Jacksmith_Creek_RA_Final_Report.pdf

FINAL

REMOVAL ACTION REPORT

Jacksmith Creek Wanigan Spill Cleanup

Platinum, Alaska

December 2024

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 2600 Denali St., STE 501B Anchorage, AK 99503

FINAL

REMOVAL ACTION REPORT

Jacksmith Creek Wanigan Spill Cleanup

Platinum, Alaska

December 2024

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: 2024.12.03 17:12:44 -05'00'

Removal Action Report Bureau of Land Management Jacksmith Creek Wanigan Spill Cleanup Platinum, Alaska

140L6320P0046 Page i

Table of Contents

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

1.0 Introduction

1.1 Report Organization

1.2 Site Location

1.3 Physical Characteristics

1.3.1 Climate and Physical Setting

1.3.2 Hydrology

1.3.3 Groundwater

1.4 Site Background

1.5 Project Objectives

1.6 Applicable Cleanup Levels

2.0 Work Performed

2.1 Mobilization and Demobilization

2.2 Debris Removal

2.3 Soil Excavation

2.4 Field Screening

2.5 Soil Sample Collection

2.5.1 Confirmation Samples

2.5.2 Total Organic Carbon Samples

2.5.3 ISM Samples

2.5.4 General Sample Collection Methods

2.6 Sample Storage, Transport and Chain of Custody Procedures

2.7 Waste Disposal

2.7.1 Landspreading

2.7.2 Metal Debris Disposal

2.7.3 Decontamination and Investigation-Derived Waste

2.8 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

Bureau of Land Management Removal Action Report Platinum, Alaska Jacksmith Creek Wanigan Spill Cleanup

Page ii 140L6320P0046

3.7 Updated Conceptual Site Model

3.7.1 Sources and Release Mechanisms

3.7.2 Contaminants of Potential Concern

3.7.3 Exposure Media and Pathways

3.7.4 Potential Receptors

4.0 Conclusions and Recommendations

4.1 Conclusions

4.2 Recommendations

5.0 References

List of Figures

Figure 1. Vicinity Map

Figure 2. Jacksmith Creek Site Map

Figure 3. Screening Sample Locations

Figure 4. Screening and Confirmation Soil Sample Locations and Detectable

Analytical Results

Figure 5. Landspread ISM Sample Grid and CUL Exceedances

Figure 6. Conceptual Site Model

List of Tables

Table 1-1. Wanigan Spill Site Location Information

Table 1-2. ADEC Soil CULs

Table 3-1. Field Screening Results

Table 3-2. Data Qualifiers for Project Samples

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

COC contaminant of concern

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

NHSW non-hazardous solid waste

NNE north-northeast

PAH polycyclic aromatic hydrocarbon

PID photoionization detector ppm parts per million

QEP Qualified Environmental Professional

RA Removal Action

RRO Residual-range organics

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 wanigan and fuel spill, 20 air miles from Platinum, Alaska. One surface soil sample was collected by BLM from the center of the wallow in 2016.

Laboratory results indicated 20,900 milligrams per kilogram (mg/kg) diesel-range organics

(DRO). Several empty fuel drums were also found in the vicinity and bears had created a wallow approximately 2-foot-deep wallow in the spill among the roots of large spruce trees.

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 20 cubic yards (CY) of soil had been contaminated.

Bethel performed the RA in two phases, the first in September of 2022 and the second phase in

June of 2024. The reason for conducting two phases was that removal of 6.76 CY in 2022, which met the screening limit requirements, exceeded the most stringent Alaska Department of

Environmental Conservation (ADEC) Method Two cleanup levels (CULs). The objective of the

RA was to remove up to 20 CY of contaminated soil exceeding the most stringent Alaska ADEC

Method Two CULs for all contaminants of concern (COCs). COCs included 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 September 2022, 6.7 CY of non-hazardous diesel-contaminated soil was excavated using a mini-excavator. Due to the remoteness of the site, the excavated contaminated soil was landspread on site, where to naturally attenuate.

