 0.016 J 1.34 0.083 J1.40 CS‐UPRR34‐2022 (Nov 14, 2022)22K1233 7070273.500 1818983.500 1.84 J 108 0.184 2.80 4.32 0.008 J 1.05 0.041 J0.98 Trip Blank (Nov 2022)22K1233 ‐‐ S.01 Surface (Oct 31, 2023)23J2567 7.28 S.901 Surface (Oct 31, 2023)23J2567 10.7 S.02 Surface (Oct 31, 2023)23J2567 353 S.03 Surface (Oct 31, 2023)23J2567 8.0 S.04 Surface (Oct 31, 2023)23J2567 12.7 S.04 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 27.2 S.05 Surface (Oct 31, 2023)23J2567 21.9 S.05 1.0 ‐ 1.5 (Oct 31, 2023)23J2567 91.5 S.06 Surface (Oct 31, 2023)23J2567 149 S.07 Surface (Oct 31, 2023)23J2567 21.5 S.07 1.0‐1.5 (Oct 31, 2023)23J2567 1030 S.08 Surface (Oct 31, 2023)23J2567 12.3 S.09 Surface (Oct 31, 2023)23J2567 15.0 S.10 Surface (Oct 31, 2023)23J2567 9.31 S.11 Surface (Oct 31, 2023)23J2567 7.74 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) pCi/g Coal Storage Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted An t i m o n y Ar s e n i c Ba r i u m Be r y l l i u m Bo r o n Ca d m i u m Ca l c i u m Ch r o m i u m , He x a v a l e n t (3 0 6 0 ) Ch r o m i u m Ch r o m i u m +I I I Co b a l t Le a d Li t h i u m Me r c u r y Mo l y b d e n u m Se l e n i u m Si l v e r Ti t a n i u m Va n a d i u m Ra d i u m 22 6 & 2 2 8 (p i C / g ) 470 3 220,000 2,300 230,000 100 6.3 1.8E+06 350 800 2300 46 5800 5800 5800 5800 7.91 848,858 91,400 212,062 66,988 1,266,486 41,330 1.27E+10 2,650,860 71.0 2,714 3,288 10,370 152 Min (mg/kg) 1.25 43.2 0.436 < 18.2 < 0.364 < 8,970 <1 < 10.4 < 11.4 < 1.20 5.33 < 9.11 < 0.0353 <1.46 26.1 8.89 ‐‐ Max (mg/kg) 5.54 219 1.24 94.5 0.518 74,000 1 28.3 27.8 7.03 21.1 15 0.122 2.7 312 47.2 2.64 Background Threshold Value 2 (mg/kg or pCi/g)7.36 280.1 1.59 96,832 34.0 33.0 8.1 28.6 312 57.9 2.91 95%UCL 4 251 139 40 092 55822 22 04 20 51 472 14 6 199 30 4 126 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting PH‐2‐0203 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐2‐0607 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐2‐1011 (June 26, 2019)1906718 / 1906719 7070103.733 1819314.921 PH‐3‐0203 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐3‐0607 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐3‐1112 (June 26, 2019)1906718 / 1906719 7070090.888 1819319.574 PH‐4‐0203 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐4‐0607 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐4‐1112 (June 27, 2019)1906718 / 1906719 7070011.530 1819372.889 PH‐5‐0203 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐5‐0607 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐5‐1012 (June 27, 2019)1906718 / 1906719 7069984.754 1819382.414 PH‐6‐1314 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 2.59 202 < 0.543 21.2 36 0.0888 J< 2.17 < 0.312 PH‐6‐2122 (June 24, 2019)1906634/1906628 7070030.165 1819139.681 5.6 119 < 0.650 21.1 6.51 < 0.0461 UJ < 2.60 < 0.346 PH‐7‐0910 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 2.47 524 < 0.548 <1 17.1 ≤17.1 < 3.29 < 0.0380 UJ < 2.19 < 0.325 PH‐7‐1516 (June 24, 2019)1906634/1906628 7069967.186 1819277.268 6.98 97 < 0.526 27.9 9.04 < 0.0366 UJ < 2.10 < 0.334 PH‐8‐1112 (June 27, 2019)1906750 7069917.254 1819200.329 7.48 78.3 < 0.512 27.9 9.54 < 0.0351 < 2.05 < 0.307 PH‐8‐1516 (June 27, 2019)1906750 7069917.254 1819200.329 6.33 85.7 < 0.501 43.7 7.94 < 0.0397 < 2.00 < 0.300 PH‐9‐0405 (June 28, 2019)1906750 7069924.775 1819114.989 8.28 109 1.09 29 148 0.0442 2.42 < 0.328 PH‐9‐1112 (June 28, 2019)1906750 7069924.775 1819114.989 6.7 68.1 < 0.537 17.8 8.36 < 0.0375 < 2.15 < 0.322 PH‐10‐1213 (June 26, 2019 1906718 / 1906719 7069907.863 1818897.646 PH‐10‐1516 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 PH‐10‐1920 (June 26, 2019)1906718 / 1906719 7069907.863 1818897.646 PH‐11‐1011 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐11‐1314 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐11‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐911‐1920 (June 26, 2019)1906718 / 1906719 7069910.020 1818911.577 PH‐12‐2425 (June 26, 2019)1906718 / 1906719 7069973.231 1818969.332 7.18 190 0.692 26.2 10.5 < 0.0394 < 2.33 < 0.350 PH‐13‐1819 (June 25, 2019)1906718 / 1906719 7069940.699 1818927.749 10.5 165 1.08 31.6 8.21 < 0.0457 < 2.74 < 0.411 PH‐14‐1920 (June 25, 2019)1906718 / 1906719 7069998.380 1818939.247 5.41 123 < 0.561 < 11.2 8.28 J< 0.0378 < 2.24 < 0.336 PH‐15‐1920 (June 24, 2019)1906634/1906628 7070035.968 1818961.838 9 127 1.04 25.6 12.8 < 0.0483 < 2.64 < 0.375 PH‐16‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 3.49 88.7 < 0.555 < 11.1 5.77 < 0.0398 < 2.22 < 0.335 PH‐916‐2021 (June 24, 2019)1906634/1906628 7070052.240 1819061.208 3.63 97.5 < 0.571 < 11.4 5.26 < 0.0413 < 2.28 < 0.326 Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Former AST Pipeline Release Area Central Power House AreaPower House Area Power Units 1 &2 Trans‐former Areas 1 Western Switch Yard Trans‐ former Area pCi/g Chem Unload & Plant Drain Area Table 1 Soil Sampling Concentrations in mg/kg Unless Otherwise Noted An t i m o n y Ar s e n i c Ba r i u m Be r y l l i u m Bo r o n Ca d m i u m Ca l c i u m Ch r o m i u m , He x a v a l e n t (3 0 6 0 ) Ch r o m i u m Ch r o m i u m +I I I Co b a l t Le a d Li t h i u m Me r c u r y Mo l y b d e n u m Se l e n i u m Si l v e r Ti t a n i u m Va n a d i u m Ra d i u m 22 6 & 2 2 8 (p i C / g ) 470 3 220,000 2,300 230,000 100 6.3 1.8E+06 350 800 2300 46 5800 5800 5800 5800 7.91 848,858 91,400 212,062 66,988 1,266,486 41,330 1.27E+10 2,650,860 71.0 2,714 3,288 10,370 152 Min (mg/kg) 1.25 43.2 0.436 < 18.2 < 0.364 < 8,970 <1 < 10.4 < 11.4 < 1.20 5.33 < 9.11 < 0.0353 <1.46 26.1 8.89 ‐‐ Max (mg/kg) 5.54 219 1.24 94.5 0.518 74,000 1 28.3 27.8 7.03 21.1 15 0.122 2.7 312 47.2 2.64 Background Threshold Value 2 (mg/kg or pCi/g)7.36 280.1 1.59 96,832 34.0 33.0 8.1 28.6 312 57.9 2.91 95%UCL 4251 139 40 092 55822 22 04 20 51 472 14 6 199 30 4 126 Location Specific Area Sample ID ‐ Depth 1 (Date)Lab Report #Northing Easting CT‐1‐Surface (June 10, 2019)COC 1906405 