2025_Akiak_Report_0001.pdf

FINAL

Site Characterization Report

For the Akiak Old Elementary School Tank Farm

ADEC File No. 2402.38.001 ADEC Hazard ID 3367

Akiak Old High School Tank Farm

ADEC File. No. 2402.38.003 ADEC Hazard ID. 3368

Akiak, Alaska

Prepared for:

BUREAU OF INDIAN AFFAIRS

ALASKA REGIONAL OFFICE

3601 C STREET

ANCHORAGE, AK 99503

Prepared by:

TANANA COMMERCIAL COMPANY LLC

PO BOX 77069

TANANA, ALASKA 99777

June 2026

Akiak Old Elementary School Tank Farm

ADEC File. No. 2402.38.003 ADEC Hazard ID. 3368

Prepared by:

Tanana Commercial Company LLC PO Box 77069 Tanana, Alaska 99777

Written by:

Shayla Marshall, QEP Project Manager

Site Characterization Report – FINAL Akiak Old Elementary School and Old High School Tank Farms June 2026 i

TABLE OF CONTENTS

1.0 SITE DESCRIPTION AND BACKGROUND

1.1 Project Purpose and Objectives

1.2 Site Location

1.3 Background

2.0 INTERVIEWS AND OWNERSHIP RECORD REVIEW

2.1 Interviews

2.2 Ownership Records Review

3.0 CONTAMINANTS OF CONCERN AND APPLICABLE

REGULATIONS

4.0 SAMPLING METHODOLOGY

4.1 Field Screening Methods

4.2 Analytical Soil Sampling Collection Methods

5.0 FIELD ACTIVITIES

5.1 Work Plan Variances

5.2 Site Characterization Activities

5.2.1 Test Pits

5.2.2 Paint Chip Sampling

5.3 Decontamination Procedures

6.0 SAMPLING RESULTS

6.1 Subsurface Conditions

6.2 Old Elementary School Tank Farm Test Pit Soil Results

6.3 Old High School Tank Farm Test Pit Soil Results

6.4 Paint Chip Sample Results

7.0 QUALITY CONTROL REVIEW

8.0 DISCUSSION

8.1 Old Elementary School Tank Farm Soil Sampling Discussion

8.2 Old High School Tank Farm Soil Sampling Discussion

8.3 Conceptual Site Model Discussion

8.3.1 Old Elementary School Tank Farm Conceptual Site Model Discussion

8.3.2 Old High School Tank Farm Conceptual Site Model Discussion

9.0 INVESTIGATIVE DERIVED WASTE MANAGEMENT

10.0 CONCLUSIONS AND RECOMMENDATIONS

11.0 REFERENCES

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TABLES

Table 1 – Old Elementary School Tank Farm Detected Soil Analytical Results Table 2 – Old High School Tank Farm Detected Soil Analytical Results

FIGURES

Figure 1 – Vicinity Map Figure 2 – Project Area Figure 3 – Historic Sample Locations, Old Elementary School Tank Farm Figure 4 – Historic Sample Locations, Old High School Tank Farm Figure 5 – 2025 Soil Sample Locations, Old Elementary School Tank Farm Figure 6 – 2025 Soil Sample Locations, Old High School Tank Farm

APPENDICES

Appendix A – Figures Appendix B – Limited Liability Reports Appendix C – Field Notes Appendix D – Old Elementary School Tank Farm Photo Pages Appendix E – Old High School Tank Farm Photo Pages Appendix F – SGS Laboratory Report and Laboratory Data Review Checklist Appendix G – Human Health Conceptual Site Model Graphic Form and Human Health

Conceptual Site Model Scoping Form and Standardized Graphic Appendix H – DEC Review Comment Table

June 2026 iii

ACRONYMS AND ABBREVIATIONS

AAC Alaska Administrative Code ADEC Alaska Department of Environmental Conservation AK Alaska AST Aboveground Storage Tanks bgs Below Ground Surface BIA Bureau of Indian Affairs BTEX Benzene, Toluene, Ethylbenzene, and Xylenes CSM Conceptual Site Model DRO Diesel Range Organics DQO Data Quality Objectives EDB 1,2-Dibromethane GAC Granulated Activated Carbon GRO Gasoline Range Organics IDW Investigation Derived Waste IGAP Indian General Assistance Program LOQ Limit of Quantitation mg/kg Milligrams Per Kilogram mL Milliliters MAC Maximum Allowable Concentration MS/MSD Matrix Spike/Matrix Spike Duplicate MTG Migration to Groundwater PAH Polyaromatic Hydrocarbon PCB Polychlorinated Biphenyls PID Photoionization Detector PPE Personal Protective Equipment ppm Parts Per Million QC Quality Control QEP Qualified Environmental Professional %R Percent Recovery RPD Relative Percent Difference SGS SGS North America TCC Tanana Commercial Company LLC VOC Volatile Organic Compound WELTS Well Log Tracking System

Site Characterization Report –FINAL Akiak Old Elementary School and Old High School Tank Farm;

June 2026 4

Akiak Old Elementary School Tank Farm

ADEC File No. 2402.38.003 ADEC Hazard ID 3368

This report outlines the 2025 remediation support activities at the Akiak Old Elementary and High School Tank Farms in Akiak, Alaska. The sites are identified as Alaska Department of Environmental Conservation (ADEC) Contaminated Sites Hazard ID 3367 (Akiak Old Elementary School Tank Farm) and Hazard ID 3368 (Akiak Old High School Tank Farm) Work is in accordance with the September 11, 2024 Contract No. 14A0524Q0005 between the Bureau of Indian Affairs (BIA) and Tanana Commercial Company LLC (TCC).

1.0 SITE DESCRIPTION AND BACKGROUND

The Property is an active ADEC Contaminated Site (File Nos. 2402.38.001 and 2402.38.003). The following outlines the purpose of the field activities, site location details, and previous field activities.

1.1 Project Purpose and Objectives

The purpose of the project is to gather information on the current site conditions for both the Elementary and Old High School Tank Farms, building on previous site investigations. This information will inform the next remediation steps and assist the design of an abatement plan and remediation plan to advance the site towards closure. The site-specific project objectives include the following:

Old Elementary School Tank Farm

• Collect soil samples to complete the delineation of known petroleum contamination west of the bulk storage tanks associated with the fuel line and former dispenser (main valve assembly);

• Conduct a thorough inspection of the areas not accessible in the 2009 investigation for indications of petroleum contamination;

June 2026 5

• Inspect the status of the bulk fuel tanks, if feasible, and inspect the integrity of the secondary containment berm and liner;

• Collect paint chips from the bulk storage tanks, if present, for lead and polychlorinated biphenyl (PCB) analysis.