In June 2024, an additional 13.4 CY of non-hazardous diesel-contaminated soil was excavated by hand. The 2024 soil was added to the landspread area, keeping the depth to 4 inches.

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 seven 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 area containing both 2022 and 2024 soil was treated as a single decision unit and one ISM sample was collected, as well as a duplicate and triplicate sample.

Additional soil sampling 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 20 CYs.

In addition to the soil removal, seven empty fuel drums, metal debris and wooden parts were collected. The wooden debris was burned in a burning barrel (using one of the empty drums).

After cooling, the ash was added to bulk bags which contained the removed debris. A total of 5 bulk bags and two larger metal pieces were removed from the site.

Page vi 140L6320P0046

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.

Based upon the results from the fuel spill cleanup at the Jacksmith Creek wanigan 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 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, BLM contracted Bethel to perform a contaminated soil and non-hazardous solid waste (NHSW) cleanup at an abandoned wanigan (cabin on skids) located

20 miles north-northeast (NNE) of Platinum, Alaska. Work was completed in accordance with the BLM Statement of Work, Bethel’s proposal dated September 23, 2020, Final Work Plan

Jacksmith Creek Wanigan 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 and 2024.

● Section 3, Results. This section provides results for the 2024 RA and includes a discussion of the results of the laboratory data review.

● Section 4, Conclusions and Recommendations. This section provides conclusions and recommendations.

● 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 Site Location

The site is located approximately 20 miles NNE of Platinum and is accessible by air from the

Platinum airstrip. Figure 1 is a vicinity map of the location. Location information is also provided in Table 1-1.

Table 1-1. Wanigan Spill Site Location Information

Township and Range Northing Easting

W1/4 Section 16, Township 09 south, Range 73 West, Seward Meridian 59°23'31.6"N 161°35'19.84"W

′ = minutes ″ = seconds ° = degrees

N = north W = west

Page 2 140L6320P0046

1.3 Physical Characteristics

1.3.1 Climate and Physical Setting

The site falls within the western transitional climate zone, characterized by tundra interspersed with boreal forests and weather patterns of long, cold winters and shorter, warm summers. The average annual precipitation is 25 inches per year (www.usclimatedata.org).

1.3.2 Hydrology

Based upon site photographs and aerial imagery, Jacksmith Creek is located approximately 100 feet to the east of the drum site. The field team will document the presence of any additional surface water bodies.

1.3.3 Groundwater

The depth and flow direction of groundwater at the Site is not known at this time. The Site is located in hilly terrain and therefore shallow groundwater is not expected.

1.4 Site Background

A wanigan (cabin on skids) was abandoned decades ago at the location. Figure 2 is a site map showing the location of the abandoned wanigan relative to Jacksmith Creek. Amongst the wreckage of the wanigan are several empty drums. A drum leaked an unknown amount of fuel at the site. Bears have wallowed in the spill creating an approximate 10-foot (ft.) by 12-ft. by 1-ft.

depression.

One surface soil sample was collected by BLM from the center of the wallow in 2016.

Laboratory results indicated 20,900 mg/kg DRO. No other samples were collected and the vertical and lateral extent are unknown.

1.5 Project Objectives

The objectives of the planned work are to clean up the site, including the removal and treatment of contaminated soil. Field work will consist of the following tasks:

● excavating up to 20 cubic yards (CY) of fuel-contaminated soil and placing into a landspread on site;

○ Bethel will over-excavate six inches in all directions beyond where field screening indicates contaminant concentrations above the CULs to ensure all contaminated soil is excavated, provided the extra six inches does not increase the total excavated soil above 20 CY.

○ The landspread will be between four and six inches thick, with four inches being optimal.

○ The landspread will be established in an open area away from shade and environmental receptors and will be raked during spreading in the direction to create the effect of windrows and increase the landspread surface area.

