Appendix D.pdf

Memorandum

Date: June 14, 2021

To: United States Army Corps of Engineers – Omaha District

Attention: Andy C. Temeyer, Project Manager United States Army Corps of Engineers – Kansas City District

Attention: Gary Shirley, Project Manager

From: Burns & McDonnell Mr. Justin Carter, Environmental Project Manager

Subject: Subsurface Investigation Summary Memorandum – Revision 2

B-21 Low Observable 2-Bay Hangar Restoration Facility Ellsworth Air Force Base, South Dakota Contract Number: W912DW18D1012, Task Order Number: W912DQ20F4013 Burns & McDonnell Project Number: 126455

EXECUTIVE SUMMARY

Burns & McDonnell completed the subsurface investigation for the construction of the Low Observable 2-Bay Hangar Restoration Facility (LO Facility) at Ellsworth Air Force Base (AFB) located near Rapid City, South Dakota (see Figure 1). The subsurface investigation was conducted under United States Army Corps of Engineers (USACE) – Kansas City District Contract Number W912DW18D1012, Task Order Number W912DQ20F4013.

The purpose of the subsurface investigation was to assess if special handling or disposal requirements are required to address soils during demolition and construction of the new building and reduce uncertainty of the project’s cost associated with soil disposal and handling.

The subsurface investigation included the completion of 48 soil borings using hollow stem augers and split-spoon samplers for the collection of 96 soil samples in accordance with the Environmental Work Plan for B-21 Low Observable 2-Bay Hangar Restoration Facility (Work Plan) dated August 27, 2020.

The field activities were completed between September 21 and September 29, 2020. The locations of the completed soil borings are shown on Figure 2. Soil samples from each boring were obtained continuously for classification and field screening. Soil samples were also collected and submitted for laboratory analysis. A list of the samples submitted from each boring is provided in Table 1.

Multiple parameters were detected in the soil samples analyzed as part of the subsurface investigation including polycyclic aromatic hydrocarbons (PAHs), per- and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs), gasoline range organics (GRO), and diesel range organics (DRO).

The concentrations of detected parameters were relatively low and did not exceed the screening levels identified in the Work Plan, with the exception of the PAHs in one soil sample and total petroleum hydrocarbons (TPH) detected at seven locations in nine samples at the LO Facility.

Benzo(a)pyrene was detected in one soil sample (EB-28/2-6 at 270 micrograms per kilogram [µg/kg]) at a concentration above the United States Environmental Protection Agency (USEPA) Residential Regional Screening Level (RSL)1 of 110 µg/kg.

1 RSLs based on a Target Risk (TR) of 1 x 10-6 and Target Hazard Quotient (THQ) of 0.1 used for initial review.

June 14, 2021

Memorandum (cont’d)

TPH was detected in nine soil samples at concentrations above the South Dakota Department of Environment and Natural Resources’ (SD DENR’s) disposal criteria established in the Chapter 9 of the SD DENR’s Petroleum Assessment and Cleanup Handbook, Version 2.0 (SD DENR, 2003) of 10 milligrams per kilogram (mg/kg) for TPH. The TPH concentrations were calculated based on the sum of the GRO and DRO concentrations. The detections above disposal criteria were from the following samples: EB-7/0-2 at 12 mg/kg, EB-8/6-10 at 20.7 mg/kg, EB-20/0-2 at 13 mg/kg, EB-21/0-2 at 19 mg/kg, EB-23/0-2 at 150 mg/kg, EB-23/2-6 at 49 kg, EB-28/0-2 at 15 mg/kg, EB-28/2-6 at 14 mg/kg, and EB-41/0-2 at 28 mg/kg. The TPH concentrations detected did not exceed the Remediation Criteria for Petroleum Contaminated Soil (Tier 1 Action Level for Soil) established in the Chapter 4 of the SD DENR’s Petroleum Assessment and Cleanup Handbook, Version 2.0 (SD DENR, 2003) of 500 mg/kg.

In addition, perfluorooctanoic acid (PFOA) and/or perfluorooctane sulfonate (PFOS) were detected in 47 soil samples. The concentrations were above the limit of detection (LOD) but below the screening value of 1,260 nanograms per gram (ng/g) provided in the Air Force Guidance Memorandum Establishing Aqueous Fill Forming Foam (AFFF) Related Waste Management Implementation Guidance (AFGM

2020-32-02) (AFGM, 2020).

Based on the results of the subsurface investigation, the soil anticipated to be encountered during the construction of the LO Facility has been divided into three categories:

• Category 1 Soil that can be reused without restriction.

• Category 2 Soil that can be reused with restrictions.

• Category 3 Soil that will be removed and disposed offsite.

Category 1 and 2 soil can be reused onsite. If excess Category 2 soil that cannot be reused onsite as part of this project is generated, it must be disposed of offsite at a permitted South Dakota Subtitle D municipal waste landfill. In general, Category 2 soil consists of soil with PFOA/PFOS concentrations above the LOD but below the screening value of 1,260 ng/g, and/or soil with TPH concentrations above the disposal criteria of 10 mg/kg but below the Tier 1 Action Level for Soil of 500 mg/kg.

Category 3 soil cannot be reused onsite and must be disposed of offsite at a permitted South Dakota Subtitle D municipal waste landfill. Approximately 400 cubic yards of Category 3 soil is expected to be encountered at the LO Facility. This soil is considered to be Category 3 soil due to benzo(a)pyrene being present in excess of the Residential RSLs.

During construction activities, soil that will not be reused onsite must be stockpiled in accordance with Administrative Rules South Dakota (ARSD) 74:56:05:21. Stockpiled soil will be segregated based on category and sampled to confirm it meets their initial classification prior to transportation offsite.

Excavated soil must be reused as part of the project or disposed of offsite. At the completion of the project, stockpiled soil may not remain on site.

INTRODUCTION

Burns & McDonnell has prepared this Subsurface Investigation Summary Memorandum (Summary Memorandum) to summarize the subsurface investigation activities completed at the proposed LO Facility at Ellsworth AFB located near Rapid City, South Dakota (see Figure 1).

The USACE, Kansas City District contracted Burns & McDonnell to provide Architectural and Engineering (A-E) services to develop a 35% concept design-build and associated documents for the construction of the new LO Facility at Ellsworth AFB. The subsurface investigation was completed as part of that work and performed by Burns & McDonnell under Contract Number W912DW18D1012, Task Order Number W912DQ20F4013.

BACKGROUND

Ellsworth AFB is located approximately ten miles northeast of Rapid City, South Dakota and consists of approximately 4,800 acres. Established in 1942, it has been the center of operations for multiple aircraft and missile systems over the years. It is currently home to the 28th Bombardment Wing, whose mission is to provide combat air power and global combat support. In 2019, the Air Force announced that Ellsworth AFB will be the first base to house an operational B-21 bomber unit. To support the B-21 program, a new LO Facility will be constructed.

The proposed footprint of the LO Facility is located on the flightline northeast of the runway and includes one new building. The LO Facility currently consists of one existing hangar, which is approximately 34,000 square feet in size (see Figure 2).

SUBSURFACE INVESTIGATION FIELD ACTIVITIES

The field activities associated with the subsurface investigation were performed September 21 through September 29, 2020. The work was completed in accordance with the procedures and scope of work presented in the Work Plan dated August 27, 2020. Boring logs from the subsurface investigation are provided in Attachment 1. Table 1 lists the soil borings and associated soil samples collected. The locations of each boring and its coordinates are shown on Figure 2.

Soil Borings The 48 soil borings associated with the subsurface investigation were continuously sampled using hollow stem augers and split-spoon samplers by FMG Engineering, Inc. (FMG). Prior to intrusive activities, the locations of the proposed borings were marked by FMG. FMG also conducted a private utility locate using ground penetrating radar and an electromagnetic scanner to mark existing utilities near the proposed boring locations, prior to the excavation (dig) permits being issued for this work.

