A05_-_PWS_-_Attachment__2_-_25241_2012_02_01_SC_Report.pdf

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NAPASKIAK FORMER BIA SCHOOL DAY TANKS

SITE CHARACTERIZATION REPORT

February 13, 2012

Prepared for:

Alaska Department of Environmental Conservation and

Lower Kuskokwim School District

Prepared by:

825 W. 8th Ave.

Anchorage, AK 99501

Prepared by: _____________________________ Lisa Nicholson Project Manager

Reviewed by: ____________________________

Stephen Witzmann, PE Senior Environmental Engineer

Napaskiak Former BIA Day Tanks Site Characterization Report DEC and LKSD i 2/13/2012

TABLE OF CONTENTS

ACRONYMS AND ABBREVIATIONS ............................................................................. iii

EXECUTIVE SUMMARY .................................................................................................. v

1. INTRODUCTION

1.1. Background

1.1.1. Site Information

1.1.2. Previous Investigations

1.2. Project Objectives

1.3. Contaminants of Concern and Regulatory Framework

1.4. Deviations from the Work Plan

2. FIELD ACTIVITIES

2.1. Drinking Water Well Sampling

2.2. Groundwater Assessment

2.3. Soil Assessment

2.3.1. Field Screening

2.3.2. Analytical Sampling

2.4. Abandoned Sewage Lagoon Assessment

2.4.1. Bench-Scale Study

2.5. Sample Management

3. FINDINGS

3.1. Drinking Water Well Sampling

3.2. Groundwater Assessment

3.3. Soil Assessment

3.3.1. Area A

3.3.2. Area B

3.3.3. Area C

3.3.4. Area D

3.4. Leaching Potential

3.5. Abandoned Sewage Lagoon Assessment

3.5.1. Bench-Scale Study

4. QUALITY ASSURANCE REVIEW

5. CONCEPTUAL SITE MODEL

5.1. Receptor Profile

5.2. Exposure Pathways

6. CONCLUSIONS

6.1. Groundwater and Drinking Water

6.2. Soil Impacts

6.3. Abandoned Sewage Lagoon Assessment

6.4. Proposed Cleanup Technique

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6.4.1. Alternatives Considered

6.4.2. Selected Remedial Alternative

7. REFERENCES

TABLES

1: DEC Cleanup Levels – in text 2: Drinking Water Sample Results – in Tables tab 3: Groundwater Sample Results – in Tables tab 4: Soil Sample Results – DRO, RRO, GRO, BTEX – in Tables tab 5: Soil Sample Results – Polynuclear Aromatic Hydrocarbons – in Tables tab 6: Soil and SPLP Extract Results for Detected Analytes – in text 7: Sewage Lagoon Sample Results – in text 8: Bench-Scale Study Sample Results – in text 9: Potential Exposure Pathways – in text 10: Summary Evaluation of Alternatives – in text

FIGURES

1: Site Location Map 2: Site Plan with Drinking Water Results 3: Site Detail with Groundwater DRO Results 4: Area A Soil Results 5: Area B Soil Results 6: Area C Soil Results 7: Area D Soil Results 8: Proposed Excavation Locations

APPENDICES

A: Field Notes B: Photographs C: Laboratory Reports, Laboratory Review Checklist, and Quality Assurance

Review D: Conceptual Site Model E: Volume Estimates F: Remedial Action Cost Estimates iii 2/13/2012

ACRONYMS AND ABBREVIATIONS

AK ................. Alaska Method AST ............... Aboveground storage tank bgs ................ below ground surface BIA ................ Bureau of Indian Affairs BOD… ........... Biological oxygen demand BTEX ............. Benzene, toluene, ethylbenzene, and xylenes CIS ................ Community Information Summaries COD .............. Chemical oxygen demand CSM .............. Conceptual site model DEC............... Alaska Department of Environmental Conservation DRO .............. Diesel-range organics EPA ............... U. S. Environmental Protection Agency GRO .............. Gasoline-range organics LCY ............... Loose cubic yards LKSD ............. Lower Kuskokwim School District MCL............... Maximum contaminant limits mg/kg ............ milligrams per kilogram mg/L .............. milligrams per liter mL ................. milliliter ND ................. Not detected OASIS ........... OASIS Environmental, Inc., an ERM company PAH ............... Polynuclear aromatic hydrocarbons PID ................ Photoionization detector ppmv ............. parts per million by volume QA/QC........... Quality assurance / quality control RCRA ............ Resource Conservation and Recovery Act RRO .............. Residual-range organics SDG .............. Sample delivery group SPLP ............. Synthetic precipitation leaching procedure VOC .............. Volatile organic compounds iv 2/13/2012 v 2/13/2012

EXECUTIVE SUMMARY

OASIS Environmental, Inc., an ERM company (OASIS) performed a site characterization at the former Bureau of Indian Affairs (BIA) school in Napaskiak, Alaska. Portions of the site characterization effort were performed under contract to the Alaska Department of Environmental Conservation (DEC). The remainder of the site characterization effort was performed under contract to the Lower Kuskokwim School District (LKSD) in preparation for building a new school on the site.

