Rohn_Final_RA_Report.pdf

FINAL

REMOVAL ACTION REPORT

Rohn Drum Spill Cleanup

Rohn, Alaska

August 2023

Contract Number: 140L6320P0046

Prepared For

U.S. Department of the Interior Bureau of Land Management Alaska 222 W. 7th Avenue, #13 Anchorage, Alaska 99513-7587

Prepared By

Bethel Environmental Solutions LLC 2605 Denali St., STE 100 Anchorage, AK 99503

FINAL

REMOVAL ACTION REPORT

Rohn Drum Spill Cleanup

Rohn, Alaska

August 2023

Contract Number: 140L6320P0046

This Report has been prepared by Bethel Environmental Solutions LLC and has been reviewed and approved for distribution.

Project Manager:

Quenton Nelson

Quenton Nelson Digitally signed by Quenton Nelson

Date: 2023.08.29 12:49:58 -04'00'

Removal Action Report Bureau of Land Management Rohn Drum Spill Cleanup Rohn, Alaska

140L6320P0046 Page i

Table of Contents

Executive Summary ...................................................................................................................... v

1.0 Introduction

1.1 Report Organization

1.2 Physical Setting

1.2.1 Geology/Hydrology

1.3 Site Background

1.4 Project Objectives

1.5 Applicable Cleanup Levels

2.0 Work Performed

2.1 Mobilization and Demobilization

2.2 Soil Excavation

2.3 Field Screening

2.4 Soil Sample Collection

2.4.1 Confirmation Samples

2.4.2 Total Organic Carbon Samples

2.4.3 ISM Samples

2.4.4 General Sample Collection Methods

2.5 Sample Storage, Transport and Chain of Custody Procedures

2.6 Waste Disposal

2.6.1 Landspreading

2.6.2 Decontamination and Investigation-Derived Waste

2.7 Deviations from the Work Plan

3.0 Results

3.1 Observations

3.2 Contaminated Soil Removal

3.3 Excavation Field Screening Results

3.4 Confirmation Soil Sample Results

3.4.1 Fuels Results

3.4.2 VOCs Results

3.4.3 PAH Compounds Results

3.5 Landspread Multi-Incremental Characterization Soil Sample Results

3.5.1 Fuels Results

3.5.2 VOCs Results

3.5.3 PAH Compounds Results

3.6 Data Quality

4.0 Conclusions and Recommendations

4.1 Conclusions

4.2 Recommendations

5.0 References

Bureau of Land Management Removal Action Report Rohn, Alaska Rohn Drum Spill Cleanup

Page ii 140L6320P0046

List of Figures

Figure 1. Vicinity Map

Figure 2. Rohn Site Map

Figure 3. Excavation and Sample Locations

Figure 4. Sidewall Screening Sample Locations

Figure 5. Excavation Confirmation Sample Locations

Figure 6. Landspread ISM Sample Grid and CUL Exceedances

List of Tables

Table 1-1. Rohn Drum Spill Site Location Information

Table 1-2. ADEC Soil CULs

Table 3-1. Field Screening Results

List of Appendices

Appendix A: Soil Sample Summary Reporting Tables

Appendix B: Photographic Log

Appendix C: Field Documentation

Appendix D: Analytical Laboratory Report

Appendix E: Data Quality Report

140L6320P0046 Page iii

Acronyms and Abbreviations

°C degrees Celsius

°F degrees Fahrenheit µg/kg micrograms per kilogram

AAC Alaska Administrative Code

ADEC Alaska Department of Environmental Conservation

AK State of Alaska Method

Bethel Bethel Environmental Solutions LLC bgs below ground surface

BLM Bureau of Land Management

CUL cleanup level

CY cubic yard

DRO diesel-range organics

DU decision unit

EPA Environmental Protection Agency

GPS global positioning system

GRO gasoline-range organics

IDW investigation-derived waste

ISM incremental screening methodology

ITRC Interstate Technology & Regulatory Council mg/kg milligrams per kilogram

N/A not applicable

PAH polycyclic aromatic hydrocarbon

PID photoionization detector ppm parts per million

QEP Qualified Environmental Professional

RA Removal Action

SIM Selected Ion Monitoring

SW Solid Waste Method

TOC total organic carbon

UCL upper confidence limit

VOC volatile organic compound

Page iv 140L6320P0046

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140L6320P0046 Page v

Executive Summary

The U.S. Department of the Interior, Bureau of Land Management Alaska (BLM) contracted

Bethel Environmental Solutions LLC (Bethel) to perform a contaminated soil removal action

(RA) at the former location of an abandoned drum, near the Rohn (Tatitna) airstrip, Alaska. In

2010, the BLM discovered an abandoned drum, labelled as JP4 fuel, in the spruce forest several hundred feet north of the Rohn (Tatitna) airstrip. The drum had been leaking and bears had created an approximately 2-foot-deep wallow in the spill among the roots of large spruce trees.

The BLM removed the half full drum shortly thereafter. The amount of fuel spilled and the vertical and lateral extents of the contamination was unknown, although the soil within the wallow exhibited a strong fuel odor when it was discovered. The BLM estimated that 10 cubic yards (CY) of soil had been contaminated.

Bethel performed the RA in August of 2022. The objective of the RA was to remove up to 10 CY of contaminated soil exceeding the most stringent Alaska Department of Environmental

Conservation (ADEC) Method Two cleanup levels (CULs). Contaminants of concern included diesel-range organics (DRO), gasoline-range organics (GRO), volatile organic compounds

(VOCs), and polycyclic aromatic hydrocarbons (PAHs). A description of the methods and results of the work performed are presented in the body of this report.

In August 2022, Bethel excavated between 11.1 and 12.5 CY of non-hazardous diesel-contaminated soil. Due to the remoteness of the site, the excavated contaminated soil was landspread on site, where it will be allowed to naturally attenuate.

Based upon field screening samples, the final excavation sidewalls and base were considered clean. Confirmation soil samples were collected from each of the excavation sidewalls, as well as the base. A total of five confirmation samples and one duplicate sample were collected.

After its construction, characterization samples were collected from the landspread using

Incremental Screening Methodology (ISM) sampling procedures. The landspread was treated as a single decision unit and one ISM sample was collected, as well as a duplicate and triplicate sample.

Additional work conducted at the site included the collection of 10 primary and one duplicate total organic carbon (TOC) samples from 10 random locations surrounding the excavation, so that site-specific Method Three CULs could be calculated, should the Method Two CULs not be met after the excavation of the contracted 10 CYs.

