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HomeMy WebLinkAboutDERR-2025-004326 Corrective Action Plan Former ABF Freight Site 55 South Redwood Road Salt Lake City, Utah Facility I.D. 4001342, Release Site FFQ and OLX PREPARED FOR PRESENTED BY CTP DEV, LLC 9350 South 150 East Sandy, Utah 84070 Tetra Tech, Inc. 4750 West 2100 South, Suite 400 Salt Lake City, UT 84120 Curt Stripeika Senior Project Manager Certified Environmental Consultant 0003 curt.stripeika@tetratech.com 26/1405/2 025 David Wilson, P.E., P.G. Senior Principal Engineer davidwilson.wilson@tetratech.com 26/1405/2 025 February 14June 5, 2025 i June 5February 14, 2025 TABLE OF CONTENTS 1.0 INTRODUCTION ..................................................................................................................................... 1 1.1 Purpose and Objective ...................................................................................................................... 1 1.2 Background ....................................................................................................................................... 1 1.3 CAP Organization ............................................................................................................................. 4 2.0 SITE CHARACTERIZATION AND CURRENT CONDITIONS ............................................................... 5 2.1 Regulatory Requirements ................................................................................................................. 5 2.2 Past Investigations and Remediation ................................................................................................ 6 2.3 Groundwater Monitoring 2024 .......................................................................................................... 7 2.3.1 Groundwater Sampling .......................................................................................................... 87 2.3.2 Summary of Groundwater Analytical Results .......................................................................... 8 2.4 UST Closure ...................................................................................................................................... 9 3.0 CORRECTIVE ACTION COMPARISON AND SELECTION ................................................................ 10 3.1 Monitored Natural Attenuation ........................................................................................................ 10 3.2 Operation of Pumping Systems ...................................................................................................... 10 3.3 Soil Excavation and Product Recovery ........................................................................................... 10 4.0 CORRECTIVE ACTION DESIGN AND CONSTRUCTION DETAILS .................................................. 12 4.1 Scope of Corrective Action.............................................................................................................. 12 4.2 Corrective Action Description .......................................................................................................... 13 4.3 Soil Confirmation Sampling ............................................................................................................. 15 5.0 PERMITTING REQUIREMENTS .......................................................................................................... 16 5.1 Division of Air Quality ...................................................................................................................... 16 5.2 Division of Water Quality ................................................................................................................. 16 5.3 Division of Waste Management and Radiation Control .................................................................. 16 5.4 Salt Lake County Health Department ............................................................................................. 16 5.5 Blue Stakes ..................................................................................................................................... 16 6.0 PUBLIC NOTIFICATION ....................................................................................................................... 17 7.0 NON-PETROLEUM WASTE MANAGEMENT PLAN ........................................................................... 18 7.1 Asbestos Containing Materials ....................................................................................................... 18 7.2 Other Suspect Wastes .................................................................................................................... 18 7.3 Sample Waste Analyses ............................................................................................................. 1918 7.4 On-Site Materials Management ...................................................................................................... 19 7.5 Materials Transportation ................................................................................................................. 19 ii June 5February 14, 2025 8.0 GROUNDWATER MONITORING PROGRAM ..................................................................................... 20 8.1 Ponded Groundwater Assessment ................................................................................................. 20 8.2 Site Closure Monitoring ................................................................................................................... 20 9.0 COMPLETION REPORT ....................................................................................................................... 22 10.0 REFERENCES .................................................................................................................................... 23 LIST OF FIGURES Figure 1 Project Site Location Figure 2 Site Features Map Figure 3 Location of UST Closure Samples Figure 4 Groundwater Elevation Contours - March 27, 2024 Figure 5 Groundwater Elevation Contours - June 6, 2024 Figure 6 Groundwater Elevation Contours – September 26, 2024 Figure 7 Groundwater Elevation Contours – October 28, 2024 Figure 8 Product Thickness Map- March 27, 2024 Figure 9 Product Thickness Map- June 6, 2024 Figure 10 Product Thickness Map- September 26, 2024 Figure 11 TPH Diesel Concentrations – October – November 2024 LIST OF TABLES Table 1 March 27, 2024, Corrected Groundwater Elevations and Product Thickness Table 2 June 9, 2024, Corrected Groundwater Elevations and Product Thickness Table 3 September 26, 2024, Corrected Groundwater Elevations and Product Thickness Table 4 October 28, 2024, Corrected Groundwater Elevations and Product Thickness Table 5 October - November 2024 Groundwater Analytical Results Table 6 Summary of UST Closure Soil Analytical Results Table 7 Summary of UST Closure Groundwater Analytical Results iii June 5February 14, 2025 LIST OF DESIGN DRAWINGS Drawing G-001 Cover Sheet Drawing C-100 Existing Conditions Plan Drawing C-101 Corrective Action Design Plan Drawing C-102 Excavation and Backfill Plan Drawing C-103 Excavation and Backfill Sections Drawing C-104 Details APPENDICES Appendix A Correspondence from Utah DERR on LUST Releases OLX and FFQ Appendix B Photographs from UST Removal of Tanks 4, 5, 6, and 7 Appendix C UST Closure Analytical Report Appendix D October 2024 Groundwater Laboratory Analytical Report Appendix E Freidman and Bruya, Inc., Letter report issued to National Warehouse Investment Company, March 30, 2000 Appendix F Tetra Tech Standard Operating Procedures Appendix G Public Notice Template iv June 5February 14, 2025 LIST OF ACRONYMS/ABBREVIATIONS Acronym/Abbreviation Definition ACM Asbestos-containing materials Atlas Atlas Technical Consultants bgs Below ground surface BTEXN Benzene, ethylbenzene, toluene, total xylenes, naphthalene CAP Corrective Action Plan CTP DEV CTP DEV, LLC (subsidiary of Larry H. Miller Real Estate) cy Cubic yard DERR UDEQ Division of Environmental Response and Remediation DRO Diesel Range Organics EPA United States Environmental Protection Agency ESA Environmental Site Assessment ETT E.T. Technologies Soil Regeneration Site F&B Friedman and Bruya FFQ DERR identification for historical LUST release from 1988 FDCP Fugitive Dust Control Plan HREC Historical Recognized Environmental Condition ISL DERR Initial Screening Levels LNAPL Light non-aqueous phase liquid LUST Leaking Underground Storage Tank mg/L Milligrams per liter MNA Monitored Natural Attenuation NWIC National Warehouse Investment Corporation OLX DERR identification for LUST release from 2024 PID Photoionization Detector PST Petroleum Storage Tank PSTF Petroleum Storage Tank Fund RCRA Resource Conservation and Recovery Act REC Recognized Environmental Condition RMP Rocky Mountain Power RSL EPA Regional Screening Level SLCWRF Salt Lake City Water Reclamation Facility SLV Salt Lake Valley [Landfill] SOP Standard Operating Procedure v June 5February 14, 2025 Acronym/Abbreviation Definition SESCs Soil erosion and sedimentation controls Sq. Ft. Square Feet STC Sump and Trap LLC SVOCs Semi-volatile organic compounds Tetra Tech Tetra Tech, Inc. TPH Total Petroleum Hydrocarbons UAC Utah Administrative Code UDAQ Utah Division of Air Quality UDEQ Utah Department of Environmental Quality UST Underground Storage Tank VOCs Volatile organic compounds 1 June 5February 14, 2025 1.0 INTRODUCTION On