2-Exhibit A Bonanza Phase II.pdf

Facilities | Environmental | Geotechnical | Materials

Cover Page

Phase II Environmental Site Assessment Bonanza Park 1665 Bonanza Drive Park City, Summit County, Utah EPA Cooperative Agreement #95815230 ACRES IDs# 259685, 259686, 259688, 259689, 259690, 259691, 259692, 259693, 259694

April 23, 2024 | Terracon Project No. 61237186 Task 4.11

Prepared for:

Utah Department of Environmental Quality/ Division Of Environmental Response and Remediation Salt Lake City, Utah

6952 South High Tech Drive Ste B Midvale, Utah 84047

P (801) 545-8500 Terracon.com

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Cover Lette r

April 23, 2024

Department of Environmental Quality Division of Environmental Response and Remediation P.O. Box 144840 Salt Lake City, Utah 84114-4840

Attn: Joseph Katz P: (801) 536-4100 E: jkatz@utah.gov

Re: Phase II Environmental Site Assessment Bonanza Park 1665 Bonanza Drive,Park City, Summit County, Utah Terracon Project No. 61237186 Task 4.11 EPA Cooperative Agreement #95815230 EPA ACRES Property IDs# 259685, 259686, 259688, 259689, 259690, 259691, 259692, 259693, 259694 Utah Department of Environmental Quality/Division of Environmental Response and Remediation Community-Wide Assessment Grant For States and Tribes

Dear Mr. Katz:

Terracon Consultants, Inc. (Terracon) is pleased to submit this Phase II Environmental Site Assessment which details the site investigation activities completed at the above-referenced site. The report presents data from field activities that included the collection of soil and groundwater samples. This investigation was conducted under EPA Cooperative Agreement #95815230 dated August 19, 2022 and guided by a Sampling and Analysis Plan reviewed and approved by EPA. Quality of data was guided by the EPA-approved Community-Wide Quality Assurance Project Plan (QAPP) dated July 21, 2023.

We appreciate the opportunity to be of service to you on this project. Should you have any questions or require additional information, please do not hesitate to contact our office.

Sincerely, Terracon Consultants, Inc.

Andy King Daniel Dean Senior Project Manager Authorized Project Reviewer Environmental Services mailto:jkatz@utah.gov https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAmrwTANUu4cThnKuig7-PVV9cpuTPmuqm https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAmrwTANUu4cThnKuig7-PVV9cpuTPmuqm

Facilities | Environmental | Geotechnical | Materials ii

Table Of Contents

1.0 Introduction

1.1 Brownfields Setting

1.2 Site Description and Background

1.3 Standard of Care

1.4 Additional Scope Limitations

1.5 Reliance

2.0 Phase II Site Investigation

2.1 Scope

2.2 Sampling Process Design

2.3 Field Data Collection

2.4 Soil Sampling

2.5 Groundwater Sampling

2.6 Field QA/QC Samples

2.7 Equipment Decontamination

2.8 Site Restoration

3.0 Laboratory Analytical Methods

4.0 Summary Of Analytical Results

4.1 Soil Data Summary

4.2 Groundwater Data Summary

5.0 Data Quality Assessment

5.1 Precision

5.2 Bias and Accuracy

5.3 Representativeness

5.4 Comparability

5.5 Completeness

5.6 Sensitivity

6.0 Data Evaluation

6.1 Soil Sample Results

6.2 Groundwater Sample Results

7.0 Conclusion

8.0 References

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Appendices

Appendix A Exhibits

Exhibit 1 Topographic Site Overview

Exhibit 2 Sampling Locations

Exhibit 3 Groundwater Surface Elevation Map

Exhibit 4 Metals Exceedances in Soil

Exhibit 5 Approximate Contaminated Fill Depth

Appendix B Soil Boring Logs

Appendix C Data Summary Tables

Table C1 Metals in Soil

Table C2 VOCs and Petroleum Hydrocarbons in Soil

Table C3 VOCs and Petroleum Hydrocarbons in Groundwater

Table C4.1 Duplicate Pairs–Metals in Soil

Table C4.2 Duplicate Pair–VOCs and Petroleum Hydrocarbons in Soil

Table C4.3 Duplicate Pair–VOCs and Petroleum Hydrocarbons in Groundwater

Appendix D Chain of Custody and Laboratory Data Sheets

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Phase II Environmental Site Assessment

Utah Department of Environmental Quality/Division of Environmental Response and Remediation Community-Wide

Assessment Grant For States and Tribes EPA Cooperative Agreement No. 95815230

Bonanza Park 1665 Bonanza Drive

Park City, Summit County, Utah ACRES IDs# 259685, 259686, 259688, 259689, 259690, 259691, 259692, 259693, 259694

Terracon Project No. 61237186 Task 4.11 April 23, 2024

1.0 Introduction

Terracon Consultants, Inc. (Terracon) has completed a Phase II Environmental Site Assessment (Phase II ESA) at the Bonanza Park Brownfields Assessment Project site located at 1665 Bonanza Drive, Park City, Utah (Exhibit 1). This Phase II ESA was completed with funding from the Utah Department of Environmental Quality/Division of Environmental Response and Remediation Community-Wide Assessment Grant For States and Tribes following the approved Sampling and Analysis Plan (SAP; Terracon 2023a), and Quality Assurance Project Plan (QAPP; Terracon 2023b).