● collecting confirmation soil samples from the excavation following ADEC guidelines for confirmation field screening and sampling;

140L6320P0046 Page 3

● collecting one baseline triplicate ISM sample from the landspread area;

● segregating and burning burnable NHSW in accordance with ADEC guidelines for air quality (material will only be burned if there are no burning restrictions in place);

● removing and disposing of approximately 10 empty drums; and

● providing a summary report of work performed and results.

1.6 Applicable Cleanup Levels

The ADEC Contaminated Sites Program does not list the Jacksmith Creek site on their contaminated sites database. Applicable soil ADEC 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, 2023). For most compounds, the

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

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

Residual-Range Organics (RRO) 10,000

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 0.7

Benzo[b]fluoranthene 15

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

Benzo[k]fluoranthene 150

Page 4 140L6320P0046

Contaminant Soil

(mg/kg)

Chrysene 600

Dibenzo[a,h]anthracene 1.5

Fluoranthene 590

Fluorene 36

Indeno[1,2,3-c,d] pyrene 15

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.

Jacksmith Creek Drum and Wanigan Location

Jacksm ith Creek

Drawn By: Contract No:Date:

SS August 2024

Figure 1

Vicinity Map Site 8 - Drum and Wanigan Location

Jacksmith Creek Wanigan Spill Cleanup Goodnews Bay, 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

Platinum

Drums and Wanigan Location

Bethel

Cold Bay

Dillingham

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 7 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

Legend Drums and Wanigan Debris Location

¹ 0 110 22055 Feet

140L6320P0046

Page 6 140L6320P0046

Ja ck sm ith

C re ek

Drawn By: Contract No:Date:

SS August 2024

Figure 2

Site Map Site 8

Jacksmith Creek Wanigan Spill Cleanup Goodnews Bay, Alaska

Notes:

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

USAF (2016)

Goodnews Bay

Drums and Wanigan Location

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 7 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

Legend Excavated Aea 2022 and 2024 Combined

2022 Excavated Area

Extent of Landfarm Cell After 2022

Extent of Combined Landfarm Cell in 2024

¹ 0 50 10025 Feet

Page 8 140L6320P0046

140L6320P0046 Page 9

2.0 WORK PERFORMED

Field activities were completed in accordance with the Final Work Plan Jacksmith Creek

Wanigan Spill Cleanup (Bethel, 2022) and the ADEC Field Sampling Guidance (ADEC, 2022), and included excavation and landspread of between 20 CY of contaminated soil, collection of confirmation samples from the sidewalls and floor of the excavation, collection of 11 randomly-spaced TOC samples, including a duplicate, and ISM sampling of the landspread. Five partially filled 1-CY bulk bags of non-burnable debris and three metal objects too large to fit in 1-CY bulk bags were also removed from the site and disposed of at the Bethel landfill. 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 two phases, in 2022 and 2024. The first phase was conducted in

September of 2002 and the second stage was conducted in June of 2024. In 2022, Bethel personnel mobilized to the site over the course of six on-site days beginning on September 7 through 12, 2022 and camped on site during the mobilization. A BLM-provided Kubota mini-backhoe was utilized for the excavation and was mobilized from Anchorage to Bethel via commercial airfreight providers. Equipment was staged in Platinum and was slung to the site via helicopter. Personnel were transferred by helicopter from either Bethel or Platinum. Bethel environmental scientist Quenton Nelson, an ADEC Qualified Environmental Professional (QEP), supervised the removal of soil and conducted field screening and laboratory sample collection.

He was assisted by Bethel employees Ross Roylance who assisted in sample collection and other tasks, and Albert Kalowiyi, who operated the mini-backhoe. Bethel personnel completed site work on September 12 and were transferred by the helicopter from the site to Platinum.

Additional load of equipment was slung out by helicopter on September 13, 2022.