Old High School Tank Farm

• Collect soil samples to complete the delineation of known petroleum contamination south of the bulk storage tanks associated with the former dispenser;

• Inspect the status of the bulk fuel tanks, if feasible, and inspect the integrity of the secondary containment berm and liner;

• Collect paint chips from the bulk storage tanks, if present, for lead and PCB analysis.

1.2 Site Location

The village of Akiak lies on the north bank of the Kuskokwim River, approximately 42 miles northeast of Bethel, Alaska (Figure 1, Appendix A). The Old Elementary School Tank Farm is located in the central portion of Akiak, approximately 350 feet east of the Old High School and 350 feet west of the Kuskokwim River (Figure 2, Appendix A). The Old High School Tank Farm is located in the central portion of Akiak, approximately 700 feet west of the Kuskokwim River (Figure 2, Appendix A).

Akiak is located in the Yukon-Kuskokwim Delta area, which is comprised largely of Quaternary alluvial deposits which have been built up through the slow accumulation of sand and silt deposited by the Yukon and Kuskokwim rivers. Most of the region is flat with a few feet of elevation marking the boundaries of major drainages and much of the surface is covered with water.

1.3 Background

The following documents summarize the latest remediation activities at the site and were reviewed for site history and recommendations for progressing the site towards closure. The sample locations for the Old Elementary School Tank Farm and Old High School Tank Farm referenced below are shown on Figures 3 and 4, respectively (Appendix A).

SLR. Old Elementary School Tank Farm, Site Characterization Report, Akiak, Alaska.

February 2010.

The tank farm consists of two vertical, welded steel, single wall tanks with removable tops. Both tanks have a capacity of 8,000 gallons and are supported on 8-by-8-inch timbers with 2-by-12-inch planking inside a 3.5-foot high gravel dike with liner. The tank farm is contained inside a 5.5-foot high chain link fence with an unlocked gate (SLR 2010).

The Old Elementary School Tank Farm was visited in October 1999 by ADEC. Weather conditions at the time of the site visit (partially frozen surface water and snow) prevented a full investigation. A slight sheen was observed around the tank fittings where water had accumulated.

The report indicated that all threaded piping had been replaced with welded piping in 1996.

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Information gathered during this visit indicated that ground water at the Site is between 18 and 30 feet below ground surface (bgs). The ground thaws seasonally between May and July. The upper 2 feet of soil was described as mud underlain by sand, which is present to the water table

(ADEC, 1999).

During a 2000 site visit by Ecology and Environment, Inc., a sheen was noted on the water within the lined bermed containment area. Soil samples were collected from nine locations outside of the containment and field screened using heated headspace with a photoionization detector (PID).

PID readings ranged from 3.9 parts per million (ppm) to 714 ppm. The maximum PID reading was from a sample collected from 2 feet bgs at the main valve assembly. An analytical sample was also collected from this location. Concentrations of gasoline range organics (GRO), diesel range organics (DRO), benzene, and ethylbenzene were all above ADEC Method Two soil cleanup levels. Maximum detected concentrations of GRO and DRO were 1,500 milligrams per kilogram (mg/kg) and 20,000 mg/kg, respectively. The main valve assembly is outside the bermed area and the extent of impact was unknown at the conclusion of the 2000 site work (E&E, 2000).

In September 2009, the Old Elementary School Tank Farm was observed in similar condition to the 2000 site visit as described in the 2000 Ecology and Environment, Inc. report (SLR 2010).

During the 2009 site visit by SLR, the two aboveground storage tanks (ASTs) were upright and stated to be in use, according to maintenance personnel associated with the Akiak schools, supplying a nearby house, the Hut (Boys and Girls Club), and teacher housing (Figure 2, Appendix A). The liner appeared in good condition and was holding water. No sheen was observed on the water within the bermed area.

A total of six test pits (TP-1 through TP-6) were excavated in the vicinity around the Old Elementary School Tank Farm (Figure 3, Appendix A). In locations where test pits were not practical or safe, such as near buildings, utilities, or roadways, a hand auger was used to assess subsurface soils.

Heated headspace results ranged from 0.0 ppm to 1,803 ppm. Elevated results (i.e., greater than 100 ppm) were observed in TP-2 and SB-1. Samples from one test pit (TP-2) and one soil boring (SB-1) contained concentrations of DRO above the ADEC Method Two soil cleanup level with a maximum detected concentration of 22,300 mg/kg. Additional petroleum constituents were detected above ADEC Method Two soil clean levels. TP-2 and SB-1 are located around the former dispenser and support the results from the 2000 investigation that found contamination in the same general area. It is estimated that 285 cubic yards of impacted soil is present at the Site;

this is considered a maximum volume because contamination at the Old Elementary School Tank Farm was not fully delineated due to access limitations.

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SLR. Old High School Tank Farm, Site Characterization Report, Akiak, Alaska. February 2010.

The tank farm consists of eight vertical, welded steel, single wall tanks with removable tops. The tanks have a total capacity of 54,000 gallons with individual AST capacities ranging from 5,000 to 9,750 gallons. The ASTs are supported on 12-by-12-inch timbers with 2-by-14-inch planking inside containment of a 2-foot-tall gravel dike with liner.

During a 2000 site visit by Ecology and Environment, Inc., stained and darkened soil and sandbags were noted within the bermed containment area at the tank farm. Soil was collected from nine locations around the outside of the containment area and field screened using heated headspace with a PID. PID readings ranged from 9.9 parts ppm to greater than 2,000 ppm with the highest field screening result at the gasoline fuel dispensing pump. One analytical soil sample was collected from 1 foot bgs adjacent to the gasoline fuel dispensing pump on the west side of the tank farm. GRO; DRO; and benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds were all detected at concentrations above ADEC Method Two soil cleanup levels. Maximum concentrations of GRO and DRO were 9,100 mg/kg and 4,300 mg/kg, respectively. The extent of contamination was unknown at the conclusion of the 2000 site work (E&E., 2000).

In September 2009, the Old High School Tank Farm was observed in similar condition to the 2000 site visit as described by Ecology and Environment, Inc. (2000) with a few exceptions described below (SLR 2010).

During the September 2009 initial site visit, eight tanks were observed in the Old High School Tank Farm; five were upright and three were toppled as a result of flooding of the Kuskokwim River in spring 2009. Of the eight tanks, two were in use, according to maintenance personnel associated with the Akiak schools, and another three were reportedly in operational condition (Figure 4, Appendix A). The tank farm is fenced, but not secure (i.e. no locks), and has a lined and bermed containment. The liner appeared in good condition where exposed and held water. Sheen was noted on the water in the containment area in three locations. It is estimated that approximately 69 cubic yards of impacted soil is present at the Site. It appears that impacted soils are limited to the south side of the tank farm, where the former dispenser was located.

2.0 INTERVIEWS AND OWNERSHIP RECORD REVIEW

To obtain additional information about the Property, TCC conducted interviews of locals knowledgeable about the site conditions and history.