behalf of CTP DEV LLC (CTP DEV), Tetra Tech, Inc. (Tetra Tech) has prepared this Corrective Action Plan (CAP) to present the corrective action for the former ABF Freight Leaking Underground Storage Tank (LUST) conditions at 55 South Redwood Road, Salt Lake City, Utah (Site, Facility I.D. 4001342). Two LUST conditions have been observed at the Site and have been designated by the Utah Department of Environmental Quality (UDEQ), Division of Environmental Response and Remediation (DERR), as historical petroleum Release FFQ from 1988, and recent discovery of petroleum Release OLX released petroleum associated withduring the closure of Tanks 4, 5, 6 and 7 on October 8, 2024, which was designated by the DERR as Release OLX. Because the environmental impacts associated with these releases overlap historically and geographically, this CAP has been prepared to address both releases concurrently to support CTP DEV’s planned cleanup and redevelopment of the Site. 1.1 PURPOSE AND OBJECTIVE This CAP describes the approach and methods selected to clean up the overlapping LUST conditions from Releases FFQ and OLXat the former ABF Freight Site. The DERR issued letters to CTP DEV dated November 18 and 26, 2024 pertaining to Releases OLX and FFQ, directing the performance of a subsurface investigation for Release OLX and development of this CAP for Release FFQ; copies of these letters are included in the CAP as Appendix A. CTP DEV proposes to completed a Site Characterization Work Plan and conduct the supplemental investigation requested by DERR for Release OLX and CTP DEV and DERR are currently reviewing available data to determine the history of releases at the Site while DERR is reviewing this CAP, which is designed to concurrently remediate the impacts from Releases FFQ and OLX. The further site characterization for Release OLX will focus on data collection to differentiate between the two releases; otherwise, s Significant site data has already been collected across the Site for more than 20 years. The CAP has been prepared in accordance with the guidance from DERR, including the Corrective Action Plan Guide, Non-Petroleum Storage Tank Trust Fund, Leaking Underground Storage Tank Sites, dated October 1, 2017. and the Corrective Action Plan Guide, Petroleum Storage Tank Trust Fund Leaking Underground Storage Tank Sites, dated June 14, 2017. Both guidance documents are referenced because Release FFQ does not have Petroleum Storage Tank Fund (PSTF) coverage and Release OLX has PSTF coverage. The All historical releases overlap and will be addressed concurrently as discussed during the CAP Meeting between CTP DEV, Tetra Tech, and DERR representatives on December 4, 2024. The CAP presents the established cleanup levels required to complete the remediation and closure of the LUSTs in cooperation with DERR. This CAP and changes to it will require approval by the DERR. 1.2 BACKGROUND The Site is a former truck terminal slated for new development within the Power District master plan, a 100-acre new commercial and residential area in Salt Lake City, Utah. The location of the Site is shown on Figure 1. The Site has served as a truck terminal with fueling operations since 1959, which pre-dates the development of Utah’s underground storage tank regulations under Utah Administrative Code (UAC) R311. The Site was operated with various underground storage tanks as presented on Table 1 below, with most tanks being closed by removal or in-place closure by the prior owner National Warehouse Investment Corporation (NWIC). However, Tanks 4, 5, 6, and 7 had not been closed by NWIC prior to the purchase of the Site property by CTP DEV on January 4, 2024. These four tanks were operated by ABF Freight from 1990 until it vacated the site in approximately May 2023. These tanks were subsequently 2 June 5February 14, 2025 closed by CTP DEV on October 8, 2024. Figure 2 shows the approximate locations of the Underground Storage Tanks (USTs). Table 1 Site Underground Storage Tank Summary Petroleum Release FFQ was reported in 1988 and according to DERR records accounted for multiple historical releases of underground storage tanks (USTs) and related product piping. A study conducted by forensic chemists Friedman and Bruya (F&B) of Seattle, Washington on behalf of NWIC, dated March 30, 2000, states that there were multiple releases from 1959 to 1988. Specifically, they cited six documented releases as listed below on Table 2. A Copy of the Friedman and Bruya report is included with this CAP for informational purposes as Appendix E. DERR Tank ID Product Type Size (gallons) Status Date Installed Date Closed 1 Diesel 12,000 Closed in place 12/21/1979 4/21/1982 2 Diesel 12,000 Closed in place 12/21/1979 4/21/1982 3 Diesel 12,000 Closed in place 12/21/1979 4/21/1982 4 Diesel 12,000 Closed and removed 12/21/1979 10/08/2024 5 Diesel 12,000 Closed and removed 12/21/1979 10/08/2024 6 Diesel 12,000 Closed and removed 12/21/1979 10/08/2024 7 Diesel 12,000 Closed and removed 12/21/1979 10/08/2024 8 Hazardous substance 10,000 Closed and removed 8/19/1980 8/19/1992 9 Waste Oil 3,000 Closed and removed 12/21/1959 8/19/1992 10 Waste Oil 3,000 Closed and removed 12/21/1959 12/8/1995 11 Gasoline 10,000 Closed and removed 12/21/1979 8/19/1992 12 Diesel 12,000 Closed in place 12/21/1967 6/6/1988 13 Diesel 12,000 Closed in place 12/21/1967 6/6/1988 14 Gasoline 5,000 Closed in place 12/21/1967 6/6/1988 3 June 5February 14, 2025 Table 2 Site Petroleum Release History Friedman and Bruya estimated that the total volume for Release FFQ was between 97,000 to 214,000 gallons, primarily diesel. The quantity released from the gasoline UST (UST I.D. 11) was unknown and not included with the above quantities. USTs 8, 9, 10, and 11 were closed and removed. No releases were reported for USTs 8, 9, and 10. USTs 1, 2, 3, 12, 13, and 14 were closed in place. USTs 1, 2, and 3 are beneath the floor of the former Fueling Building, and USTs 12, 13, and 14 are located under the asphalt on the east side of the former Fueling Building. There were significant releases from UST 1, 2, 3, 12, 13, and 14 according to the F&B report. It also appeared to F&B that USTs 4, 5, 6 and 7 leaked before 1988 and subsequent UDEQ tank inspection records (i.e., inspections showed staining in the tank fill ports); however, these tanks continued to be operated by ABF Freight with likely releases until ABF Freight vacated the Site in approximately May 2023. These tanks were subsequently closed by removal by CTP DEV on October 8, 2024. In response to the presence of historical releases, a groundwater recovery trench and water treatment facility were installed at the northwest corner of the property in 2001. The purpose was to intercept diesel light non-aqueous phase liquid (LNAPL) and preclude migration off the property. The trench extends from the northwest corner traversing south and east a combined 600 feet along the property boundary at this downgradient corner of the property. The trench was coupled to a 16-inch diameter well where a downhole electric pump recovered water and an LNAPL pump skimmed petroleum liquids. The recovered water and petroleum mix was treated by oil-water separation and the water was discharged under a permit to the Salt Lake City Water Reclamation Facility (SLCWRF). Since startup of the remediation system in 2001, approximately 22,000 gallons of free product (light non-aqueous phase liquid, LNAPL) are reported to have been recovered and over 11 million gallons of groundwater treated and discharged to the SLCWRF sanitary sewer. A free product skimming system manufactured by Xitech, was installed in three wells within the former Fueling Building in 2012 or 2013. The skimmers were placed in wells EXT-B, EXT- C and EXT-D. In 2006, additional corrective action was performed by Atlas Technical Consultants (Atlas) on behalf of NWIC to remove source material by soil excavation. Since then, there have been six additional soil excavations. These occurred in 2007, 2010, 2013, 2014, 2019, and 2020. An estimated 6,000 cubic yards of impacted soil were removed from the Site and disposed of at E.T. Technologies Soil Regeneration Time Period Product Type Estimated Volume (gallons) Estimated Release Area (sq. ft.) DERR UST I.D. Release Mechanism 1959 to 1979 Diesel 20,000 to 40,000 35,000 to 50,000 12, 13 &14 Ongoing line leaks Pre – June 1979 Diesel 7,000 to 24,000 Unknown 12, 13 &14 Catastrophic tank failure 1979 to 1988 Diesel 15,000 to 30,000 30,000 to 40,000 1, 2 & 3 Ongoing (dispenser piping and overfills) 1979 to 1988 Diesel 50,000 to 100,000 60,000 to 80,000 1, 2, 3, 4, 5, 6 & 7 Ongoing (common distribution line leaks) 1983 to 1988 Diesel 5,000 to 20,000 10,000 to 20,000 6 & 7 Ongoing (corroded siphon pipe) 1979 to 1988 Gasoline Unknown Unknown 11 Ongoing (Overfills and dispenser leak) 4 June 5February 14, 2025 Site. Atlas submitted a CAP Update, dated April 22, 2022, to perform more soil excavation. The plan did not specify the locations where soil excavation would occur. It is CTP DEV’s understanding that the CAP update was not implemented. 1.3 CAP ORGANIZATION This CAP in organized in the following sections in accordance with DERR’s CAP guidance referenced in Section 1.1:  Section 1.0: Introduction – States the purpose and objectives and provides Site background for the CAP.  