Due to the limits of the 2022 excavation not meeting the CULs, a second phase was conducted to remove additional soil. Attempts were made to schedule the work in 2023, but due to persistent unruly weather patterns, these attempts failed. In June 2024, Bethel personnel mobilized to the site over the course of five on-site days, beginning on June 23, 2024 and camped on site during the mobilization. Bethel environmental scientist Quenton Nelson, an

ADEC QEP, supervised the removal of soil and conducted field screening and laboratory sample collection. He was assisted by Bethel employees Brett Calhoon and Josh Scollard, assisted in hand excavation and sample collection. Bethel personnel completed site work on

June 28 and departed the site for Bethel.

2.2 Debris Removal

Seven empty drums were found scattered throughout the site area. The drums were smashed down using the mini-excavator and. containerized in 1-CY bulk bags.

The burnable material was burned on site to reduce the volume of material to be transported to an alternative disposal facility. Burning took place at an appropriate time (late fall) when vegetation was not dry.

Page 10 140L6320P0046

The wood debris was moved to one of the metal barrels for use as a burn barrel. Burning was conducted in accordance with the ADEC air quality guidelines which include burning only dry wood (less than 22 percent moisture). A full-time fire watch was conducted and the fire was put out with water from the creek in the evening of each day. After the material has been burned, all of the ash and non-burnable components such as nails, screws and hinges were disposed of in a bulk bag.

Metal debris removed from the site included three objects too big to fit into 1 CY bulk bags. Five, 1 CY bulk bags were partially filled with the general metal debris, crushed drums, and ash.

2.3 Soil Excavation

2022 Excavation

Excavation of contaminated soil began at the bear wallow on September 8 and ended on

September 9, 2022. A mini-backhoe operated by qualified personnel was used to excavate soil.

Once excavated, contaminated soil was deposited directly from the back-hoe bucket into a six-cubic-foot wheelbarrow, as a means of measuring the volume of soil excavated. Cobbles six inches or greater in diameter were removed from the wheelbarrow and piled near to the hole to be used as back fill, as permitted by the ADEC Technical Memorandum Petroleum Hydrocarbon

Cleanup for Oversize Materials (ADEC, 2005).

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 of 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 photoionization detector (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 30 wheelbarrow loads were excavated. At 6 cubic feet per wheelbarrow load, that is

180 cubic feet or 6.7 CY. The total dimensions of the final excavation, shaped as a rough diamond, with two 6-ft sides, one 5-ft side, and one 9-ft. side. The maximum excavation depth was 4 ft. below ground surface (bgs).

2024 Excavation

In 2024 excavation began on June 24 and ended on June 27, 2024. 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). 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 of 4 to

6 inches.

140L6320P0046 Page 11

The excavation began at the edge of the 2022 excavation limits, at the side which indicated the contamination remained on the south side. The field crew found the 2022 limits by surveying where samples had been collected and surveyed in 2022. The excavation began where 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 724 5-gallon bucket loads were excavated by hand. At 0.5 cubic feet per bucket load, that is 362 cubic feet or 13.4 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 extended 4 to 5 feet bgs. The northwest side of the excavation was 6.5 ft. long; the northeast side, 8.5 ft. long; the southeast side, 11.5 ft. long; and, the southwest side, 13.8 ft.

long. The northeast portion of the excavation was excavated down 5 ft. bgs. and the remainder of the excavation to 4 ft. bgs.

During excavation, two lithographic unit were encountered. The upper 2.0 feet of the excavation was in a damp, dark brown silt with clay down to approximately 2.0 ft. bgs. The lower 3 feet of the excavation was in a light brown to tan silt with sand and cobbles. Groundwater was not encountered.

The total amount of soil excavated between 2022 and 2024 was 13.4 CY+ 6.7 CY = 20.1 CY.

2.4 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 3 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).

Figure 3 shows the locations of the field screening samples. Five field screening samples were collected from the northeastern southeastern excavation sidewalls, three from the northwestern excavation sidewall, seven from the southwestern sidewall, and five from the floor of the excavation. Three samples were collected from the base of the excavation. As only 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 lower portion of the silt layer with clay, and the middle to lower screening samples were collected from the middle to lower portion of the silt layer with sand and cobbles. 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). See Figure 3 for locations of the excavation boundary and field screening sample locations.