The project involved installing and sampling temporary monitoring well points, collecting drinking water samples from nearby water supply wells, assessing the surface and subsurface soil by digging and sampling test pits at four areas of potential concern, and evaluating an abandoned sewage lagoon. Contaminants of potential concern include diesel-range organics (DRO), residual-range organics (RRO), gasoline-range organics (GRO), benzene, toluene, ethylbenzene, and xylenes (BTEX), volatile organic compounds (VOC), and polynuclear aromatic hydrocarbons (PAH).

OASIS installed temporary monitoring well points between the site and three potential receptors; the current school drinking water well, the community drinking water well, and Napaskiak Slough. Well point WP-1, located between the site and the current school well, did not produce enough water to collect samples. The other two well points were sampled for DRO, RRO, GRO, BTEX, and PAHs. All analytical results were below DEC Table C groundwater cleanup levels except DRO. The DRO concentrations in the two samples were 2.42 milligrams per liter (mg/L) and 1.68 mg/L, exceeding the cleanup level of 1.5 mg/L.

OASIS collected three drinking water samples from two nearby water supply wells; two from the current school well (pre-treatment and post-treatment) and one pre-treatment sample from the community well located west of the site. The samples were analyzed for VOCs. The drinking water wells were not analyzed for DRO. No VOCs were detected in the samples.

OASIS and their subcontractor used a small excavator to dig 25 test pits at four areas of concern; either known release locations or aboveground storage tank farms. The samples were analyzed for DRO, RRO, GRO, and BTEX. Five samples were also analyzed for PAH. Each area contained test pits with DRO concentrations exceeding DEC Method Two MTG cleanup levels; analytical results ranged up to 26,100 milligrams per kilogram (mg/kg) DRO. Several test pit samples also exceeded cleanup levels for benzene, ethylbenzene, naphthalene, 1-methylnaphthalene, and/or 2-methylnaphthalene.

Two soil samples were also submitted for synthetic precipitation leaching procedure (SPLP) extraction and the extracts were analyzed for DRO and PAH. The DRO contamination appears to be leachable at high concentrations; OASIS estimates that at soil concentrations greater than 1,000 mg/kg DRO, DRO may leach from soils at concentrations that exceed surface water standards.

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OASIS estimated the quantity of soil exceeding soil cleanup levels, assuming that the DEC approves removal or treatment of only the top two feet of soil from the site. A total volume of approximately 1,000 loose cubic yards (LCY) will require treatment or excavation and disposal.

OASIS collected samples from an abandoned sewage lagoon located on the property to evaluate the thickness of biosolids remaining in the sewage lagoon and the amount of water in the lagoon. Solids samples from the lagoon were analyzed for chemical oxygen demand (COD) and biological oxygen demand (BOD). The results of the analyses indicate that sewage solids are present and still biologically active. In order to leave the sewage solids in place, the lagoon must be de-watered and the sewage solids must be treated. OASIS proposes that the most feasible in-situ treatment for the lagoon is the addition of quicklime to raise the pH of the biosolids.

OASIS performed a bench-scale study treating sewage solids samples with varying quantities of lime. The study results indicate that approximately 900 pounds of quicklime will be needed to treat the sewage solids.

A variety of remediation alternatives were assessed to better understand their ability to address potential risk posed by the fuel-contaminated soil:

Alternative 1: Excavation and Offsite Disposal

Alternative 2: Onsite Treatment and Disposal

Alternative 3: Aggressive Onsite Treatment

Alternative 4: In Place Landfarming

Of these alternatives, Alternative 4: In Place Landfarming appears to be the most appropriate, and is being proposed as the cleanup technique for the site in accordance with 18 AAC 75.335(c)(5).