Section 2.0: Site Characterization and Current Conditions – Provides a review of past Site characterization activities for soils and groundwater, a discussion of applicable UST regulations, and a summary of current conditions to be addressed by the selected corrective actions.  Section 3.0: Corrective Action Comparison and Selection – Presents the basis for selection of the planned corrective action and compares it to alternatives with rationale for selecting the planned remedy.  Section 4.0: Corrective Action Design and Construction Details – Describes the recommended corrective action details, basis for design, and steps to implement the selected corrective action.  Section 5.0: Permitting Requirements – Presents the required notifications and permitting to support the selected corrective action.  Section 6.0: Public Notification – Describes the requirements for public notice and means for informing the adjacent property owners of the planned corrective action.  Section 7.0: Non-Petroleum Waste Management Plan – Establishes the procedures for characterization, on-site handling and staging, and disposal to mitigate possible environmental hazards to human health and the environment.  Section 8.0: Groundwater Monitoring Program – Outlines the quality assurance inspections, monitoring, sampling, and analysis to support the corrective action process and demonstrate completion of the work.  Section 9.0: Completion Report – Describes the elements of the Completion Report to be prepared following implementation of the corrective action.  Section 10.0: References – Provides a list of references to documents used to prepare this CAP. 5 June 5February 14, 2025 2.0 SITE CHARACTERIZATION AND CURRENT CONDITIONS This CAP is based on existing Site data that have been previously collected by Tetra Tech, Atlas, and others performing work for the former owner of the property. A summary of these conditions is presented in this section, which supports the basis for corrective action alternatives evaluation and remedy selection as presented in Section 3, and the basis for corrective action design presented in Section 4. The Site is bordered by Redwood Road to the west, South Temple Street to the north, and Rocky Mountain Power (RMP) which includes a power generation facility, and a laydown yard, east and south respectively. The typical soil encountered in past Site investigations and corrective action soil excavations consists of clayey silts to a depth of approximately 11 feet below ground surface (bgs), underlain by clean sand. Past use of the Site was a historic landfill from the late 1800s to the early 1900s, which is known as the South Temple Landfill. Remnants of municipal waste have been encountered in shallow subsurface soils across the Site at depths ranging from approximately 1 to 6 feet bgs. Also, the Site has undergone corrective action that has involved the removal and disposal of petroleum impacted soil as described in Section 1.2. Replacement soils placed in the excavations consisted of pea gravel, creating pockets of high permeability zones. The excavation areas are within the former Fueling Building and areas west and north of the former Fueling Building. Figure 2 shows past excavation areas. The previous soil excavations were performed piecemeal as they were excavated while the freight terminal was an active trucking facility. 2.1 REGULATORY REQUIREMENTS According to Utah Administrative Code (UAC) R311-211-6, the “Petroleum Storage Tank (PST) Facility Cleanup Standards,” incorporate by reference the DERR’s Initial Screening Levels (ISLs) table dated November 1, 2005, which lists screening levels for PST sites. If the DERR Director determines that a release from an UST has occurred, the Director shall evaluate whether the contamination at the site exceeds ISLs for the released constituents. The Director may then require owners and operators to submit information that DERR believes will assist in making this evaluation. If all impacts are below initial screening levels, the Director shall evaluate the site for No Further Action determination. If impacts from a release are above the ISLs, the Director shall require owners and operators to submit relevant information required to evaluate the site using the Tier 1 Screening Criteria. The Tier 1 Screening Criteria were incorporated into the rule on November 1, 2005. Tier 1 screening criteria require that the following conditions exist for use of these less conservative cleanup criteria compared to the ISLs. 1. No buildings, property boundaries or utility lines are located within 30 horizontal feet of the highest measured concentration of any contaminant that is greater than the initial screening levels but less than or equal to the Tier 1 screening levels. 2. No buildings, property boundaries or utility lines are located within 30 horizontal feet of the highest measured concentration of any contaminant that is greater than the initial screening levels but less than or equal to the Tier 1 screening levels. 3. No water wells or surface water are located within 500 horizontal feet of the highest measured concentration of any contaminant that is greater than the initial screening levels but less than or equal to the Tier 1 screening levels. If Tier 1 Screening Criteria are met, the Director shall evaluate the site for No Further Action determination. If any of the Tier 1 Screening Criteria are not met, owners and operators shall conduct a site investigation to provide information to the DERR regarding the factors outlined in Subsection R311- 6 June 5February 14, 2025 211-5(3) and 40 CFR Part 280, which has already been completed for the Site except as described in Section 1.1 for the OLX Release. Upon completion of the site investigation, the owners and operators may propose that the ISLs or Tier 1 Screening Criteria be used for corrective action standards or may propose for evaluation and approval of the DERR, alternative (less stringent) site-specific cleanup standards based upon an analysis of the factors outlined in Subsection R311-211-5(3). CTP DEV currently proposes use of the ISLs established in Subsection R311-211-6(1) as the site-specific cleanup standards but may elect to consider alternative cleanup standards based on the outcome and effectiveness of CAP implementation. 2.2 PAST INVESTIGATIONS AND REMEDIATION Tetra Tech performed a Phase I Environmental Site Assessment (ESA) for the Site beginning in August 2023 to support environmental due diligence phase for purchase of the property by CTP DEV. The Phase I ESA provided a summary of Site environmental conditions and identified a Recognized Environmental Condition (REC) and one Historical REC (HREC) as defined by ASTM Standard E 1527-21. These conditions are copied from the Phase I ESA Report dated October 27, 2023, and presented below for background information purposes.  REC - The Subject Property is undergoing corrective action due to a diesel release from the on- site Fueling Building, underground storage tanks and/or ancillary piping. The release is identified as Leaking Underground Storage Tank Site (LUST) “FFQ” with the State of Utah Department of Environmental Quality, Division of Environmental Response and Remediation (DERR). The facility identification number is 4001342. Ongoing cleanup efforts began in 2001 with a dedicated free product recovery system. As of 2019, approximately 20,500 gallons of diesel had been recovered. Recent reports indicate that considerable free product continues to exist in the western third of the Subject Property. It is Tetra Tech’s understanding from discussions with Atlas, the consultant for [NWIC], that free product recovery within the Fueling Building is ongoing.  HREC - The Subject Property is listed under CERCLIS for the South Temple Street Landfill. Review of the DERR documents shows the South Temple Street Landfill as having an address of 1407 West North Temple. The landfill operated from 1895 to 1930 and accepted municipal and industrial waste. The address places the CERCLIS site approximately 1000 feet northeast from the Subject Property. The approximate size of the landfill was 175 acres; and the Subject Property appears to have been part of the landfill property, or at least have overlapping boundaries. The landfill was given a no further action status based on investigative activities and contaminant levels that were at or below U.S. Environmental Protection Agency (EPA) Regional Screening Levels (RSLs). Prior investigation and remedial action on the Subject Property consisting of soil excavation on the Subject Property, encountered non-engineered fill and is likely present along with deleterious materials consisting of municipal wastes at select locations within the boundaries of the Subject Property. The DERR further clarified that the South Temple Landfill site (EPA ID UT0001767318) includes the entirety of the Subject Project and was designated No Further Remedial Action Planned (NFRAP) by the EPA in 2000 based on the former industrial use of the property. The DERR states that the Site was never “archived” and could be reopened in the future by the EPA if a change of land use occurs that threatens human health and the environment. Tetra Tech performed a Phase II ESA and completed a Phase II ESA Report dated October 27, 2023 on behalf of CTP DEV to further evaluate the UST release and South Temple Landfill. Findings from that investigation verified the presence of LNAPL across the western part of the Site, and