The confirmation and ISM characterization samples were analyzed for DRO, GRO, VOCs, and

PAHs. All of the analyte concentrations detected in the confirmation samples were determined to be below the respective most stringent ADEC Method Two CUL, when analyzed by the laboratory. DRO was determined to be the only analyte above the applicable ADEC Method

Two CUL, in the landspread ISM characterization samples.

Because the ADEC Method Two cleanup levels were met, Method Three CULs were not calculated for this report. The TOC sample results, however, are included.

Page vi 140L6320P0046

Based upon the results from the fuel spill cleanup at the Rohn drum spill site, it is recommended that the former spill location be considered clean, requiring no further action.

The landspread, however, currently consists of soil above the ADEC Migration to Groundwater

CUL for DRO, which is the current most stringent ADEC CUL applicable to the Rohn site. It is therefore recommended that the landspread be monitored periodically using ISM sampling techniques to characterize the soil. Because the natural attenuation of the landspread is likely to progress somewhat slowly, an attenuation period of three to five years is recommended between sampling events. The next sampling event should occur sometime between 2025 and

2027.

This Executive Summary is provided for the convenience of the reader and should not be relied upon without considering the entire report.

140L6320P0046 Page 1

1.0 INTRODUCTION

The U.S. Department of the Interior, Bureau of Land Management (BLM) contracted Bethel

Engineering and Consulting LLC (Bethel) to perform a contaminated soil removal action (RA) at the former location of an abandoned drum, near the Rohn (Tatitna) Airstrip, Alaska. Work was completed in accordance with the BLM Statement of Work, Bethel’s proposal dated 23

September 2020, Final Work Plan Rohn Drum Spill Cleanup (Bethel, 2022), and Alaska

Department of Environmental Conservation (ADEC) Field Sampling Guidance (ADEC, 2022).

1.1 Report Organization

This report is organized into the following sections:

● Section 1, Introduction. This section describes the physical setting of the site, including the geology, groundwater source and usage, and climate.

● Section 2, Work Performed. This section describes the field activities that took place during 2022.

● Section 3, Results. This section provides results for the 2022 RA and includes a discussion of the results of the laboratory data review.

● Section 4, Conclusions and Recommendations. This section provides conclusions and recommendations for the 2022 RA.

● Section 5, References. This section lists references that were used in development of this report.

● Appendix A. Soil Sample Summary Reporting Tables

● Appendix B. Photographic Log

● Appendix C. Field Documentation

● Appendix D. Analytical Laboratory Report

● Appendix E. Data Quality Report

1.2 Physical Setting

The site is located in a narrow river valley at the northern side of the Alaska Range. The climate is dominated by bitterly cold winters with short clear days and relatively little precipitation, mostly in the form of snow. Being situated between 50 to 70 degrees North latitude, the site’s climate can be characterized as a humid continental climate. The average annual precipitation is between 18 and 20 inches per year (US Forest Service, 2022). The site’s location information is provided in Table 1-1. See Figure 1 for the site location and vicinity.

Table 1-1. Rohn Drum Spill Site Location Information

Township and Range Northing (U.S. survey feet) Easting (U.S. survey feet)

Section 33, Township 26 North, Range 22 West, Seward Meridian

3031597.656473 1747154.802942

Page 2 140L6320P0046

1.2.1 Geology/Hydrology

The site is situated at confluence of the Kuskokwim and Tatina Rivers. As such, the site’s sediments are dominated by alluvial deposits consisting of various grain sizes, including sands, silts, gravels, and cobbles. The depth to groundwater is unknown.

1.3 Site Background

In 2010, the BLM discovered an abandoned drum, labelled as JP4 fuel, in the spruce forest several hundred feet north of the Rohn (Tatitna) airstrip. The drum had been leaking and bears had created an approximately 2-foot-deep wallow in the spill among the roots of large spruce trees.

The BLM removed the half full drum shortly thereafter. The amount of fuel spilled and the vertical and lateral extents of the contamination was unknown, although the soil within the wallow exhibited a strong fuel odor when it was discovered. The BLM estimated that 10 cubic yards (CY) of soil had been contaminated.

1.4 Project Objectives

The objectives of the work were to conduct an RA at the site of the known fuel spill at the drum spill site, including the following:

● mobilize field personnel from Anchorage to the Rohn (Tatitna) Airstrip, Alaska;

● remove contaminated soil with a limit of 10 CY;

● collect the required number of field screening samples from the excavation limits and test them with a photoionization detector (PID);

● collect the required number of confirmation soil samples from the final excavation limits;

● landspread the contaminated soil removed from the excavation, to allow for natural attenuation;

● collect one baseline triplicate Incremental Screening Methodology (ISM) sample from the landspread, for characterization purposes; and

● regrade the excavation sidewalls to resemble natural conditions and prevent animal or human injury or entrapment.

1.5 Applicable Cleanup Levels

The ADEC Contaminated Sites Program does not list the Rohn Drum site on their contaminated sites database. Applicable soil ADEC cleanup levels (CULs) are the most stringent listed in 18

Alaska Administrative Code (AAC) 75 Oil and other Hazardous Substances Pollution Control

(18 AAC 75), Tables B1 and B2 Under 40-inch Zone (ADEC, 2021). For most compounds, the

Migration to Groundwater CULs are the most stringent, but Human Health (direct contact) CULs are more stringent for some volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). A summary of the CULs is listed in Table 1-2.

140L6320P0046 Page 3

Table 1-2. ADEC Soil CULs

Contaminant Soil

(mg/kg)

Fuels by AK101, AK102 & AK103

Gasoline-Range Organics (GRO) 300

Diesel-Range Organics (DRO) 250

Fuel-Related VOCs by SW8260C

Benzene 0.022

Ethylbenzene 0.13

Toluene 6.7

Xylenes (total) 1.5

Other VOCs Varies by Compound

PAHs by SW8270D-SIM

1-Methylnaphthalene 0.41

2-Methylnaphthalene 1.3

Acenaphthene 37

Acenaphthylene 18

Anthracene 390

Benz(a)anthracene 0.28

Benzo[a]pyrene 0.27

Benzo[b]fluoranthene 2.0

Benzo[g,h,i]perylene 2,300

Benzo[k]fluoranthene 20

Chrysene 82

Dibenzo[a,h]anthracene 0.20*

Fluoranthene 590

Fluorene 36

Indeno[1,2,3-c,d] pyrene 2.0*

Naphthalene 0.038

Phenanthrene 39

Pyrene 87

AK = Alaska Method SIM = selected ion monitoring SW = solid waste method See Acronyms and Abbreviations for other definitions.