2.1 Interviews

Olenka Jones, mayor of Akiak, provided TCC transport to a truck of field work use and an orientation of the project site. At the old elementary school, the tank farm and old classrooms were no longer in use. The building was built in the 1960s and operated until the new school was built.

in 1985-1986, but the buildings have since been boarded up. The Old High School is the current store and was built in the 1990s. The building is in poor condition with walls and floors falling in.

June 2026 8

She was not aware if the High School Tanks were still in use, but they were topped in the 2009 flood. The heating oil at the store is located in the front of the building, so the tanks are likely not currently in use. She was not aware of any spills or fuel smells from the tank farms. There used to be a metal hose line from the tanks to the barge. Only diesel was stored in the tanks.

The river is eroding the ground near the old school with the river now less than 100 yards away.

Permafrost is also melting at a high rate and is now at least 6 feet deep.

Ted Williams, Assistant Indian General Assistance Program (IGAP) Coordinator, said the old BIA school is near the river which is eroding. The old BIA school comprised of an old generator, old generator, old school, and three tanks. Currently none of the former BIA infrastructure is being used and the buildings are boarded up.

Ruth Ivan, IGAP Coordinator, discussed the BIA site with field personnel, confirming that the bank was eroded about 60 feet in the previous year, and expressed the community’s goal to remove all buildings and infrastructure within 200 feet of the bank. The community would like to see the building and tanks within 200 feet of the river be removed or demolished, but she does not know what funds would be used.

Michael, School Maintenance, confirmed that the pipeline running through the Old BIA Elementary School Tank Farm comes from a header and goes to the new school.

2.2 Ownership Records Review

A Limited Liability Report was received by First American Title. The following documents were obtained for both properties and copies of the documents referenced above are provided in Appendix B.

Lot 6, Block 14, Tract A, US Survey 5068, Townsite of Akiak, Bethel Recording District (Old Elementary School Tank Farm)

• Deed recorded April 9, 1986: The Secretary of the Interior, Bureau of Indian Affairs conveys the school land and improvements to the State of Alaska Department of Education.

The parcels include Lot 4, Block 14, Tract A, US Survey 5068 and Lot 2, Block 16, Tract A, US Survey 5068.

• U.S. Survey No. 5068 was originally dated July 20, 1972, modified on October 20, 1992, and most recently filed March 8, 2011: The survey from 1992 shows Lot 4 as being replatted into Lots 5 (south) and 6 (north). Lot 6 contains a house, garage, two classroom buildings, wood deck, school building, and fuel tanks on the 68,405 square feet parcel. No infrastructure is shown on Lot 5.

Lot 7, Block 13, Tract A, US Survey 5068, Townsite of Akiak, Bethel Recording District (Old High School Tank Farm)

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• Quitclaim Deed recorded January 25, 2007: The Yupiit School District granted the property, excluding the tank farm and vocational/education shop building, to the City of Akiak.

• Agreement recorded July 6, 2007: The Yupiit School District executed a quitclaim without warranty to the City of Akiak. The conveyance excluded the tank farm and vocational/education shop building, which was retained by the Yupiit School District.

• Facilities Use Agreement recorded July 27, 2007: The agreement is between the City of Akiak and the Yupiit School District. The agreement indicates that the Yupiit School District will be the exclusive user of the tank farm and vocational/education shop building.

• U.S. Survey No. 5068 was originally dated July 20, 1972, modified on October 20, 1992, and most recently filed March 8, 2011: There is no infrastructure shown on the survey, but the total area is shown as 17,951 square feet.

3.0 CONTAMINANTS OF CONCERN AND APPLICABLE

REGULATIONS

Analytical results from 2009 indicated that petroleum hydrocarbon-contaminated soil is present at the Old High School Tank Farm, with concentrations of GRO, DRO, BTEX, 1-methylnaphthalene, and 2-methylnaphthalene (polyaromatic hydrocarbons (PAH)), above ADEC Method Two Under 40 Inch Zone Migration to Groundwater.

Analytical results from 2009 also indicated that petroleum hydrocarbon-contaminated soil is present at the Elementary Former Tank Farm with concentrations of GRO, DRO, benzene, toluene, xylenes, 1-methylnaphthalene, 2-methylnaphthalene, and naphthalene (PAH) above Method Two Under 40 Inch Zone Migration to Groundwater.

Since leaded fuels may have been stored at the tank farm, lead and 1,2-dibromoethane (EDB) were included in the sampling suite during these field activities and are considered potential contaminants of concern.

Soil samples collected during the field activities compared to the cleanup levels outlined in the following regulations:

• Soil: Method Two Under 40 Inch Zone Migration to Groundwater and Human Health and Inhalation levels outlined in Tables B1 and B2 in 18 Alaska Administrative Code (AAC) 75.341, Oil and Other Hazardous Substances Pollution Control (October 18, 2023)

Paint chips were collected for waste characterization purposes to determine if lead-based paint or PCB-based paint were used on the tanks. These samples were provided to various waste disposal providers to evaluate disposal options for the site’s ASTs, and soil samples were collected from the surface surrounding the tanks.

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4.0 SAMPLING METHODOLOGY

The analytical soil sampling methods used during the field activities are outlined below. All procedures were conducted in accordance with the Alaska Department of Conservation Field Sampling Guidance (2024).

4.1 Field Screening Methods

Field screening samples were collected during the field activities. The PID was calibrated daily prior to field activities. The field headspace readings from the hand boring sampling activities were collected by filling re-sealable quart size bags approximately 1/3 to 1/2 full with soil. The bags were agitated before being allowed to develop for at least 10 minutes, but no longer than an hour.

During this time the soils were warmed to a minimum temperature of 40°F. After the samples have been warmed and allowed to develop, the probe of the PID was inserted into the bag about one-half of the headspace depth and the highest displayed reading were recorded in the field notes along with other pertinent information such as time of collection and reading, the soil characteristics, depth at which the sample was collected, and the field personnel.

4.2 Analytical Soil Sampling Collection Methods

Analytical soil samples were collected as described in the methods outlined below. Samples for volatile analysis were collected directly from the auger cuttings and/or excavator bucket at the time of the sampling activities. Volatile samples were collected within 2 minutes of sample retrieval.

Soil samples were collected using clean spoons or disposable equipment and placed directly into clean laboratory-provided containers. Volatile samples were collected first and preserved with 25-milliliters (mL) of methanol, per Alaska (AK) Methods. Samples were collected from the most likely contaminated areas based on field screening data.

5.0 FIELD ACTIVITIES

The field activities conducted July 14 to 16, 2025 included soil and paint chip sampling at the Former BIA Elementary and High School Tank Farms. Additionally, a visual survey was conducted of the areas around the Elementary Tank Farm that were not previously assessed for contamination. Field notes of the field activities are provided in Appendix C. Photographs of the field activities from the Old Elementary School Tank Farm and Old High School Tank Farm are provided in Appendices D and E, respectively.