Page 12 140L6320P0046

2.5 Soil Sample Collection

2.5.1 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). Figure 4 shows the locations of the confirmation samples. A total of seven confirmation samples and one duplicate sample were collected, as detailed below.

● The northwest sidewall confirmation sample was identified as JC-NWSS01 and was collected at a depth of 3 feet bgs.

● The northeast sidewall confirmation sample was identified as JC-NESS02 and was collected at a depth of 4 feet bgs.

● The southeast sidewall confirmation sample was identified as JC-SESS03 and was collected at a depth of 3.5 feet bgs.

● The southwest sidewall confirmation sample was identified as JC-SWSS04 and was collected at a depth of 1.5 feet bgs.

● The second southwest confirmation sample was identified as JC-SWSS05 and was collected at a depth of 1.5 feet bgs.

● The first floor of the excavation confirmation sample was identified as JC-BSS06 and collected at a depth of 5 feet bgs. A duplicate of this sample was collected and was identified as JC-BSS07.

● The second floor of the excavation confirmation sample was identified as JC-BSS08 and collected at 5 feet bgs.

The confirmation sample locations were measured using a survey-grade GPS. See Figure 3 for locations of the excavation boundary and confirmation sample locations.

2.5.2 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. See Figure 3 for the

TOC sample locations.

2.5.3 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

140L6320P0046 Page 13 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 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. Figure 5 depicts the ISM sampling grid layout.

2.5.4 General Sample Collection Methods

Analytical soil sample collection followed the protocols outlined in the Final Work Plan Jacksmith

Creek Wanigan 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 4 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.

2.6 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 helicopter. Ambient daytime air temperatures were in the low 60s degrees Fahrenheit (°F). Once collected, samples were placed in a cooler and the

Page 14 140L6320P0046 cooler was placed in the area shaded by vegetation. Frozen gel ice was added to the cooler the next day, immediately upon arrival in Bethel, and maintained at 4 degrees Celsius (°C) ± 2 °C.

The samples were transferred from Bethel to Anchorage via Northern Air Cargo. Samples were then delivered by Bethel personnel to the SGS Laboratory in Anchorage. The analytical report is provided in Appendix D.

2.7 Waste Disposal

2.7.1 Landspreading

The 2022 excavated soil was spread on site over an area stripped of vegetation. The soil then was spread using hand rakes into a 21-ft.-by-23.5-ft. rectangular area, to an approximate thickness of 4.4 inches, creating a or 493.5-ft2 landspread where the soil will be allowed to naturally attenuate. A final pass was then made over the landspread, raking in an east-west direction to create furrows parallel to prevailing winds to aid in the natural attenuation of the soil.

The 2024 excavated soil was added to the landspread (not covering any of the 2022 soil), extending the landspread to a 34.5-ft.-by-56.5-ft. rectangular area, creating an approximately

3.3-inch-thick 1,949.25 ft2 landspread. Figure 5 presents both the 2022 and 2024 landspread boundaries and dimensions.

The four corners of the landspread, including both the 2022 and 2024 landspread areas, were measured using a survey-grade GPS to ±1-foot horizontal and 0.1-foot vertical accuracy. For the purpose of identifying the landspread for future follow-up sampling events, the landspread can be identified by connecting the landspread’s four surveyed corners with lines. The area of land encompassed by these lines constitutes the landspread.

2.7.2 Metal Debris Disposal

Three metal object too large to fit in 1-CY bulk bags and five, 1-CY bulk bags filled with the general metal debris, crushed drums, and ash were disposed at the Bethel Landfill.

2.7.3 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 Bethel 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.

2.8 Deviations from the Work Plan

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

● Residual-range organics (RRO) were reported in the laboratory reports. This compound was not a COC and was not included in the work plan. The compound was not included on tables or discussed in this report. All detected results for RRO were well below the

CUL of 10,000 mg/kg.