Page 4 140L6320P0046

Site 7

Kenai

Homer

Seward

McGrath

Anchorage

Drawn By: Contract No:Date:

SS March 2023

Figure 1

Vicinity Map Site 7 - Drum Location

BLM Abandoned Drum Site Rohn, Alaska

Notes:

1. Image Source: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community Source: Esri, Maxar, Earthstar Geographics, IGN, and the GIS User Community

Abandoned Drum Site

Bethel

McGrath

Fairbanks

Anchorage

Dillingham

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 5 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

Legend Approximate Drum Location

Cities_pt

USA Topo Maps

¹ 0 110,000 220,00055,000 Feet

140L6320P0046

Page 6 140L6320P0046

140L6320P0046 Page 7

Figure 2. Rohn Site Map

Page 8 140L6320P0046

140L6320P0046 Page 9

2.0 WORK PERFORMED

Field activities were completed in accordance with the Final Work Plan Rohn Drum Spill

Cleanup (Bethel, 2022) and the ADEC Field Sampling Guidance (ADEC, 2022), and included excavation and landspread of between 10 to 12.5 CY of contaminated soil, collection of confirmation samples from the sidewalls and floor of the excavation, collection of 11 randomly-spaced total organic carbon (TOC) samples, including a duplicate, and ISM sampling of the landspread. The following sections describe the activities conducted and methods used for each task performed during the RA. Appendix B contains photographs of key field activities. Appendix

C contains field notes.

2.1 Mobilization and Demobilization

The work was performed in August 2022. Bethel personnel mobilized to the site on 25 August

2022 via fixed wing charter flight and camped on site and/or overnighted in the Rohn

Roadhouse safety cabin during the mobilization. Because the site is located along the Iditarod route, in a historic, protected area, the contaminated soil was excavated by hand using hand tools to minimize the felling of trees. Bethel environmental scientist Quenton Nelson, an ADEC

Qualified Environmental Professional (QEP), led the excavation of soil and conducted field screening and laboratory sample collection. He was assisted by Bethel employees Amy

Wockenfuss, an ADEC Qualified Sampler and Ross Roylance, a laborer. Bethel personnel completed site work on 29 August and departed the site for Birchwood, AK on 30 August.

2.2 Soil Excavation

Excavation of contaminated soil began on 27 August and ended on 29 August. The contaminated soil was excavated by hand using handtools. Once excavated, contaminated soil was deposited in five-gallon buckets and lifted out of the excavation and carried to a nearby six-cubic-foot wheelbarrow, into which it was transferred. Cobbles six inches or greater in diameter were removed from the five-gallon buckets and piled near the excavation to be used as back fill, as permitted by the ADEC Technical Memorandum Petroleum Hydrocarbon Cleanup for

Oversize Materials (ADEC, 2005). Hydrocarbons do not normally adhere significantly to sediment of this size; separating it from smaller sediment ensures that the yardage calculated to have been removed reflects the actual contaminated sediments. Once full, the wheelbarrow was pushed to the prepared land spread area and dumped. Subsequent loads were dumped from the wheelbarrow in regularly spaced piles to ensure the soil could be easily hand spread to the required landspread thickness, 4 to 6 inches.

The excavation began at the center of the bear wallow, where the contaminated sample had previously been collected, and extended laterally and vertically as determined by the QEP, using PID readings and olfactory observations to screen the soil as it was excavated. Per the contract, an attempt was not made to separate any overburden. See Appendix B for photographs of the excavation and excavation process.

A total of 50 wheelbarrow loads were excavated. At 6 cubic feet per wheelbarrow load, that is

300 cubic feet or 11.1 CY. The final excavation dimensions vary by depth, based upon the lithology of the soil and how the fuel spread as it infiltrated the ground. In total, the excavation

Page 10 140L6320P0046 extended 4.7 feet below the ground surface (bgs). The upper 2.7 feet of the main excavation was measured to be 9.65 feet long and 7.8 feet wide. The soil in the upper 2.7 feet consisted of a grey, fine, silty sand. The lower 2 feet of the main excavation was measured to be 7.9 feet long and 7.0 feet wide, creating a bench on all four sides of the excavation at 2.7 feet bgs. The soil in the lower 2 feet consisted of a grey sand with cobbles. A 2.5- feet -by-2- feet alcove was extended into the northwest wall, 1.8 feet northeast of the southwest sand and cobble bench, immediately under where the drum had been located, to remove a vein of contaminated soil that extended in that direction. The alcove extended from the ground surface to 4.7 feet bgs. When calculated using the dimensions of the excavation, approximately 12.5 CY of contaminated soil were excavated. The difference in total CY excavated between the two methods of calculating is at likely accounted for by the 6-inch plus cobbles that were removed from the excavated soil, the compaction of the soil before excavation, and mounded soil in the wheelbarrow loads.

2.3 Field Screening

The PID was calibrated using 100 parts per million (ppm) isobutylene and a clean air blank prior to use each day. Heated headspace field screening was conducted in accordance with the approved work plan and 2022 ADEC Field Sampling Guidance (Bethel, 2022; ADEC, 2022).

Once preliminary field screenings indicated that contaminated soil above 20 ppm had been removed from all four sidewalls as well as the floor, the final field screening samples were collected from the four sidewalls and floor, following Table 2B of the ADEC Field Sampling

Guidance (ADEC, 2022). Six field screening samples were collected from the longer northwestern and southeastern excavation sidewalls, four were collected from the shorter northeastern and southwestern excavations sidewalls, and five from the floor of the excavation.

Since two lithological layers were observed in the excavation, the sidewall screening samples were split between the two layers. The upper screening samples were collected from the base of the silty sandy layer, and the lower screening samples were collected from the vertical center of the layer of cobbly sand. See Figure 4 for sketches of the vertical and horizontal spacing of the field screening samples in the sidewalls of the excavation. Section 3.3 presents a discussion of the field screening results from the excavation.

The field screening locations were measured using a survey-grade global positioning system

(GPS), however, as the excavation was advanced in a heavily wooded area, the trees obscured the GPS, satellite connection and prevented the target accuracy of plus or minus one foot horizontal and 0.1-foot vertical. See Section 2.7 for a more detailed discussion of this issue. See

Figure 3 for locations of the excavation boundary and field screening sample locations.