Qualified Environmental Professional (QEP) Shayla Marshall and Dale Erickson of TCC collected the samples and directed the field work. Shayla and Dale were supported by Jamie Gilila, a local HAZWOPER laborer and excavator operator.

5.1 Work Plan Variances

In general, the work followed the ADEC-approved work plan as written, with the following exceptions:

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• Old High School Tank Farm Test Pit 6 (TP6) was unable to be advanced and sampled to full depth due to encountering unidentified yellow liner, likely indicating they were within one foot of the water line, according to excavator operator. (Photo 30)

• All but one tank at the Old High School Tank Farm were submerged (Photos 19 and 20) and unable to be sampled but appeared to be same color as the accessible tank (Photo 22) that was sampled.

• Due to a lack of indication of contamination and close proximity of the test pits (Photo 34), only five test pits were advanced at the Old High School Tank Farm. Test Pit TP5-HS was not advanced.

• Test Pits from the Old High School Tank Farm did not extend past 6 feet bgs due to soils sloughing into the test pits.

• Several of the test pits/shallow borings shifted at both site from those reflected on the proposed location figure. This was based on the accessibility or site conditions.

5.2 Site Characterization Activities

The site characterization activities included advancing soil test pits and paint chip sampling.

5.2.1 Test Pits

The test pits were that were advanced to assess the current soil conditions and were placed in the following locations:

Old Elementary School Tank Farm Locations

• Test Pits TP1-ES through TP5-ES: Verify current extent of contamination estimated in 2009 report

• Test Pits TP1-ES, TP3-ES, and TP6-ES: Assess contamination along fuel lines

• Test Pit TP7-ES: Step-out test pit based on conditions encountered in the sites test pits

Old High School Tank Farm Locations

• Test Pits TP1-HS and TP6-HS: Assess lateral extent of contamination from former sample

SB-14

• Test Pits TP2-HS and TP4-HS: Assess current extent of contamination from SB-10

• Test Pit TP3-HS: Determine current concentration of contaminants near former Sample

SB-10

Hand tools (e.g., hand auger, shovel) or excavator (Old High School Tank Farm locations only) were insufficient to reach desired depth with sufficient recovery, an excavator was used to advance each test pit instead. Test pits were advanced to 6 feet bgs at the Old School High School Tank farm due to sloughing of soils in the test pits. At the Old Elementary School Tank Farm, the maximum depth of the test pits was 11 feet bgs and was based on the total length of auger tooling.

Test Pit locations for the Old Elementary School Tank Farm and the Old High School Tank Farm are shown in Figures 5 and 6, respectively.

In addition, a site reconnaissance of the area was conducted prior to advancing the test pits to

June 2026 12 identify if there are additional areas needing investigation or indicative releases since the previous investigation work at the site. No other locations were noted.

5.2.2 Paint Chip Sampling

Two paint chip samples were collected, one from the only accessible tank at the Old High School Tank Farm, and one at the Old Elementary School Tank Farm from both tanks. Paint chips were observed on the platform beneath the Old Elementary School Tank Farm tanks and in the water surrounding the Old High School Tank Farm tanks.

5.3 Decontamination Procedures

The hand auger was decontaminated between test pits by washing with alconox-water solution, followed by a tap water then deionized water rinse. The decon water was treated with granulated activated carbon (GAC).

6.0 SAMPLING RESULTS

The samples were submitted to SGS North America, Inc. (SGS) laboratory in Anchorage, Alaska for sample analysis. The soil results are described in further detail below.

6.1 Subsurface Conditions

Surface soils at the site consisted primarily of brown silty sands, grading from higher silt content in shallow areas to higher sand content with increasing depth. Sand was generally encountered around 1.8 feet past more organic silts. Stained or gray soil indicating contamination was encountered in Test Pits TP3-ES and TP4-ES. Groundwater was not encountered during the field activities.

6.2 Old Elementary School Tank Farm Test Pit Soil Results

Samples were collected and submitted for analysis from each test pit. In select test pits, two samples were collected to assess the lateral extent of contamination in the hole. Exceedances in the ADEC Method 2 Migration to Groundwater Cleanup (MTG) level were reported in 10 of the 12 samples. DRO was also detected above the maximum allowable concentration (MAC) in Test Pit TP1-ES at 2 feet bgs. In addition, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, naphthalene, 1-methylnapthalene, and 2-methylnaphthalene were reported at concentrations greater than cleanup levels.

Detectable analytical results from the primary soil samples, duplicate soil samples, and soil trip blanks are listed in the following page on Table 1.

6.3 Old High School Tank Farm Test Pit Soil Results

Samples were collected and submitted for analysis from each test pit. Detectable concentrations of lead, DRO, PCBs, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, acetone, benzene, toluene, xylenes, and benzo[b]fluoranthene were detected in one or more samples. No analytes were detected at concentrations above cleanup levels.

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Detectable analytical results from the primary soil samples, duplicate soil samples, and soil trip blanks are listed in the following page on Table 2.

6.4 Paint Chip Sample Results

Samples were collected and submitted for analysis from the paint from both tank farms. Lead and PCB were detected at levels greater than regulatory criteria from the tanks at the Old Elementary School Tank Farm while only lead was detected at elevated levels at the tank at the Old High School Tank Farm. The sample results from the paint chips collected from the Old Elementary School Tank Farm and Old High School Tank Farm are including on Tables 1 and 2, respectively.

Table 1 - Old Elementary School Tank Farm Detected Soil Sample Results

Analyte Analysis Unit Cleanup Level PAINT-ES TP-1-ES-2 TP-1-ES-9 TP-2-ES-8 TP-3-ES-5.8 TP-3-ES-10.7 TP-23-ES-10.7~ TP-4-ES-11 TP-5-ES-11 TP-25-ES-11~ TP-6-ES-3 TP-6-ES-5.2 TP-7-ES-7.3 STB TRIP

BLANK

Sample Depth - ft - - 2 9 8 5.8 10.7 10.7 11 11 11 3 5.2 7.3 - - Field Headspace MiniRae 3000 ppmv - - 321 32.0 0.4 907 403 403 391 0.2 0.2 80.2 39.2 48.7 - - Lead SW6020B mg/kg 400 87,100 18.2 - - - - - - - - - - - - - 1,2-Dibromoethane SW8260D-SIM ug/kg 0.24 - - - - 0.885 U - - - - - - - - - - Gasoline Range Organics (GRO) AK101 mg/kg 300 - 16.9 - - 149 - - 55.5 - - - - - - - Diesel Range Organics (DRO) AK102 mg/kg 250 - 21,700 89 28.9 8,830 812 1,110 1,240 37.1 15.0 J 12,400 1,170 2,820 - - Polychlorinated Biphenyls (PCB)