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1. INTRODUCTION

OASIS Environmental, Inc., an ERM company (OASIS) was contracted by the Alaska Department of Environmental Conservation (DEC) in May 2011 under Notice-to-Proceed 18-4002-11-033C to complete environmental site characterization at the former Bureau of Indian Affairs (BIA) School in Napaskiak, Alaska. The project objective was to delineate petroleum impacts around four locations associated with known or suspected contamination.

In August 2011, the Lower Kuskokwim School District (LKSD) contracted OASIS to expand the DEC site characterization in preparation for construction of a new school on the site. The LKSD project includes assessment of an abandoned sewage lagoon located at the site. In addition, the LKSD asked that OASIS evaluate the suitability of the Napaskiak landfill for disposal of impacted soil from the former BIA school site.

The two projects were performed concurrently in order to minimize costs to both clients.

Both clients agreed that OASIS would prepare one report for all concerned parties. This document presents the background information, project objectives, deviations from the original scope, discussion of work performed in September 2011, and the results of the characterization.

1.1. Background

1.1.1. Site Information

Napaskiak is a predominantly Yup’ik Eskimo village located on the east bank of the Kuskokwim River, along Napaskiak Slough, 7 miles southeast of Bethel (Figure 1). The community lies at approximately 60.708060° North latitude and 161.766110° West longitude; Sec. 08, T007N, R071W, Seward Meridian. Napaskiak is located in the Bethel Recording District. The area encompasses 3.5 square miles of land and 0.4 square miles of water. Napaskiak is strongly influenced by storms and weather patterns in the Bering Sea and also by inland continental weather. Average annual precipitation is 16 inches, with 50 inches of snowfall. Summer temperatures range from 42 to 62 degrees Fahrenheit (°F), and winter temperatures average -2 to 19 °F (CIS 2009).

The site is located in the floodplain of the Kuskokwim River and consists of fluvial and floodplain deposits. Groundwater depth is less than 10 feet below ground surface (bgs).

The former BIA school site is located on the west side of the village adjacent to Napaskiak Slough; it lies about 160 feet south of the slough (Figure 2). The site has several buildings including the former school and the utility building. Two former aboveground storage tank (AST) containment areas are present to the south of the school and utility buildings.

1.1.2. Previous Investigations

In 2001, OASIS conducted an area-wide reconnaissance of the Napaskiak tank farms (OASIS 2002). Adjacent to the abandoned BIA school and utility building, day tanks

2 2/13/2012 were present (Area A, Figure 3). The tanks are now gone but cribbing denotes the area where the tanks were located. A stained area was noted at this location and a sample collected from 3 feet below ground surface (bgs) within the stained area had a diesel-range organics (DRO) concentration of 38,900 mg/kg and napthlanene at 83.4 mg/kg.

Other petroleum constituents were below DEC soil cleanup levels. A drinking water well is located about 550 feet southeast of the stained area at the Z. John Williams School.

Three other spill areas have been identified in this immediate area as shown on Figure

3. One is to the west of the day tank area and was a release from BIA fuel piping (Area B). Another is located southwest of the day tank release at a former containment area;

the spill was related to cracked piping (Area C). The fourth known release is believed to be from a leaking fuel header valve just north of the utility building. A second former AST containment area is located south of the former school (Area D). This area had not been sampled prior to this investigation (LKSD 1994).

1.2. Project Objectives

The primary objectives of the two projects are presented below:

Delineate the extent of soil impacts as related to the three larger releases (Areas A, B, and C) at the former BIA School area, hereafter referred to as “the Site.”

Assess whether there are any impacts related to the previously uninvestigated AST containment area (Area D).

Evaluate contaminant impacts to groundwater by collecting groundwater samples between the Site and nearby drinking water wells.

Assess water quality in drinking water wells within 500 feet of the Site.

Assess the presence of sewage solids in the abandoned sewage lagoon and estimate the quantity of lime needed to treat the sewage solids.

Characterize the soil at the Napaskiak landfill to help obtain a Class III municipal solid waste landfill permit for Napaskiak.

1.3. Contaminants of Concern and Regulatory Framework

The releases from the day tanks and piping consisted of heating fuel. Contaminants of potential concern associated with heating fuel are benzene, toluene, ethylbenzene and total and xylenes (BTEX), gasoline-range organics (GRO), DRO, and polynuclear aromatic hydrocarbons (PAH). Table 1, shown below, provides analytical methods for each contaminant of potential concern, the DEC soil cleanup levels per 18 AAC 75.341, Tables B1 and B2, under 40-inch zone, most stringent exposure pathway, and the groundwater cleanup levels per 18 AAC 75. 345, Table C. Drinking water well volatile organic compound (VOC) sampling results will be compared to the drinking water standards (maximum contaminant levels [MCL]) established in 18 AAC 80.