Following the utility clearance, the 30 soil borings located on concrete/asphalt were cored with a coring machine by FMG’s subcontractor, Custom Concrete Coring, LLC. FMG used a Mobile® B57 drill rig to advance the hollow stem augers and continuously sample the soil using split-spoon samplers. The drilling and sampling equipment were decontaminated prior to beginning field activities and between sampling intervals. Water generated from decontamination activities was collected and containerized in 55-gallon drums and staged at the Ellsworth AFB as directed by Ellsworth AFB personnel.

Surficial concrete was encountered at the majority of the soil boring locations. The thickness of the concrete ranged from approximately 0.8 to 3.7 feet, where encountered (Table 1).

Each of the soil borings were completed to their targeted depth. Soil samples from each boring were obtained continuously. A Burns & McDonnell field geologist classified the soil samples collected in general accordance with the Unified Soil Classification System, screened the recovered soil with a photoionization detector (PID) equipped with a 10.6 electron volt lamp, and collected soil samples for laboratory analytical testing. Following soil classification, screening, and sampling the excess soil sample material and soil boring cuttings were containerized in 55-gallon drums and staged at Ellsworth AFB, as directed by Ellsworth AFB personnel.

Soil Sample Collection Soil samples were collected from each of the 48 soil borings and submitted under chain-of-custody protocols to Eurofins Lancaster Laboratories Environmental, LLC, a fixed-based, Department of Defense Environmental Laboratory Accreditation Program accredited laboratory located in Lancaster, Pennsylvania. Soil samples were analyzed for the following constituents:

• PFAS via USEPA Method 537, Revision 1.1, Department of Defense (DoD)/Department of Energy (DOE) Quality Systems Manual (QSM) for Environmental Laboratories, Version 5.1 (2017), Table B-17 (Standard list of 14);

• VOCs via USEPA SW-846 5035A/8260C;

• PAHs via USEPA Method SW-846 3510C/8270D Selective Ion Monitoring (SIM);

• TPH-GRO via USEPA Method SW-846 3510C/8270D; and

• TPH-DRO via USEPA Method SW-846 3510C/8270D.

Ninety-six soil samples and ten duplicate samples were collected and analyzed. The number of soil samples collected from each boring varied based on the location.

• One soil sample was collected from each of the 24 soil borings located within the footprint of the existing hangar and on flightline apron pavement. The soil samples were collected from the 2-foot interval immediately below ground surface (bgs) or the pavement/subbase at each of these soil boring locations.

• Three soil samples were collected from each of the 19 soil borings completed within footprint of the proposed LO Facility. Soil samples were collected from each of these borings from the following intervals: 0 to 2 feet bgs (or immediately below pavement/subbase), approximately 2 to 6 feet bgs, and approximately 6 to 10 feet bgs.

• Three soil samples were collected from each of the three soil borings completed adjacent to the underground storage tanks. Soil samples were collected from each of these borings from the following intervals: 0 to 2 feet bgs (or immediately below pavement/subbase), 2 to 6 feet bgs, and 6 to 10 feet bgs.

• Three soil samples were collected from each of the two soil borings completed within footprint of the proposed new aerospace ground equipment fuel island. Soil samples were collected from each of these borings from the following intervals: 0 to 2 feet bgs (or immediately below pavement/subbase), 2 to 6 feet bgs, and 6 to 10 feet bgs.

In the case pavement/subbase was present, the depths of the samples collected and labeled as 2 to 6 feet bgs and 6 to 10 feet bgs were adjusted. The actual depth interval of each sample, along with the date collected and the name and location of each sample is listed in Table 1.

Soil Boring Abandonment Following sampling, each of the soil borings were abandoned by FMG using bentonite chips in accordance with the State of South Dakota Well Construction Standards 74:02:04:70 (Requirements for Plugging Other Test Holes). The surface at each boring location was restored to match adjacent surface (i.e., concrete, asphalt, soil). Abandonment activities were completed on the same day the soil boring was completed.

Investigation Derived Waste Nine 55-gallon drums of investigation derived waste (IDW) were generated as part of this SOW. This includes two drums of solids (soil) and seven drums of water generated during the completion of the work. One composite IDW soil sample and one composite IDW water sample were collected and submitted for analysis of the following:

• PFAS via USEPA Method 537, Revision 1.1, QSM 5.1, Table B-17 (Standard list of 14);

• Toxicity Characteristic Leaching Procedure (TCLP) Resource Conservation and Recovery Act RCRA Metals via USEPA Methods 1311/3010A/6010C/D/7470A;

• TCLP Semivolatile Organic Compounds (SVOCs) via USEPA Methods 1311/3510C/8270D;

• TCLP Pesticides via USEPA Methods 1311/3510C/8081B;

• TCLP Herbicides via USEPA Methods 1311/8151A;

• TCLP VOCs via USEPA Methods 1311/5030C/8260C;

• PAHs via USEPA Method SW-846 3546/8270D SIM for solids and 3510C/8270D for liquids;

• PCBs via USEPA Method SW-846 3546/8082A for solids and 3510C/8082A for liquids;

• TPH-GRO via USEPA Method 5035A/8015C for solids and 5030C/8015C for liquids; and

• TPH-DRO via USEPA Method 3546/8015C for soil and 3510C/8015C for liquids.

The liquid IDW sample was also analyzed for:

• pH via USEPA Method SW-846 9040C and

• Flashpoint via USEPA Method 1010A.

In addition, the soil IDW sample was analyzed for ignitability in accordance with the methods outlined in United States Code of Federal Regulations (40 CFR § 261.21).

SUBSURFACE INVESTIGATION RESULTS

The following sections summarize the results of the subsurface investigation work.

Geology Silty clay was generally encountered from the surface or immediately below the concrete to the terminal depth of the boring (maximum depth was 10 feet bgs). At five soil borings completed to a depth of 10 feet bgs (EB-10, EB-11, EB-12, EB-13, and EB-42), a gravel layer was encountered as shallow as 5.6 feet bgs. The gravel layer extended to depth at these borings. For six soil borings completed to a depth of 10 feet bgs (EB-23, EB-24, EB-31, EB-32, EB-36, and EB-38), there was interbedded gravel/sand seams approximately 6 inches thick. There was an approximate 6-inch thick seam of gravel identified in Soil Boing EB-1. At Soil Boing EB-17, sandy clay was encountered at approximately 8 feet bgs. At Soil Boring EB-48, there was approximately 1.4 feet of gravel/sand beneath the subbase layer. At Soil Boring EB-35, clay was encountered directly beneath the subbase. The majority of the gravels and sands encountered appeared to be fill.

Field Screening and Soil Observations During the subsurface investigation, the majority of the PID readings from the soil samples, with the exception of EB-36, EB-38, and EB-39, were similar to background readings and ranged between 0.0 and

1.7 parts per million. At the three soil borings (EB-36, EB-38, and EB-39) with PID readings above background, field staff also noted a hydrocarbon odor. No visual indications of potential hydrocarbon impacts were noted. No other indications of potential soil impacts were observed in the soil borings.

Data Validation In accordance with the Work Plan, project data was reviewed and validated. Information related to this effort is presented in the Quality Control Summary Report (QCSR) included as Attachment 2. As presented in the QCSR, the data collected are valid for use, as qualified, with the following exceptions:

• Due to lack of matrix spike/matrix spike duplicate recoveries for 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene, these non-detect data points were rejected (UR) in primary samples EB- 7/0-2 and EB-25/0-2.