● 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

140L6320P0046 Page 15 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 16 140L6320P0046

2W7

B1

B3 ls4 toc1 toc2 toc3 toc4 toc5 toc6 toc7 toc8 toc9 toc10

NE5

NW1

NW2

NW3

SE5

SW1

SW2

SW3

SW4

SW5

SW6

B2

B4

B5

NE1&3

NE2&4

SE1&3

SE2&4

Drawn By: Contract No:Date:

SS August 2024

Figure 3

Screening Sample Locations Site 8

Jacksmith Creek Wanigan Spill Cleanup Goodnews Bay, Alaska

Notes:

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

USAF (2016)

Goodnews Bay

Drums and Wanigan Location

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 7 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

Legend

#* Confirmation Screening Sample Location

Total Organic Carbon Sample Locations

Excavated Aea 2022 and 2024 Combined

2022 Excavated Area

¹ 0 5.5 112.75 Feet

Page 18 140L6320P0046

2W7

B1

GRO (mg/kg) 5.63 J DRO (mg/kg) 24.8 J

JC-SWSS04

GRO (mg/kg) 5.27 J DRO (mg/kg) 35.3

JC-SWSS05

GRO (mg/kg) 3.27 J DRO (mg/kg) 72.1

GRO (mg/kg) 3.54 J DRO (mg/kg) 23.9

JC-BSS06

JC-BSS07 (DUP)

GRO (mg/kg) 3.25 J DRO (mg/kg) 47.3

JC-BSS08

GRO (mg/kg) 3.41 J DRO (mg/kg) 12.3 J

JC-NWSS01

GRO (mg/kg) 3.20 J DRO (mg/kg) 40.3

JC-NESS02

GRO (mg/kg) 3.78 J DRO (mg/kg) 18.1 U

JC-SESS03

B3#*

NE5

NW1

NW2

NW3

SE5

SW1

SW2

SW3

SWSWWW

SW4

WWWWWWWWSWWW2

SW5 **####

SW6

B2

B4

B5

NE1&3

NE2&4

SE1&3

SE2&4

Drawn By: Contract No:Date:

SS September 2024

Figure 4

Screening and Confirmation Soil Sample Locations and Detectable

Analytical Results

Site 8 Jacksmith Creek Wanigan Spill Cleanup

Goodnews Bay, Alaska

Notes:

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

USAF (2016)

Goodnews Bay

Drums and Wanigan Location

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 7 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

Legend #* Confirmation Soil Sample Location

Excavated Aea 2022 and 2024 Combined

2022 Excavated Area

¹ 0 3.5 71.75 Feet

140L6320P0046 GRO (mg/kg) 300 DRO (mg/kg) 250

Applicable CUL

Page 20 140L6320P0046

Drawn By: Contract No:Date:

SS August 2024

Figure 5

Landspread ISM Grid and Exceedances

Site 8 Jacksmith Creek Wanigan Spill Cleanup

Goodnews Bay, Alaska

Notes:

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

USAF (2016)

Goodnews Bay

Drums and Wanigan Location

Bethel Environmental Solutions LLC 2605 Denali Street

Anchorage, Alaska 99503

Alaska State Plane Zone 7 U. S. Survey Feet

Horizontal Datum: NAD 1983 (2011)

Legend 2024 Grid Sub-cell

2024 Grid Boundary

Extent of Landfarm Cell After 2022

Extent of Combined Landfarm Cell in 2024

0 6.5 133.25 Feet

140L6320P0046

DRO (mg/kg) 250 Applicable CUL

Primary Sample DRO (mg/kg) 1,660 Duplicate Sample DRO (mg/kg) 1,070 Triplicate Sample DRO (mg/kg) 1,530 DRO 95% UCL (mg/kg) 1,94

Landspread ISM Results above the CUL

Landfarm Area Dimensions

2022 = 21 ft. X 23.5 ft.= 493.5 sq. ft.

2024 = 34.5 ft. X 56.5 ft. = 1,949.25 sq. ft.