7069603.505 1818981.732 4.53 91.1 < 0.539 18.2 7.75 < 0.0452 < 2.16 < 0.323 CT‐2‐Surface (June 10, 2019)COC 1906405 7069742.697 1819071.901 8.42 180 0.707 38.6 15 < 0.0519 < 2.22 < 0.334 CT‐3‐Y‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 3.79 95 < 0.510 17.1 6.49 < 0.0517 < 2.04 < 0.306 CT‐3‐Surface (June 11, 2019)COC 1906405 7069634.283 1819162.671 4.56 115 < 0.537 21.1 7.69 < 0.0539 < 2.15 < 0.322 FCS‐1‐Surface (June 12, 2019)COC 1906405 7070122.062 1819458.168 < 0.894 3.62 84.7 0.458 < 27.9 < 0.559 50600 13.4 3.02 7.86 < 14.0 < 0.0504 < 1.12 < 2.23 < 0.335 24.4 19.5 3.5 FCS‐1‐0709 (June 19, 2019)COC 1906561 7070122.062 1819458.168 < 0.864 4.07 116 0.574 < 21.6 < 0.432 40600 19 3.5 6.51 12 < 0.0383 < 0.864 < 1.73 < 0.259 55 21.6 0.93 J FCS‐2‐Surface (June 12, 2019)COC 1906405 7069977.823 1819565.309 < 0.401 UJ 3.1 74.3 J 0.502 22.8 0.55 40100 16.6 2.66 8.15 13.8 < 0.0417 < 0.502 < 1.00 < 0.150 35 J23.7 0.41 FCS‐2‐0708 (June 19, 2019)COC 1906561 7069977.823 1819565.309 < 1.03 2.99 78.9 0.486 < 25.8 < 0.516 44900 13.9 3.31 5.67 < 12.9 < 0.0470 < 1.03 < 2.06 < 0.310 32.7 13.8 1.2 J FCS‐3‐Surface (June 12, 2019)COC 1906405 7069740.284 1819744.758 < 0.536 4.01 86.2 0.588 22.9 < 0.335 50700 17 3.16 7.04 15.6 < 0.0452 < 0.669 < 1.34 < 0.201 30.5 26.5 4.01 FCS‐3‐0607 (June 20, 2019)COC 1906561 7069740.284 1819744.758 < 0.802 3.33 89.8 < 0.321 < 20.1 < 0.401 57500 29.2 2.09 6.08 < 10.0 < 0.0388 3.87 < 1.60 < 0.241 36.4 13.5 0.81 J FCS‐4‐Berm‐Surface (June 12, 2019)COC 1906405 7070154.651 1819491.097 11.9 3.41 65.7 0.402 < 20.6 < 0.411 26300 28.8 2.73 362 < 10.3 < 0.0393 1.97 < 1.65 < 0.247 33.4 14 2.06 FCS‐4 02‐03' Berm (July 9, 2019)COC 1907225 7070154.651 1819491.097 1.05 9.74 145 0.428 28.9 0.82 28100 <1 11.7 ≤11.7 5.13 66.9 < 9.93 0.0702 0.909 < 1.59 < 0.238 92.3 13.4 3.18 FCS‐4 08‐09' Native (July 9, 2019)COC 1907225 7070154.651 1819491.097 < 0.691 4.58 187 0.4 < 21.6 < 0.432 48400 <1 9.12 ≤9.12 3.27 6.5 < 10.8 < 0.0376 < 0.863 < 1.73 < 0.259 60.2 16.6 0.84 FCS‐5‐Berm‐Surface (June 12, 2019)COC 1906405 7070074.177 1819567.860 < 0.762 4.27 102 0.655 < 23.8 < 0.476 48000 18.3 3.45 9.04 16.9 < 0.0397 < 0.953 < 1.91 < 0.286 47.1 27.6 2.39 FCS‐5 02‐03' Berm (July 9, 2019)COC 1907225 7070074.177 1819567.860 1.86 16.9 186 0.458 31.3 0.823 42600 9.98 3.61 149 < 10.3 0.0571 < 0.822 < 1.64 2.28 105 14.6 0.61 FCS‐5 12‐12.5' Native (July 9, 2019)COC 1907225 7070074.177 1819567.860 < 0.781 4.95 138 0.472 < 24.4 < 0.488 60200 12.3 3.46 7.81 < 12.2 < 0.0437 < 0.976 < 1.95 < 0.293 54 19.2 2.34 FCS‐6‐Berm‐Surface (June 12, 2019)COC 1906405 7069838.042 1819740.929 < 0.840 3.5 67.4 0.502 < 26.2 < 0.525 52200 15 2.83 6.04 14.5 < 0.0464 < 1.05 < 2.10 < 0.315 30.8 23.6 1 FCS‐6 1.5‐3' Berm (July 9, 2019)COC 1907225 7069838.042 1819740.929 < 0.677 < 0.529 94.8 < 0.339 40.3 < 0.423 5940 < 8.46 < 0.846 10.6 < 10.6 < 0.0394 < 0.846 < 1.69 < 0.254 65.8 < 4.23 7.34 FCS‐6 10‐11' Native (July 9, 2019)COC 1907225 7069838.042 1819740.929 < 0.697 4.17 151 < 0.348 < 21.8 < 0.436 48500 < 8.71 2.57 5.28 < 10.9 < 0.0378 < 0.871 < 1.74 < 0.261 30.4 J14 J0.88 WWP‐1‐0506 (June 20, 2019)COC 1906561 7069160.561 1818679.345 < 0.943 2 78.7 0.443 < 23.6 < 0.472 14600 19 2.41 12.2 < 11.8 < 0.0373 1.1 < 1.89 < 0.283 65.2 11 0.66 J WWP‐2‐0405 (June 20, 2019)COC 1906561 7069032.709 1818762.723 < 0.951 2.06 97.2 0.43 < 23.8 < 0.476 26000 14.6 2.47 5.5 < 11.9 < 0.0404 < 0.951 < 1.90 < 0.285 34 9.73 0.61 J WWP‐3 00"‐04" (July 9, 2019)COC 1907225 7068958.464 1818864.099 < 0.720 2.97 105 0.717 26.6 < 0.450 34000 14.5 3.55 8.46 14.5 < 0.0374 < 0.900 < 1.80 < 0.270 56.3 17.6 1.2 WWP‐4‐0203 (July 3, 2019)COC 1907131 7068797.899 1818932.898 < 0.701 1.83 93.9 0.733 25.2 < 0.438 10000 28.3 3.47 6.79 < 10.9 < 0.0429 < 0.876 < 1.75 < 0.263 65.2 18.6 0.88 WWP‐Berm 1‐Surface (June 11, 2019)COC 1906405 7069006.864 1818962.203 < 0.722 3.88 95.6 0.623 25.6 < 0.451 57300 20.2 3.07 7.68 16.1 < 0.0407 < 0.902 < 1.80 < 0.271 52.2 29.8 0.68 WWP‐Berm 1‐0307 (June 21, 2019)COC 1906561 7069006.864 1818962.203 < 1.16 4.4 1400 2.41 934 1.59 79500 35.2 5.33 19.1 22.4 < 0.0479 2.56 7.9 0.352 1550 46.3 2.1 J WWP‐Berm 2‐Surface(June 11, 2019)COC 1906405 7068919.329 1819003.919 < 0.845 4.33 110 0.704 < 26.4 < 0.528 56700 19.8 3.63 8.04 16.7 < 0.0444 < 1.06 < 2.11 < 0.317 47.8 29.6 3.03 WWP‐Berm 2‐0305 (June 20, 2019)COC 1906561 7068919.329 1819003.919 < 1.12 4.53 1440 2.01 699 1.43 90700 1 40.1 ≤40.1 4.92 21.5 20.2 < 0.0470 3.47 7.27 0.351 1500 41.5 1.7 J WWP‐Berm 2‐1012 (June 20, 2019)COC 1906561 7068919.329 1819003.919 < 0.897 4.82 193 0.534 < 22.4 < 0.449 79400 <1 15.7 ≤15.7 4.01 12.5 17.9 < 0.0484 < 0.897 < 1.79 < 0.269 106 25.7 0.88 J WWP‐Berm 3‐Surface (June 11, 2019)COC 1906405 7068824.973 1819049.196 < 0.809 2.6 54.1 < 0.404 < 25.3 < 0.505 47800 10.4 2.04 4.64 < 12.6 < 0.0427 < 1.01 < 2.02 < 0.303 20.1 15.9 3.2 WWP‐Berm 3‐0307 (June 20, 2019)COC 1906561 7068824.973 1819049.196 < 1.09 4.5 1330 2.19 839 1.48 82100 37.7 5.16 23.3 20.6 < 0.0492 3.15 7.01 < 0.327 1470 48 4.4 WWP‐Berm‐4‐0102 (July 3, 2019)COC 1907131 7068905.213 1818779.369 < 0.751 4.44 286 0.409 24.6 < 0.469 137000 13.1 2.95 8.28 18.8 < 0.0409 1.02 < 1.88 < 0.282 77.7 31.7 1.2 WWP‐Sed‐1 (June 13, 2019)COC 1906405 7068685.890 1819030.435 1.96 22.5 1040 1.91 677 2.99 89000 41.6 6.5 39.4 30.7 0.0688 1.44 21.5 1.55 1040 45.9 1.2 BG‐1 Soil (June 11, 2019)COC 1906405 7070870.893 1818952.498 < 0.821 5.54 109 0.764 < 25.7 < 0.513 40100 1 19.6 ≤19.6 4.38 9.61 < 12.8 0.108 < 1.03 < 2.05 < 0.308 26.7 20.7 ‐‐ BG‐2a (June 12, 2019)COC 1907131 7070068.657 1821186.156 < 0.834 2.9 43.2 0.5 < 26.1 < 0.521 26900 <1 < 10.4 ≤10.4 2.92 21.1 < 13.0 0.0576 < 1.04 < 2.08 < 0.313 26.1 8.89 0.55 BG‐2b (June 12, 2019)COC 1907131 7070393.754 1818321.563 < 0.599 3.17 74.4 0.698 70.1 0.399 22700 1 J16.2≤16.2 3.99 8.78 12.5 < 0.0382 < 0.749 2.7 < 0.225 112 23.3 0.76 BG‐3‐Soil (Coal) (June 13, 2019)COC 1906405 7070178.722 1821404.205 < 0.957 1.25 44.5 1.03 54.6 < 0.598 < 8,970 <1 28.3 ≤28.3 < 1.20 5.33 < 14.9 