• Confirmation VOC reanalyzes were performed for EB-36/0-2 and EB-48/0-2 slightly past the 14-day holding time. These were performed as a corrective action to confirm data reported in the original analysis that yielded one or more QC results outside control limits. These reanalyses were for confirmation only and did not impact overall completeness of the data, as the original data were confirmed and used. Detections for the reanalyzed run were qualified estimated (J) and nondetects were rejected (UR).

The data qualifiers used include:

• J to denote estimated concentrations detected above the limit of detection (LOD) but below the limit of quantitation (LOQ) or to denote estimated concentrations due to one or more QC outliers;

• JU to note trace detections disregarded as false positive and qualified as undetected;

• U to denote the compound was not detected;

• UJ to denote the compound was not detected but the LOD is an estimated value; and

• UR to denote the data was qualified as rejected at the LOD.

In the sections below, the data qualifiers are presented in parenthesis behind the concentration reported.

For additional information, please refer to the QCSR (see Attachment 2).

Laboratory Analytical Results The soil results were screened against the following:

• USEPA Industrial and Residential RSLs for soil (USEPA, 2020);

• AFGM 2020-32-02 (AFGM, 2020);

• South Dakota Remediation Criteria for Petroleum-Contaminated Soil (SD DENR, 2003); and

• South Dakota Disposal Criteria for Petroleum-Contaminated Soil (SD DENR, 2003).

The screening values are listed in the analytical results summary tables (see Table 2).

Soil Analytical Results Multiple analytes were detected in the soil samples collected from the LO Facility. A summary of the soil sample analytical detections is provided in Table 2, and key analytical results are discussed below.

Copies of the analytical laboratory test reports and comprehensive analytical summary table are provided in the QCSR (see Attachment 2).

• PAHs: One or more PAHs were detected in 70 of the 96 soil samples collected. The PAH – benzo(a)pyrene was detected above the EPA residential RSL of 110 µg/kg in one sample (EB- 28/2-6) at a concentration of 270 µg/kg.

• PFAS: One or more PFAS compounds were detected in 61 of the 96 soil samples at concentrations below the applicable screening levels. PFOA and PFOS were detected in 47 of the 96 soil samples. For the purposes of comparison to the soil reuse criteria established in AFGM 2019-32-01, the total PFOS/PFOA concentration was also calculated. The combined concentrations were above the LOD, but below the screening value of 1,260 ng/g provided in the AFGM 2020-32-02 (AFGM, 2020). Where detected, the total PFOS/PFOA concentration ranged from 0.21 to 80.4 ng/g.

• VOCs: One or more VOCs were detected in 95 of the 96 of the soil samples. The compounds detected included 2-butanone, 2-hexanone, acetone, benzene, carbon disulfide, cyclohexane, ethylbenzene, methyl acetate, methyl-cyclohexane, toluene, and xylenes (m&p- and o-). Each of the detections were below their respective screening values.

• Petroleum Hydrocarbons: DRO was detected in 22 of the 96 soil samples collected at concentrations ranging from 5.7 J mg/kg to 150 mg/kg. GRO was detected in five of the 96 soil samples at concentrations ranging from 1.4 mg/kg to 5.7 J mg/kg. The highest DRO concentration was detected at EB-23/0-2 (150 mg/kg) and the highest GRO concentration was detected at EB-8/6-10 (5.7 J mg/kg). TPH concentrations exceeded the SD DENR’s disposal criteria of 10 mg/kg for TPH in nine samples (EB-7/0-2 at 12 mg/kg, EB-8/6-10 at 20.7 mg/kg, EB-20/0-2 at 13 mg/kg, EB-21/0-2 at 19 mg/kg, EB-23/0-2 at 150 mg/kg, EB-23/2-6 at 49 kg, EB-28/0-2 at 15 mg/kg, EB-28/2-6 at 14 mg/kg, and EB-41/0-2 at 28 mg/kg). However, the DRO and GRO concentrations detected at the MPF did not exceed the South Dakota Remediation Criteria for Petroleum Contaminated Soil (Tier 1 Action Level for Soil) (SD DENR, 2003) of 500 mg/kg either individually or in total.

Industrial Derived Waste Analytical Results A summary of the IDW analytical results is provided in Table 3 and discussed below.

• Ignitability: The IDW soil sample was determined to be not ignitable to air, flame, friction, or water.

• Flashpoint: The IDW water sample did not exhibit hazardous waste characteristics of having a flashpoint below 60 degrees Celsius.

• pH: The pH of the IDW water sample did not exhibit hazardous waste characteristics of having a pH less than 2 standard units (S.U.) or greater than 12.5 S.U.

• TCLP VOCs: There were no detections of TCLP VOCs in the IDW soil and water samples.

• TCLP SVOCs: There were no detections of TCLP SVOCs in the IDW soil and water samples.

• TCLP Pesticides: There were no detections of TCLP pesticides in the IDW soil and water samples.

• TCLP Herbicides: There were no detections of TCLP herbicides in the IDW soil and water samples.

• TCLP Metals: Barium, cadmium, chromium, and lead were detected in the TCLP leachate for the IDW soil sample, and barium and chromium were detected in the TCLP leachate for the IDW water sample. However, each of the analytes were detected at concentrations significantly below the USEPA Maximum Concentration of Contaminants for the Toxicity Characteristic.

• TPH: GRO and DRO were detected in the IDW soil sample, and only DRO was detected in the IDW water sample. The TPH concentration in the IDW soil sample did not exceed the SD DENR’s disposal criteria of 10 mg/kg. The TPH concentration in the IDW water sample did not exceed SD Groundwater Quality Standard of 10,000 µg/L.

• PCBs: There were no detections of PCBs in the IDW soil and water samples.

• PAHs: Seven PAHs were detected in the IDW soil sample. There were no PAHs detected in the IDW water sample. All PAHs detected in the soil IDW were very low concentrations. There are no hazardous waste disposal criteria for PAH; however, all detections were below USEPA Residential and Industrial RSLs.

• PFAS: PFAS parameters were not detected in the IDW soil sample. PFAS parameters were detected in the IDW water sample, and the Total PFOA/PFOS concentration was 96.5 ng/L.

Based on the analytical results, the soil IDW was below the screening value of 1,260 ng/g provided in the AFGM 2020-32-02 (AFGM, 2020) establishing AFFF-related waste management implementation guidance. The IDW water sample was slightly over the USEPA Lifetime Health Advisory (LHA) level of 70 ng/L referenced in the AFGM 2020-32-02 (AFGM, 2020) establishing AFFF-related waste management implementation guidance, thus requiring treatment or disposal via incineration.

Burns & McDonnell personnel triple treated the IDW water through a portable granular activated carbon treatment unit on November 11, 2020. Following treatment, a sample was collected and submitted for analysis of PFAS via USEPA Method 537, Revision 1.1, QSM 5.1, Table B-17 (Standard list of 14). As shown on Table 3, the treated IDW liquid sample had a PFOA/PFOS result of 4.0 ng/L, which is below the USEPA LHA of 70 ng/L. A copy of the analytical laboratory test report is located in Attachment 3.

Based on these results and discussions with Ellsworth AFB Environmental personnel, the IDW soil can be disposed of offsite. The IDW water can be discharged to an industrial or sanitary drain as directed by AFB personnel.

SOIL CLASSIFICATION

Based on the estimated amount of excavation work required for this project and the results of the Subsurface Investigation, the soil was evaluated to determine whether the soil within the project footprint can be reused onsite during construction activities. Chapter 9 of the SD DENR’s Petroleum Assessment and Cleanup Handbook, Version 2.0 (SD DENR, 2003), USEPA Industrial and Residential RSLs for soil and AFGM 2020-32-02 (AFGM, 2020) were used for this evaluation. The following categories of soil were determined to be present:

Category 1: Soil without Reuse Restrictions:

• Category 1 soil is defined as soil without detections above the applicable screening levels and PFOA/PFOS concentrations below the LOD.