¹

Page 22 140L6320P0046

140L6320P0046 Page 23

Figure 6. Conceptual Site Model

Page 24 140L6320P0046

140L6320P0046 Page 25

3.0 RESULTS

Results of the 2024 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, 2023). Data tables of the analytical results are provided in Appendix A.

3.1 Observations

During excavation, two lithographic units were encountered. The upper 2.0 feet of the excavation was in a damp, dark brown silt with clay down to approximately 2.0 ft. bgs. The lower

3 feet of the excavation was in a light brown to tan silt with sand and cobbles. Groundwater was not encountered.

3.2 Contaminated Soil Removal

A total of approximately 20.1 CY of contaminated soil were removed during the excavation.

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 24 field screening samples collected at the excavation are provided on Table

3-1. The excavation field screening sample locations are shown on Figure 3. PID field screening results ranged from 0.4 ppm to 2.2 ppm.

Table 3-1. Field Screening Results

PID Screening Sample Location in Excavation Depth Collected

(feet bgs)

Result

(ppm)

Corresponding

Confirmation Sample

NE 1 Northeast Sidewall 1 1.3 N/A

NE 2 Northeast Sidewall 1 0.7 N/A

NE 3 Northeast Sidewall 4 1.2 N/A

NE 4 Northeast Sidewall 4 1.5 JC-NESS02

NE 5 Northeast Sidewall 2.5 2.0 N/A

NW-1 Northwest Sidewall 0.67 2.0 N/A

NW-2 Northwest Sidewall 3 1.4 N/A

NW-3 Northwest Sidewall 3 2.2 JC-NWSS01

SW-1 Southwest Sidewall 1.5 1.2 JC-SWSS05

SW-2 Southwest Sidewall 1.5 1.3 JC-SWSS04

SW-3 Southwest Sidewall 3.5 0.6 N/A

SW-4 Southwest Sidewall 3.5 0.6 N/A

SW-5 Southwest Sidewall 3.5 0.6 N/A

SW-6 Southwest Sidewall 4.5 1.1 N/A

Page 26 140L6320P0046

PID Screening Sample Location in Excavation Depth Collected

(feet bgs) Result (ppm)

Corresponding Confirmation Sample

SW-7 Southwest Sidewall 4.5 0.4 N/A

SE-2 Southeast Sidewall 1.5 0.8 N/A

SE-3 Southeast Sidewall 2.5 1.2 N/A

SE-4 Southeast Sidewall 3.5 1.5 JC-SESS03

SE-5 Southeast Sidewall 3.5 0.8 N/A

B-1 Bottom 4 0.4 N/A

B-2 Bottom 5 1.3 JC-BSS08

B-3 Bottom 4 0.4 N/A

B-4 Bottom 5 3.5 JC-BSS06

B-5 Bottom 4 0.4 N/A

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

3.4 Confirmation Soil Sample Results

Seven soil confirmation samples were analyzed for GRO, DRO, RRO, 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, 2023). 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 4 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 seven confirmation samples, including the duplicate, with sample JC-SWSS04, from the southwest sidewall having the highest concentration, 5.63 J mg/kg. DRO was detected in all seven confirmation samples, including the duplicate, with sample JC-BSS08, from the bottom of the excavation having the highest concentration, 47.3 mg/kg.

3.4.2 VOCs Results

No VOCs were detected above their respective detection limits.

Nineteen VOCs, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, 1,2,3-trichloropropane, 1,2-dibromoethane, benzene, bromodichloromethane, bromomethane, carbon tetrachloride, 2-hexanone, chloroform, cis-1,3-dichloropropene, dibromochloromethane, dibromomethane, hexachlorobutadiene, naphthalene, trans-1,2-dichloropropene, trichloroethene, and vinyl chloride, had all or some 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

140L6320P0046 Page 27 concentrations above the CULs is highly unlikely, given the concentrations of the other 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, 2023). 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. Error! Reference source not found. 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 1,660, 1,070, and 1,530 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 1,943 mg/kg, indicating that, with 95% confidence, the true average concentration of the soil in the landfill is below 1,943 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 8.17 J mg/kg. The

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

UCL.