related petroleum hydrocarbon impacts to soils around former LUSTs and downgradient from the LUSTs and Fueling 7 June 5February 14, 2025 Building. Elevated arsenic in soil and groundwater was also observed at select location that exceeded EPA RSLs for residential and industrial land use. Seven of the 14 soil samples exceeded the EPA Industrial RSL of 3 mg/kg for arsenic; and all values (even non-detect samples with detection levels limited to 2.12 mg/kg or higher), exceeded the EPA Residential RSL of 0.68 mg/kg. However, the naturally occurring, background concentration for arsenic in Utah soils has been observed to exceed the RSLs and can range from 15 mg/kg and higher depending on location . The DERR has established an action/cleanup level of 14 mg/kg for arsenic at the nearby Power District Voluntary Cleanup Program (VCP) Site (also situated on the historical South Temple Landfill), with values below this level being considered background concentrations.Therefore, tThe concentrations of arsenic observed presence of arsenic at the Site is considered naturally occurring at the concentrations identified during the Phase II ESA were all below 14 mg/kg, and are therefore considered naturally occurring. In 2024, on behalf of CTP DEV, Tech Tech began operation and maintenance of the remediation system. As part of the weekly operations, a few select wells were gauged for depth-to-water and depth-to-product. Wells that showed significant product thickness were bailed to remove the diesel. Quarterly depth-to- water and depth-to-product measurements were made on a larger set of wells, continuing with the same wells that Atlas was previously gauging for NWIC. Quarterly events were performed in March, July, and September 2024; and an annual groundwater sampling event was performed at the end of October, and the beginning of November 2024, which included additional depth-to-water and depth-to-product measurements. Results from the gauging of the wells and analytical results from the sampling are discussed in the next section of this report The Xitech free-product recovery system failed in March 2024, presumably from a voltage surge, and was taken out of service at that time. The perimeter groundwater recovery system continued to operate until early October 2024 when the power to the property was terminated by Rocky Mountain Power in anticipation of building demolition at the Site. The total product recovered by the system was estimated to be approximately 20,700 gallons. Following system termination, the groundwater recovery sump in the remediation building was grouted to the top of the water column in preparation for Site demolition and the corrective actions described in this CAP. 2.3 GROUNDWATER MONITORING 2024 Water levels and LNAPL, if present, were measured at all existing on-site and off-site monitoring wells accessible and in good repair that are associated with the Site. Fifty-three wells were gauged in March, June, and September 2024. Fewer wells were gauged in October 2024, because some wells were not accessible due to a homeless population trespassing on the Site. Depth-to-water and depth-to-product measurements were performed using an electronic oil-water interface probe accurate to 0.01 feet. Tables 1, 2, 3, and 4 provide depth to water and depth to product measurements for March, June, September, and October 2024. Figures 4, 5, 6, and 7 show groundwater contour elevations for each monitoring event. Groundwater elevations were corrected for wells with measurable product thicknesses. Figures 8, 9, and 10 show LNAPL thicknesses in March, June, and September 2024 across the Site. No LNAPL thickness map was prepared for October because of the accessibility issue described above and the absence of data especially from within the Fueling Building where the homeless populations was encamped. In general groundwater flow is to the northwest, consistent with previous years. Hydraulic gradients were estimated between monitoring wells W-4 and W-21 for each event. The hydraulic gradient showed little change between events with a gradient of 0.011 measured in March and 0.012 measured in June, September, and October 2024. 8 June 5February 14, 2025 The LNAPL thickness measurements show the LNAPL plume to be thickest within the footprint of the former Fueling Building and then tapering toward the northwest corner of the property. Perimeter wells W- 20, W-21, W-9, and RW-A showed LNAPL was present during each monitoring event. However, LNAPL was not observed in any of the off-site wells. 2.3.1 Groundwater Sampling Tetra Tech performed groundwater sampling on October 28, 31, and November 1, 2024. Water levels and LNAPL, if present, were measured at all existing on-Site and off-Site prior to any purging and sampling as previously discussed. Monitoring wells sampled were HD-6, HD-4, HD-1, W-19, W-M, RW-4, MW-7, W-11, W-3, W-F, MW-H, W-25, W-27A, HI-SW, W-22, W-23, W-24, and MW-3. Wells were not sampled if LNAPL and/or a heavy sheen were identified in the well during the well gauging or purging efforts, and the presence of these conditions was recorded and reported with the sample results. Samples were collected using disposable polyethylene bailers. Chemical-resistant gloves were worn by field staff during sample collection and replaced between sample locations to minimize potential cross- contamination. Wells were purged a minimum of three well casing volumes before sample collection. Purge water from the wells was thin spread on the asphalt away from property lines or storm grate intakes. The following decontamination procedures were used for non-disposable groundwater sampling equipment.  Rinse with distilled water  Wash and scrub with environmental detergent and distilled water  Rinse with distilled water  Wipe and air dry. Reasonable efforts were made to use disposable or dedicated field equipment. All reusable sampling equipment (e.g., interface probe and water level indicator) were decontaminated as described above prior to beginning field sampling, between sampling locations, and at the completion of field activities. The person collecting the samples was responsible for sample custody from the time of sample collection to receipt by a laboratory or until samples were shipped. A sample is considered under custody if one of the following conditions applies:  The sample is in a person’s possession  The sample is in that person’s view after being in his or her possession  The sample was in that person’s possession and then placed in a secured location  The sample is in a designated secure area. A Chain-of-Custody Record with its assigned sample numbers accompanied all samples to the laboratory. When samples were shipped, custody seals were attached to each cooler to ensure that tampering with the samples did not occur in transit, and the shipment air bill became part of the Chain-of-Custody documentation. 2.3.2 Summary of Groundwater Analytical Results The groundwater sample results for which constituents were detected in one or more samples are presented on Table 5. The results are compared against the following screening criteria:  Initial Screening Levels developed by DERR as conservative, preliminary evaluation criteria for petroleum hydrocarbon constituents associated with LUST sites. 9 June 5February 14, 2025  Tier 1 Screening Criteria developed by DERR, which are less conservative than ISLs and can be applied to LUST sites for evaluation and cleanup under the specific geographical criteria specified by DERR and presented in Section 2.1. All groundwater sample results were below the applicable screening criteria listed above and shown on Table 5 except for total petroleum hydrocarbons (TPH) as diesel (DRO). Samples from on-site wells MW- H (24.8 mg/L) and HD-4 (10.4 mg/L) exhibited concentrations of TPH-DRO exceeding the groundwater Tier 1 level of 10 mg/L. Other wells sampled on-site were above the ISL of 1 mg/L for TPH DRO except for HD-1 which was below. Off-site wells W-25 and W-27A, located across Redwood Road, and W-24, located north of South Temple Street were below the ISL. Wells HI-SW, W-22, and W-23, located on the north side of South Temple Street, north of the northwest property corner were above the ISL but below the Tier 1 level. Figure 11 shows the TPH DRO values for the sampled wells. 2.4 UST CLOSURE On January 4, 2024, the Larry H. Miller (LHM) group purchased the former ABF Freight property from NWIC with the intent to re-develop it as a new commercial property within The Power District. As part of the redevelopment, all buildings that were on the property have been razed. USTs 4, 5, 6, and 7 were removed on October 8, 2024. Based on the results of the closure samples, visible evidence of soil staining in the UST excavation, and the presence of diesel LNAPL on the water surface, there was a release from the UST system consisting of these tanks. Confirmation soil and groundwater sample analytical results confirm that significant impacts to both soil and groundwater exist near these former tanks. Tables 6 and 7, respectively, summarize the soil and groundwater results for the samples collected following the UST removals. Appendix B presents select photographs taken during the UST removal showing impacts to soil and groundwater and staining on the tanks. Appendix C presents the analytical report for the UST closure samples. Based on these results and submittal of the UST Closure Report to the DERR by Spackman Enterprises, which performed the UST removal work, DERR issued the letter for Release OLX dated November 18, 2024, as described previously in Section 1.1. 