• Category 1 soil can be reused onsite without restrictions. If excess Category 1 soil, beyond what can be reused onsite in association with this project is generated, there are no anticipated restrictions on its disposition.

Category 2: Soil with Reuse Restrictions:

Category 2 soil has been separated into two subcategories, Category 2A and Category 2B. Both categories can be reused onsite without restrictions. However, if excess Category 2 soil that cannot be reused onsite in association with this project is generated, it must be disposed of offsite. The disposal restrictions differ by subcategory.

• Category 2A: Soil with Reuse Restrictions Based on PFOA/PFOS o Category 2A soil is defined as soil with:

PFOA/PFOS concentrations above the LOD but below the 1,260 ng/g, and

Concentrations of the remaining constituents below other applicable screening levels.

o Category 2A soil can be reused onsite without restrictions. If excess Category 2A soil, beyond what can be reused onsite in association with this project is generated, it must be disposed of offsite at a permitted South Dakota Subtitle D municipal waste landfill.

• Category 2B: Soil with Reuse Restrictions Based on TPH o Category 2B soil is defined as soil with:

TPH concentrations (DRO and GRO either individually or in total) between 10 and 500 mg/kg, Concentrations of the remaining constituents below other applicable screening levels.

o Category 2B soil can be reused onsite without restrictions. If excess Category 2B soil, beyond what can be reused onsite in association with this project is generated, it must be disposed of offsite at a permitted South Dakota Subtitle D municipal waste landfill.

If soil qualifies as Category 2B and has PFOA/PFOS concentrations above the LOD but below the 1,260 ng/g, it should be handled as Category 2B soil. Coordination with the specific disposal facility and SD DENR Waste Management Program will be required in advance to secure approval of Category 2 soil disposal. Depending on the outcome of those conversations, soil with TPH concentrations over 100 mg/kg may require alternative means of disposal.

Category 3: Soil Requiring Offsite Disposal:

• Category 3 soil is defined as soil:

o One or more PAH detected above their respective Residential RSL, and o TPH concentrations (DRO and GRO either individually or in total) between 10 and 500 mg/kg, and o Concentrations of the remaining constituents below other applicable screening levels including the PFOA/PFOS screening level of 1,260 ng/g.

• Category 3 soil must be it must be disposed of offsite at a permitted South Dakota Subtitle D municipal waste landfill, provided the soil is not contaminated with PFOA and/or PFOS. If the soil is contaminated with PFOA and/or PFOS, the disposal of this soil must follow Air Force Policy AFGM 2020-32-02. Coordination with the specific disposal facility, SD DENR Waste Management Program and Air Force Civil Engineer Center (AFCEC) Restoration personnel located at Ellsworth AFB will be required to confirm these requirements are met for disposal and secure approval in advance of disposal.

The approximate areas and associated depths of Category 1, 2 and 3 soils are shown on Figure 3.

It is anticipated that majority of disturbed soil will be reused onsite for this project, with the exception of Category 3 soil. However initial estimates indicate the following volumes of excess soil (i.e., soil not able to be reused onsite as part of this project) may be generated and therefore require disposal as described in this document:

• Approximately 2,700 cubic yards of excess Category 1 soil,

• Approximately 5,100 cubic yards of excess Category 2A soil, and

• Approximately 1,400 cubic yards of Category 2B soil.

In addition, approximately 400 cubic yards of Category 3 soil is expected to be encountered at the LO Facility, based on a vertical impacted interval of 0 to 6 feet bgs and a surficial area of approximately 1,800 square feet. This soil will require offsite disposal as described above.

The actual volume of excess soil requiring disposal may vary significantly from the volumes estimated based onsite conditions, management of soil onsite during construction, and confirmation sampling.

SOIL STOCKPILE REQUIREMENTS

Any soil that will be taken offsite must be segregated based on Category, stockpiled, and sampled prior to it be transported offsite. Soil will be stockpiled onsite in accordance with the ARSD 74:56:05:21.

Stockpiled soil will be sampled to confirm it meets the initial classification. Each sample will be analyzed for the following parameters, though additional parameters may be required by the specific disposal facility:

• PFAS via USEPA Method 537, Revision 1.1, QSM 5.1, Table B-17 (Standard list of 14);

• VOCs via USEPA SW-846 5035A/8260C;

• PAHs via USEPA Method SW-846 3510C/8270D SIM;

• TPH–GRO via USEPA Method SW-846 3510C/8270D; and

• TPH–DRO via USEPA Method SW-846 3510C/8270D.

The number of stockpile samples required is based upon the size of the stockpile. The schedule for number of samples to stockpile size is presented below:

Stockpile Size (cubic yards) Number of Stockpile Samples

0 to 100 2 101 to 1,000 3 1,001 to 50,000 5 50,001 to 100,000 10 >100,000 10 + 1 for each additional 50,000 cubic yards

Stockpile sample results will be compared to the applicable screening values prior to being taken offsite.

Excavated soil must be reused as part of the project or disposed of offsite. At the completion of the project, stockpiled soil may not remain on site.

DISCUSSION

The PAH, benzo(a)pyrene was detected at concentrations above its residential screening level in one sample at the LO Facility. Approximately 400 cubic yards of this soil will likely be encountered during demolition and/or construction activities as illustrated on Figure 3. This soil has been classified as Category 3 soil and will require disposal at a permitted South Dakota Subtitle D municipal waste landfill, provided the soil is not contaminated with PFOA and/or PFOS. If the soil is contaminated with PFOA and/or PFOS, the disposal of this soil must follow Air Force Policy AFGM 2020-32-02.

PFAS were detected a relatively low concentrations in soil samples collected from the LO Facility and will likely be encountered during demolition and/or construction activities. The total PFOA/PFOS concentrations detected were above the LOD, but below the screening value of 1,260 ng/g provided in the AFGM 2020-32-02 (AFGM, 2020) establishing AFFF-related waste management implementation guidance in approximately 60 percent of the samples. Soil with total PFOA/PFOS concentrations within this range has been classified as Category 2A soil. In accordance with information provided by Ellsworth AFB during the LO Hangar 65% Review Meeting on October 22, 2020, soil with total PFOA/PFOS concentrations detected above the LOD, but below the screening value of 1,260 ng/g may be reused onsite in association with the project that generated it. However, if excess soil is generated, it must be disposed at an appropriately permitted South Dakota Subtitle D municipal waste landfill. The approximate extent of Category 2A soil is shown on Figure 3.

TPH were also detected at relatively low concentrations in soil samples collected from the LO Facility and will likely be encountered during demolition and/or construction activities. Soil with TPH concentrations (DRO and GRO either individually or in total) between 10 and 500 mg/kg have been classified as Category 2B soil. In accordance with Chapter 9 of the SD DENR’s Petroleum Assessment and Cleanup Handbook, Version 2.0 (SD DENR, 2003), soil with total TPH concentrations below 500 mg/kg may be reused onsite in association with the project that generated it. However, if excess soil is generated, it must be disposed at a permitted South Dakota Subtitle D municipal waste landfill. The approximate extent of Category 2B soil is shown on Figure 3.

Overall, the concentrations detected as part of the subsurface investigation were relatively low. However, they do not preclude higher concentrations or other impacts from being encountered during the construction of the LO Facility. The results of the subsurface investigation and the soil management information will be incorporated into the project design.

REFERENCES

AFGM, 2020. Air Force Guidance Memorandum Establishing Aqueous Fill Forming Foam (AFFF)

Related Waste Management Implementation Guidance. 2020-32-02. September.

Burns & McDonnell, 2020. Environmental Work Plan for B-21 Low Observable 2-Bay Hangar

Restoration Facility. A (Work Plan).