The site is comprised of approximately 5.43 acres of land consisting of the addresses, Summit County Assessor Parcel Numbers (APN), and land uses listed below:

Address APN Acres ACRES

ID

Use

1635 Bonanza Drive PSA-46-A-X 0.43 259685 Vacant, former Maverik Station

1665 Bonanza Drive PSA-46-RE-B-X 1.01 259686 Vacant, former medical clinic

1685 Bonanza Drive PSA-46-RE-C-X 0.42 259688 Vacant, former hardware store and miscellaneous commercial uses

1705 Bonanza Drive PSA-46-RE-D-X 0.37 259689 Vacant, former car wash

Bonanza Park | Park City, Utah

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Address APN Acres ACRES

ID

Use

1401 Kearns Boulevard PCA-110-G-1-X 1.2 259690 Vacant, former church and miscellaneous commercial uses

1409 Kearns Boulevard KBC-A-X 0.59 259691 Vacant, former coffee shop

1415 Kearns Boulevard KBC-B-X 0.54 259692 Vacant

1420 Munchkin Road PCA-110-G-2- A-X

0.32 259693 Vacant

1490 Munchkin Road PCA-110-G-3-X 0.55 259694 Vacant, former automotive repair shop, former Anayas Market

1.1 Brownfields Setting

The Utah Division of Environmental Quality (UDEQ)/Division of Environmental Response and Remediation (DERR) is the recipient of an EPA Brownfields Assessment Grant (Grant) to inventory, characterize, assess, and conduct cleanup planning along with public outreach activities for eligible Brownfield sites within the State of Utah.

Previous environmental investigations at the site had identified the presence of contaminants including metals and petroleum, but the nature and extent of impacts had not been defined. The site was approved for investigation under the Grant via a Site Eligibility Determination Outline dated August 17, 2023. The Phase II ESA was completed following the EPA-approved SAP and QAPP.

1.2 Site Description and Background

Multiple environmental investigations were previously conducted at the site. These investigations included a Phase I Environmental Site Assessment (ESA) and Limited Site Investigation (LSI) conducted at the site by Terracon in September 2017 (Terracon 2017a and 2017b, respectively), and an underground storage tank (UST) closure (Maverik 2020).

Based on the historical review, the site appeared to be vacant until approximately 1967.

One building was developed on present-day 1401 Kearns Blvd by 1976. Three additional buildings were developed on present-day 1420 and 1490 Munchkin Road from 1978–1983.

Four additional buildings were developed on the eastern and northern portion of the site from 1993–2009. Silver King Coffee was present in the northern parking area by 2011. All buildings on the site except for the former Maverik building were demolished between September 2020 and August 2021.

The previous investigations identified the following real or potential presence of a hazardous substance, pollutant, or contaminant:

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Metals-impacted fill soils: The LSI identified non-native fill soils that were impacted by arsenic and lead. LSI soil samples reported arsenic concentrations as high as 145 mg/kg lead concentrations as high as 3,880 mg/kg (sample location TER-8, Exhibit 2).

Petroleum release: A former Maverik gasoline filling station located in the northeastern corner of the site operated from 1986 to 2020 and had four reported releases during that time. The UST closure report (Maverik 2020) did not evaluate groundwater. The Terracon LSI reported diesel-range petroleum hydrocarbons in groundwater exceeding the DERR Initial Screening Level (ISL) and gasoline-range petroleum hydrocarbons in groundwater exceeding the DERR Tier 1 Screening Level (Tier 1) at sample location TER-11 (Exhibit 2).

Historical automobile service and repair on the site: Historical research identified a former automobile service and repair business at the site address 1490 Munchkin Road.

From 1982 to sometime between 1992 and 1994 the northern half of the building was used for this purpose. General automobile service and repairs were conducted, including engine and transmission work. There was reportedly a nearly 40-year-old oil/water separator at the site, but it was located in an area that Terracon could not access during the Phase I ESA or

LSI.

This Phase II ESA was conducted to further assess soil and groundwater impacts at the site.

Sampling of subsurface soil and groundwater was conducted to fully evaluate environmental risks to future users of the site.

1.3 Standard of Care

Terracon’s services were performed in a manner consistent with generally accepted practices of the profession undertaken in similar studies in the same geographical area during the same time. Terracon makes no warranties, either express or implied, regarding the findings, conclusions, or recommendations. Please note that Terracon does not warrant the work of laboratories, regulatory agencies, or other third parties supplying information used in the preparation of the report. These Phase II ESA services were performed in accordance with the scope of work agreed with the UDEQ/DERR, our client, as reflected in our proposal and consistent with ASTM E1903-19, Standard Practice for Environmental Site Assessments: Phase II Environmental Site Assessment.

1.4 Additional Scope Limitations

Findings, conclusions, and recommendations resulting from these services are based upon information derived from the on-site activities and other services performed under this scope of work; such information is subject to change over time. Certain indicators of the presence of hazardous substances, petroleum products, or other constituents may have been latent, inaccessible, unobservable, non-detectable, or not present during these services. We cannot represent that the site contains no hazardous substances, toxic materials, petroleum products, or other latent conditions beyond those identified during this Phase II ESA investigation. Subsurface conditions may vary from those encountered at

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Facilities | Environmental | Geotechnical | Materials 4 specific borings, wells, or during other surveys, tests, assessments, investigations, or exploratory services. The data, interpretations, findings, and our recommendations are based solely upon data obtained at the time and within the scope of these services.

1.5 Reliance

This report has been prepared for the exclusive use of the UDEQ/DERR. Any authorization for use or reliance by any other party (except a governmental entity having jurisdiction over the site) is prohibited without the express written authorization of the UDEQ/DERR and Terracon. Reliance by authorized parties will be subject to the terms, conditions, and limitations stated in the underlying contract between the UDEQ/DERR and Terracon. The limitation of liability defined in the terms and conditions is the aggregate limit of Terracon’s liability to all relying parties unless otherwise agreed in writing.

2.0 Phase II Site Investigation

2.1 Scope

The proposed Phase II ESA scope of work described in the SAP was intended to gather the necessary data to evaluate the environmental impacts and risks to site users from contaminants in soil and groundwater at the site. It is anticipated that the property will be redeveloped for residential and/or commercial use. These activities were conducted in accordance with a site-specific SAP that was approved by EPA and the UDEQ/DERR for this site. The SAP established specific site objectives, sampling process design, and details regarding site-specific sampling and analyses and was used in conjunction with the EPA-approved QAPP.