10 June 5February 14, 2025 3.0 CORRECTIVE ACTION COMPARISON AND SELECTION As discussed during the CAP Meeting on December 4, 2024, with attendance from CTP DEV, Tetra Tech, and DERR, CTP DEV plans to perform the additional corrective action described in this CAP after consideration of a range of alternatives, prior Site remediation experience, and improved access to the subsurface resulting from CTP DEV’s planned Power District development. The planned approach consists of additional source removal through soil excavation and LNAPL recovery, which is the most aggressive remedial alternative considered. Recommendation of this remedy was based on Tetra Tech’s evaluation of three potential corrective actions as described in this section. CTP DEV has proceeded to prepare this CAP, corrective action design drawings, and supplemental materials per DERR’s requirements as described in the remaining sections of this CAP. 3.1 MONITORED NATURAL ATTENUATION Monitored natural attenuation (MNA) was evaluated and determined to be insufficient to achieve regulatory requirements and CTP DEV’s Site redevelopment objectives within a reasonable time. The release size estimated by F&B in 1988 was between 97,000 to 214,000 gallons, and only 20,700 gallons of free product are estimated to have been recovered to date through the existing recovery systems (not accounting for product removed through soil excavations). Tetra Tech believes that too much free product and absorbed product in soil near the fluctuating water table exists for meaningful degradation and MNA to be effective or efficient for this Site. It is expected that following more aggressive mass removal as the selected corrective action that MNA will occur in the groundwater to achieve regulatory requirements for Site closure. 3.2 OPERATION OF PUMPING SYSTEMS Continuing operation of the existing product and groundwater recovery systems, and augmentation with additional pumping systems, were considered and determined to be ineffective to achieve regulatory requirements and CTP DEV’s Site redevelopment objectives. The existing remediation system was designed by Montgomery Watson with DERR approval on April 28, 2000. The system was designed to recover LNAPL at the northwest corner of the property for the specific purpose of preventing LNAPL from migrating off Site; and the system has fulfilled this objective effectively. However, the system was not designed to remediate impacted soils or recover free product within the interior of the plume. The addition of more pumping wells, trenches and sumps would reduce the time requirement for product recovery, but this approach will not address the presence of hydrocarbon-stained soil at the water table (i.e., smear zone), which will continue to impact shallow groundwater for a long time. Therefore, continued operation and build-up of the pumping system will not satisfy the corrective action objectives nor meet CTP DEV’s Site redevelopment objectives. 3.3 SOIL EXCAVATION AND PRODUCT RECOVERY Because CTP DEV has purchased the property and intends to redevelop it for mixed commercial and residential use, the existing structures will be removed providing an opportunity to access and remove impacted soil and LNAPL directly. This corrective action approach could not be performed previously while ABF Freight was operating the Site as a truck terminal, except for small, disconnected areas where excavations and product removal could be performed; these efforts proved effective but with limited overall effectiveness because the entire mobile product plume could not be address. 11 June 5February 14, 2025 After Site demolition, asphalt and concrete will be removed in phases from the excavation area, and clean overburden soil will be removed and staged away from the excavation area. Because the excavation area is so large, the excavation will be performed in segments (or “cuts”) as further discussed in Section 4. Impacted soil will be excavated and properly disposed of at a pre-approved landfill like prior soils selectively excavated and removed from the Site. During the excavation and following soil removal, LNAPL will be skimmed from the water surface, collected in a vacuum tanker truck, and hauled off Site for separation, treatment, and disposal. Figure 10 shows the estimated extent of the LNAPL plume based on product thickness measurements taken on September 26, 2024. The area to be excavated will generally cover the plume extent with possible limitations on the north and west sides of the plume where the actual extents of LNAPL migration are expected to coincide with the existing recovery trench. Section 4 and the corrective action drawings referenced therein provide additional details regarding this selected corrective action. 12 June 5February 14, 2025 4.0 CORRECTIVE ACTION DESIGN AND CONSTRUCTION DETAILS The selected remedy to effectively address both Releases FFQ and OLXthe release conditions is soil excavation and LNAPL recovery. This corrective action will build upon the previous soil and free product removals at the Site and consist of sequential excavation of areas containing impacted soil and LNAPL. The following corrective action Design Drawings, included with this CAP, present details of the project boundaries, existing monitoring wells, excavation limits, corrective action process, LNAPL recovery, and partial backfilling of the excavation for support the work:  Drawing G-001 Cover Sheet  Drawing C-100 Existing Conditions Plan  Drawing C-101 Corrective Action Design Plan  Drawing C-102 Excavation and Backfill Plan  Drawing C-103 Excavation and Backfill Sections  Drawing C-104 Details 4.1 SCOPE OF CORRECTIVE ACTION The primary activities and objectives for this corrective action are listed below, and the paragraphs that follow elaborate on these activities. CTP DEV will retain a remediation contractor with DERR UST Closure Certification (Contractor) to perform most of the work (including all work associated with managing petroleum impacted soils). Tetra Tech will provide field oversight and direction as the Engineer representing CTP DEV through completion of the work and UST closure reporting.  Conduct a Job Hazard analysis and develop a project-specific Health and Safety Plan.  Mobilize and prepare for Site work, including establishment of stormwater pollution prevention measures, excavation areas, haul routes, staging areas, and equipment and worker parking areas.  Excavate approximately 38,300 cubic yards (cy) of soil to remove clean overburden soil and expose the LNAPL layer and smear zone containing residual diesel fuel and other petroleum constituents for removal and off-site disposal, as described in subsequent bullets.  Segregate relatively clean (i.e., petroleum-free) overburden soil and backfill placed in prior excavations for on-site staging and future use as backfill soil.  Load, haul, and transport petroleum-impacted soil for disposal at the Salt Lake Valley Landfill in accordance with landfill requirements for acceptance of petroleum impacted soil.  Place approximately 11,200 cy of clean aggregate (or crushed concrete) to subdivide the excavation cuts for subsequent LNAPL removal and groundwater treatment with the aggregate berms providing vehicle access into the excavation.  Remove LNAPL from the groundwater surface using sorbent booms,a vacuum truck, and high- pressure water equipment and/or other methods to extract free product (plus limited groundwater) for off-site separation, treatment, and disposal.  Enhance groundwater treatment within the open excavation if required to achieve applicable cleanup criteria (e.g., air sparging and/or chemical treatment).  Monitor groundwater within the open excavation and retained monitoring wells to demonstrate achievement of applicable cleanup criteria. 13 June 5February 14, 2025  Backfill the excavation upon achievement of the cleanup standards or as required to support CTP DEV development of the property while continuing to monitor groundwater following completion of the corrective actions described herein. Backfilling will occur only after soil confirmation sampling is completed and data has been evaluated for site-specific needs. 