DoD/DOE, 2017. Department of Defense/Department of Energy Consolidated Quality Systems Manual

(QSM) for Environmental Laboratories, Version 5.1. September.

SD DENR, 2003. Petroleum Assessment and Cleanup Handbook, Version 2.0. March.

USEPA, 2017. National Functional Guidelines for Organic Superfund Methods Data Review (NFGO).

January.

USEPA, 2020. Regional Screening Levels (RSLs) – Generic Tables. May.

JLC/jlc cc: Brian Hoye (Burns & McDonnell ENS-KC) Andy Mashek (Burns & McDonnell A&F-KC) Brent Legreid (Burns & McDonnell A&F-KC)

Enclosures:

Tables:

Table 1: Subsurface Investigation Sampling Locations Table 2: Summary of Detections Table 3: Summary of IDW Analytical Results

Figures:

Figure 1: Location and Vicinity Map Figure 2: Summary of Key Detections Figure 3: Soil Classification Plan

Attachment 1: Boring Logs and Field Notes Attachment 2: Quality Control Summary Report (includes Laboratory Reports) Attachment 3: Analytical Laboratory Test Report for Treated IDW Liquid Sample

TABLES

TABLE 1: SUBSURFACE INVESTIGATION SAMPLING LOCATIONS

B-21 Low Observable 2-Bay Hangar Restoration Facility

Ellsworth Air Force Base, South Dakota

SITE BORING

CONCRETE/

ASPHALT

THICKNESS*

(feet)

SAMPLE NAME

INTERVAL INTERVAL BGS FIELD SAMPLE ID SAMPLE DATE LAB SAMPLE ID PAHs PFAS VOCs DRO GRO

EB-1/0-2 9/24/2020 410-15264-4 X X X X X

EB-1001/0-2 Duplicate (EB-1001/0-2) 9/24/2020 410-15264-5 X X X X X

EB-2 0.0 0-2 0-2 EB-2/0-2 9/24/2020 410-15264-2 X X X X X

EB-3 0.0 0-2 0-2 EB-3/0-2 9/23/2020 410-14982-13 X X X X X

EB-4 0.0 0-2 0-2 EB-4/0-2 9/23/2020 410-14982-12 X X X X X

EB-1/0-2 9/22/2020 410-14884-10 X X X X X

EB-1005/0-2 Duplicate (EB-1005/0-2) 9/22/2020 410-14884-11 X X X X X

EB-6 0.0 0-2 0-2 EB-6/0-2 9/22/2020 410-14884-9 X X X X X

EB-7 0.0 0-2 0-1.9 EB-7/0-2' 9/22/2020 410-14884-8 X X X X X

0-2 0-2 EB-8/0-2 9/29/2020 410-15666-6 X X X X X

2-6 2-6 EB-8/2-6 9/29/2020 410-15666-7 X X X X X

EB-8/6-10 9/29/2020 410-15666-8 X X X X X

EB-1008/6-10 Duplicate (EB-1008/6-10) 9/29/2020 410-15666-9 X X X X X

0-2 0-2 EB-9/0-2 9/29/2020 410-1566-2 X X X X X

2-6 2-6 EB-9/2-6 9/29/2020 410-15666-3 X X X X X

6-10 6-10 EB-9/6-10 9/29/2020 410-15666-4 X X X X X

0-2 1.5-3.5 EB-10/0-2 9/28/2020 410-15425-18 X X X X X

2-6 3.5-6 EB-10/2-6 9/28/2020 410-15425-19 X X X X X

6-10 6-10 EB-10/6-10 9/28/2020 410-15666-1 X X X X X

0-2 0-2 EB-11/0-2 9/29/2020 410-15666-18 X X X X X

EB-11/2-6 9/29/2020 410-1566619 X X X X X

EB-1011/2-6 Duplicate (EB-1011/2-6) 9/29/2020 410-15666-20 X X X X X

6-10 6-10 EB-11/6-10 9/29/2020 410-15666-21 X X X X X

0-2 1.8-2.6 EB-12/0-2 9/29/2020 410-15666-15 X X X X X

2-6 2.6-6 EB-12/2-6 9/29/2020 410-15666-16 X X X X X

6-10 6-10 EB-12/6-10 9/29/2020 410-15666-17 X X X X X

0-2 1.8-3.9 EB-13/0-2 9/29/2020 410-15666-11 X X X X X

2-6 3.9-5.9 EB-13/2-6 9/29/2020 410-15666-12 X X X X X

6-10 5.9-10 EB-13/6-10 9/29/2020 410-15666-13 X X X X X

EB-14 0.0 0-2 0-2 EB-14/0-2 9/29/2020 410-15666-23 X X X X X

EB-15 1.6 0-2 1.6--3.8 EB-15/0-2 9/22/2020 410-14884-7 X X X X X

EB-16 0.0 0-2 0-2 EB-16/0-2 9/23/2020 410-14982-15 X X X X X

0-2 0-2 EB-17/0-2 9/28/2020 410-15425-7 X X X X X

2-6 2-6 EB-17/2-6 9/28/2020 410-15425-8 X X X X X

6-10 6-10 EB-17/6-10 9/28/2020 410-15425-9 X X X X X

0-2 2.2-4 EB-18/0-2 9/28/2020 410-15425-10 X X X X X

EB-18/2-6 9/28/2020 410-15425-11 X X X X X

EB-1018/2-6 Duplicate (EB-1018/2-6) 9/28/2020 410-15425-12 X X X X X

6-10 6-10 EB-18/6-10 9/28/2020 410-15425-13 X X X X X

0-2 2.4-4.4 EB-19/0-2 9/28/2020 410-15425-14 X X X X X

2-6 4.4-6 EB-19/2-6 9/28/2020 410-15425-15 X X X X X

6-10 6-10 EB-19/6-10 9/28/2020 410-15425-16 X X X X X

EB-20 3.2 0-2 3.2-5 EB-20/0-2 9/22/2020 410-14884-6 X X X X X

EB-21 3.6 0-2 3.6-5 EB-21/0-2 9/22/2020 410-14884-5 X X X X X

LO Facility 0.0

EB-1 0.0

EB-13 1.8

EB-19 2.4

1.8

0.0EB-9

EB-10 1.5

EB-11

Laboratory Analytical

EB-17 2.0

EB-18 2.2 2-6 2-6

0-2 0-2

EB-5 0.0 0-2 0-2

EB-8 0.0

6-10 6-10

2-6 2-6

EB-12

Ellsworth Air Force Base, South Dakota

SITE BORING

CONCRETE/

ASPHALT

THICKNESS*

(feet)