2.2 Sampling Process Design

The sampling strategy for soil and groundwater was designed to gather the necessary data to evaluate the environmental impacts resulting from metals-impacted fill, petroleum releases, and auto repair operations identified in previous investigations. Exhibit 2 (Appendix A) shows the soil and groundwater sampling locations.

The exact location of each sampling location was dictated by drilling equipment access constraints, utilities and underground features, and safety. Thirteen soil borings were advanced to a depth of 20 feet below ground surface (bgs) to allow subsurface soil sampling, and five borings were advanced to depths of 35-40 feet bgs to allow subsurface soil sampling and intercept the groundwater table for groundwater sampling. A groundwater sample was unable to be collected from one of these deeper borings (B-3) due to boring collapse and refusal. Groundwater samples were collected from four soil borings using temporary monitoring wells.

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The following soil samples were collected from the soil borings:

Petroleum Hydrocarbons: Total Petroleum Hydrocarbons (TPH) Gasoline Range Organics (GRO), TPH Diesel Range Organics (DRO), and Total Recoverable Petroleum Hydrocarbons (TRPH): One sample for petroleum hydrocarbons analysis was collected from borings B-1, B-2, B-3, B-4, and B-5 at the most impacted depth interval (field-identified based on PID readings, staining, visual observations, etc.) or, if impacts were not observed, at the soil/groundwater interface.

Volatile Organic Compounds (VOCs): One sample for VOCs analysis was collected from borings B-1, B-2, B-3, B-4, and B-5 at the most impacted depth interval (field-identified based on PID readings, staining, visual observations, etc.)

or, if impacts were not observed, at the soil/groundwater interface.

Resource Conservation and Recovery Act (RCRA) 8 Metals: Three soil samples for RCRA 8 metals were collected from all 18 borings. RCRA 8 metals samples were collected at the surface (or as close as practicable), at the most impacted depth interval (field-identified based on X-ray Fluorescence [XRF] instrument readings), and from underlying native soils.

The following groundwater samples were collected from borings B-1, B-2, B-4, and B-51:

Petroleum Hydrocarbons (TPH-GRO, TPH-DRO, TRPH): One sample for petroleum hydrocarbons was collected from boring B-1, B-2, B-4, and B-5.

VOCs: One sample for VOCs was collected from boring B-1, B-2, B-4, and B-5.

Tables C1 through C4 (Appendix C) present the results of the soil and groundwater sampling.

Samples were delivered to the analytical laboratory within holding times for all analytical methods to generate definitive analytical data which are critical to this assessment. Table 1

1 A groundwater sample could not be collected from boring B-3 as planned. During the first drilling attempt using direct-push drilling equipment, the boring collapsed during removal of the drill string after collection of a soil sample at 36.5 feet bgs. Field personnel attempted to re-drill the boring twice using auger equipment. During the first attempt with auger equipment the auger flight broke at approximately 15 feet bgs. A second attempt to re-drill the boring with auger equipment was aborted when drilling refusal occurred at approximately 25 feet bgs. No further attempts were made to complete the boring.

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Facilities | Environmental | Geotechnical | Materials 6 below provides a summary description of the sample locations, sample types, sample naming convention, laboratory analyses, and sampling rationale.

Table 1: Summary of Sampling Locations

Sample Location

Rationale Soil Sample Interval

Sample Matrix Analytes

B-1 through B-18

Characterization of metals-impacted fill soils and underlying native soils

Surface, most impacted fill interval, sub-fill native

Soil RCRA 8 Metals

B-1, B-2, B- 3, B-4

Characterization of petroleum release from former Maverik station

Most impacted fill interval, or soil/groundwater interface

Soil

Groundwater (B-1, B-2, B-4 only)

VOCs, TPH-GRO, TPH-DRO, TRPH

B-5

Characterization of potential impacts from former auto repair facility

Most impacted fill interval, or soil/groundwater interface

Soil

Groundwater

VOCs, TPH-GRO, TPH-DRO, TRPH

2.3 Field Data Collection

Following SAP approval, the public utility location service (Blue Stakes of Utah) was notified at least 48 hours prior to commencing drilling activities. A private utility location service was used to locate potential utilities and other subsurface obstacles in the immediate vicinity of each soil boring location.

Terracon conducted the soil and groundwater sampling between January 23 and January 25, 2024. The mechanized drilling services were performed by Utah-licensed well driller Direct Push Services. Terracon environmental personnel directed and supervised the drilling and activities, logged the soil borings, and collected field samples.

During advancement of the soil borings, soils were continuously cored in approximate 5-foot intervals and observed to document subsurface soil types, color, relative moisture content, PID readings, and sensory evidence of environmental impacts.

Detailed lithological descriptions are included on the soil boring logs provided in Appendix B.

Fill thickness varied across the site, ranging from less than 1 to approximately 8.5 feet bgs.

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Underlying native soils generally consisted of gravelly sands and silts with localized zones of clays and gravels at depth. Depth to groundwater, where encountered, ranged from approximately 33 to 35 feet bgs. Groundwater flow direction was determined to be toward the northwest (Exhibit 3), based on relative groundwater elevations measured from temporary piezometers that were installed in borings B-2, B-4, and B-5.

2.4 Soil Sampling

Soil samples were collected from direct-push borings following the procedures detailed in Standard Operating Procedure (SOP) 5, Geoprobe Sampling, provided in Appendix B of the EPA-approved QAPP. During advancement of the borings, soils were logged as detailed in SOP 1, Soil Sampling and Logging, provided in Appendix B of the EPA-approved QAPP.

2.5 Groundwater Sampling

Groundwater samples were collected from four of the borings following the procedures detailed in SOP 5, Geoprobe Sampling, provided in Appendix B of the EPA-approved QAPP.