3.5.2 VOCs Results

No VOCs were detected in the ISM samples.

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.

Page 28 140L6320P0046

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 ADEC Laboratory Checklist for each data package. Appendix D contains the Level II Laboratory Data Report.

The data validation review determined the overall quality of the Jacksmith Creek 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. Table 3-2 lists the qualifiers applied to sample results and the reason for qualification.

Table 3-2. Data Qualifiers for Project Samples

Sample Name Method Analyte Original

Result

Validated

Result Units Reason Code

JC-NWSS01 AK101 GRO 3.41 J 3.41 QH mg/kg Detected in TB

JC-NESS02 AK101 GRO 3.20 J 3.20 QH mg/kg Detected in TB

JC-SESS03 AK101 GRO 3.78 J 3.78 QH mg/kg Detected in TB

JC-SWSS04 AK101 GRO 5.63 5.63 QH mg/kg Detected in TB

JC-SWSS05 AK101 GRO 5.27 J 5.27 QH mg/kg Detected in TB

JC-BSS06 AK101 GRO 3.27 J 3.27 QH mg/kg Detected in TB

JC-BSS07 AK101 GRO 3.54 4.54 QH mg/kg Detected in TB

JC-BSS08 AK101 GRO 3.25 J 3.25 QH mg/kg Detected in TB

JC-TBSS01 AK101 GRO 1.96 J 1.96 QH mg/kg Detected in TB

JC-NWSS01* SW9060A TOC 0.883 0.883 QH % MS %R > CL

JC-TC04* SW9060A TOC 1.34 1.34 QL % MS %R < CL

Notes:

*this sample was collected in 2022, the ID is identical to 2024 sample, but this result is not being used for the 2024 excavation confirmation results, only for the TOC result.

J = the result is estimated due to detection below the reporting limit QH = the result is considered estimated, biased high, due to detection in the trip blank or quality control issue QL = the result is considered estimated, biased low, due to quality control failure MS = matix spike CL = control limits %R = percent recovery

3.7 Updated Conceptual Site Model

An updated Conceptual Site Model (CSM) for the site is shown in Error! Reference source not found.. The CSM is intended to show the potential present and future routes or pathways that site contaminants may take as they move from a release location to a potential receptor.

140L6320P0046 Page 29

3.7.1 Sources and Release Mechanisms

The source of soil contamination was a direct release from drums of diesel or heating oil associated with a wanigan.

3.7.2 Contaminants of Potential Concern

Final confirmation samples from the excavation (wanigan) area indicates that all fuel related compounds have been removed from the site at concentrations above the applicable CULs. The landspread area contains DRO at concentrations above the CUL, with a 95%UCL of 1,943 mg/kg.

3.7.3 Exposure Media and Pathways

Releases from the landspread to the surface may directly affected surface soil. DRO is not assimilated by plant roots nor by the animals that may ingest site plants.

Potential exposure media includes surface soil. Surface water is not a potential exposure media because these are not present close to the site. Air is not considered impacted since DRO is not volatile.

3.7.4 Potential Receptors

Current receptors include site visitors and subsistence harvesters.

Page 30 140L6320P0046

140L6320P0046 Page 31

4.0 CONCLUSIONS AND RECOMMENDATIONS

An RA was conducted for a fuel spill at the Jacksmith Creek wanigan spill site, near Platinum, 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 20 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 approximately 20.1 CY of contaminated soil over two phases of work conducted in 2022 and 2024. Seven characterization soil samples were collected from the excavation, including one duplicate sample. These samples were analyzed for DRO, GRO, RRO, 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 Jacksmith Creek Wanigan spill has been excavated.

The excavated soil was subsequently spread in a 34.5-ft.-by-56.5-ft. or 1,949.25-ft2 landspread

(2024 dimensions) to a thickness of approximately 3.3 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.