SAMPLE NAME

INTERVAL INTERVAL BGS FIELD SAMPLE ID SAMPLE DATE LAB SAMPLE ID PAHs PFAS VOCs DRO GRO

Laboratory Analytical

0-2 0-2 EB-22/0-2 9/24/2020 410-15264-6 X X X X X

2-6 2-6 EB-22/2-6 9/24/2020 410-15264-7 X X X X X

6-10 6-10 EB-22/6-10 9/24/2020 410-15264-8 X X X X X

0-2 0-2 EB-23/0-2 9/24/2020 410-15264-10 X X X X X

2-4 2-4 EB-23/2-6 9/24/2020 410-15264-11 X X X X X

6-10 6-10 EB-23/6-10 9/24/2020 410-15264-12 X X X X X

0-2 1.4-3.4 EB-24/0-2 9/25/2020 410-15285-13 X X X X X

EB-24/2-6 9/25/2020 410-15285-14 X X X X X

EB-1024/2-6 Duplicate (EB-1024/2-6) 9/25/2020 410-15285-15 X X X X X

6-10 6-10 EB-24/6-10 9/25/2020 410-15285-16 X X X X X

EB-25 1.4 0-2 1.4-3.4 EB-25/0-2 9/25/2020 410-15285-17 X X X X X

EB-26 1.6 0-2 1.6-3.6 EB-26/0-2 9/21/2020 410-14884-2 X X X X X

EB-27 0.0 0-2 0-2 EB-27/0-2 9/28/2020 410-15425-3 X X X X X

0-2 0-2 EB-28/0-2 9/24/2020 410-15264-13 X X X X X

2-6 2-6 EB-28/2-6 9/24/2020 410-15264-14 X X X X X

6-10 6-10 EB-28/6-10 9/24/2020 410-15264-15 X X X X X

EB-29 0.0 0-2 0-2 EB-29/0-2 9/23/2020 410-15264-1 X X X X X

0-2 1.4-3.4 EB-30/0-2 9/25/2020 410-14285-1 X X X X X

2-6 3.4-6 EB-30/2-6 9/25/2020 410-14285-2 X X X X X

6-10 6-10 EB-30/6-10 9/25/2020 410-14285-3 X X X X X

0-2 1.8-3.8 EB-31/0-2 9/23/2020 410-14982-5 X X X X X

2-6 3.8-6 EB-31/2-6 9/23/2020 410-14982-6 X X X X X

6-10 6-10 EB-31/6-10 9/23/2020 410-14982-7 X X X X X

0-2 1.8-3.8 EB-32/0-2 9/23/2020 410-14982-9 X X X X X

2-6 3.8-6 EB-32/2-6 9/23/2020 410-14982-10 X X X X X

6-10 6-10 EB-32/6-10 9/23/2020 410-14982-11 X X X X X

EB-33 1.8 0-2 1.8-3.8 EB-33/0-2 9/21/2020 410-14884-1 X X X X X

EB-34 3.7 0-2 2.7-4.7 EB-34/0-2 9/22/2020 410-14884-4 X X X X X

EB-35-2 9/28/2020 410-15425-5 X X X X X

EB-1035/0-2 Duplicate (EB-1035/0-2) 9/28/2020 410-15425-6 X X X X X

0-2 2.4-4 EB-36/0-2 9/25/2020 410-15285-9 X X X X X

2-6 4-6 EB-36/2-6 9/25/2020 410-15285-10 X X X X X

6-10 6-10 EB-36/6-10 9/25/2020 410-15285-11 X X X X X

0-2 2.4-4.4 EB-37/0-2 9/21/2020 410-14679-1 X X X X X

2-6 4.4-6 EB-37/2-6 9/21/2020 410-14679-2 X X X X X

6-10 6-10 EB-37/6-10 9/21/2020 410-14679-3 X X X X X

0-2 2-4 EB-38/0-2 9/23/2020 410-14982-1 X X X X X

2-6 4-6 EB-38/2-6 9/23/2020 410-14982-2 X X X X X

6-10 6-10 EB-38/6-10 9/23/2020 410-14982-3 X X X X X

EB-39 2.3 0-2 1.6-4 EB-33/0-2 9/21/2020 410-14679-4 X X X X X

EB-40 2.2 0-2 2.2-4.2 EB-33/0-2 9/21/2020 410-14679-5 X X X X X

EB-41 0.0 0-2 0-2 EB-33/0-2 9/28/2020 410-15425-1 X X X X X

LO Facility

EB-37 2.4

1.4

EB-31 1.8

EB-30

EB-22 0.0

EB-24 1.4 2-6 3.4-6

EB-28 0.0

EB-23 0.0

1.8

EB-35 2.2 0-2 2.2-4.2

EB-36 2.4

EB-32

EB-38 2.0

Ellsworth Air Force Base, South Dakota

SITE BORING

CONCRETE/

ASPHALT

THICKNESS*

(feet)

SAMPLE NAME

INTERVAL INTERVAL BGS FIELD SAMPLE ID SAMPLE DATE LAB SAMPLE ID PAHs PFAS VOCs DRO GRO

Laboratory Analytical

0-2 1.4-3.4 EB-42/0-2 9/25/2020 410-15285-5 X X X X X

2-6 3.4-6 EB-42/2-6 9/25/2020 410-15285-6 X X X X X

EB-42/6-10 9/25/2020 410-15285-7 X X X X X

EB-1042/6-10 Duplicate (EB-1042/6-10) 9/25/2020 410-15285-8 X X X X X

0-2 2-4 EB-43/0-2 9/24/2020 410-15264-21 X X X X X

2-6 4-6 EB-43/2-6 9/24/2020 410-15264-22 X X X X X

6-10 6-10 EB-43/6-10 9/24/2020 410-15264-23 X X X X X

0-2 1.4-3.4 EB-44/0-2 9/24/2020 410-15264-16 X X X X X

EB-44/2-6 9/24/2020 410-15264-17 X X X X X

EB-1044/2-6 Duplicate (EB-1044/2-6) 9/24/2020 410-15264-18 X X X X X

6-10 6-10 EB-44/6-10 9/24/2020 410-15264-19 X X X X X

EB-45-2 9/21/2020 410-14679-7 X X X X X

EB-1045/0-2 Duplicate (EB-1045/0-2) 9/21/2020 410-14679-8 X X X X X

EB-46 2.2 0-2 2.2-4.2 EB-46/0-2 9/21/2020 410-14679-6 X X X X X

0-2 1-3.4 EB-47/0-2 9/29/2020 410-15666-25 X X X X X

2-6 3.4-6 EB-47/2-6 9/29/2020 410-15666-26 X X X X X

6-10 6-10 EB-47/6-10 9/29/2020 410-15666-27 X X X X X

0-2 2.2-4.2 EB-48/0-2 9/29/2020 410-15666-28 X X X X X

2-6 4.2-6 EB-48/2-6 9/29/2020 410-15666-29 X X X X X

6-10 6-10 EB-48/6-10 9/29/2020 410-15666-30 X X X X X

Notes:

* Includes thickness of subbase, if encountered.

bgs = below ground surface DRO = diesel range organics

EB = environmental boring GRO = gasoline range organics

ID = identification LO = Low Observable 2-Bay Hangar Restoration Facility

PAH = polycyclic aromatic hydrocarbons PFAS = per- and polyfluoroalkyl substances

X = Indicates sample was analyzed for the listed compounds.

LO Facility

EB-42 1.4

6-10 6-10

EB-43 2.0

2-6 3.4-6

EB-45 0.8 0-2 0.4-2.4

EB-47 1.0

EB-48 2.2

EB-44 1.4

TABLE 2: SUMMARY OF DETECTIONS

Ellsworth Air Force Base, South Dakota

LAB SAMPLE ID FIELD SAMPLE ID INTERVAL SAMPLE DATE

Diesel Range

Organics (DRO) Gasoline Range Organics (GRO) TPH* 2-Butanone 2-Hexanone Acetone Benzene Carbon Disulfide Cyclohexane Ethylbenzene Methyl Acetate

Methy-cyclohexane Toluene m&p-Xylene o-Xylene

Units (mg/kg) (mg/kg) (mg/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) Method No. 8015C DRO 8015C GRO CALC 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD

CAS No. NE NE NE 78-93-3 591-78-6 67-64-1 71-43-2 75-15-0 110-82-7 100-41-4 79-20-9 108-87-2 108-88-3 108-38-3 106-42-3 95-47-6

USEPA Residential RSLs NE NE NE 2700000 200000 6100000 1200 77000 650000 5800 7800000 NE 490000 550000 650000 USEPA Industrial RSLs NE NE NE 19000000 1500000 67000000 5100 350000 2700000 25000 120000000 NE 4700000 2400000 2800000