4.2 CORRECTIVE ACTION DESCRIPTION Existing Site conditions are shown on Drawing C-100, including the locations of historical ABF Freight operations as they existed prior to recent building demolitions performed from December 2024 to January 2025. This drawing shows property boundaries, approximate elevation contours, the estimated LNAPL plume boundary, and the perimeter LNAPL recovery trench location in the northwest corner. The notes on this drawing present the requirements for Contractor site preparation activities and field engineering to be provided by the Engineer. Drawing C-101 shows the general Corrective Action Design Plan, including the estimated extents of the excavations, which encompass the LNAPL Plume but have been squared to facilitate phased, sequential excavation of the impacted soils. This plan shows the estimated division of the corrective action work relating to the larger, non-PSTF, Release FFQ on the north side of the Site and the smaller, PSTF, Release OLX on the south side of the Site. The approximate proportion for these areas is two-thirds for the non-PSTF area and one-third for the PSTF area, which will be validated through the forthcoming site investigation described in Section 1.1 and upon agreement with the DERR. This plan presents the project area boundaries, Site ingress and egress, general excavation directions, soil erosion and sedimentation controls (SESCs), and the planned clean overburden stockpile area. Details for the excavation and backfilling process are presented on Drawing C-102, which shows the sequential order recommended for Contractor cuts beginning in the northwest corner of the property at “Cut 1” and sequentially excavating Cuts 1 through 18, until the excavation is complete, and all petroleum-impacted soil has been removed. Coarse aggregate backfill consisting of imported rock or crushed concrete (if available) will be used to systematically stabilize the excavation cuts and develop through roads for access to the water table for LNAPL removal, water treatment, and monitoring. Drawing C-103 shows the cross-sections referenced on Drawing C-102, which complement the plan drawing showing the design depths of excavations and lines and grades for placement of the aggregate backfill. The notes on Drawings C-102 and C-103 present details on the excavation sequencing, aggregate backfill, berm construction, and LNAPL removal. The configuration of the cuts and aggregate berms may vary from those shown on the drawings based on discussions with the selected Contractor and value engineering; however the general approach and sequence for excavation will remain as shown on the drawings. The excavation limits to the west and north near the northwest corner of the property are the LNAPL recovery trench or property lines, depending on the extent of visible petroleum staining in the soil. Excavation boundaries to the south and east will be determined in the field based on visual observations, field screening with a photoionization detector (PID), and soil analytical testing for excavation side-wall samples as described in Section 4.1. The actual excavations boundaries may be shorted in areas such as planned Cut 12, if visible petroleum staining or LNAPL are not observed west all the way to the property boundary. It is noted that RMP has a new laydown yard on part of the former ABF Freight property that forms a boundary to the east of the proposed corrective action work area. Based on available data, the excavation is anticipated to be terminated west of the RMP laydown area. The total excavation depth will terminate at approximately 11-12 feet bgs, based on field observations and direction from the Engineer. Previous excavations performed by Atlas revealed that the bulk of diesel residuals terminates at 11 feet and deeper excavation depths encountered loose clean sands that resulted in rapid water influx and unstable excavation conditions. The Design Drawings conservatively 14 June 5February 14, 2025 show a maximum excavation depth of 12 feet, but actual excavations will be limited to the depth required to remove petroleum impacted soil. Depending on the actual extent of LNAPL and diesel-impacted soil, additional excavation may be required at a future time north of the planned excavation extent beneath South Temple Street; however, this is not currently anticipated and confirmation soil sampling and analysis as described in Section 4.1 will be used to verify the completion of lateral excavations in all direction around the LNAPL plume. Excavated soils will be segregated into clean overburden soil for temporary stockpiling on Site and reuse as excavation backfill upon completion of remediation. The DERR has directed, and CTP DEV agrees that no soil exceeding ISLs or other regulatory limits for other chemicals of concern may be used as backfill at the Site. Soil containing trash characteristic of municipal solid waste will not be used as backfill; however, generally inert materials such as construction and demolition debris previously placed as fill material (e.g., concrete, brick, wood, limited metals, etc.) mixed with soil may be reused as backfill provided it meets the criteria above in terms of ISLs and other regulatory limits as applicable. The use of inert waste used as road building material and fill material are excluded from the C&D landfill requirements (R315-305-1(c)(2) and includes the existing site fill unless it exhibits the chemical characteristics described above. Petroleum impacted soil will be loaded directly into trucks for transportation and disposal at an appropriate landfill facility as directed by the Engineer based on existing analytical results. All analytical results collected to date indicate that the LNAPL and soils are nonhazardous, petroleum-impacted (primarily diesel fuel), solid waste. Historical disposition of excavated soils by NWIC and its contractor Atlas has been through the E.T. Technologies Soil Regeneration Site (ETT) and the Salt Lake Valley (SLV) Landfill, which currently have adjacent operations and cooperate in managing petroleum impacted soils. The ETT and SLV Landfill are the current designated location(s) for disposal of the petroleum impacted soils, and the Engineer will coordinate with the operators at these facilities to direct the impacted soils to the correct facility for treatment (i.e., ETT) and disposal (SLV Landfill), as appropriate based on their requirements for petroleum impacted soil. The report to be submitted following the site investigation for Release OLX will include supplemental results documenting the absence of hazardous substances in samples collected during December 2024. However, Bbecause the Site was historically part of the historical South Temple Landfill, the DERR has directed CTP DEV to maintain an inspection and waste management plan as part of this CAP for management of potential non-petroleum wastes if they are excavated during the work. Section 7 of this CAP presents this contingency plan for unidentified waste and Drawing C-104 includes notes to the Contractor for unidentified waste management procedures, as directed by the DERR. After the aggregate berms for a few cuts have been established (e.g., Cuts 1, 2 and 3), the Engineer will direct Sump and Trap LLC (STC) of Salt Lake City to mobilize appropriate equipment to the Site to remove the LNAPL from the groundwater surface. The Contractor will facilitate access to the individual cut sections where STC will provide a 5,000-gallon or smaller vacuum tanker truck to remove LNAPL. STC will use a pressure washer to force LNAPL into the corners of each cut where it can use a vacuum to recover the petroleum free product. Periodic visits by STC will be performed and access berms must be constructed between the cuts as shown on Drawing C-102 and excavation cross-sections (Drawing C- 103) to provide ingress and egress into the excavations. STC will remove the LNAPL while making efforts to minimize the amount of groundwater pumped by the vacuum trucks. The recovered liquids will be transported to STC’s Woods Cross, Utah operation for separation, recovery of the product for beneficial reuse, and permitted discharge/disposal of the removed water. Upon completion of the soil excavation and off-site disposal, and the LNAPL removal, CTP DEV and the Engineer will assess the residual presence of petroleum hydrocarbon constituents in the shallow groundwater exposed within the open water ponds. Assessment of the on-site groundwater will be 15 June 5February 14, 2025 performed as described in Section 8, Groundwater Monitoring Program. It is anticipated that upon removal of the petroleum sources in the soil and LNAPL that dissolved constituent concentrations in the groundwater will also dissipate over time. The open excavations with ponded water will be secured by the existing perimeter fence to prevent potential human exposures, and if necessary, deterrents such as sound devices or predator decoys will be placed around the ponds to deter birds from inhabiting them. The ponds will remain open as long as Site development allows to facilitate natural aerobic biodegradation of dissolved petroleum constituents. CTP DEV will also consider the application of air injection or chemical additives to the pond water surfaces to enhance the biodegradation, depending on the results of groundwater monitoring. Through implementation of this corrective action, secondary source materials consisting of LNAPL, and petroleum impacted soils with the highest concentrations of petroleum hydrocarbons will be removed. These actions will protect human health and the environment, minimize potential future degradation of groundwater, and reduce potential future worker exposures to achieve the risk-based requirements for construction workers and future land users, and thus achieve the DERR requirements for LUST closure. 