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TABLE 1: DEC CLEANUP LEVELS

Analyte Laboratory Method Soil

Cleanup Level in mg/kg

Groundwater Cleanup Level in mg/L

Benzene EPA Method 8021B 0.025 0.005

Toluene EPA Method 8021B 6.5 1.0

Ethylbenzene EPA Method 8021B 6.9 0.7

Total Xylenes EPA Method 8021B 63 10

GRO Alaska Method AK101 300 2.2

DRO Alaska Method AK102 250 1.5

RRO Alaska Method AK 103 10,0001 1.1

VOC EPA 524.2 Various Various

Acenaphthene EPA Method 8270c-SIM 180 2.2

Acenaphthylene EPA Method 8270c-SIM 180 2.2

Anthracene EPA Method 8270c-SIM 3,000 11

Benzo(a)anthracene EPA Method 8270c-SIM 3.6 0.0012

Benzo(b)fluoranthene EPA Method 8270c-SIM 12 0.0012

Benzo(k)fluoranthene EPA Method 8270c-SIM 120 0.012

Benzo(a)pyrene EPA Method 8270c-SIM 0.492 0.0002

Benzo(g,h,i)perylene EPA Method 8270c-SIM 14002 1.1

Chrysene EPA Method 8270c-SIM 360 0.12

Dibenzo(a,h)anthracene EPA Method 8270c-SIM 0.492 0.00012

Fluoranthene EPA Method 8270c-SIM 1,400 1.5

Fluorene EPA Method 8270c-SIM 220 1.5

Indeno(1,2,3-cd)pyrene EPA Method 8270c-SIM 4.92 0.0012

Naphthalene EPA Method 8270c-SIM 20 0.73

Phenanthrene EPA Method 8270c-SIM 3,000 11

Pyrene EPA Method 8270c-SIM 1,000 1.1 Notes:

1 Under 40-inch zone, ingestion pathway 2 Under 40-inch zone, direct contact pathway EPA- U.S. Environmental Protection Agency mg/kg – milligrams per kilogram mg/L - milligrams per liter N/A – Not Applicable SIM – Selective Ion Monitoring

1.4. Deviations from the Work Plan

A work plan (OASIS 2011) and a work plan addendum (OASIS 2011a) were prepared for the project. The work plans were adhered to with the following exceptions:

OASIS collected a pre-treatment sample from the community drinking water well which is greater than 500 feet from the area of concern. This was one of the two community water wells and one of the three wells in Napaskiak, including the school well and a community well located east of the school.

Due to an oversight, the drinking water samples were analyzed using EPA Method 8260B instead of EPA Method 524.2.

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Due to extremely slow recharge at one temporary well point, groundwater samples were collected from only two of the three temporary well points that were installed. The DEC project manager (Grant Lidren) approved this change while visiting the site.

Due to poor recharge of the other two well points, no duplicate groundwater sample was collected, again with the Mr. Lidren’s approval.

Due to time constraints, only two samples were analyzed using the SPLP procedure, as only two of the samples collected for the LKSD portion of the project were thought to be highly contaminated.

Due to time constraints, OASIS did not evaluate the soil types at the landfill.

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2. FIELD ACTIVITIES

OASIS Environmental scientists Eric Boyette and Sarah Christiansen performed site characterization activities between September 12 and 19, 2011. Robert Lindsey of Dale Construction operated a backhoe provided by Village Safe Water to dig test pits. OASIS subcontracted TestAmerica, Inc. in Anchorage, Alaska to analyze the site characterization samples. The project field notes are included as Appendix A. Selected photographs of the field activities are included as Appendix B.

2.1. Drinking Water Well Sampling

The Z. John Williams School principal, Talbert Bentley, informed OASIS that three wells exist in Napaskiak; the school drinking water well and two community drinking water wells. The two community wells are greater than 500 feet from the former BIA school.

OASIS collected two samples from the school well house; a pre-treatment sample and a post-treatment sample. An additional pre-treatment drinking water sample was collected from the community drinking water well located approximately 800 feet west-southwest of the site. OASIS collected this sample even though it was greater than 500 feet because it was the closest well to the site. The drinking water sample locations are shown in Figure 2.