2.4 Soil Sample Collection

2.4.1 Confirmation Samples

Confirmation soil samples were collected using disposable sample spoons from each of the excavation sidewalls and floor in accordance with Table 2B of the 2022 ADEC Field Sampling

Guidance (ADEC, 2022). A total of five confirmation samples and one duplicate sample were collected, as detailed below.

140L6320P0046 Page 11

● The northern sidewall confirmation sample was identified as RD-NSS01 and was collected at a depth of 2.7 feet bgs. A duplicate of this sample was collected and was identified as

RD-NSS02.

● The southern sidewall confirmation sample was identified as RD-SSS02 and was collected at a depth of 2.7 feet bgs.

● The eastern sidewall confirmation sample was identified as RD-ESS03 and was collected at a depth of 2.7 feet bgs.

● The western sidewall confirmation sample was identified as RD-WSS04 and was collected at a depth of 2.7 feet bgs.

● The floor of the excavation confirmation sample was identified as RD-BSS05 and collected at a depth of 4.7 feet bgs.

The confirmation sample locations were measured using a survey-grade GPS, however, as the excavation was advanced in a heavily wooded area, the trees obscured the GPS satellite connection and prevented the target accuracy of plus or minus one foot horizontal and 0.1-foot vertical. See Section 2.7 for a more detailed discussion of this issue. See Figure 3 for locations of the excavation boundary and confirmation sample locations.

2.4.2 Total Organic Carbon Samples

Using a hand auger, ten test holes were advanced in random locations surrounding the excavation to varying depths corresponding to those in the excavation. Ten TOC samples and one duplicate were collected from the bottom of each test hole, for the purpose of calculating a

Method Three Alternative Cleanup Level, if necessary.

The TOC sample locations were measured using a survey-grade GPS, however, as the excavation area was in a heavily wooded area, the trees obscured the GPS, satellite connection and prevented the target accuracy of plus or minus one foot horizontal and 0.1-foot vertical.

See Section 2.7 for a more detailed discussion of this issue. See Figure 3 for the TOC sample locations.

2.4.3 ISM Samples

A single ISM sample, including a duplicate and triplicate sample was collected from the landspread for baseline characterization purposes. ISM procedures described by the Interstate

Technology & Regulatory Council (ITRC) were followed (ITRC, 2020).

For the purposes of ISM sampling, the landspread was considered to be a single decision unit

(DU). A thirty-point grid, composed of thirty rectangular segments, defined by six columns and five rows was established atop the landspread. Each rectangular segment was then divided into four quadrants and one quadrant was randomly selected to be the sampling point from which a subsample would be collected from each of the gird segments, resulting in thirty sub-samples.

Each of the thirty sub-samples was collected from an approximate depth of two inches and composited with the remaining 29 subsamples, resulting a single ISM sample. The duplicate and triplicate were collected following the same procedures. The duplicate subsamples, however, were collected from one of the three remaining unsampled rectangle quadrants, while

Page 12 140L6320P0046 the triplicate subsamples were collected from one of the two remaining unsampled rectangle quadrants, ensuring that no segment quadrant was sampled more than once.

The four corners of the landspread were measured using a survey-grade GPS, however, as the excavation area was in a heavily wooded area, the trees obscured the GPS, satellite connection and prevented the target accuracy of plus or minus one foot horizontal and 0.1-foot vertical. See

Section 2.7 for a more detailed discussion of this issue. Figure 6 depicts the ISM sampling grid layout.

2.4.4 General Sample Collection Methods

Analytical soil samples collection followed the protocols outlined in the Final Work Plan Rohn

Drum Spill Cleanup (Bethel, 2022). Samples were collected in the appropriate certified-cleaned laboratory-provided glass sample jars with Teflon-lined lids. Sample containers were filled as required by the analytical method. For field-preserved methods, such as GRO and VOCs, 25 milliliters of laboratory-provided methanol with surrogate were added to a pre-tared 4-ounce jar immediately prior to sample collection. Next, approximately 50 grams of soil were quickly placed in the jar, ensuring the soil was completely covered in methanol. Samples analyzed for volatile components were collected first, followed by semi-volatiles, then non-volatile analytes. For unpreserved sample aliquots, containers were filled to the top with care taken to prevent soil from touching the lid threads, which could compromise the integrity of the seal.

Soil samples were submitted to SGS Laboratory in Anchorage, Alaska. Analytical methods employed for this project included the following:

● GRO by AK 101;

● DRO by AK 102;

● VOCs by US Environmental Protection Agency (EPA) SW8260D;

● PAH by EPA Method 8270D-SIM; and

● TOC by EPA Method SW9060A-Mod.

Figure 5 shows the locations of all of the confirmation soil samples collected within the excavation boundary. One duplicate sample was collected (RD-NSS02). Results are discussed in Section 3.0.

2.5 Sample Storage, Transport and Chain of Custody Procedures

Due to the remoteness of the site and duration of the project, gel ice could not be kept frozen throughout the duration of the field effort. Frozen gel ice was, therefore, not available immediately following collection. To compensate, the collection of samples was delayed as long as possible and samples were not collected until the last full day on site, the day before the morning extraction from the site via fixed-wing charter. Ambient daytime air temperatures were in the low 60s degrees Fahrenheit (°F). Once collected, samples were placed in a cooler and the cooler was placed in the area shaded by vegetation. Frozen gel ice was added to the cooler the next day, immediately upon arrival in Anchorage, and maintained at 4 degrees Celsius (°C)

± 2 °C. The samples were delivered by Bethel personnel to the SGS Laboratory in Anchorage.

The analytical report is provided in Appendix D.

140L6320P0046 Page 13

2.6 Waste Disposal

2.6.1 Landspreading

The excavated soil was spread on site in a 34-foot by 24-foot area that had previously been stripped of vegetation, to an approximate thickness of four inches, creating a landspread where the soil will be allowed to naturally attenuate. The soil was spread using hand rakes.

2.6.2 Decontamination and Investigation-Derived Waste

Investigation-derived waste (IDW) consisted of disposable sampling equipment and personal protective equipment. IDW was disposed of as solid waste at the Nome Landfill. Any soil remaining on the non-disposable hand tools, such as shovels and rakes was scraped off and the hand tools were scrubbed utilizing and Alconox wash, followed by a freshwater rinse. The same procedure was followed on the mini-backhoe loader bucket, excavator bucket, and tires.