4.3 SOIL CONFIRMATION SAMPLING The Engineer will collect confirmation soil samples from the excavation floor and around the excavation perimeter sidewalls. It is proposed that samples be collected from the sidewalls at a depth within the vadose zone or approximately 1 foot above the current depth to groundwater (i.e., approximately 6-7 feet bgs). Samples will be collected every 200 linear feet to document residual petroleum concentrations that remain following soil excavation. No samples from the eExcavation floor samples will be collected approximately every 100 linear feet using an off-set square pattern to document residual TPH-DRO concentrations (if any) that remain following soil excavation. The floor samples will be collected using the excavator bucket because these materials will be recovered from below the groundwater surfaceare planned at this because the excavation floor will be at a depth of approximately 11-12 feet bgs, and previous excavations found that impacts did not extend below this depth and further assessment of residual impacts with depth will come from groundwater analysis. Efforts will be made to collect these samples so that they are not compromised by residual constituents in the groundwater. Sidewall samples will be collected every 100 linear feet to document residual petroleum concentrations that remain following soil excavation at a depth within the vadose zone or approximately 1 foot above the current depth to groundwater (i.e., approximately 6-7 feet bgs). The 100-foot spacing for side-wall samples is recommended instead of 50-foot spacings because of the large scale of this excavation site compared to typical LUST sites. The Engineer will collect samples from areas of visible sidewall staining and/or elevated PID readings for analysis of potential high- concentration soils. The number of soil confirmation samples to be collected, based on the spacing described above, is estimated to be about 10 excavation floor samples and 12 sidewall samples. The side-wallconfirmation soil samples will be field screened for visual petroleum staining and for volatile organic compounds (VOCs) using a photoionization detector (PID) to document the field conditions of the samples. Samples will be collected in laboratory-supplied containers and analyzed by a Utah Certified Laboratory for benzene, ethylbenzene, toluene, total xylenes, naphthalene (BTEXN) by EPA Method 8260 and TPH-DRO by EPA Method 8015. All field documentation, use of the PID, equipment decontamination, and soil and groundwater sampling shall follow the Tetra Tech Standard Operating Procedures presented in Appendix F. 16 June 5February 14, 2025 5.0 PERMITTING REQUIREMENTS Implementation of this CAP will require correspondence and potential permitting through the following agencies. This list is not all-inclusive, and all applicable local, state, or federal rules, codes, or laws will be followed by CTP DEV, the Engineer, and the Contractor. Documentation of notifications, permits, or approvals obtained from other agencies will be submitted to the DERR project manager. 5.1 DIVISION OF AIR QUALITY As per UAC R307-309, any source 1/4 acre or greater in size is required to submit a Fugitive Dust Control Plan (FDCP) to the Utah Division of Air Quality (UDAQ). The FDCP is required to help sources minimize the amount of fugitive dust generated during excavation and trucking operations that will occur during remedial activities. A FDCP will be prepared by the Contractor (with input by the Engineer) in accordance with state regulations for delivery to the UDAQ and receipt of Fugitive Dust Permit from the UDAQ. Because petroleum vapors may be emitted into the atmosphere during the corrective action process, the UDAQ will be notified and provided the required information to determine if the work can be done under de minimis conditions, or if an air discharge permit or approval letter will be required. Because the petroleum at the Site is primarily diesel fuel and not gasoline and the duration of the work is expected to be limited to two toapproximately three months, the potential for vapors is low and an air discharge permit is not expected to be required by the Engineer ; however, an evaluation will be completed and a VOC emissions permit received from the UDAQ if applicable. 5.2 DIVISION OF WATER QUALITY There are groundwater, surface water, or re-injection requirements for this project. If conditions change and discharge to surface water becomes a requirement, proper permits will be obtained from the Division of Water Quality before such actions. 5.3 DIVISION OF WASTE MANAGEMENT AND RADIATION CONTROL Past use of the Site as a historical landfill presents the possibility of encountering soil and/or waste that contains constituents other than petroleum. If this occurs, the procedures presented in Section 7, Non- Petroleum Waste Management Plan, will be implemented and the DERR will be informed. It is expected that DERR and CTP DEV will coordinate efforts with the Division of Waste Management and Radiation Control if hazardous materials are encountered to ensure compliance with sample collection, permitting, transportation, and disposal of such materials. 5.4 SALT LAKE COUNTY HEALTH DEPARTMENT The Salt Lake County Health Department will be notified at least 72 hours before the commencement of Field work related to the corrective action. 5.5 BLUE STAKES Blue Stakes of Utah will be notified before the commencement of excavation activities related to the corrective action for utility clearances. 17 June 5February 14, 2025 6.0 PUBLIC NOTIFICATION Prior to implementing the corrective action, the potentially affected public will be notified of the corrective action plans and timing in accordance with UAC R315-124. Public notification is required to reach the segment of the public that may be directly affected by the release or the corrective action process. Public notice will be conducted by direct notification to adjoining property owners that could be affected. If significant concerns are raised by affected individuals and/or businesses, a public meeting may be necessary and will be coordinated with the DERR. A copy of the proposed public notice is included in Appendix G. The public notice includes all requirements outlined in the Public Notice Template published by DERR in the DERR Corrective Action Plan Guide 18 June 5February 14, 2025 7.0 NON-PETROLEUM WASTE MANAGEMENT PLAN The past use of the Site as a historical landfill presents the possibility for soil and/or waste to contain contaminants other than petroleum that may require characterization and special handling procedures for proper disposal. This waste management plan establishes the procedures for characterization, on-site handling and staging, and disposal to mitigate possible environmental hazards to human health and the environment if conditions other than petroleum hydrocarbons are encountered during implementation of the planned correction actions. 7.1 ASBESTOS CONTAINING MATERIALS Given the historic use of the area for solid waste disposal, asbestos-containing materials (ACM) and/or Transite® siding/piping may be encountered at this Site. If encountered, aA Utah Certified Asbestos Inspector will be availableinspect the materials during excavation activities to identify if these materialsACM is present and to collect bulk samples of all suspect ACM encountered. All samples will be submitted to an approved laboratory for determination of the asbestos content. Excavation activities will temporarily cease in areas that encounter possible ACM until sample results determine if ACM is present or not present. Excavation work will be adjusted to work in other areas until the assessment work is completed. Any suspected ACM will be segregated, sampled, and managed in accordance with Utah Division of Air Quality Asbestos Program rules. When If ACM is confirmed to be present, a Utah-certified asbestos contractor will be contacted to submit an emergency notification to UDAQ for proper removal of the ACM. The ACM will be properly containerized into poly bags and/or placed into 55-gallon, open-top drums for transport and disposal at the Mountain View Landfill, located at 6976 West California Avenue in Salt Lake City, Utah, or another facility permitted to receive ACM waste. After removal of the ACM waste, the Engineer will perform a visual clearance inspection to verify that the ACM waste has been removed prior to resuming soil removal operations at that location. All work will be completed in accordance with local, state, and federal regulations. 7.2 OTHER SUSPECT WASTES During excavation activities, excavated soil will be field screened for impacts to soil and or other suspect waste not related to the petroleum impacts that may require special management and disposal. The field screening may be performed by the Engineer and/or Contractor, who are both qualified environmental professionals to screen for such conditions. Field screening will be by visual identification (e.g., different colored materials), olfactory observations (smells), and/or use of a photoionization detector (PID) to identify suspect VOC wastes, or other environmental impacts (e.g., excessive solid waste not suitable for use as backfill). The DERR has specifically noted that cyanide and mercury have been identified as chemicals of concern at the former South Temple Landfill, with potential concentrations of cyanide at levels considered dangerous to worker health. Cyanide is identifiable by blue/green stained soil and shall be managed as described herein. Once impacted soil or waste is observed, excavation activities will be terminated in that location for sample collection and analysis to identify a suitable waste management strategy. Excavation work will be adjusted to work in other areas until the assessment work is completed. Additional waste streams discovered unrelated to the petroleum impacts will be coordinated with DERR through verbal and written notification by CTP DEV or its representative to assure agency engagement in managing the waste using best practices. 