Aroclor-1254 SW8082A ug/kg 1000 20,500,000 46.6 U - - - - - - - - - - - - - Other PCBs SW8082A ug/kg - ND ND - - - - - - - - - - - -

Volatile Organic Compounds (VOC) - 1,2,4-Trimethylbenzene SW8260D ug/kg 610 - 132 U 105 U 104 U 3,960 2,080 1,990 1,510 148 U 199 U 174 U 170 U 124 U 76.5 U 78.0 U 1,3,5-Trimethylbenzene SW8260D ug/kg 660 - 33.1 U 26.3 U 25.9 U 5,310 1,590 1,610 1,490 37.0 U 49.7 U 43.6 U 42.5 U 30.8 U 19.0 U 19.5 U 4-Isopropyltoluene SW8260D ug/kg - - 106 U 84.0 U 82.5 U 1,050 189 188 368 119 U 159 U 140 U 136 U 99.0 U 61.1 U 62.3 U Ethylbenzene SW8260D ug/kg 130 - 33.1 U 26.3 U 25.9 U 18.8 J 41.3 U 34.1 U 31.0 U 37.0 U 49.7 U 43.6 U 42.5 U 30.8 U 19.0 U 19.5 U Isopropylbenzene (Cumene) SW8260D ug/kg 5600 - 33.1 U 26.3 U 25.9 U 44.1 U 27.5 J 25.9 J 31.0 U 37.0 U 49.7 U 43.6 U 42.5 U 30.8 U 19.0 U 19.5 U n-Propylbenzene SW8260D ug/kg 9100 - 33.1 U 26.3 U 25.9 U 44.1 U 48.4 J 43.7 J 31.0 U 37.0 U 49.7 U 43.6 U 42.5 U 30.8 U 19.0 U 19.5 U Naphthalene SW8260D ug/kg 38 - 33.1 U 26.3 U 25.9 U 3,660 1,670 1,480 872 62.1 49.7 U 43.6 U 42.5 U 30.8 U 19.0 U 19.5 U sec-Butylbenzene SW8260D ug/kg 42000 - 33.1 U 26.3 U 25.9 U 44.1 U 98.9 89.1 31.0 U 37.0 U 49.7 U 43.6 U 42.5 U 30.8 U 19.0 U 19.5 U Toluene SW8260D ug/kg 6700 - 33.1 U 26.3 U 25.9 U 50.5 J 34.6 J 22.3 J 32.7 J 37.0 U 29.1 J 43.6 U 42.5 U 34.1 J 19.0 U 19.5 U Xylenes (total) SW8260D ug/kg 1500 - 99.0 U 78.8 U 77.3 U 765 250 254 212 111 U 149 U 131 U 128 U 92.3 U 57.2 U 58.4 U Other VOCs SW8260D ug/kg varies - ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Polyaromatic Hydrocarbons (PAH) 1-Methylnaphthalene 8270E SIM ug/kg 410 - 235 U 19.6 U 20.1 U 14,800 694 237 428 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - 2-Methylnaphthalene 8270E SIM ug/kg 1300 - 235 U 19.6 U 20.1 U 3,150 366 154 33 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Acenaphthene 8270E SIM ug/kg 37000 - 235 U 19.6 U 20.1 U 547 66 48.2 63.5 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Acenaphthylene 8270E SIM ug/kg 18000 - 235 U 19.6 U 20.1 U 75.2 14.6 J 8.47 J 12.6 J 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Anthracene 8270E SIM ug/kg 390000 - 235 U 19.6 U 20.1 U 61.1 19.6 U 19.6 U 8.82 J 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Benzo(a)Anthracene 8270E SIM ug/kg 700 - 243 J 19.6 U 20.1 U 28.4 19.6 U 19.6 U 16.5 J 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Benzo[a]pyrene 8270E SIM ug/kg 1900 - 96.3 J 19.6 U 20.1 U 20.2 U 19.6 U 19.6 U 19.6 U 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Benzo[b]Fluoranthene 8270E SIM ug/kg 20000 - 452 19.6 U 20.1 U 20.8 J 19.6 U 19.6 U 20.4 J 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Biphenyl 8270E SIM ug/kg - - - - - 230 - - - - - - - - - - Chrysene 8270E SIM ug/kg 600000 - 346 19.6 U 20.1 U 46.8 19.6 U 6.70 J 26.0 J 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Fluoranthene 8270E SIM ug/kg 590000 - 119 J 19.6 U 20.1 U 296 35.7 38.3 105 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Fluorene 8270E SIM ug/kg 36000 - 235 U 19.6 U 20.1 U 928 89.8 58.9 79.3 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Naphthalene 8270E SIM ug/kg 38 - 188 U 15.7 U 16.0 U 555 122 84.5 27.7 15.8 U 15.7 U 451 U 16.3 U 18.4 U - - Phenanthrene 8270E SIM ug/kg 39000 - 235 U 19.6 U 20.1 U 799 61.5 32.7 56.7 19.8 U 19.6 U 563 U 20.3 U 23.0 U - - Pyrene 8270E SIM ug/kg 87000 - 2800 19.5 J 20.1 U 237 29.2 32.6 123 19.8 U 19.6 U 563 U 20.3 U 21.5 J - - Other PAHs 8270E SIM ug/kg varies - ND ND ND ND ND ND ND ND ND ND ND ND - -

Notes:

* 18 AAC 75 Table B1 and B2 Migration to Groundwater (MTG) Cleanup Level (October 18, 2023) ~ Duplicate of preceeding sample mg/kg Milligram per kilogram ug/kg Microgram per kilogram

89 Analyte detected below MTG Cleanup Level 3,660 Analyte detected above MTG Cleanup Level

21,700 Concentration exceeds the DRO (12,500 mg/kg) Maxium Allowable Concentration (October 18, 2023) 132 U Analyte non-detect 188 U Analyte non-detect; detection limit above cleanup levecl

J Estimated concentration ND Non-detect

- Not sampled or not applicable

June 2026 Old BIA School Site, Akiak, Alaska Page 1 of 1

Table 2 - Old High School Tank Farm Detected Soil Sample Results

Analyte Analysis Unit Cleanup Level PAINT-HS TP-1-HS-1 TP-1-HS-5.5 TP-2-HS-1.5 TP-2-HS-6 TP-3-HS-1.5 TP-23-HS-1.5~ TP-3-HS-6 TP-4-HS-1 TP-4-HS-6 TP-6-HS-1.5 TP-6-HS-4 STB TRIP