For each of the three samples, the water was purged for approximately 10 minutes prior to filling the sample containers. The drinking water samples were analyzed using EPA Method 8260B rather than EPA Method 524.2, as discussed in Section 1.4.

2.2. Groundwater Assessment

Three temporary well points, consisting of 1-foot long stainless steel screens and 3/4-inch diameter galvanized pipe risers, were installed at the locations shown on Figure 3.

The points were installed by hand using a slide hammer to drive the points to the depth of refusal. The well points were sited between the project area and potential receptors;

WP-1 was located between the site and the school drinking water well; WP-2 was located between the site and the community drinking water well; and WP-3 was located between the site and Napaskiak Slough.

Well point WP-1 was installed to a depth of approximately 4 feet below ground surface (bgs). Well point WP-2 was driven to a depth of approximately 9 feet bgs. Well point WP-3 was driven to a depth of approximately 3 feet bgs. The well points were allowed to sit for 24 hours prior to sampling.

The groundwater samples were collected using a no-purge technique per the DEC’s request. The points were very slow to recharge and the crew was unable to collect all the sample bottles required for analysis within a single day. Well point WP-1 was extremely slow to recharge. The crew did not collect a sample from this well or a duplicate groundwater sample per the DEC project manager’s on-site approval.

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The groundwater samples were analyzed for the following sets of compounds:

DRO using Alaska Method (AK) 102, RRO using AK 103, GRO using AK 101, BTEX using EPA Method 8021B, VOCs (which include the BTEX compounds) using EPA Method 8260B, and

PAH using EPA Method 8270M with selective ion monitoring (SIM).

Following sample collection, the well points were removed using the backhoe that was used to dig the test pits for the soil assessment.

2.3. Soil Assessment

On September 16 – 18, 2011, OASIS directed the advancement of 25 test pits in and surrounding Areas A, B, C, and D as shown on Figure 3. The operator used a Bobcat mini excavator to dig the test pits. This was a smaller excavator than was planned for the site, but due to the site being surrounded by wooden boardwalks, a smaller excavator was needed. The mini-excavator was unable to dig below 10 feet bgs.

Initially, five test pits were dug at each area. After the initial test pits were all completed and field data indicated that in some areas the volume of contaminated soil extended beyond the area initially investigated, OASIS returned to extend the area of investigation by adding test pits A6, B6, C6, C7, and C8 at the locations shown on Figure 3.

2.3.1. Field Screening

OASIS collected field screening samples from the bucket of the excavator at approximate 2-foot intervals from near-surface to the total depth of the test pit. The field screening involved a photoionization detector (PID) heated headspace technique where re-sealable plastic bags were filled 1/3 to 1/2 full of soil. The soil was warmed for 10 to 15 minutes on the warm engine cover on the excavator, away from any exhaust emissions. The crew then inserted a PID probe into the plastic bag and recorded the concentrations of organic vapors in parts per million by volume (ppmv).

2.3.2. Analytical Sampling

The OASIS crew selected the analytical sample depth for each test pit based on the results of the field screening. In general, the depth with the highest PID result was chosen. OASIS then directed the excavator operator to collect a bucket load of soil from the selected depth and collected the sample from undisturbed soil at the center of the bucket.

The sampler immediately placed the soil in the appropriate sample jars for analysis of DRO, RRO, GRO, and BTEX using the analytical methods in Section 2.2. Samples to be analyzed for volatile contaminants, including GRO and BTEX, were immediately preserved with methanol.

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Two samples of impacted soil were submitted for synthetic precipitation leaching procedure (SPLP) extraction. The extracts were analyzed for DRO and PAH using the methods in Section 2.2.

2.4. Abandoned Sewage Lagoon Assessment

Treatment and land disposal is being considered for the sewage solids from the former sewage lagoon, located east of Area A in Figure 3. Federal regulations (40 CFR 503.33) require measures be taken to address vector attraction reduction when sewage solids are disposed on land. The regulations provide for a range of potential vector attraction reduction techniques, of which alkali (lime) addition appears to be the most practical for the former BIA school site, given the remote location and limited community resources.

It may be appropriate to allow sewage solids to remain in place following treatment.

OASIS examined the abandoned sewage lagoon located east of Area A in Figure 3.

The lagoon dimensions are 25 feet by 34 feet. The crew used a Sludge Judge® sampler to collect columns of soil, water, and sewage solids from three locations to evaluate the thickness of sewage solids in the lagoon. The samples were collected from the edges of the sewage lagoon by the OASIS crew using hip waders. No samples were collected from the center of the lagoon.