19 June 5February 14, 2025 7.3 SAMPLE WASTE ANALYSES All samples collected for waste characterization will be placed in laboratory-supplied containers, properly labeled, placed on ice in laboratory-supplied coolers and transported under chain of custody protocol to a Utah-certified laboratory (e.g., ChemTech Ford). Laboratory analysis for unknown contaminants shall include Recourse Conservation and Recovery Act (RCRA) metals by EPA Method 6010, VOCs by EPA Method 8260, polychlorinated biphenyls (PCBs) by EPA Method 8082, and semi-volatile organic compounds (SVOCs) by EPA Method 8270. 7.4 ON-SITE MATERIALS MANAGEMENT During excavation activities, if material is encountered that requires on-site storage pending laboratory analysis, the material shall be managed as follows:  Material shall be placed on-site in stockpiles not to exceed 100 cubic yards in an area that is away from clean overburden stockpiles or soil impacted with diesel awaiting transportation.  The material shall be stockpiled on areas covered with asphalt or 6-mil polyethylene sheeting over soil. If material storage will be on the ground, soil samples will be collected from the soil beneath the stockpile to confirm all suspected contaminants have been removed following material stockpile removal.  Containment berms around stockpiles shall be constructed to prevent runoff onto surrounding soils and/or stormwater collection grates.  Stockpiled material will be covered with 6-mil polyethylene sheeting or tarps as appropriate based on the size and layout of the stockpiles. 7.5 MATERIALS TRANSPORTATION All trucks transporting the materials will be covered/tarped prior to leaving the Site. The trucks will also be cleaned of debris prior to exiting the Site to prevent track-out of potentially contaminated materials. All trucks will have completed bills of lading and/or waste manifests prior to leaving the Site. Weigh tickets and other documents (profiles/manifests) will be included in the Corrective Action Completion Report to document proper management of the waste. 20 June 5February 14, 2025 8.0 GROUNDWATER MONITORING PROGRAM Closure of the two LUST releases will require achievement of the site-specific cleanup standards described in Section 2.1 (i.e., ISLs or other applicable standards agreed by DERR). The soil and LNAPL removal described in this CAP will eliminate the source of impacts observed as dissolved-phase TPH- DRO concentrations in the groundwater, and the groundwater concentrations are expected to attenuate over time. Monitoring of groundwater will be performed following the soil excavation and LNAPL removal, including monitoring of ponded groundwater in the open excavations and groundwater at the periphery of the site using existing groundwater monitoring wells. The program for assessing groundwater in the open- water ponds and in monitoring wells is described in this section. 8.1 PONDED GROUNDWATER ASSESSMENT The open excavations with ponded water will be sampled periodically, starting with bi-monthly measurements for an initial 6-month period (i.e., three events); after which, the sampling frequency will be adjusted based on the results of the first three sample events and the need for excavation backfilling based on the land development schedule. Four samples will be collected per event from four differing areas within the excavation limits. Samples will be collected in laboratory-supplied containers and analyzed by a Utah Certified Laboratory for BTEXN by EPA Method 8260 and TPH-DRO by EPA Method 8015. All field documentation, equipment decontamination, and groundwater sampling shall follow the Tetra Tech Standard Operating Procedures presented in Appendix F. The ponds will remain open as long as Site development allows to facilitate natural aerobic biodegradation of dissolved petroleum constituents. The Site will remain secured by the existing perimeter fence to prevent potential human exposures, and if necessary, deterrents such as sound devices or predator decoys will be placed around the ponds to deter birds from inhabiting them while they are open. 8.2 SITE CLOSURE MONITORING Post corrective action, groundwater monitoring will be performed quarterly for the first year following corrective action and then semi-annually (if necessary) until it can be demonstrated that corrective action objectives have been met and constituents of concern (e.g., TPH-DRO) are below the designated cleanup standards described in Section 2.1. CTP DEV proposes groundwater monitoring of the following existing wells, which will be protected during corrective action. On-Site Wells Monitor wells W-9, W-19, W-20, and W-21. See Figure 2 for well locations. Off-Site Wells Monitor wells W-22, W-23, W-24, W-25, W-26, and W-27A. See Figure 2 for well locations. In the event, groundwater samples collected from the open water ponds described in Section 8.1 do not meet the cleanup standards, and CTP DEV needs to close the excavations to support development, four new wells will be installed within the excavation boundaries as replacement wells to allow continued groundwater monitoring. The locations of the wells will be equal distance apart and within the interior of the former diesel plume boundary and be based on the results of the open water sampling. 21 June 5February 14, 2025 Similarly, if existing off-site wells show concentrations above the cleanup standards listed in Section 2.1 of the CAP beginning in the second year of monitoring, then additional off-site wells may be installed to further characterize downgradient conditions. The placement of thelocations for supplemental wells will be coordinated with the DERR to enhance site characterization. The wells will be constructed with 2-inch PVC according to Standard Operating Procedure (SOP) 21 Monitoring Well Construction, provided in Appendix F. The wells will be sampled according to SOP-08 or SOP-8A in Appendix F. Samples will be collected in laboratory-supplied containers and analyzed by a Utah Certified Laboratory for BTEXN by EPA Method 8260 and TPH-DRO by EPA Method 8015. 22 June 5February 14, 2025 9.0 COMPLETION REPORT In accordance with UAC R315-101-6(d), CTP DEV will prepare and submit to DERR for review and approval a Corrective Action Completion Report when corrective action activities are completed. The report will document the following:  Narrative of the work performed, including deviations from this CAP, if any, as approved during the work by the DERR.  As-built drawings to show the final limits of excavation.  Total weight of soil disposed of at the ETT and/or the SLV Landfill (or other destinations if required based on the materials encountered and managed through the waste management plan).  Table summarizing all soil loads removed from the Site. The table will include the date for each load, the manifest number, and the weight on the disposal ticket. Copies of all the manifests will be included as an appendix.  Table summarizing the confirmation soil sample results compared to the ISLs and Tier 1 screening criteria.  Scaled maps showing all environmental sample locations.  Soil boring logs and/or well construction details.  Copies of applicable sample collection data forms and laboratory analytical reports. The Corrective Action Completion Report will provide a final summary of the corrective action process to support LUST closures for Releases FFQ and OLXthe facility. 23 June 5February 14, 2025 10.0 REFERENCES Corrective Action Plan Guide, Petroleum Storage Tank Trust Fund, Leaking Underground Storage Tank Sites. Department of Environmental Quality Division of Environmental Response and Remediation, June 14, 2017. Corrective Action Plan Guide Non-Petroleum Storage Tank Trust Fund Leaking Underground Storage Tank Sites, Utah Department of Environmental Quality Division of Environmental Response and Remediation, Leaking Underground Storage Tank Program, October 1, 2017. Phase I Environmental Site Assessment Report, October 27, 2023, Tetra Tech, Inc. Phase II Environmental Site Assessment Report, October 27, 2023, Tetra Tech, Inc. Soil Excavation Corrective Action Plan (CAP) Update, Atlas, April 12, 2022. Figures Tables Design Drawings Appendix A Correspondence from Utah DERR on LUST Releases OLX and FFQ Appendix B Photographs from UST Removal of Tanks 3, 4, 5, and 6 Appendix C UST Closure Analytical Report Appendix D October 2024 Groundwater Laboratory Analytical Report Appendix E Freidman and Bruya, Inc., Letter report issued to National Warehouse Investment Company, March 30, 2000 Appendix F Tetra Tech Standard Operating Procedures Appendix G Public Notice Template 3475 East Foothill Boulevard, Pasadena, CA 91107 USA p. +1 (626) 351-4664 f. +1 (626) 351-5291 info@tetratech.com Tetra Tech is Leading with Science® to provide innovative, sustainable solutions that help our clients address their water, environment, infrastructure, resource management, energy, and international development challenges. We are proud to be home to leading technical experts in every sector and to use that expertise throughout the project life cycle. Our commitment to safety is ingrained in our culture and at the forefront of every project. We combine the resources of a global, multibillion dollar company with local, client-focused delivery. tetratech.com