BLANK

Sample Depth - ft - - 1 5.5 1.5 6 1.5 1.5 6 1 6 1.5 4 - - Field Headspace MiniRae 3000 ppmv - - 2.5 2.6 0.0 0.0 0.0 0.0 0.0 1.8 3.1 1.1 1.6 - - Lead SW6020B mg/kg 400 511 - 61.7 - - - - - - - - - - - 1,2-Dibromoethane SW8260D-SIM ug/kg 0.24 - - - - - - - 0.112 U - 0.235 U - - - - Gasoline Range Organics (GRO) AK101 mg/kg 300 - - 2.98 J - - - - - - 3.75 J - - - - Diesel Range Organics (DRO) AK102 mg/kg 250 - 58.7 32.5 22.0 J 22 24.4 J 26.4 15.2 J 33.1 11.3 J 47.2 40.2 - - Polychlorinated Biphenyls (PCB)

Aroclor-1254 SW8082A ug/kg 1000 688 U - 80.7 - - - - - - - - - - - Other PCBs SW8082A ug/kg - ND - ND - - - - - - - - - - -

Volatile Organic Compounds (VOC) - 1,2,4-Trimethylbenzene SW8260D ug/kg 610 - 119 U 115 U 119 U 97.5 U 128 J 143 U 89.3 U 96.0 U 188 U 90.0 U 158 U 76.5 U 78.0 U 1,3,5-Trimethylbenzene SW8260D ug/kg 660 - 22.1 J 26.0 J 29.8 U 24.5 U 44.7 J 17.2 J 22.3 U 24.0 U 47.0 U 22.4 U 39.5 U 19.0 U 19.5 U Acetone SW8260D ug/kg 38000 - 296 U 287 U 299 U 245 U 533 U 359 U 223 U 240 U 470 U 224 U 250 J 191 U 195 U Benzene SW8260D ug/kg 22 - 6.30 J 8.02 J 14.9 U 12.2 U 26.6 U 17.9 U 11.2 U 12.0 U 23.5 U 11.2 U 19.8 U 9.52 U 9.75 U Toluene SW8260D ug/kg 6700 - 43.3 64.2 29.8 U 24.5 U 85.2 43.6 J 41.6 16.7 J 39.5 J 20.0 J 39.5 U 19.0 U 19.5 U Xylenes (total) SW8260D ug/kg 1500 - 129 83.7 J 89.3 U 73.3 U 323 141 J 77.6 J 72.1 U 141 U 37.4 J 119 U 57.2 U 58.4 U Other VOCs SW8260D ug/kg varies - ND ND ND ND ND ND ND ND ND ND ND ND ND

Polyaromatic Hydrocarbons (PAH) Benzo[b]Fluoranthene 8270E SIM ug/kg 20000 - 9.65 J 20.2 U 22.5 U 19.7 U 24.2 U 22.7 U 19.7 U 20.3 U 19.7 U 20.2 U 24.5 U - - Other PAHs 8270E SIM ug/kg varies - ND ND ND ND ND ND ND ND ND ND ND ND -

Notes:

* 18 AAC 75 Table B1 and B2 Migration to Groundwater (MTG) Cleanup Level (October 18, 2023) ~ Duplicate of preceeding sample mg/kg Milligram per kilogram ug/kg Microgram per kilogram

61.7 Analyte detected below MTG Cleanup Level

511 Analyte detected above MTG Cleanup Level

119 U Analyte non-detect

26.6 U Analyte non-detect; detection limit above cleanup levecl

J Estimated concentration ND Non-detect

- Not sampled or not applicable

June 2026 Old BIA School Site, Akiak, Alaska Page 1 of 1

June 2026 16

7.0 QUALITY CONTROL REVIEW

ADEC Laboratory Data Review Checklists were completed for the SGS reports. The laboratory reports and checklists are included in Appendix F. The ADEC’s 2022 Guidelines for Data Reporting were used for this review. The following is a summary of the quality control (QC) issues affecting data quality or usability.

• GRO was not selected as an analysis on the chain of custody for the trip blank. Since GRO was not detected at levels above cleanup standards in the project samples, the data is considered to be usable.

• The limit of quantitation (LOQs) for numerous volatile organic compounds (VOCs) and PAHs exceeded the soil ADEC cleanup level. The affected LOQs are italicized in the tables following the laboratory checklist. Since the sample exceeded cleanup levels for other analytes, the data is considered usable for the project purpose of determining if additional investigation or remedial actions are warranted.

• The matrix spike/matrix spike duplicate (MS/MSD) were outside the percent recovery (%R) or relative percent difference (RPD) for several samples for lead, trichlorofluoromethane, and PAHs. For lead, the project samples are well over cleanup levels so it does not affect the sample results. For trichlorofluoromethane and PAHs, the affected project samples did not have detectable concentrations or concentrations above the reporting limit. Therefore, the MS/MSDs do not appear to impact the project samples for these parameters.

• The RPD is above the data quality objective (DQO) for the analytes associated with the following sample pairs. With the exception of 1-methylnapthlene in TP-3-ES-10.7, the primary and duplicate sample pairs were either both above or both below cleanup standards. For the project purpose, the highest concentration is considered when determining if additional investigation or if contamination is present in the sample location.

o TP-3-ES-10.7 and TP23-ES-10.7: 1-methylnapthalene (98%), 2-methylnapthalene (82%), phenanthrene (61%);

o TP-5-ES11 and TP25-ES-11: DRO (85%); and o TP3-HS-1.5 and TP23-HS-1.5: trimethylbenzene (89%), toluene (65%), xylene

(78%)

8.0 DISCUSSION

A discussion of the results from the July 2025 sampling are described in further detail below.

8.1 Old Elementary School Tank Farm Soil Sampling Discussion

Samples were collected at locations to confirm the 2009 extent of contamination. Based on the results from the 2025 sampling activities, the lateral extent of contamination appears larger than

June 2026 17 initially estimated with only one test pit containing concentrations less than cleanup levels. The vertical extent of contamination was also unable to be determined in all but Test Pit TP1-ES. Due to the accessibility of the site for heavy equipment, a hand auger was used to advance the test pits and only 11 feet of tooling was brought to the project site. Based on the results, contamination appears to be deeper than initially estimated and extends beyond 11 feet in the area surrounding the fuel line, although concentrations decreased with depth based on analytical results and field headspace readings.

The highest DRO concentrations were from samples collected near the fuel lines (Test Pits TP1- ES and TP6-ES), although no other analytes exceeded cleanup levels in those test pits.

Alternatively, Test Pits TP3-ES and Test Pit TP4-ES also contained VOCs and PAHs at levels above cleanup criteria.

8.2 Old High School Tank Farm Soil Sampling Discussion

Samples were collected from test pits advanced in the former locations of areas that historically exceeded cleanup levels. The test pits were advanced to 6 feet bgs, which is deeper than the depth which exceedances were reported in 2009. No indications of contamination were identified during the 2025 field activities.