2.7 Deviations from the Work Plan

The following deviation were made from plans specified in the work plan:

● An attempt was made to measure all sample locations and the four corners of the landspread using a survey-grade GPS to an accuracy of plus or minus one foot horizontal and 0.1-foot vertical, however, as the excavation area was in a heavily wooded area, trees obscured the GPS satellite connection and prevented the target accuracy from being met on all but a few points, the locations of screening samples RD-B1, RD-B2, RD-B4, and

RD-B5, as well the southeast corner of the landspread. Because the remainder of the points were within an accuracy of multiple feet, which would not result in an accurate depiction of the excavation on a map, the recorded field measuring tape measurements and sketches were utilized to draft to-scale diagrams of the excavation and landspread boundaries, as wells as the screening and confirmation sample locations. These diagrams were then superimposed over the points that met the survey target accuracy on a map, to provide an accurate depiction of the layout and location of the excavation, landspread, and samples. See Figure 3, Figure 5, and Figure 6. It should be noted that no field measurements were collected for the TOC sample, so the survey data must be relied on for their location.

● Due to the remoteness of the site and duration of the project, gel ice could not be kept frozen throughout the duration of the field effort. Frozen gel ice was, therefore, not available immediately following collection. To compensate, the collection of samples was delayed as long as possible and samples were not collected until the last full day on site, the day before the morning extraction from the site via fixed-wing charter. Ambient daytime air temperatures were in the low 60s °F. Once collected, samples were placed in a cooler and the cooler was placed in the area shaded by vegetation. Frozen gel ice was added to the cooler the next day, immediately upon arrival in Anchorage, and maintained at 4 °C ± 2 °C. The samples were delivered by Bethel personnel to the SGS Laboratory in

Anchorage.

Page 14 140L6320P0046

RD-B5

RD-B3

WW-1

WW-4

NW-4

NW-2

NW-1

NW-3WW-6

WW-5

WW-3

WW-2

SW-2

SW-3

SW-1

SW-4 EW-4

EW-1

EW-5

EW-2

EW-6

EW-3

RD-B1

RD-B2

RD-B4

RD-TC01

RD-TC02

RD-TC03

RD-TC04

RD-TC05

RD-TC06

RD-TC07

RD-TC08

RD-TC09

RD-TC10

Drawn By: Contract No:Date:

SS March 2023

Figure 3

Excavation and Sample Locations Site 7 - Drum Location

BLM Abandoned Drum Site Rohn, Alaska

Notes:

1. Image Source: Source: Esri, Maxar, Earthstar Geographics, IGN, and the GIS User Community

USAF (2016)

Abandoned Drum Site

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 5 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

¹ 0 3 61.5 Feet

140L6320P0046

Excavation Boundary

Legend Total Organic Carbon Sample Locations

Surveyed Screening Sample Location

) Field Measured Field Screening Location

Excavation Bench

Page 16 140L6320P0046

Drawn By: Contract No:Date:

SS April 2023

Figure 4

Sidewall Screening Sample Locations

Site 7 - Drum Location BLM Abandoned Drum Site

Rohn, Alaska

Abandoned Drum Site

Source: Esri, Maxar, Earthstar Geographics, IGN, and the GIS User Community

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

140L6320P0046

Page 18 140L6320P0046

Figure 5

Excavation Confirmation Sample Locations

Site 7 - Drum Location BLM Abandoned Drum Site

Rohn, Alaska

Notes:

1. Image Source: World Imagery (Clarity): Source: Esri, Maxar, Earthstar Geographics, IGN, and the GIS User Community

USAF (2016)

Abandoned Drum Site

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 5 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

0 1.5 30.75 Feet

140L6320P0046

Excavation Boundary

Legend Total Organic Carbon Sample Locations

Surveyed Screening Sample Location

Field Measured Field Screening Location

Excavation Bench

GRO (mg/kg) 300 DRO (mg/kg) 250 1,3,5‐Trimethylbenzene ( µg/kg) 660 Benzene (µg/kg) 22 Ethylbenzene (µg/kg) 130 Total Xylenes (µg/kg) 1,500 Toluene (µg/kg) 6,700 n‐Propylbenzene (µg/kg) 9,100

Applicable CUL

GRO (mg/kg) 2.61 J DRO (mg/kg) 14.2 J Ethylbenzen (µg/kg) 16.2 J Toluene ( µg/kg) 23.1 J

RD-ESS03

GRO (mg/kg) 2.91 J

RD-NSS01

GRO (mg/kg) 2.85 J

RD-SSS02

GRO (mg/kg) 3.3 J DRO (mg/kg) 32.8

RD-WSS04

GRO (mg/kg) 1.85 J DRO (mg/kg) 30.8 1,3,5‐Trimethylbenzene ( µg/kg) 17.9 J Benzene (µg/kg) 3.84 J Ethylbenzene (µg/kg) 20.5 J Total Xylenes (µg/kg) 64.4 J Toluene (µg/kg) 35 n‐Propylbenzene 10.6 J

RD-BSS05

GRO (mg/kg) 1.69 J DRO (mg/kg) 10.5 J

RD-NSS02

Page 20 140L6320P0046

Figure 6

Landspread ISM Sample Grid and CUL Exceedances Site 7 - Drum Location

BLM Abandoned Cabin Sites Buckland, Alaska

Notes:

1. Image Source: Source: Esri, Maxar, Earthstar Geographics, IGN, and the GIS User Community

USAF (2016)

Bethel Anchorage

Unalakleet

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 5 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

¹ 0 5 102.5 Feet

140L6320P0046

Legend DU Segment Boundaries

DU Segment Quadrant Boundaries

DRO (mg/kg) 250 Applicable CUL

Abandoned Drum Site

Primary Sample DRO (mg/kg) 3,030 Duplicate Sample DRO (mg/kg) 2,430 Triplicate Sample DRO (mg/kg) 2,690 DRO 95% UCL (mg/kg) 3,223.9

Landspread ISM Results above the CUL

Page 22 140L6320P0046

140L6320P0046 Page 23

3.0 RESULTS

Results of the 2022 RA are provided in this section. Soil sample analytical results are compared with ADEC Method Two CULs promulgated in 18 AAC 75 Articles 3 and 9, Oil and Other

Hazardous Substance Pollution Control Regulations (ADEC, 2021). Data tables of the analytical results are provided in Appendix A.