0.0601 < 1.20 < 2.39 < 0.359 260 47.2 ‐‐ BG‐4‐Soil (June 13, 2019)COC 1906405 7069599.224 1819723.307 < 0.881 4.08 78.1 0.478 < 27.5 < 0.550 40700 <1 12.6 ≤12.6 3.11 6.31 < 13.8 < 0.0484 < 1.10 < 2.20 < 0.330 26.7 14.8 0.57 BG‐5‐Soil (June 14, 2019)COC 1906405 7068616.982 1819399.171 < 0.583 2.38 80.2 0.436 < 18.2 < 0.364 41900 <1 13.4 ≤13.4 2.91 5.39 < 9.11 < 0.0353 < 0.729 < 1.46 < 0.219 95.9 12.8 0.34 BG‐6 (July 3, 2019)COC 1907131 7070406.164 1818217.233 < 0.635 4.39 105 J 0.967 57 0.518 50900 <1 24.5 ≤24.5 7.03 J11.3 14< 0.0414 < 0.794 < 1.59 < 0.238 63 31.2 J2.64 BG‐7 (July 3, 2019)COC 1907131 7069927.666 1818402.678 < 0.673 2.93 174 1.24 78.1 0.444 59600 <1 15.4 ≤15.4 2.3 19.8 14.1 < 0.0389 0.886 < 1.68 < 0.252 312 26.3 1.1 BG‐8 (July 3, 2019)COC 1907131 7069235.086 1818981.155 < 0.721 4.44 219 0.64 94.5 0.472 74000 <1 UJ 16.9 ≤16.9 3.19 11.1 15 0.122 < 0.901 < 1.80 < 0.270 241 24.5 0.85 6020B 6020B 6020B 6020B 6010D 6020B 6010D 7199 6020B 1 Calc 6020B 6020B 6010D 7471B or 7471 A ‐ CTF 6020B or 6010 ‐ CTF 6020B 6020B 6010D 6010D Notes:Qualifiers U ‐ The analyte was analyzed for, but was not detected J/UJ ‐ The associated result is estimated GP ‐ Geoprobe Rig bgs ‐ below ground surface TPH‐GRO ‐ Total Petroleum Hydrocarbons ‐ Gasoline Range Organics Laboratory reporting limit exceeds potentially applicable regulatory standard. Sonic ‐ Sonic Rig TPH‐DRO ‐ Total Petroleum Hydrocarbons ‐ Diesel Range Organics HA ‐ Hand Auger Concentration or radioactivity exceeds potentially applicable human health regulatory standard. HV ‐Hydrovac SW ‐ Surface Water pCi/g ‐ picocuries of radioactivity per gram R Laboratory result was rejected during AECOM data validation process SWL ‐ Static Water Level mg/kg ‐ milligram per kilogram PCBs ‐ Polychlorinated Biphenols For sum of Ra226/228: For the sum of the radiums, the benchmark is identified as the Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings (40 CFR §192.12). While these regulations are only applicable to the control of residual radioactive material at designated Carbon Plant VCP SI Background Background Concentrations and Potentially Applicable Regulatory Thresholds UTAH DERR ISL/Tier 1 (mg/kg) EPA RSLs Comp Worker (mg/kg) or EPA Screening Level for Ra 226&228 (pCi/g) (Direct Contact) Site‐Specific SSL or Utah SSCLs (mg/kg or pCi/g) (SSLs are based on leaching from CCR berm at WWP Area) 40 CFR 761.61 ‐ PCBs (High Occupancy Areas (mg/kg) Cooling Tower Basin Waste Water Pond Area 1 ‐ Interval sampled is shown as last 4 digits of the sample ID. EXAMPLE: CS‐1‐2023 means the soil sample was collected between the depths of 20' and 23' below ground surface.. pCi/g Method SM7500 GPC & Calc for combined 226&228 Pace Lab Background Former Coal Storage Area Analytical Method and appropriate at other CERCLA sites. The regulations identify a standard of 5 pCi/g above background for use of assessing the combined levels of Ra‐226 and Ra‐228. For Ra 226 and Ra 228: USEPA, 2018a. Preliminary Remediation