SD Remediation Criteria for Petroleum Contaminated Soil (Tier 1 Action Levels for Soil) 500 500 500 NE NE NE 200 NE NE 10000 NE NE 15000 300000 300000 Petroleum Disposal Criteria from SD Petroleum Assessment & Cleanup Handbook 10 10 10 NE NE NE NE NE NE NE NE NE NE NE NE

Air Force Guidance Memorandum AFFF PFOA/PFOS NE NE NE NE NE NE NE NE NE NE NE NE NE NE NE 410-15264-4 EB-1/0-2 0-2 09/24/2020 6.0 J 0.33 JU 6.0 1.9 U 0.95 U 45 J 0.49 J 0.57 U 0.47 U 0.70 J 0.95 U 0.64 J 1.0 J 0.95 U 0.38 U 410-15264-5 EB-1001/0-2 (Duplicate of EB-1/0-2) 0-2 09/24/2020 5.7 J 0.65 JU 5.7 2.6 U 1.3 U 55 0.66 U 0.79 U 0.66 U 0.53 U 1.3 U 0.79 U 0.79 U 1.3 U 0.53 U 410-15264-2 EB-2/0-2 0-2 09/24/2020 5.6 U 0.44 JU ND 2.2 J 0.97 U 57 J 0.79 J 0.58 U 1.1 J 1.2 J 0.97 U 1.0 J 1.8 J 0.97 U 0.39 U

410-14982-13 EB-3/0-2 0-2 09/23/2020 6.1 U 0.35 JU ND 1.9 U 0.95 U 40 1.6 J 0.57 U 2.7 J 2.0 J 0.95 U 2.4 J 3.0 J 0.95 U 0.38 U 410-14982-12 EB-4/0-2 0-2 09/23/2020 5.4 U 0.31 JU ND 12 J 1.0 U 170 J 2.5 J 1.2 J 2.8 J 1.6 J 1.9 J 1.7 J 3.0 J 1.0 U 0.41 U 410-14884-10 EB-5/0-2 0-2 09/22/2020 8.2 J 0.38 JU 8.2 2.8 J 0.91 U 70 0.56 J 0.55 U 0.46 U 0.47 J 0.91 U 0.76 J 0.93 J 0.91 U 0.37 U 410-14884-11 EB-1005/0-2 (Duplicate of EB-5/0-2) 0-2 09/22/2020 8.0 J 0.32 JU 8.0 1.9 U 0.96 U 61 1.0 J 0.57 U 1.4 J 1.1 J 0.96 U 1.2 J 1.7 J 0.96 U 0.38 U 410-14884-9 EB-6/0-2 0-2 09/22/2020 8.8 J 0.44 JU 8.8 5.0 J 1.0 U 95 0.96 J 0.62 U 1.2 J 0.68 J 5.3 1.2 J 1.4 J 1.0 U 0.41 U 410-14884-8 EB-7/0-2 0-2 09/22/2020 12 J 0.37 JU 12 1.8 UJ 0.92 UJ 110 J 1.9 J 0.55 UJ 4.1 J 5.0 J 0.92 UJ 3.2 J 5.6 J 0.92 UJ 0.37 UJ 410-15666-6 EB-8/0-2 0-2 09/29/2020 6.7 J 0.64 JU 6.7 3.5 J 4.3 U 67 2.2 J 0.86 J 2.1 U 2.6 J 1.8 J 3.9 J 4.6 J 1.3 J 1.1 U 410-15666-7 EB-8/2-6 2-6 09/29/2020 11 U 2.1 J 2.1 9.2 J 4.5 U 150 1.8 J 1.7 J 1.3 J 2.7 J 4.7 J 2.2 J 3.7 J 2.2 U 1.1 U 410-15666-8 EB-8/6-10 6-10 09/29/2020 15 5.7 J 20.7 3.9 U 3.9 U 25 0.93 J 2.0 U 1.3 J 0.83 J 3.9 U 1.3 J 1.5 J 2.0 U 0.99 U 410-15666-9 EB-1008/6-10 (Duplicate of EB-8/6-10) 6-10 09/29/2020 11 U 0.58 JU ND 4.4 J 3.9 U 80 0.77 J 2.0 U 0.90 J 0.69 J 3.4 J 0.88 J 1.3 J 2.0 U 0.98 U 410-15666-2 EB-9/0-2 0-2 09/29/2020 8.8 J 0.32 JU 8.8 5.9 J 4.3 UJ 440 J 1.4 J 2.2 UJ 2.2 J 1.7 J 6.6 J 2.4 J 3.0 J 2.2 UJ 1.1 UJ 410-15666-3 EB-9/2-6 2-6 09/29/2020 11 U 0.60 JU ND 4.3 U 4.3 U 17 U 2.1 U 2.1 U 2.1 U 1.1 U 4.3 U 2.1 U 2.1 U 2.1 U 1.1 U 410-15666-4 EB-9/6-10 6-10 09/29/2020 6.2 J 0.64 JU 6.2 5.2 J 4.1 U 94 0.60 J 2.1 U 2.1 U 1.0 U 4.1 U 2.1 U 0.93 J 2.1 U 1.0 U

410-15425-18 EB-10/0-2 0-2 09/28/2020 12 U 0.96 JU ND 3.8 U 3.8 U 53 2.5 J 1.9 U 3.5 J 3.8 J 3.8 U 2.8 J 4.9 1.9 U 0.96 U 410-15425-19 EB-10/2-6 2-6 09/28/2020 12 U 0.85 JU ND 2.1 J 4.0 U 50 0.86 J 2.0 U 0.87 J 0.51 J 4.0 U 0.91 J 1.2 J 2.0 U 1.0 U 410-15666-1 EB-10/6-10 6-10 09/28/2020 11 U 0.37 JU ND 4.1 J 3.9 U 50 2.9 J 2.0 U 2.0 U 2.3 J 1.1 J 2.1 J 3.5 J 2.0 U 0.40 J 410-15666-18 EB-11/0-2 0-2 09/29/2020 12 U 0.38 JU ND 4.7 J 4.1 UJ 160 J 1.6 J 2.0 UJ 2.8 J 3.0 J 2.4 J 2.2 J 3.6 J 2.0 UJ 1.0 UJ 410-15666-19 EB-11/2-6 2-6 09/29/2020 11 U 0.37 JU ND 4.0 U 4.0 U 60 1.4 J 2.0 U 2.3 J 2.8 J 4.0 U 2.9 J 3.7 J 2.0 U 1.0 U 410-15666-20 EB-1011/2-6 (Duplicate of EB-11/2-6) 2-6 09/29/2020 11 U 0.40 JU ND 3.5 J 4.2 UJ 49 J 2.5 J 1.0 J 4.3 J 5.7 J 4.2 UJ 3.3 J 7.0 J 2.1 UJ 1.1 UJ 410-15666-21 EB-11/6-10 6-10 09/29/2020 10 U 0.24 JU ND 2.1 J 3.6 U 36 4.8 1.8 U 1.3 J 1.8 J 3.6 U 2.2 J 4.0 J 1.1 J 0.46 J 410-15666-15 EB-12/0-2 0-2 09/29/2020 13 U 1.4 1.4 4.5 U 4.5 U 37 1.3 J 2.3 U 2.1 J 2.1 J 4.5 U 1.8 J 2.9 J 2.3 U 1.1 U 410-15666-16 EB-12/2-6 2-6 09/29/2020 12 U 5.5 J 5.5 14 J 3.4 U 290 J 0.64 J 1.7 U 1.7 U 0.42 J 1.8 J 0.54 J 0.75 J 1.7 U 0.84 U 410-15666-17 EB-12/6-10 6-10 09/29/2020 12 U 0.49 JU ND 6.1 J 3.5 U 78 1.3 J 1.7 U 1.7 U 1.5 J 3.5 U 1.3 J 2.2 J 1.7 U 0.87 U 410-15666-11 EB-13/0-2 0-2 09/29/2020 11 U 0.81 JU ND 3.6 J 4.5 U 54 1.1 J 2.2 U 1.4 J 1.4 J 1.4 J 1.2 J 2.0 J 2.2 U 1.1 U 410-15666-12 EB-13/2-6 2-6 09/29/2020 12 U 0.71 JU ND 2.6 J 3.9 U 39 1.7 J 1.9 U 1.9 J 1.1 J 1.8 J 2.0 J 2.4 J 1.9 U 0.97 U 410-15666-13 EB-13/6-10 6-10 09/29/2020 8.7 J 0.30 JU 8.7 7.2 J 3.9 U 60 3.2 J 2.0 U 2.0 U 1.3 J 3.9 U 1.6 J 3.1 J 1.1 J 0.50 J 410-15666-23 EB-14/0-2 0-2 09/29/2020 6.4 J 0.42 JU 6.4 3.6 J 4.6 UJ 84 J 2.2 J 1.6 J 2.2 J 3.8 J 4.6 UJ 3.6 J 5.2 J 1.2 J 1.1 UJ 410-14884-7 EB-15/0-2 0-2 09/22/2020 6.4 J 0.25 JU 6.4 2.4 J 0.91 UJ 57 J 2.2 J 0.55 UJ 4.2 J 4.1 J 0.91 UJ 3.6 J 5.1 J 0.97 J 0.36 UJ 410-14982-15 EB-16/0-2 0-2 09/23/2020 5.6 U 0.31 JU ND 1.7 U 0.83 U 22 J 1.3 J 0.50 U 2.5 J 2.4 J 0.83 U 2.0 J 3.0 J 0.83 U 0.33 U