2.6 Field QA/QC Samples

Field duplicates were collected at a minimum rate of 10 percent with one trip blank (laboratory-supplied blank) per sample shipment with VOCs analyses. Duplicate and trip blank samples included one trip blank, seven duplicate soil samples, and one duplicate groundwater sample.

The original sample and corresponding duplicate samples are detailed below:

Soil Samples

Sample ID Duplicate ID Analytes

B-2 @ 0.5 B-112 @ 0.5 RCRA 8 Metals

B-2 @ 4 B-112 @ 4 RCRA 8 Metals

B-2 @ 6 B-112 @ 6 RCRA 8 Metals

B-4 @ 0.5 B-114 @ 0.5 RCRA 8 Metals

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B-9 @ 4 B-119 @ 4 RCRA 8 Metals

B-10 @ 5.5 B-110 @ 5.5 RCRA 8 Metals

B-2 @ 33.5 B-112 @ 33.5 TPH-GRO, TPH-DRO, TRPH,

VOCs

Groundwater Samples

Sample ID Duplicate ID Analytes

B-4 GW B-114 GW

TPH-GRO, TPH-DRO, TRPH,

VOCs

2.7 Equipment Decontamination

Clean disposable, single-use sampling equipment was used to conduct the soil and groundwater sampling and was properly disposed of after each use. Drilling equipment and any other non-single use equipment items used were cleaned using a high-pressure washer prior to beginning the project and between boring locations.

2.8 Site Restoration

Site restoration was conducted by backfilling the borings with bentonite chips and finishing with concrete, asphalt, or native soil to match the surrounding surface.

3.0 Laboratory Analytical Methods

Soil and groundwater samples (including field duplicates and trip blanks) were placed in iced coolers and shipped under chain-of-custody protocols via overnight courier to Pace Analytical National Center for Testing & Innovation (Pace) in Mt. Juliet, Tennessee (a Utah- Certified Laboratory).

Samples were analyzed using the following methods:

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Table 2: Analytical Method Summary

Parameter Matrix

(Solid/Liquid) Analytical Method

No. of Samples1

RCRA 8 metals Soil SW-846 6010B, 7471 60

VOCs, TPH-GRO Soil SW-846 8260 6

TPH-DRO Soil SW-846 8015 6

VOCs, TPH-GRO Groundwater SW-846 8260B 5

TPH-DRO Groundwater SW-846 3511/8015 5

TRPH Groundwater SW-846 1664A 5

VOCs, TPH-GRO Water (trip blank) SW-846 8260B 1

1Includes field duplicate samples.

4.0 Summary Of Analytical Results

The following sections summarize the analytical results. A summary of the analytical results is provided in Table C1 through C4 (Appendix C). Copies of the analytical reports and sample chain-of-custody records are provided in Appendix D.

Constituent concentrations in soil were compared to the following screening levels:

UDEQ DERR Initial Screening Levels (ISLs) and Tier 1 Screening Levels (Tier 1) for petroleum hydrocarbons in soil

EPA Regional Screening Levels (RSLs) for Residential and Industrial use scenarios

Constituent concentrations in groundwater were compared to the following screening levels:

UDEQ DERR ISLs and Tier 1 criteria for petroleum hydrocarbons in groundwater

EPA Maximum Contaminant Levels (MCLs)

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Utah Ground Water Quality Standards (UGWQS; UAC-R317-6-2.1)

EPA Target Groundwater Concentrations (TGC) Vapor Intrusion Screening Levels (VISLs) for Residential and Commercial use scenarios

4.1 Soil Data Summary

Fifty-four soil samples and six field duplicate samples were analyzed for RCRA 8 metals.

Five soil samples and one field duplicate were analyzed for TPH-GRO, TPH-DRO, TRPH, and VOCs. Soil samples that exceeded one or more applicable screening levels are detailed below.

Metals: Arsenic was reported at concentrations above the Industrial RSL of 3 milligrams per kilogram (mg/kg) in all soil samples that were analyzed for RCRA 8 metals, with the maximum arsenic concentration reported at 528 mg/kg (Table C1). Cadmium concentrations exceeded the Industrial RSL in 14 soil samples. Lead concentrations exceeded the Residential RSL screening guidance of 200 mg/kg in ten samples and the Industrial RSL of 800 mg/kg in 11 samples, with the maximum lead concentration reported at 15,700 mg/kg. Mercury was reported at a concentration above the Residential RSL in one sample and above the Industrial RSL in one sample, with the maximum mercury concentration reported at 286 mg/kg.

Sample Analyte Exceedance

B-1 @ 0.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Industrial RSL

B-1 @ 4

Arsenic Cadmium

Lead Mercury

Industrial RSL Residential RSL Industrial RSL

Residential RSL

B-1 @ 6 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Industrial RSL

B-2 @ 0.5 Arsenic Lead

Industrial RSL Residential RSL

B-2 @ 4 Arsenic Lead

Industrial RSL Residential RSL

B-2 @ 6 Arsenic Industrial RSL

B-3 @ 0.5 Arsenic Industrial RSL

B-3 @ 2.5 Arsenic Lead

Industrial RSL Residential RSL

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B-3 @ 5 Arsenic

Cadmium Industrial RSL

Residential RSL

B-4 @ 0.5 Arsenic Industrial RSL

B-4 @ 2.5 Arsenic Industrial RSL

B-4 @ 4 Arsenic Industrial RSL B-5 @ 0.5 Arsenic Industrial RSL B-5 @ 5 Arsenic Industrial RSL

B-5 @ 8 Arsenic

Cadmium Industrial RSL

Residential RSL B-6 @ 0.5 Arsenic Industrial RSL

B-6 @ 3.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Residential RSL

B-6 @ 5 Arsenic Industrial RSL B-7 @ 0.5 Arsenic Industrial RSL B-7 @ 2 Arsenic Industrial RSL B-7 @ 7 Arsenic Industrial RSL