Goals for Radionuclides . PRG Calculator, default mode. Value for composite worker soil, adjusted to a cancer risk level of 1E‐5. Accessed March. https://epa‐prgs.ornl.gov/radionuclides/ processing or depository (Title I) sites under Section 108 of UMTRCA , USEPA has provided guidance that these criteria should be considered relevant USGS ‐ United States Geological Survey HMW PAHs ‐ High Molecular Weight PAHs RSLs ‐ Regional Screening Levels PAHs ‐ Polycyclic Aromatic Hydrocarbons EPA ‐ Environmental Protection Agency LMW PAHs ‐ Low Molecular Weight PAHs 2 ‐ Background threshold values were only calculated for analytes that had six or more concentrations reported above the laboratory reporting limits. Table 2 Groundwater Sampling Concentrations in mg/l Unless Otherwise Noted) SG T ‐HE M / N o n ‐Po l a r Ma t e r i a l SG T ‐ Di e s e l Ra n g e Or g a n i c s (D R O ) (C 1 0 ‐ C2 8 ) C1 1 ‐C1 2 Al i p h a t i c hy d r o c a r b o n s C1 1 ‐C1 3 Al k y l Na p h t h a l e n e s C1 2 ‐C2 2 Po l y a r o m a t i c hy d r o c a r b o n s C1 3 ‐C1 6 Al i p h a t i c hy d r o c a r b o n s C1 7 ‐C2 1 Al i p h a t i c hy d r o c a r b o n s C2 2 ‐C3 5 Al i p h a t i c hy d r o c a r b o n s TP H C6 ‐C1 0 (G R O ) C5 & C 6 Al i p h a t i c hy d r o c a r b o n s C7 & C 8 Al i p h a t i c hy d r o c a r b o n s C9 & C 1 0 Al i p h a t i c hy d r o c a r b o n s C9 & C 1 0 Al k y l Be n z e n e s Me t h y l te r t ‐bu t y l et h e r be n z e n e to l u e n e et h y l b e n z e n e xy l e n e s , to t a l na p h t h a l e n e (b a s e d on 82 7 0 E SI M ) Te t r a c h l o r o e t h e n e Tr i c h l o r o e t h y l e n e ci s ‐1, 2 ‐Di c h l o r o e t h e n e tr a n s ‐1, 2 ‐ Di c h l o r o e t h e n e 1, 1 ‐Di c h l o r o e t h e n e vi n y l ch l o r i d e 1, 4 ‐Di o x a n e (s y n o n y m p, Di o x a n e ) Ch l o r o e t h a n e Is o p r o p y l b e n z e n e (s y n o n y m : Cu m e n e ) Me t h y l c y c l o h e x a n e m, p ‐Xy l e n e o‐Xy l e n e 0.005 1.0 0.70 10 0.005 0.005 0.07 0.1 0.007 0.002 10 / 10 1 / 10 10.2 4.09 3.07 10.2 204 204 1 / 10 6.13 6.13 10.2 4.09 0.2/0.2 0.005 / 0.3 1 / 30.7 / 410 / 10 0.7 / 0.7 0.005 1.0 0.70 10 0.005 0.005 0.07 0.1 0.007 0.002 0.00046 0.014 0.00046 1.1 0.0015 0.19 1.20E‐04 0.011 0.00049 0.025 0.068 0.28 1.90E‐05 0.00046 8.3 0.45 0.19 0.19 max min Location Specific Area Sample ID Lab Report #Northing Easting Top of Casing Elev NAVD 88 Date GW Elev Measured Depth to GW GW Elev 1906560 7070323.116 1819202.117 6089.25 7/3/2019 18.36 6070.89 15 99.4 2.52 <0.00955 0.0142 20.1 13.1 1.23 <0.02 <0.02 <0.02 <0.02 <0.000191 None 7070323.116 1819202.117 6089.25 11/29/2022 Dry Dry CS‐2 1906560 7070520.955 1819210.376 6090.58 7/3/2019 19.45 6071.13 < 5.00 <0.02 <0.002 <0.002 <0.002 <0.002 <0.002 <0.00019 CS‐3 1906473 7070684.457 1819000.500 < 5.00 CS‐4 1906473 7070271.158 1818959.311 5.31 0.08945 a 0.0655 <0.00958 <0.00958 <0.00958 <0.00958 <0.00958 2005325 7070305.548 1819137.72 5/11/2020 20.20 6066.87 22K2221/22K2222 