3.1 Observations

During excavation, two lithographic unit were encountered. The upper 2.7 feet of the excavation was in a moist, grey, fine silty sand. The lower 2 feet of the excavation was in a damp, grey, medium sand with cobbles. Groundwater was not encountered.

3.2 Contaminated Soil Removal

A total of between 11.1 to 12.5 CY of contaminated soil were removed during the excavation.

Estimations of the total volume differ based upon the method of estimating. Based upon field screening, olfactory observations, and confirmation samples, the four walls and floor of the excavation were all considered “clean.”

3.3 Excavation Field Screening Results

The results from 26 field screening samples collected at the excavation are provided on Table

3-1. The excavation field screening sample locations are shown in Figure 3 and Figure 4 for the excavation sidewalls and Figure 3 for the excavation floor locations. PID field screening results ranged from 0 ppm to 5.8 ppm.

Table 3-1. Field Screening Results

PID Screening Sample Location in Excavation Depth Collected

(feet bgs) Result (ppm)

Corresponding Confirmation Sample

NW-1 Northeast Wall 2.7 1.26 N/A

NW-2 Northeast Wall 2.7 14.82 RD-NSS01 & RD-NSS02

NW-3 Northeast Wall 3.7 4.42 N/A

NW-4 Northeast Wall 3.7 4.25 N/A

SW-1 Southwest Wall 2.7 6.05 RD-SSS02

SW-2 Southwest Wall 2.7 4.63 N/A

SW-3 Southwest Wall 3.7 2.92 N/A

SW-4 Southwest Wall 3.7 1.7 N/A

EW-1 Southeast Wall 2.7 0.82 N/A

EW-2 Southeast Wall 2.7 3.55 N/A

EW-3 Southeast Wall 2.7 4.97 RD-ESS03

EW-4 Southeast Wall 3.7 1.5 N/A

EW-5 Southeast Wall 3.7 0 N/A

EW-6 Southeast Wall 3.7 0 N/A

Page 24 140L6320P0046

PID Screening Sample Location in Excavation Depth Collected

(feet bgs) Result (ppm)

Corresponding Confirmation Sample

WW-1 Northwest Wall 2.7 5.92 RD-WSS04

WW-2 Northwest Wall 2.7 0.58 N/A

WW-3 Northwest Wall 2.7 0 N/A

WW-4 Northwest Wall 3.7 0 N/A

WW-5 Northwest Wall 3.7 0 N/A

WW-6 Northwest Wall 3.7 0 N/A

B-1 Base 4.7 3.44 N/A

B-2 Base 4.7 0.52 N/A

B-3 Base 4.7 1.79 N/A

B-4 Base 4.7 0.21 N/A

B-5 Base 4.7 4.63 RD-BSS05

B-6 Base 4.7 0 N/A

N/A = not applicable See Acronyms and Abbreviations for definitions.

3.4 Confirmation Soil Sample Results

Soil confirmation samples were analyzed for GRO, DRO, VOCs, and PAHs. Table A-1 in

Appendix A presents the complete soil sample results, where they are compared to the most stringent of the ADEC CULs listed in Tables B1 and B2 Under 40-inch Zone of the 18 AAC 75

Oil and Other Hazardous Substances Pollution Control (ADEC, 2021). In most cases, the

Migration to Groundwater CULs are the most stringent, but Human Health (direct contact) CULs are more stringent for some VOCs and PAHs. Figure 5 shows the sample locations and the detectable analyte results.

3.4.1 Fuels Results

Confirmation sample results for GRO and DRO were below the applicable ADEC CULs of 300 and 250 mg/kg, respectively, in each of the samples. GRO was detected in all six confirmation samples, including the duplicate, with sample RD-WSS04, from the northwest sidewall having the highest concentration, 3.3 J mg/kg. DRO was detected in four of the six samples, including the duplicate, with sample RD-WSS04, from the northwest sidewall, having the highest concentration, 32.8 mg/kg.

3.4.2 VOCs Results

No VOCs were detected above their respective applicable CUL. Benzene, ethylbenzene, toluene, total xylenes, n-propylbenzene, and 1,3,5-trimethylbenzene, however, were detected in samples below their applicable respective CULs. Benzene, which has an applicable CUL of 22 micrograms per kilogram (µg/kg), was detected in sample RD-BSS05 at a concentration of 3.84

J µg/kg. Ethylbenzene, which has an applicable CUL of 130 µg/kg, was detected in samples

RD-ESS03 and RD-BSS05 at concentrations of 16.2 J µg/kg and 20.5 J µg/kg, respectively.

Toluene, which has an applicable CUL of 6,700 µg/kg, was detected in samples RD-ESS03 and

140L6320P0046 Page 25

RD-BSS05 at concentrations of 23.1 J and 35 µg/kg, respectively. Total xylenes, which have an applicable CUL of 1,500 µg/kg, were detected in sample RD-BSS05 at a concentration of 64.4 J µg/kg. N-propylbenzene, which has an applicable CUL of 9,100 µg/kg, was detected in sample

RD-BSS05 at a concentration of 10.6 J µg/kg. Finally, 1,3,5-Trimethylbenzene, which has an applicable CUL of 660 µg/kg, was detected in sample RD-BSS05 at a concentration of 17.9 J µg/kg.

Eleven other VOCs, 1,1,1,2-tetrachloroethane, 1,2,3-trichloropropane, 1,2-dibromoethane, 2-hexanone, bromoform, chloroform, dibromochloromethane, dibromomethane, hexachlorobutadiene, trichloroethene, and vinyl chloride, although not detected in any of the confirmation samples, had analysis detection limits greater than the applicable respective CUL.

Although it cannot be definitively stated that these analytes were not present in the samples at concentrations above the applicable respective CUL, their presence at concentrations above the

CULs is highly unlikely, given the concentrations of the other VOC analytes in the samples.

3.4.3 PAH Compounds Results

No PAH compounds were detected above their applicable respective CULs.

3.5 Landspread Multi-Incremental Characterization Soil Sample Results

A single DU, multi-incremental soil sample, including a duplicate and a triplicate was collected to characterize the landspread, and was analyzed for GRO, DRO, VOCs, and PAHs. Table A-2 in

Appendix A presents the complete soil sample results, where they are compared to the most stringent of the ADEC CULs listed in Tables B1 and B2 Under 40-inch Zone of the 18 AAC 75

Oil and Other Hazardous Substances Pollution Control (ADEC, 2021). In most cases, the

Migration to Groundwater CULs are the most stringent, but Human Health (direct contact) CULs are more stringent for some VOCs and PAHs. Figure 6 shows the ISM sampling grid layout with the results exceeding the respective applicable results.