The collection locations are shown in Figure 3. OASIS collected three samples from each location:

A sample for a limited bench-scale study to determine whether the addition of alkali would be a practical treatment option for any remaining sewage solids;

A sample for analysis of chemical oxygen demand (COD); and

A sample for analysis of biological oxygen demand (BOD).

The BOD sample was collected on the day that the crew left Napaskiak due to a short, 48-hour hold time, required by the analytical methods.

2.4.1. Bench-Scale Study

A limited bench scale study was performed to estimate the amount of alkali (lime) required to treat the sewage solids. The dose rate of lime required was estimated based on the following regulatory requirements (40 CFR 503.33(b)(6)):

Raise the pH to at least 12 Maintain a pH of at least 12 without additional lime addition for 2 hours Maintain a pH of at least 11.5 without additional lime addition for an additional 22 hours

Three 200 milliliters (mL) sewage solids samples were collected from each location for the bench-scale study. Before conducting the study the environmental scientist recorded the initial pH of each soil sample, using pH strips.

Each of the samples was treated with varying quantities of hydrated lime, the type of lime commonly used in gardening. The environmental scientist estimated the quantity of lime used to treat the first two samples from each location; 1 teaspoon for the first

8 2/13/2012 sample and ½ teaspoon for the second sample. For the third sample from each location, level measuring spoons were used to add the lime. The sample from location WW-1 was treated with ¼ teaspoon of lime; the sample from WW-2 was treated with ½ teaspoon lime; and the sample from WW-3 was treated with ¾ teaspoon lime.

The pH of the treated soil was recorded after 2 hours. The pH was recorded again after 24 hours.

2.5. Sample Management

OASIS placed all the analytical samples in coolers on ice to maintain a temperature of 4°C ± 2°C until the samples were received at the laboratory. Due to the difficulties in shipping from Napaskiak to Anchorage, the crew kept the samples in Napaskiak until they left on September 19, 2011. They transported the samples on the same flight they took to Bethel from Napaskiak.

OASIS used Northern Air Cargo to ship the samples from Bethel to Anchorage.

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3. FINDINGS

This section presents the findings of the site characterization efforts. The results of the sampling are presented in Tables 2 through 8 and on Figures 2 through 8. Tables 2 through 5 are located in the Tables tab at the end of the report text. Tables 6 through 8 are included below in the report text. The laboratory reports are included in Appendix C.

3.1. Drinking Water Well Sampling

The analytical results from the drinking water samples are included in Table 2. No VOCs were detected above the reporting limits in any of the drinking water samples. In addition, all reporting limits were below the published maximum contaminant levels except for 1,2-dibromoethane. The MCL of this compound is 0.00005 milligrams per liter (mg/L) and the reporting limit for the project samples was 0.001 mg/L. Measuring 1,2-dibromoethane generally requires specialized analytical techniques to provide detection limits needed to reach MCLs; 1,2-dibromoethane was used as an anti-knock additive in leaded gasoline and is unlikely to be a concern at this Site given the types of fuel present.

3.2. Groundwater Assessment

The analytical results from the groundwater samples are included in Table 3. As mentioned in Section 2.2, no sample was collected from WP-1.

Several analytes were detected above reporting limits in WP-2 including DRO, RRO, GRO, BTEX, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 1-methylnaphthalene, 2-methylnaphthalene, and naphthalene. All detected analyte results were below DEC cleanup levels except DRO. The DRO concentration of 2.42 exceeded the cleanup level of 1.5 mg/L.

No analytes were detected above reporting limits in well point WP-3 except DRO. Again, the DRO concentration of 1.68 mg/L exceeded the DEC Table C groundwater cleanup level of 1.5 mg/L.

Although depth-to-water was measured in all three of the well points, OASIS did not determine the elevation difference between the well points and no groundwater flow direction or gradient can be calculated; although during normal or low water flow on the Kuskokwim River, groundwater would be expected to flow to the northwest toward the river.

3.3. Soil Assessment

The soil sample analytical results are included in Tables 4 and 5. Figures 4 through 7 present the PID and DRO results from the four areas of concern.