7070305.548 1819137.72 11/29/2022 25.65 6061.42 R <1 <0.01 <0.001 <0.0004 <0.001 <0.001 <0.001 <0.0007 CS‐UPRR‐32 22K2221/22K2222 7070675.300 1818916.900 6085 11/30/2022 24.26 6060.74 <5 <1 <0.01 <0.001 <0.0004 <0.001 <0.001 <0.001 <0.0007 CS‐UPRR‐34 22K2221/22K2222 7070367.300 1818979.800 6082.42 11/29/2022 21.80 6060.62 <5 <1 <0.01 <0.001 0.0006 <0.001 <0.001 <0.001 <0.0007 PH‐3 1906718 7070090.888 1819319.574 6094.59 7/3/2019 23.36 6071.23 PH‐93 (Duplicate)1906718 PH‐6 1906634 / 1906628 7070030.165 1819139.681 6094.57 7/3/2019 23.91 6070.66 < 5.00 < 0.501 <0.02 <0.02 <0.02 <0.04 <0.000197 <0.02 <0.02 <0.02 <0.02 <0.02 <0.01 <0.5 <0.02 <0.02 <0.02 <0.02 <0.02 PH‐96 (Duplicate)1906634 / 1906628 < 5.00 < 0.502 <0.002 <0.002 <0.002 <0.004 <0.000194 <0.002 <0.002 <0.002 <0.002 <0.002 <0.001 <0.05 <0.002 <0.002 <0.002 <0.002 <0.002 W. Transformer Area PH‐11 1906718 / 1906719 7069910.02 1818911.577 6084.54 7/3/2019 17.68 6066.86 PH‐12 1906683 / 1906673 7069973.231 1818969.332 6086.78 7/3/2019 19.01 6067.77 < 5.00 <0.002 <0.002 <0.002 <0.004 <0.000191 <0.002 <0.002 <0.002 <0.002 <0.002 <0.001 <0.05 0.0213 <0.002 <0.002 <0.002 <0.002 PH‐13 1906683 / 1906673 7069940.699 1818927.749 6083.69 7/3/2019 16.29 6067.40 < 5.00 <0.002 <0.002 <0.002 <0.004 <0.000191 <0.002 <0.002 <0.002 <0.002 <0.002 <0.001 <0.05 <0.002 <0.002 <0.002 <0.002 <0.002 PH‐14 1906683 / 1906673 7069998.38 1818939.247 6080.22 7/3/2019 12.64 6067.58 < 5.00 <0.002 <0.002 <0.002 <0.004 <0.000191 <0.002 <0.002 <0.002 <0.002 <0.002 <0.001 <0.05 <0.002 <0.002 <0.002 <0.002 <0.002 PH‐15 1906718 / 1906719 7070035.968 1818961.838 6079.78 7/3/2019 11.75 6068.03 5.1 <0.002 <0.002 <0.002 0.0188 0.03066 0.00151 <0.002 <0.002 <0.002 <0.002 <0.002 <0.001 <0.05 <0.002 0.0135 <0.002 0.0253 0.00536 PH‐16 1906683 / 1906673 7070052.24 1819061.208 < 5.00 1.13 <0.2 <0.2 <0.2 0.463 <0.02 <0.02 <0.02 0.564 0.0466 0.0714 <0.02 <0.02 <0.02 <0.02 <0.02 <0.01 <0.5 <0.02 0.0447 0.0491 0.0366 <0.02 2005325 5/11/2020 17.88 6064.94 22K2221/22K2222 11/30/2022 21.86 6060.96 <5 <1 <0.01 <0.001 <0.0004 <0.001 <0.001 <0.001 <0.0007 <0.001 <0.0003 U <0.001 <0.001 <0.001 <0.0003 U <0.0002 <0.001 <0.001 <0.001 <0.001 PH‐9201 (Duplicate)22K2221/22K2222 <5 <1 <0.01 <0.001 <0.0004 <0.001 <0.001 <0.001 <0.0007 <0.001 <0.0003 U <0.001 <0.001 <0.001 <0.0003 U <0.0002 <0.001 <0.001 <0.001 <0.001 FCS‐1 1906560 7070122.062 1819458.168 6090.71 7/3/2019 17.63 6073.08 < 6.55 FCS‐2 1906560 7069977.823 1819565.309 6092.69 7/3/2019 17.92 6074.77 < 6.56 FCS‐3 1906560 7069740.284 1819744.758 6103.31 7/3/2019 23.71 6079.60 < 5.00 2005325 5/11/2020 23.20 6071.13 None 11/29/2022 Dry Dry WWP‐1 1906560 7069160.561 1818679.345 6052.05 7/3/2019 5.23 6046.82 5.3 WWP‐2 1906560 7069032.709 1818762.723 6047.04 7/3/2019 2.67 6044.37 < 5.00 WWP‐Berm‐2 1906634 / 1906628 also 1907131 (Cr+VI)7068919.329 1819003.919 6051.73 7/3/2019 11.04 6040.69 < 5.00 WWP‐Berm‐4COC 1907131 7068905.213 1818779.369 6042.44 7/3/2019 0.39 6042.05 6.4 2005325 5/11/2020 