B-8 @ 0.5 Arsenic Industrial RSL

B-8 @ 2.5 Arsenic Lead

Industrial RSL Residential RSL

B-8 @ 6 Arsenic Industrial RSL B-9 @ 0.5 Arsenic Industrial RSL

B-9 @ 4

Arsenic Cadmium

Lead Mercury

Industrial RSL Residential RSL Industrial RSL Industrial RSL

B-9 @ 5 Arsenic

Cadmium Industrial RSL

Residential RSL

B-10 @ 0.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Residential RSL

B-10 @ 1.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Industrial RSL

B-10 @ 5.5 Arsenic Industrial RSL

B-11 @ 0.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Industrial RSL

B-11 @ 3.5 Arsenic Industrial RSL

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Cadmium Lead

Residential RSL Industrial RSL

B-11 @ 5 Arsenic Industrial RSL B-12 @ 0.5 Arsenic Industrial RSL

B-12 @ 4.5 Arsenic Lead

Industrial RSL Residential RSL

B-12 @ 6 Arsenic Industrial RSL B-13 @ 0.5 Arsenic Industrial RSL

B-13 @ 2 Arsenic Lead

Industrial RSL Industrial RSL

B-13 @ 5 Arsenic Industrial RSL B-14 @ 0.5 Arsenic Industrial RSL

B-14 @ 2 Arsenic Lead

Industrial RSL Residential RSL

B-14 @ 6 Arsenic Industrial RSL B-15 @ 0.5 Arsenic Industrial RSL

B-15 @ 3.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Industrial RSL

B-15 @ 6 Arsenic Industrial RSL

B-16 @ 0.5 Arsenic

Cadmium Lead

Industrial RSL Residential RSL Industrial RSL

B-16 @ 2.5 Arsenic Industrial RSL B-16 @ 4.5 Arsenic Industrial RSL B-17 @ 0.5 Arsenic Industrial RSL

B-17 @ 1.5 Arsenic Lead

Industrial RSL Residential RSL

B-17 @ 9 Arsenic Industrial RSL B-18 @ 0.5 Arsenic Industrial RSL B-18 @ 2.5 Arsenic Industrial RSL B-18 @ 4 Arsenic Industrial RSL

Duplicate Samples

B-112 @ 0.5 Arsenic Industrial RSL

B-112 @ 4 Arsenic Lead

Industrial RSL Residential RSL

B-112 @ 6 Arsenic Industrial RSL B-114 @ 0.5 Arsenic Industrial RSL

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B-119 @ 4

Arsenic Cadmium

Lead Mercury

Industrial RSL Residential RSL Industrial RSL Industrial RSL

B-110 @ 5.5 Arsenic Industrial RSL

Petroleum Hydrocarbons: None of the soil samples exceeded a screening level for petroleum hydrocarbons (Table C2). MDLs were below screening values for all petroleum hydrocarbons.

VOCs: None of the soil samples reported VOC concentrations above MDLs or above a screening level for VOCs (Table C2). MDLs were slightly higher than the Residential RSL for one compound (1,2-dibromo-3-chloropropane) in four of the five soil samples that were analyzed for VOCs.

4.2 Groundwater Data Summary

Four groundwater samples and one field duplicate were analyzed for TPH-GRO, TPH-DRO, TRPH, and VOCs. Groundwater samples that exceeded one or more applicable screening levels are detailed below.

Petroleum Hydrocarbons: None of the groundwater samples exceeded a screening level for petroleum hydrocarbons (Table C3). MDLs were below screening values for all petroleum hydrocarbons.

VOCs: Two VOC compounds exceeded the Residential TGC VISL in the groundwater sample from boring B-5 (Table C3). The reported concentrations exceeded the Residential TGC VISL but were below the MCL.

Sample Analyte Exceedance

B-5 GW

Chloroform

Trichloroethene Residential VISL Residential VISL

5.0 Data Quality Assessment

All laboratory analytical data were subject to internal reduction and validation prior to external release of the data, as detailed in the laboratory’s Quality Assurance Manual.

Following receipt of the laboratory analytical results by Terracon, the data were reviewed to evaluate compliance with Data Quality Indicators (DQIs) outlined in Sections D1, D2, and D3 of the QAPP.

Documentation provided with the laboratory analytical results reports included case narratives; analytical data with minimum method detection limits (MDLs) and reported detection limits (RDLs) reporting limits listed for all analyses; surrogate recoveries for

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GC/MS analyses with laboratory control limits; chain-of-custody records; a quality control summary including method blanks, matrix spike/matrix spike duplicates (MS/MSD) with control limits, laboratory control samples, and duplicates (LCS/LCSD) with control limits;

and application of data qualifiers where warranted.

Assessment of the DQIs for Precision, Bias and Accuracy, Representativeness, Comparability, Completeness, and Sensitivity are presented in the following subsections.

The laboratory results are assumed to be in control and the data is useable as presented unless specifically described below.

5.1 Precision

Precision was evaluated on the basis of relative percent difference (RPD) as a measure of reproducibility between LCS/LCSD pairs and MS/MSD pairs (analytical precision) and between field samples and field duplicate samples (field precision).

The RPD is calculated to evaluate precision using the following equation.

RPD = 𝑿𝟏−𝑿𝟐

ቀ𝑿𝟏+𝑿𝟐𝟐 ቁ 𝒙𝟏𝟎𝟎 Where X1 and X2 are the reported concentrations of the samples being evaluated.

5.1.1 Analytical Precision

A summary of the Quality Control assessment for analytical precision is presented below.