8.3 Conceptual Site Model Discussion

A conceptual site model (CSM) was updated for the site with a focus on the identifying exposure pathways that may need further investigation per the ADEC’s January 2017 Guidance on Developing Conceptual Site Models. The Human Health Conceptual Site Model Graphic Form and Human Health Conceptual Site Model Scoping Form and Standardized Graphic are included in Appendix G. Due to the results of the field activities, individual CSMs were prepared for each site.

8.3.1 Old Elementary School Tank Farm Conceptual Site Model Discussion The primary source of contamination at the site are leaks and spills from ASTs and pipelines. The 2025 investigation identified DRO, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, naphthalene, are 1-methylnaphthalene, and 2-methylnaphthalene being present at the site in the soil between 0 and 11 feet bgs. In addition, GRO, benzene, toluene, xylenes and multiple PAHs (benzo[a]anthracene, benzo[b]flurorene, chrysene, fluoranthene, fluorene, and pyrene) were reported in the 2009 field activities.

The pathways identified as complete in the CSM include: incidental soil ingestion, dermal absorption of contaminants from soil, inhalation of outdoor air, and inhalation of indoor air (due to the proximity of structures within 30 feet of contaminated test pit samples).

Much of the site that is contaminated is vegetated so inhalation of fugitive dust and direct contact with sediment is not considered potentially complete or warranting further investigation

Further investigation is recommended to assess the following pathways:

June 2026 18

• Ingestion of Groundwater – Groundwater was not encountered during the 2009 or 2025 field activities with depths of 14 and 11 feet bgs, respectively. According to the 2010 Old High School Tank Farm, Site Characterization Report, groundwater is utilized as a drinking water source with two houses (closest just over 500 feet from the site) having their own wells. According to the ADEC Drinking Water Program, the Akiak Community System (Water System No. AK2272005) is served primarily by one well and two others are not hooked up. According to the information provided on the Alaska Department of Natural Resources Well Log Tracking System (WELTS), the primary well (WL003) is 170 feet deep and was installed on October 11, 2001. The well log (25922) indicated that wet and heaving silty sands were encountered between 59 and 80 feet bgs but water bearing soils were encountered starting at 140 feet bgs.

A well log for the BIA School in Akiak was available on WELTS (Well 119854). The well log was from November 13, 1964 and had a well depth of 40 feet. No well log was available.

Further investigation into the total depth of contamination at the site will be required to determine if the contamination may extend to the water bearing zone.

• Ingestion of Surface Water and Dermal Exposure to Contaminants in Groundwater and Surface Water – the site is located near the Kuskokwim River and topographically upgradient of the surface water body. The area has also been prone to flooding in recent past. It is unknown whether the contamination extends downgradient towards the river.

Further assessment of the extent of contamination is warranted to determine if this pathway is complete.

The site is in a residential area and near the current school. As a result, the current and future receptors will include residents, commercial or industrial workers, site visitors, trespassers, subsistence users, and construction workers.

8.3.2 Old High School Tank Farm Conceptual Site Model Discussion The primary source of contamination at the site are leaks and spills from ASTs and pipelines.

Previous investigations have identified DRO, GRO, benzene, toluene, ethylbenzene, xylenes, 1-methylnaphthalene, and 2-methylnaphthalene being present at the site in the soil between 0 and 2 feet bgs. However, based on the 2025 sample results, concentrations have decreased and no longer exceed cleanup levels. As a result, the pathways are considered insignificant.

9.0 INVESTIGATIVE DERIVED WASTE MANAGEMENT

Investigation derived waste included soil, sampling disposables, and personal protective equipment (PPE). Soil cuttings were not containerized due to all cuttings being used for samples.

Investigation derived waste (IDW) was comprised of gloves, spoons, Ziplock bags, and other sampling disposables which were disposed of as solid waste at the Akiak landfill.

June 2026 19

10.0 CONCLUSIONS AND RECOMMENDATIONS

The 2025 field activities focus was on completing the delineation of known petroleum contamination, inspecting the status of the bulk fuel tanks, and collecting paint chips in order to assess future remedial actions at both the Old Elementary School Tank Farm and Old High School Tank Farm sites.

Contamination remains present at the Old Elementary School Tank Farm with the extent of contamination and volume appearing be greater than the 2009 estimate. The lateral and vertical extent of contamination is not known, although Test Pit TP2-ES may be the eastern extent of contamination along the fuel line. Due to the presence of utilities (e.g., leach field, fuel lines to the new offsite tank farm) and limited access, heavy equipment could not be used to advance test pits in the area and may limit future remedial action.

Contamination was not observed at the Old High School Tank Farm. While contamination was not encountered in the area investigated as part of this 2025 effort, there is a possibility that contamination may be encountered if the tank farm is to be decommissioned in the future and the liner is removed.

The status of the bulk fuel tank farms were also evaluated. According to the local contacts, neither tank farm is in use. Liners appear in tact in both tank farms and standing water is present. Samples collected from the paint of the tanks contained lead (both tank farms) and PCBs (Old Elementary School Tank Farm only). Decommissioning/demolition of the tank farms will warrant management of the water in the bermed areas, noting paint chips were observed on the platform (Old Elementary School Tank Farm) and in the containment area water (Old High School Tank Farm). The of lead and PCB wastes will require disposal outside of the community.

Based on the results of the July 2025 field activities and conceptual site model, we recommend the following to advance the site towards closure:

• Request site closure for the Old High School Tank Farm. Site closure will be reviewed under a separate cover.

• Additional soil sampling at the Old Elementary School Tank Farm to identify the lateral and vertical extents of contamination.

• Once the area of Old Elementary School Tank Farm contamination has been fully defined, evaluate cleanup methods for the site in consideration of the potential impacts to the permafrost at the site and limited resources in the community (e.g., landfarm, dig and haul, in-situ treatments, limited removal action of hot spots).

June 2026 20

11.0 REFERENCES

ADEC. Oil and Other Hazardous Substances Pollution Control, 18 AAC 75. 18 October 2023.

ADEC. Field Sampling Guidance. August 2024.

SLR. Site Characterization Report, Old High School Tank Farm, Akiak, Alaska. February 2010.

SLR. Site Characterization Report, Old Elementary School Tank Farm, Akiak, Alaska. February 2010.

Ecology and Environment, Inc. Aboveground Storage Tank Farm Reconnaissance, Akiak, Alaska.

December 2000.