6.44 6046.16 22K2221/22K2222 11/30/2022 8.31 6044.29 <5 <0.0007 WWP‐201 Dup‐0520 2005325 Analytical Method 1664 SGT SW‐846 8015 SGT Notes:Qualifiers U ‐ The analyte was analyzed for, but was not detected TPH‐GRO ‐ Total Petroleum Hydrocarbons ‐ Gasoline Range Organics J/UJ ‐ The associated result is estimated TPH‐DRO ‐ Total Petroleum Hydrocarbons ‐ Diesel Range Organics R Laboratory result was rejected during AECOM data validation process Concentration or radioactivity exceeds potentially applicable human health regulatory standard. MCL ‐ maximum contaminant level PCBs ‐ Polychlorinated Biphenols Laboratory reporting limit exceeds potentially applicable regulatory standard. References: Utah Department of Environmental Quality (UDEQ). 2016b. Standards of Quality for Waters of the State. Utah Division of Water Quality. UAC R317‐2. Total Coliform/E‐coli (org/ 100mL) 1819587.8687069974.612 DRO Fractionation 6082.821819011.1167070067.19 Duplicate of PH‐201 11/30/2022 Coal Storage Area CS‐1 CS‐201 Sampled June 2019 (no permanent well constructed) Duplicate Sample of PH‐3 7/3/2019 Duplicate Sample of PH‐6 7/3/2019 6087.07 GRO Fractionation Potentially Applicable Regulatory Thresholds EPA MCL (mg/L) UTAH DERR ISL/Tier 1 (mg/L) or SSCLs for Fractionations of DRO (CS‐1) and GRO (PH‐16) (mg/L) UDWQ GWQS Table 1 (mg/L) Or, for 1,4 Dioxane‐ EPA RSL Tap Water Screening Level (mg/L) EPA RSLs tap water (mg/L) Price River Upstream Water Dissolved (mg/L) Wastewater Ponds Area Former Coal Storage Area WWP‐201 Power Units 1 &2 Transformer Areas PH‐201 Chem Unload & Plant Drain Line Areas Former Coal Storage Area Power House Area Central Power House Area Sampled June 2019 (no permanent well constructed) Duplicate of WWP‐201 5/11/2020 SW‐846 8270D SIM / 8270D FS SW‐846 8270D SIM / 8270D FS for all samples analyzed after July 1, 2019 FCS‐201 6094.33 Conversion Factors for Dissolved Metals not specifically addressed in UAC 317‐2 obtained from USEPA 2019. 1 ‐ Utah Screening Level for 1,4 dioxane set at EPA tap water standard per VCP PM. a ‐ value estimated based on sum of 8270 TPH (DRO) fractionation. One half the detection limit assumed for concentrations below the reporting limit. *Per UAC 317‐2, dissolved metals method involves filtration of the sample in the field, acidification of the sample in the field, no digestion process in the laboratory, and analysis by EPA approved laboratory methods for the required detection levels. SGT ‐ Silica Gel Treatment pCi/L ‐ picocuries of radioactivity per liter of water 6052.61818683.8347069185.586 SW‐846 8260C SW‐846 8260D (for all samples analyzed after July 1, 2019 MPN ‐ Most Probable Number EPA ‐ Environmental Protection Agency RSLs ‐ Regional Screening Levels mg/L ‐ milligram per liter DERR ‐ Utah Division of Environmental Response and Remediation PAHs ‐ Polycyclic Aromatic Hydrocarbons LMW PAHs ‐ Low Molecular Weight PAHs HMW PAHs ‐ High Molecular Weight PAHs Turbidity of unfiltered groundwater sample exceeded 10 NTUs