Laboratory Set L1699664 (Soil and Groundwater Samples):

o The RPDs for the MSD (Laboratory Batch WG2216271) associated with mercury and the MSD (Batch WG2216891) associated with lead were outside the laboratory’s control limits. As a result, a J3 flag was used to qualify this data. The affected soil samples had detections well below applicable regulatory screening levels. Additionally, other DQIs were in control. It is not anticipated that the analytical precision issue will affect the conclusions of this report.

Based on the results of the RPD analyses of the MS/MSD and LCS/LCSD samples and the evaluation provided above, analytical precision is considered within control for Laboratory Set L1699664 (soil and groundwater) with the exceptions listed above.

5.1.2 Field Precision

Six field duplicate soil samples were analyzed for RCRA 8 metals, one field duplicate soil sample was analyzed for TPH-GRO, TPH-DRO, TRPH, and VOCs, and one field duplicate groundwater sample was analyzed for TPH-GRO, TPH-DRO, TRPH, and VOCs. A summary of the Quality Control assessment for field precision is presented below.

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Per the QAPP, analytical results for original samples and field duplicate pairs that are less than five times the laboratory’s Reported Detection Limit (RDL) in the analytical reports were considered within control if the difference between the sample concentration and its duplicate was less than two times the RDL. When analytical results for the original sample and the field duplicate pairs are greater than five times the RDL, the duplicate pair was considered within control when the RPDs for the field duplicate pairs were within the QAPP’s control limits (50% for soil samples, 25% for groundwater samples).

Laboratory Set L1699664 (Soil Samples): Six duplicate soil sample pairs were run for RCRA 8 metals. One duplicate sample pair was run for VOCs and petroleum hydrocarbons.

o RCRA 8 Metals in Soil (Table C4.1)

Six field duplicate soil sample pairs were run for RCRA 8 metals. All metals were in control for three of these duplicate pairs, and each metal was in control for at least four of the duplicate pairs.

Arsenic for duplicate pair B-2 @ 0.5/B-112 @ 0.5 was not in control because the difference between the sample results was greater than 2 x RDL. Additionally, the calculated RPD for arsenic in duplicate pair B-9 @ 4/B-119 @ 4 was 56.6%, just above the control limit of 50%. Hence, this pair is not within control. Both sample pairs were above the Industrial RSL as were all samples collected during this investigation.

Barium for duplicate pair B-4 @ 0.5/B-114 @ 0.5 had a calculated RPD of 86.0%, above the control limit of 50%. All samples collected in this investigation were orders of magnitude below the Residential RSL for barium, and barium is not considered a contaminant of concern at the site.

Cadmium for duplicate pair B-2 @ 0.5/B-112 @ 0.5 was not in control because the difference between the sample results was greater than 2 x RDL. Multiple samples collected during this investigation exceeded the Residential RSL for cadmium and are considered to have exceeded this limit to be conservative despite one of the six duplicate pairs not being within control.

Lead for duplicate pair B-2 @ 0.5/B-112 @ 0.5 was not in control because the calculated RPD of 159.7% was greater than the control limit of 50%. Sample B-2 @ 0.5 had a lead concentration of 201 mg/kg, slightly exceeding the screening guidance of 200 mg/kg. It is considered to have exceedance this guidance to be conservative. Duplicate pair B-9 @ 4/B-119 @ 4 had a calculated RPD of 51.4%, slightly exceeding the 50% control limit. Both concentrations (15,700 and 9,280 mg/kg) were well above the Industrial RSL of 800 mg/kg. Additionally, several other soil samples collected during this investigation exceeded a regulatory screening level.

Mercury for duplicate pair B-2 @ 0.5/B-112 @ 0.5 was not in control because the difference between the sample results was greater than 2 x RDL. Both samples

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Facilities | Environmental | Geotechnical | Materials 16 were orders of magnitude below regulatory screening levels. Duplicate pair B-9 @ 4/B-119 @ 4 had a calculated RPD of 73.0% exceeding the 50% control limit.

Both concentrations (286 and 133 mg/kg) were well above the Industrial RSL of 46 mg/kg.

Silver for duplicate pair B-9 @ 4/B-119 @ 4 was not in control because the calculated RPD was 58.9% exceeding the 50% control limit. Both of these samples were well below regulatory screening levels as were all other samples that were analyzed for silver.

o VOCs and Petroleum Hydrocarbons in Soil (Table C4.2)

Reported concentrations for VOCs and petroleum hydrocarbons were all within control.

Laboratory Set L1699664 (Groundwater Samples): One duplicate groundwater sample pair was run for VOCs and petroleum hydrocarbons.

o VOCs and Petroleum Hydrocarbons in Groundwater (Table C4.3)

Reported concentrations for VOCs and petroleum hydrocarbons in groundwater were all in control.

Based on the results of the RPD analyses of the field duplicate sample pairs and the evaluation provided above, field precision is considered within control for Laboratory Set L1699664.

5.2 Bias and Accuracy

Bias and Accuracy were evaluated through a review of the method blanks, trip blanks, percent recoveries for LCS/LCSD, and percent recoveries for MS/MSD summaries provided by the laboratory. Method blanks and trip blanks were considered within control (i.e., accuracy) if the constituents analyzed were less than the analytical method reporting limits.

LCS/LCSD and MS/MSD analyses were considered within control if the percent recoveries were within the laboratory’s established limits (i.e., bias). A summary of the Quality Control assessment for Bias and Accuracy is presented below.

Laboratory Set L1699664 (Soil and Groundwater Samples):

o Accuracy—Method and Laboratory Blank: All analytes in the method blanks were less than the laboratory RDLs, with the exception of an estimated concentration (J value) in the method blank for selenium (Batch WG2216889) and chloroform (Batch WG2215119). A B flag was applied to this data. These analytes were detected well below regulatory screening levels within the affected samples. It is not anticipated that the accuracy issue will affect the conclusions of this report.