APPENDIX A

Figures

VICINITY MAP

BETHEL D-6 TOPO (1954)

OLD ELEMENTARY AND HIGH

SCHOOL TANK FARMS

AKIAK, ALASKA 1

FIGURE

TANANA COMMERCIAL

COMPANY

DATE:

5/7/2026

PROJECT SITE

NAPASKIAK VILLAGE

LAGOON

NGRAPHIC SCALE (IN FEET)

0 500 1000 2000 40001000

Ku sk ok wi m R ive r

PROJECT AREA

OLD ELEMENTARY AND HIGH

SCHOOL TANK FARMS

AKIAK, ALASKA 2

FIGURE

TANANA COMMERCIAL

COMPANY

DATE:

5/7/2026

Old Elementary School Tank Farm

N

JULY 2021 GOOGLE EARTH PRO IMAGERY

GRAPHIC SCALE (IN FEET)

0 200 400 800 1600400

Old High School Tank Farm

KUSKOKWIM RIVER

Water Plant

Private Water Well

Private Water Well

X

X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X

X

X

X

X

X

X

X

X

BE

RM

FE

NC

E

FU

EL

L

IN

E

FUEL LINE

TP-3

FUEL LINES IN AREA; EXACT LOCATION

UNKNOWN DURING 2009 FIELD ACTIVITIES;

NO SAMPLES COLLECTED IN THIS AREA

LE

AC

H

FI

EL

D

(N O T

ES

T

PI

T

AC

CE

SS

DU

RI

NG

S

EP

TE

M

BE

R

FI

EL

D

AC

TI

VI

TI

ES

HEAVILY VEGETATED AREA

(NO TEST PIT ACCESS

DURING SEPTEMBER 2009

FIELD ACTIVITIES)

TP-4

TP-6

SB-2

SB-1

TP-1

TP-2

TP-5

2009 ESTIMATED EXTENT OF

CONTAMINATION TO BE VERIFIED

DURING 2025 FIELD ACTIVITIES

NO

LONGER

IN USE

NO

LONGER

IN USE

HISTORIC SAMPLE LOCATIONS OLD ELEMENTARY SCHOOL TANK FARM

AKIAK, ALASKA 3

FIGURE

TANANA COMMERCIAL

COMPANY

DATE:

5/7/2026

N

JULY 2021 GOOGLE EARTH PRO IMAGERYLEGEND

Soil Boring location sampled in September 2009. RED denotes samples that exceeded ADEC Cleanup Levels.

Test Pit location. BLACK denotes sample concentration was less than ADEC Cleanup Levels.

Approximate location of fenceX

Approximate location of buried fuel line

GRAPHIC SCALE (IN FEET)

0 5 20 40

Approximate property boundary

TOPPLED

TANKS

BERM

APPROXIMATE LOCATION OF BURIED FUEL LINE

(NOT TO BE USED FOR LOCATE PURPOSES)

3" LINE

AKIAK JAIL

BOARDWALK

BO

ARDW

ALK

X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X

X X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

3" LINE

WATER/SEWER

SB-15

SB-1

SB-2

SB-3

SB-4

SB-5

SB-6

SB-7

SB-8

SB-9

SB-10

SB-11 TP-1

SB-12

SB-13

SB-14

ESTIMATED EXTENT OF

CONTAMINATION IDENTIFIED

DURING 2009 FIELD ACTIVITIES

TANKS

NO

LONGER

IN USE

HISTORIC SAMPLE LOCATIONS OLD HIGH SCHOOL TANK FARM

AKIAK, ALASKA 4

FIGURE

TANANA COMMERCIAL

COMPANY

DATE:

5/7/2026

N

JULY 2021 GOOGLE EARTH PRO IMAGERYLEGEND

Soil Boring location sampled in September 2009. RED denotes samples that exceeded ADEC Cleanup Levels.

Test Pit location. BLACK denotes sample concentration was less than ADEC Cleanup Levels.

Approximate location of fenceX

Approximate location of buried fuel line

GRAPHIC SCALE (IN FEET)

0 5 20 40

X

X

X

X

X

X

X

X

X

X

X

NO

LONGER

IN USE

BE

RM

FE

NC

E

FU

EL

L

IN

E

FUEL LINE

SB-2

SB-1 TP6-ES

TP2-ES

TP1-ES

TP5-ES

TP3-ES

TP4-ES

2009 ESTIMATED EXTENT OF

CONTAMINATION

X

X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X

X

X

X

X

X

X

X

X

POWER POLE

TP7-ES

OLD ELEMENTARY SCHOOL

PAINT-ES

Naph: 62.1 mg/kg (11 ft)

DRO: 2,820 mg/kg (7.3 ft)

DRO: 12,400 mg/kg (3 ft) 1,170 mg/kg (5.2 ft)

DRO: 21,700 mg/kg (2 ft) DRO: 89 mg/kg (9 ft)

DRO: 8,830 mg/kg (5.8 ft) 1,110 mg/kg (10.7 ft)

1,2,4-TMB: 3,960 ug/kg (5.8 ft)

1,3,5-TMB: 5,310 ug/kg (5.8 ft)

Napth: 3,660 ug/kg (5.8 ft)

1-Methylnapth: 14,800 ug/kg (5.8 ft)

2-Methylnapth: 3,150 ug/kg (5.8 ft)

2,080 ug/kg (10.7 ft)

1,610 ug/kg (10.7 ft)

1,670 ug/kg (10.7 ft)

694 ug/kg (10.7 ft)

366 ug/kg (10.7 ft)

DRO: 1,240 mg/kg (11 ft) 1,2,4-TMB: 1,510 ug/kg (11 ft) 1,3,5-TMB: 1,490 ug/kg (11 ft) Napth: 872 ug/kg (11 ft) 1-Methylnapth: 428 ug/kg (11 ft)

Lead: 87,100 mg/kg Aroclor-1254: 20,500,000 mg/kg

LE

AC

H

FI

EL

D

(N O T

ES

T

PI

T

AC

CE

SS

NO

LONGER

IN USE

2025 SOIL SAMPLE

LOCATIONS

OLD ELEMENTARY SCHOOL TANK FARM

AKIAK, ALASKA 5

FIGURE

TANANA COMMERCIAL

COMPANY

DATE:

5/7/2026

N

JULY 2021 GOOGLE EARTH PRO IMAGERYLEGEND

GRAPHIC SCALE (IN FEET)

0 5 20 40

Approximate location of fenceX

Soil Boring location sampled in September 2009 that exceeded ADEC Cleanup Levels.

Approximate location of buried fuel line

Approximate property boundary

Sample location from 2025. BLUE denotes sample concentration was less than ADEC Cleanup Levels.

Sample location from 2025. RED denotes sample concentration was greater than ADEC Cleanup Levels.

TANKS

NO

LONGER

IN USE

TOPPLED

TANKS

BERM

APPROXIMATE LOCATION OF BURIED FUEL LINE

3" LINE

AKIAK JAIL

BOARDWALK

BO

ARDW

ALK

X

X

X

X

X

X

X

X

X

X

X X

X

X

X

X

X X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

3" LINE

WATER/SEWER

TP1-HSTP6-HS

TP4-HS

TP2-HS

TP…