3.3.1. Area A

The PID results from Area A ranged from 0.1 parts per million by volume (ppmv) to greater than 1,000 ppmv. One depth from each test pit was selected for analytical

10 2/13/2012 sampling, generally from the highest PID value. As shown in Table 4, the DRO concentrations in Area A range from not-detected (ND) in A3 at 0.5 feet bgs and A6 at 6 feet bgs to 19,800 mg/kg in A2 at 2 feet bgs. The sample from A2 is the only sample to exceed DEC Method Two Soil Cleanup Levels for DRO; the migration-to-groundwater (MTG) cleanup level of 250 mg/kg, the ingestion cleanup level of 10,250 mg/kg and the inhalation cleanup level of 12,500 mg/kg. However, elevated PID readings at location A5, suggest that contamination at that location may also exceed cleanup levels. All other analytical results for DRO, RRO, GRO, and BTEX were either ND or below DEC cleanup levels. The sample from A6 was also analyzed for PAH’s. No PAH’s were detected in the sample.

3.3.2. Area B

The PID results for Area B ranged from 1.4 ppmv to greater than 485 ppmv. The DRO results for the analytical samples ranged from ND in B5 at 0.5 feet bgs and in B6 at 6 feet bgs to 2,940 mg/kg in B3 at 0.5 feet bgs. The DRO result from B3 was the only result to exceed the DEC MTG soil cleanup level. All other DRO, RRO, GRO, and BTEX results were below cleanup levels.

3.3.3. Area C

The PID results for Area C ranged from 0.1 ppmv to greater than 1,500 ppmv. The DRO results for the analytical samples ranged from ND in C4 at 8 feet bgs and in C6 at 0.5 feet bgs to 15,600 mg/kg in C7 at 8 feet bgs. The DRO results from all test pit analytical samples except for those from C4 and C6 exceeded DEC MTG cleanup levels. The samples from C3 and C7 also exceed the ingestion and inhalation soil cleanup levels.

The benzene results for the samples collected from C2 at 8 feet bgs, C3 at 8 feet bgs, and C7 at 8 feet bgs (0.274, 0.267, and 0.241 mg/kg, respectively) exceeded the MTG cleanup level of 0.025 mg/kg. The ethylbenzene results from C2 at 8 feet (12.3 mg/kg) and C7 at 8 feet bgs (8.44 mg/kg) exceeded the MTG cleanup level of 6.9 mg/kg. The RRO, GRO, toluene, and total xylene results from the Area C samples did not exceed the corresponding cleanup levels. No BTEX compounds exceeded the ingestion or inhalation cleanup levels

The samples from C3, C4, C7, and C8 were also analyzed for PAH’s. The results are included in Table 5. The C3 sample exceeded cleanup levels for naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene. The C7 sample exceeded cleanup levels for naphthalene only. All other PAH results were below cleanup levels.

3.3.4. Area D

The PID results for Area D ranged from 0.6 ppmv to greater than 260 ppmv. The DRO results for the analytical samples ranged from ND in D5 at 4 feet bgs to 26,100 mg/kg in D1 at 0.5 feet bgs. The DRO results from D1, D2, and D3 exceeded the DEC MTG cleanup level. All other DRO, RRO, GRO, and BTEX results were below cleanup levels.

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3.4. Leaching Potential

SPLP extractions were performed on the samples collected from test pits C7 and C8.

The extracts were analyzed for DRO and PAH’s and the results were provided in mg/L.

The results are presented in Tables 4 and 5. The SPLP results for DRO and the detected PAH compounds are summarized below in Table 6.

Table 6: Soil and SPLP Extract Results for Detected Analytes

Analyte

DEC Cleanup Levels

Sample Location

C7 - 8 feet bgs C8 - 6 feet bgs

NK-11-SS-23 NK-11-SS-25

Soil Water Soil Extract Soil Extract

DRO 250 1.5 15600 4.55 316 0.712

Acenaphthene 180 2.2 ND (0.858) ND (0.0500) 0.024 ND (0.0500)

Anthracene 3000 11 0.0364 ND (0.0500) ND (0.0179) ND (0.0500)

Fluoranthene 1400 1.5 0.0608 ND (0.0500) ND (0.0179) ND (0.0500)

Fluorene 220 1.5 1.41 ND (0.0500) 0.0578 ND (0.0500)

Naphthalene 20 0.73 34.6 0.237 1.21 ND (0.0500)

Notes:

Bolded and shaded values exceed DEC cleanup levels All soil values in mg/kg and all water/extract values in mg/L

The DRO concentration in soil in the C7 sample is very high (15,600 mg/kg). The corresponding SPLP extract contains 4.55 mg/L DRO. This concentration is above DEC groundwater cleanup levels. The DRO concentration in the C8 sample is much lower (316 mg/kg) and the corresponding SPLP extract contains only 0.712 mg/L DRO.