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Facilities | Environmental | Geotechnical | Materials 17 o Accuracy—Trip Blank: All analytes in the trip blank were less than the laboratory RDLs.

o Surrogate Recoveries: The laboratory noted that surrogate recovery limits for 1,2-dichloroethane-d4 (Batch WG2152870) were exceeded resulting in a J1 flag.

Additionally, it was noted that the surrogate recovery for o-terphenyl (Batch WG2215736) cannot be used for control limit evaluation due to dilution, resulting in a J7 value. Other surrogates were in control as were other DQIs. This is not expected to affect the usability of the data.

o The laboratory noted that the sample concentration in the MS/MSD for lead (Batch WG2216893) and the MS for TPH-DRO (Batch WG2215736) is too high to evaluate accurate spike recoveries. A V value was assigned to this data. The affected lead sample exceeded the Residential RSL as did multiple other samples collected during this investigation. TPH-DRO was non-detect in the affected samples. Additionally, other DQIs were considered acceptable. This is not expected to affect the usability of the data or alter the conclusions of this report.

o The laboratory noted that barium, chromium, and lead (Batch WG2216889), arsenic, barium, cadmium, chromium, lead, selenium, and silver (Batch WG2216893), and mercury (Batch WG2216271) failed the method required serial dilution test and/or subsequent post-spike criteria indicating matrix interference.

An O1 qualifier was assigned to this data. The analytes in the affected samples were well under regulatory reporting limits with the exception of lead, arsenic, and cadmium which exceeded the Residential RSL or guidance. These analytes also exceeded regulatory screening levels in multiple other non-affected samples.

To be conservative, it is assumed that these screening levels were exceeded (when applicable) in these samples despite failing the serial dilution test.

o Bias—LCS/LCSD Percent Recoveries: The LCS/LCSD for 1,1,2-trichlorotrifluoroethane (Batch WG2215119) and acrolein (Batch WG2221393) were above the established quality control range for accuracy. A J4 value was assigned to this data. These analytes were not detected in the affected samples and are not considered contaminants of concern at the site. This is not expected to affect the usability of the data.

o Bias—MS/MSD Percent Recoveries: The MS/MSD for barium and silver (Batch WG2216885, lead (Batches WG2216889 and WG2216891), and mercury (Batch WG2216271) interfered with the ability to make any accurate determination causing a low spike value. A J6 qualifier was applied to this data. The affected soil samples were all non-detect except for lead in duplicate sample B-112 @ 4 which exceeded the Residential RSL guidance of 200 ppm. The original sample also exceeded this guidance as did multiple non-affected samples collected during this investigation. As a result, this is not expected to affect the usability of the data or conclusions of this report.

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As a result, these accuracy and bias issues are not anticipated to affect the usability of the data.

Bias and Accuracy are considered within control for Laboratory Set L1699664 with the minor exceptions listed above.

5.3 Representativeness

Representativeness is a qualitative parameter most concerned with proper design and execution of the sampling program to produce data that accurately and precisely represent environmental conditions. Selection of analytical methods, sampling methods, and locations representative of the media sampled were set forth in the SAP. Representativeness in the field was achieved by implementing the approved SAP and using appropriate sampling methods, sample containers, sample handling, and preservation methods.

Representativeness in the laboratory was achieved by using the proper analytical procedures, meeting sample holding times, and analyzing and assessing laboratory QA/QC samples.

5.3.1 Field Representativeness

Sampling was conducted in general accordance with the SAP and associated SOPs. The following deviations from the SAP occurred during the sampling event.

A few borings were moved slightly to accommodate drill rig access, avoid large equipment/debris, or avoid identified utilities. It is unlikely that small changes in the locations of these borings had a significant effect on data quality.

A groundwater sample was not collected from boring B-3 as planned due to boring collapse and drilling refusal (see Footnote 1 in Section 2.2). No qualitative or quantitative indications of a petroleum or VOC release were observed in the soil samples from boring B-3, thus, this deviation is not considered to have affected field representativeness.

5.3.2 Laboratory Representativeness

The laboratory noted that two groundwater samples collected for VOCs had headspace in the vials. One of these samples was the Trip Blank. No VOCs exceeded regulatory screening levels in any of the samples analyzed. It is unlikely that this issue will affect the conclusions of this report.

A MS/MSD sample was not run for TPH-GRO, TRPH, or VOCs in soil or groundwater.

A MS/MSD was run for TPH-DRO in soil, but the sample was not from one collected in the field during this investigation. No MS/MSD was run for TPH-DRO in groundwater. Not enough sample was collected in the field to run a MS/MSD for these analytes, and the laboratory did not have enough sample in the batch to run a MS/MSD. Results for petroleum hydrocarbons and VOCs in soil and groundwater

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Facilities | Environmental | Geotechnical | Materials 19 were all below any regulatory screening levels. Additionally, other DQIs were in control. It is unlikely that this issue will affect the conclusions of this report.

Sample analyses followed the analytical methods listed in the SAP or equivalent EPA-approved variations of the listed methods. They were analyzed within method-specified holding times.

Representativeness is considered within control with the minor exceptions listed above.

5.4 Comparability

Comparability is a qualitative term expressing the confidence with which one data set can be compared to another. The comparability goal was achieved using standardized sampling procedures in accordance with the SAP and QAPP, use of standardized and approved laboratory analytical methods, and reporting the analytical results in appropriate and consistent units.

Sampling was conducted in general accordance with the SAP and associated SOPs.

Deviations from the SAP occurred during the sampling event and are discussed in Section 5.3.

Sample analyses followed the analytical methods listed in the SAP, equivalent approved methods, or variations of the listed methods.

The units of measure reported by the laboratory were consistent with the units of measure used by the regulatory screening levels.

The number of field duplicates specified in the approved SAP was at least 10% of the field samples for soil and groundwater.

Soil Samples: Six soil duplicates were analyzed for 54 RCRA 8 Metals or 11.1% which exceeds the 10% goal. One soil duplicate was analyzed for petroleum hydrocarbons and VOCs for five soil samples or 20%, which exceeds the 10% goal.