Petroleum Hydrocarbons Volatile Organic Compounds (VOCs)

Ellsworth Air Force Base, South Dakota

LAB SAMPLE ID FIELD SAMPLE ID INTERVAL SAMPLE DATE

Diesel Range

Organics (DRO) Gasoline Range Organics (GRO) TPH* 2-Butanone 2-Hexanone Acetone Benzene Carbon Disulfide Cyclohexane Ethylbenzene Methyl Acetate

Methy-cyclohexane Toluene m&p-Xylene o-Xylene

Units (mg/kg) (mg/kg) (mg/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) (ug/kg) Method No. 8015C DRO 8015C GRO CALC 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD 8260C DOD

CAS No. NE NE NE 78-93-3 591-78-6 67-64-1 71-43-2 75-15-0 110-82-7 100-41-4 79-20-9 108-87-2 108-88-3 108-38-3 106-42-3 95-47-6

USEPA Residential RSLs NE NE NE 2700000 200000 6100000 1200 77000 650000 5800 7800000 NE 490000 550000 650000 USEPA Industrial RSLs NE NE NE 19000000 1500000 67000000 5100 350000 2700000 25000 120000000 NE 4700000 2400000 2800000

SD Remediation Criteria for Petroleum Contaminated Soil (Tier 1 Action Levels for Soil) 500 500 500 NE NE NE 200 NE NE 10000 NE NE 15000 300000 300000 Petroleum Disposal Criteria from SD Petroleum Assessment & Cleanup Handbook 10 10 10 NE NE NE NE NE NE NE NE NE NE NE NE

Air Force Guidance Memorandum AFFF PFOA/PFOS NE NE NE NE NE NE NE NE NE NE NE NE NE NE NE

Petroleum Hydrocarbons Volatile Organic Compounds (VOCs)

410-15425-7 EB-17/0-2 0-2 09/28/2020 12 U 0.52 JU ND 3.6 U 3.6 UJ 24 2.0 J 1.8 U 2.7 J 5.6 3.6 UJ 3.4 J 6.3 1.8 U 0.91 U 410-15425-8 EB-17/2-6 2-6 09/28/2020 12 U 0.39 JU ND 5.6 J 3.7 UJ 67 1.9 J 1.8 U 1.0 J 0.98 J 3.7 UJ 1.6 J 2.4 J 1.8 U 0.92 U 410-15425-9 EB-17/6-10 6-10 09/28/2020 12 U 0.85 JU ND 4.0 U 4.0 UJ 16 J 2.7 J 2.0 U 1.3 J 1.9 J 4.0 U 2.8 J 3.6 J 1.1 J 1.0 UJ

410-15425-10 EB-18/0-2 0-2 09/28/2020 12 U 0.41 JU ND 4.5 J 4.1 UJ 79 1.3 J 2.0 U 2.0 U 0.82 J 2.6 J 1.5 J 2.0 J 2.0 U 1.0 U 410-15425-11 EB-18/2-6 2-6 09/28/2020 12 U 0.35 JU ND 6.0 J 3.8 UJ 62 1.7 J 0.80 J 1.1 J 0.97 J 3.8 UJ 1.8 J 2.4 J 1.9 U 0.96 U 410-15425-12 EB-1018/2-6 (Duplicate of EB-18/2-6) 2-6 09/28/2020 12 U 0.38 JU ND 3.6 J 3.9 UJ 48 1.6 J 1.9 U 1.0 J 0.88 J 3.9 UJ 1.6 J 2.2 J 1.9 U 0.97 U 410-15425-13 EB-18/6-10 6-10 09/28/2020 12 U 0.42 JU ND 3.2 J 3.8 UJ 66 1.8 J 1.9 U 1.3 J 1.2 J 1.8 J 2.0 J 2.4 J 1.9 U 0.94 U 410-15425-14 EB-19/0-2 0-2 09/28/2020 12 U 0.57 JU ND 4.7 J 3.7 U 68 1.8 J 1.9 U 1.8 J 3.7 J 1.9 J 2.5 J 4.1 J 1.9 U 0.94 U 410-15425-15 EB-19/2-6 2-6 09/28/2020 12 U 1.0 JU ND 4.2 J 3.9 U 62 1.3 J 2.0 U 1.3 J 0.82 J 2.2 J 1.3 J 1.9 J 2.0 U 0.99 U 410-15425-16 EB-19/6-10 6-10 09/28/2020 11 U 2.2 J 2.2 2.7 J 4.7 U 45 2.8 J 2.3 U 2.7 J 1.7 J 4.7 U 2.8 J 3.4 J 2.3 U 1.2 U 410-14884-6 EB-20/0-2 0-2 09/22/2020 13 J 0.36 JU 13 5.9 J 0.89 UJ 180 J 1.7 J 0.54 UJ 1.9 J 4.0 J 0.89 UJ 2.0 J 4.5 J 0.89 UJ 0.36 UJ 410-14884-5 EB-21/0-2 0-2 09/22/2020 19 0.31 JU 19 2.1 J 0.85 UU 46 J 1.8 J 0.51 UJ 0.42 UJ 4.0 J 0.85 UJ 2.9 J 4.6 J 0.85 UJ 0.34 UJ 410-15264-6 EB-22/0-2 0-2 09/24/2020 7.2 J 0.53 JU 7.2 4.5 J 1.2 U 58 J 2.2 J 3.9 J 3.2 J 4.3 J 1.2 U 2.5 J 5.4 J 1.2 U 0.46 U 410-15264-7 EB-22/2-6 2-6 09/24/2020 5.8 U 1.1 JU ND 3.4 J 0.93 UJ 90 J 1.6 J 0.56 UJ 1.8 J 4.3 J 0.93 UJ 2.4 J 4.7 J 0.93 UJ 0.37 UJ 410-15264-8 EB-22/6-10 6-10 09/24/2020 5.9 U 0.39 JU ND 4.4 J 1.1 U 79 1.4 J 0.66 U 0.77 J 0.47 J 1.1 U 1.4 J 1.6 J 1.1 U…