3.5.1 Fuels Results

DRO was detected above the respective applicable ADEC CUL of 250 mg/kg in the primary, duplicate, and triplicate Landspread ISM samples, at concentrations of 3,030, 2,430, and 2,690 mg/kg, respectively. Using the DRO concentrations from the primary, duplicate, and triplicate samples, a 95% upper confidence limit (UCL) of the arithmetic mean was calculated for DRO using the procedures and calculations detailed in the ITRC’s Incremental Sampling

Methodology Update (ITRC, 2020). These calculations resulted in a 95% UCL of 3,223.9 mg/kg, indicating that, with 95% confidence, the true average concentration of the soil in the landfill is below 3,223.9 mg/kg.

GRO was not detected above the applicable ADEC CULs of 300 mg/kg, respectively, in the primary, duplicate, or triplicate ISM samples. The highest GRO detection was 16.3 mg/kg. The

GRO concentrations are far below the relevant CUL and do not warrant the calculation of a 95%

UCL.

Page 26 140L6320P0046

3.5.2 VOCs Results

No VOCs were detected above the respective applicable CUL in the ISM samples. Toluene and total xylenes, however, were detected in the primary, duplicate, and triplicate samples, below their applicable CULs of 6,700 and 1,500 µg/kg, respectively. The highest toluene concentration detected was 38.5 J µg/kg and the highest total xylenes concentration detected was 73.7 J µg/kg. Given that the highest toluene and total xylenes concentrations were far below the applicable CULs, the calculation of a 95% UCL for these compounds was not necessary.

Nine other VOCs, 1,2,3-trichloropropane, 1,2-dibromoethane, 2-hexanone, dibromochloromethane, dibromomethane, hexachlorobutadiene, trichloroethene, and vinyl chloride, although not detected in any of the ISM samples, had analyses detection limits greater than the applicable CULs. Although it cannot be definitively stated that these analytes were not present in the samples at concentrations above the applicable respective CULs, their presence at concentrations above the CULS is highly unlikely give the concentrations of the other VOC analytes in the samples. Given that VOCs were not detected in the samples, the calculation of a

95% UCL for these compounds was not necessary and could not be performed.

3.5.3 PAH Compounds Results

No PAH compounds were detected in the ISM samples.

3.6 Data Quality

A data quality assessment of laboratory data for soil samples was performed on the laboratory data. Laboratory data were evaluated using laboratory-supplied control criteria. The data review included assessments of holding times, blanks, matrix spike/matrix spike duplicate and laboratory control spike sample recoveries, duplicate sample relative percent differences, reporting limits, and an overall assessment of the data.

Appendix E contains the data quality assessment which includes an ADEC Laboratory Checklist for the data package. Appendix D contains the Level II Laboratory Data Report.

The data validation review determined the overall quality of the Rohn cleanup samples to be acceptable. Precision, accuracy, representativeness, comparability, and completeness were deemed acceptable, and the data are usable for the purposes of this project. Project sample results affected by quality control anomalies have been flagged accordingly.

140L6320P0046 Page 27

4.0 CONCLUSIONS AND RECOMMENDATIONS

An RA was conducted for a fuel spill at the Rohn drum spill site, near the Rohn (Tatitna) airstrip, Alaska. The RA was performed with the objective of removing contaminated soil above the most stringent ADEC Method Two CULs. Background total organic carbon samples were collected from the site, so that site specific Method Three CULs could be calculated, if the ADEC Method

Two CULs were not met after the excavation of the contracted 10 CYs. This report, however, does not present Method Three CULs, as the Method Two CULs were met. The TOC sample results, however, are presented in Table A-3 in Appendix A. Conclusions from this RA are discussed below.

4.1 Conclusions

The excavation removed between 11.1 and 12.5 CY of contaminated soil, slightly over the contracted amount. Six characterization soil samples were collected from the excavation, including one duplicate sample. These samples were analyzed for DRO, GRO, VOCs, and

PAHs. Analyte concentrations were below the most stringent ADEC Method Two CULs in all confirmation samples, indicating that all soil exceeding the Method Two CULs related to the

Rohn drum spill has been excavated.

The excavated soil was subsequently spread in a 34-foot by 24-foot landspread to a thickness of approximately four inches, to optimize conditions for natural attenuation. A grid was then established atop the landspread and the landspread was sampled using ISM sampling methods to characterize the soil. The ISM primary, duplicate, and triplicate samples were analyzed by a laboratory for DRO, GRO, VOCs, and PAHs. The analytical results of these samples indicated that DRO was the only analyte with concentrations above the most stringent ADEC Method Two

CULs in the landspread soil. DRO concentrations from the primary, duplicate, and triplicate samples were used to calculate a 95% UCL of 3,223.9 mg/kg, indicating with 95% confidence that the average concentration of DRO in the landspread soil was below 3,223.9 mg/kg at the time of the construction of the landspread.

4.2 Recommendations

Based upon the conclusions from the fuel spill cleanup at the Rohn drum spill site, it is recommended that the former spill location be considered clean, requiring no further action.

The landspread, however, currently consists of soil above the ADEC Migration to Groundwater

CUL for DRO, which is the current most stringent ADEC CUL applicable to the Rohn drum spill site. It is therefore recommended that the landspread be monitored periodically using ISM sampling techniques to characterize the soil. Because the natural attenuation of the landspread is likely to progress somewhat slowly, an attenuation period of three to five years is recommended between sampling events. The next sampling event should occur sometime between 2025 and 2027.

Page 28 140L6320P0046

140L6320P0046 Page 29

5.0 REFERENCES

ADEC. (2005, September 1). Technical Memorandum. Petroleum Hydrocarbon Cleanup for

Oversized Material.

ADEC. (2017, January). Policy Guidance on Developing Conceptual Site Models.

ADEC. (2017, March). Technical Memorandum. Data Quality Objectives, Checklists, Quality

Assurance Requirements for Laboratory Data and Sample Handling.

ADEC. (2021, November 18). 18 AAC 75 Oil and Other Hazardous Substances Pollution

Control. Alaska.

ADEC. (2022). Field Sampling Guidance.

Bethel. (2022, August). Final Work Plan, Rohn Drum Spill Cleanup, Rohn Alaska.

ITRC. (2020, February). Incremental Sampling Methodology Update.