Groundwater Samples: One groundwater duplicate was analyzed for four groundwater samples for petroleum hydrocarbons and VOCs or 25%, which exceeds the 10% goal.

Comparability is considered within control.

5.5 Completeness

Completeness is the ratio of valid measurements to the number of planned measurements, expressed as a percentage, and the completeness goal for the project is 90%. The sampling program is deemed to meet the DQIs for valid measurements. The samples collected were submitted and analyzed by the laboratory according to the chain-of-custody. Additionally, April 23, 2024 | Terracon Project No. 61237186 Task 4.11

Facilities | Environmental | Geotechnical | Materials 20 the data collection followed the procedures and requirements as described in the approved QAPP and SAP. The data are considered usable as qualified. The analytical completeness for this sampling event was 100%.

The SAP detailed 60 soil samples (including field duplicates) for metals in soil, six soil samples for petroleum hydrocarbons and VOCs (including a field duplicate), and six groundwater samples for petroleum hydrocarbons and VOCs (including a field duplicate).

All of these samples were collected, with the exception of one groundwater sample that could not be collected from boring B-3 as planned. The sample completeness score exceeds the 90% project goal.

With acknowledgement of qualified results for the analytes listed above, the analytical data are acceptable for their intended use to evaluate constituent concentrations compared to applicable regulatory screening levels.

5.6 Sensitivity

Sensitivity refers to the capability of a method or instrument to discriminate between measurement responses representing different levels of the variable of interest. The sensitivity goal is for RDLs to be below comparative screening levels, which vary considerably by analyte and in value and applicability. Overall, the level of sensitivity was sufficient to allow the identification of soil and groundwater constituents above applicable regulatory screening levels.

Laboratory Set L1699664 (Soil and Groundwater Samples):

o RCRA 8 Metals in Soil (Table C1): The RDLs were all less than the EPA Residential RSLs for analytes reported as less than the RDL.

o Petroleum Hydrocarbons in Soil (Table C2): The RDLs were all less than the Utah ISLs, Utah Tier 1 screening levels, and EPA Residential RSLs (as applicable), for analytes reported as less than the RDL.

o VOCs in Groundwater (Table C2): The RDLs were all less than the Utah ISLs, Utah Tier 1 screening levels, and EPA Residential RSLs (as applicable), for analytes reported as less than the RDL with the following exceptions: 1,2-dibromo-3-chloropropane (all samples). This analyte is not considered a contaminant of concern at the site and was not detected in any sample. This is not anticipated to affect the conclusions of this report.

o Petroleum Hydrocarbons in Groundwater (Table C3): The RDLs were all less than the Utah ISLs, Utah Tier 1 screening levels, UGWQS, and EPA MCLs (as applicable), for analytes reported as less than the RDL.

o VOCs in Groundwater (Table C3): The RDLs were all less than Utah ISLs, Utah Tier 1 screening levels, UGWQS, EPA MCLs, and EPA VISLs (as applicable), for analytes reported as less than the RDL. The exceptions to this were acrolein;

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Facilities | Environmental | Geotechnical | Materials 21 acrylonitrile; benzene; bromodichloromethane; carbon tetrachloride; chloroform;

1,2-dibromo-3-chloropropane; 1,2-dibromoethane; hexachloro-1,2-butadiene;

naphthalene; trichloroethene, and vinyl chloride which exceeded at least one of these screening levels in at least one sample. Only trichloroethene in B-5 was detected above the RDL, and this analyte exceeded the Residential VISL. None of the other groundwater samples had detections of these analytes above RDLs, although the estimated (J value) chloroform concentration in B-5 slightly exceeded the Residential VISL. Few of these analytes are considered contaminants of concern for this site. Hence, this sensitivity issue for groundwater samples is not anticipated to affect the conclusions of this report.

The DQIs for Comparability were achieved. As such, Comparability was deemed acceptable.

6.0 Data Evaluation

Following is an overview of the contaminants identified in soil and groundwater by the current Phase II ESA.

6.1 Soil Sample Results

6.1.1 Field Observations

Fill material was observed extending to a maximum depth of approximately 8.5 feet bgs at boring B-17 in the southeastern portion of the site. The fill materials typically yielded higher XRF field readings for lead and arsenic, as compared to near-surface soils and the native soils below the fill materials.

6.1.2 Metals

Several metals including arsenic, cadmium, lead, and mercury were identified at concentrations exceeding Industrial and/or Residential RSLs in the fill materials. The maximum concentrations of these metals were identified in fill material collected from a depth of 4 feet bgs at boring B-9. The mercury exceedances were identified in fill samples from two boring locations (B-1 and B-9, both in the northeastern portion of the site) while the arsenic, cadmium, and lead exceedances were widely distributed across the site.

Analytical results from native soils underlying the fill material indicate that native soils have not been impacted by metals leaching from overlying contaminated fill materials. With limited exceptions, metals concentrations in native soils were below Residential RSLs. Native soils exceeded the Industrial RSL for lead at boring B-1, and slightly exceeded the Residential RSL for cadmium at borings B-1, B-3, B-5, and B-9. It is possible that the native soil samples from these borings were impacted by sluffing of overlying contaminated fill

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Facilities | Environmental | Geotechnical | Materials 22 material. All samples from native soils exceeded the Industrial RSL for arsenic, but the concentrations present are indicative of natural background concentrations.

Metals exceedances in soil are presented in Exhibit 4. The approximate depth of metals-contaminated fill soils throughout the site is presented in Exhibit 5. Per the data presented in Exhibit 5, the volume of metals-contaminated fill soils is estimated to be approximately 28,178 cubic yards. The metals-contaminated fill soil depths presented in Exhibit 5 and the associated volume estimate utilized data from the investigation and the previous Terracon LSI.