US Forest Service. (2022, August 29). Historical Annual Precipitation (Alaska). Retrieved April

18, 2023, from https://hub.arcgis.com/datasets/80907fbc5b6c4512951da227ddf4758b/explore

Page 30 140L6320P0046

140L6320P0046 Appendix A

Appendix A:

Soil Sample Summary Reporting Tables

Appendix A 140L6320P0046

Client Sample ID: RD-NSS01 RD-SSS02 RD-ESS03 RD-WSS04 RD-BSS05

Lab Sample ID: 1225265019 1225265020 1225265021 1225265022 1225265023

Matrix: Soil/Solid (dry weight) Soil/Solid (dry weight) Soil/Solid (dry weight) Soil/Solid (dry weight) Soil/Solid (dry weight)

Location: Northeast Sidewall Southwest Sidewall Southeast Sidewall Northwest Sidewall Base

Sample Date: 8/29/2022 4:35 PM 8/29/2022 5:00 PM 8/29/2022 4:50 PM 8/29/2022 5:00 PM 8/29/2022 5:05 PM

Analysis Analyte Unit 18AAC75MigGW >

8270D SIM (PAH) 1-Methylnaphthalene ug/kg 410 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) 2-Methylnaphthalene ug/kg 1300 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Acenaphthene ug/kg 37000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Acenaphthylene ug/kg 18000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Anthracene ug/kg 390000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Benzo(a)Anthracene ug/kg 700 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Benzo[a]pyrene ug/kg 1500 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Benzo[b]Fluoranthene ug/kg 15000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Benzo[g,h,i]perylene ug/kg 2300000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Benzo[k]fluoranthene ug/kg 150000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Chrysene ug/kg 600000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Dibenzo[a,h]anthracene ug/kg 1500 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Fluoranthene ug/kg 590000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Fluorene ug/kg 36000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Indeno[1,2,3-c,d] pyrene ug/kg 15000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Naphthalene ug/kg 38 13.9 U 13.9 U 10.7 U 11.9 U 10.3 U

8270D SIM (PAH) Phenanthrene ug/kg 39000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

8270D SIM (PAH) Pyrene ug/kg 87000 17.3 U 17.4 U 13.4 U 14.9 U 12.9 U

AK101 Gasoline Range Organics mg/kg 300 2.91 J 2.85 J 2.61 J 3.30 J 1.85 J

AK102 Diesel Range Organics mg/kg 250 13.8 U 14.2 U 14.2 J 32.8 30.8

MI-ITRC ISM (Feb 2012) Multi-Incremental Sub Sampling

SM21 2540G Total Solids % NA 71.8 70.5 91.9 82.2 95.9

SW8260D 1,1,1,2-Tetrachloroethane ug/kg 22 24.0 U 27.4 U 18.6 U 27.3 U 8.85 U

SW8260D 1,1,1-Trichloroethane ug/kg 32000 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

SW8260D 1,1,2,2-Tetrachloroethane ug/kg 3 2.40 U 2.75 U 1.87 U 2.73 U 0.885 U

SW8260D 1,1,2-Trichloroethane ug/kg 1.4 1.20 U 1.38 U 0.930 U 1.37 U 0.443 U

SW8260D 1,1-Dichloroethane ug/kg 92 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

SW8260D 1,1-Dichloroethene ug/kg 1200 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

SW8260D 1,1-Dichloropropene ug/kg NA 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

SW8260D 1,2,3-Trichlorobenzene ug/kg 150 120 U 138 U 93.0 U 137 U 44.3 U

SW8260D 1,2,3-Trichloropropane ug/kg 0.031 2.40 U 2.75 U 1.87 U 2.73 U 0.885 U

SW8260D 1,2,4-Trichlorobenzene ug/kg 82 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

SW8260D 1,2,4-Trimethylbenzene ug/kg 610 120 U 138 U 93.0 U 137 U 44.3 U

SW8260D 1,2-Dibromo-3-chloropropane ug/kg NA 120 U 138 U 93.0 U 137 U 44.3 U

SW8260D 1,2-Dibromoethane ug/kg 0.24 1.80 U 2.06 U 1.40 U 2.04 U 0.665 U

SW8260D 1,2-Dichlorobenzene ug/kg 2400 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

SW8260D 1,2-Dichloroethane ug/kg 5.5 2.40 U 2.75 U 1.87 U 2.73 U 0.885 U

SW8260D 1,2-Dichloropropane ug/kg 30 12.0 U 13.8 U 9.30 U 13.7 U 4.42 U

SW8260D 1,3,5-Trimethylbenzene ug/kg 660 30.0 U 34.3 U 23.3 U 34.1 U 17.9 J

SW8260D 1,3-Dichlorobenzene ug/kg 2300 30.0 U 34.3 U 23.3 U 34.1 U 11.1 U

Job1225265

Table A-1: Excavation Confirmation Sample Results

Description: BLM Rohn Drum

Client Sample ID:

Lab Sample ID:

Matrix:

Location:

Sample Date:

Analysis Analyte Unit 18AAC75MigGW >

8270D SIM (PAH) 1-Methylnaphthalene ug/kg 410

8270D SIM (PAH) 2-Methylnaphthalene ug/kg 1300

8270D SIM (PAH) Acenaphthene ug/kg 37000

8270D SIM (PAH) Acenaphthylene ug/kg 18000

8270D SIM (PAH) Anthracene ug/kg 390000

8270D SIM (PAH) Benzo(a)Anthracene ug/kg 700

8270D SIM (PAH) Benzo[a]pyrene ug/kg 1500

8270D SIM (PAH) Benzo[b]Fluoranthene ug/kg 15000

8270D SIM (PAH) Benzo[g,h,i]perylene ug/kg 2300000

8270D SIM (PAH) Benzo[k]fluoranthene ug/kg 150000

8270D SIM (PAH) Chrysene ug/kg 600000

8270D SIM (PAH) Dibenzo[a,h]anthracene ug/kg 1500

8270D SIM (PAH) Fluoranthene ug/kg 590000

8270D SIM (PAH) Fluorene ug/kg 36000

8270D SIM (PAH) Indeno[1,2,3-c,d] pyrene ug/kg 15000

8270D SIM (PAH) Naphthalene ug/kg 38

8270D SIM (PAH) Phenanthrene ug/kg 39000

8270D SIM (PAH) Pyrene ug/kg 87000

AK101 Gasoline Range Organics mg/kg 300

AK102 Diesel Range Organics mg/kg 250

MI-ITRC ISM…