The detected PAH in soil results that are below DEC soil cleanup levels have corresponding SPLP extract results of ND. The naphthalene soil result in the C7 sample is above the soil cleanup level and though the corresponding extract result is detectable, it is below groundwater cleanup levels.

The results above illustrate that water running through soil with high DRO concentrations will leach DRO from the soil that may impact the soil and groundwater below the contaminated soil. Soil that contains lower DRO concentrations will not leach DRO into the substrate. Based on the above results, OASIS estimates that a concentration of 1,000 mg/kg DRO may be the cutoff for leachable versus non-leachable contamination.

3.5. Abandoned Sewage Lagoon Assessment

The dimensions of the abandoned sewage lagoon are 25 feet by 34 feet. The locations for the lagoon samples are shown in Figure 3. The results for the three sample locations are shown below in Table 7.

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Table 7: Sewage Lagoon Sample Results

Sample Location Water

Depth (feet)

Sewage solids

Thickness (feet)

COD

(mg/L)

BOD

(mg/L)

WW-1 1.9 0.25 1,770 88.6

WW-2 1.0 0.33 972 14.1

WW-3 1.3 0.42 1,380 31.0

The sewage solids thickness in the sewage lagoon samples ranged from 3 inches to 5 inches and the water depth ranged from 1.0 to 1.9 feet. Volume estimates are provided for water and sewage solids in Section 6.

The average COD result from the three samples is 1,374 mg/L and the average BOD result is 44.6 mg/L. Both the COD and BOD are higher than the average for oxygen content of water, suggesting that the samples collected are sewage solids that exist in an anaerobic environment. The low BOD:COD ratio suggests that the sewage solids have had long exposure to the atmosphere and that the solids have degraded considerably. In other words, natural processes have resulted in considerable biodegradation of the waste.

3.5.1. Bench-Scale Study

The results from the bench-scale study are shown below in Table 8.

Table 8: Bench-Scale Study Results

Sample ID Dose pHinitial pH2-hour pH24-hour

1a 1 tsp* 6 12.5 12.5

2a 1 tsp* 5 12.5 12.5

3a 1 tsp* 5 12.5 13

1b 1/2 tsp* 6 12 12.5

2b 1/2 tsp* 6 12 12

3b 1/2 tsp* 6 12 12

1c 1/4 tsp 6 10.5 10.5

2c 1/2 tsp 6 11.5 12

3c 3/4 tsp 6 12 12

Notes:

* - Volume was estimated

The first six hydrated lime dosages for the “a” and “b” samples were estimated by the environmental scientist and used to refine the estimated volume of lime used to treat the “c” sample. The “c” sample dosages were measured using standard kitchen teaspoon measures. The results of the bench-scale study for samples 1c, 2c, and 3c show that at least ½ teaspoon is needed per 200 mL of sewage solids to treat the sewage solids to EPA standards. The ½ teaspoon dosage was used on sample WW-2, which had a

13 2/13/2012 lower COD and BOD than the other two samples. To estimate the volume of lime needed to treat the sewage solids, a more conservative ¾ teaspoon lime was used per 200 mL sewage solids.

14 2/13/2012

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4. QUALITY ASSURANCE REVIEW

Laboratory Quality Assurance/ Quality Control (QA/QC) data associated with the analysis of project samples have been reviewed to evaluate the integrity of the analytical data generated during the September 2011 site characterization sampling at the Former BIA School Day Tanks in Napaskiak, Alaska. Drinking water samples, groundwater samples, and soil samples were shipped to TestAmerica in Anchorage, Alaska and results were reported in two sample delivery groups (SDG’s), AUI0080 and AUI0093.

PAH, SPLP DRO, and SPLP PAH samples were subcontracted to TestAmerica in Spokane, Washington. Samples were collected, reported, and shipped in general accordance with the DEC-approved work plan (OASIS 2011).

All data were reviewed in accordance with United States Environmental Protection Agency (USEPA) National Functional Guidelines for Organic Methods (EPA 2008) and DEC regulatory guidance documents (DEC 2005; 2008; 2009; 2010). This data review focused on the following QC parameters and their effect on the quality of data and usability: sample handling and chain-of-custody documentation; holding time compliance; field QC (trip blanks, field duplicates); laboratory QC (method blanks, laboratory control samples (LCS) and LCS duplicates (LCSD), surrogates, matrix spikes (MS) and MS duplicates (MSD)); method reporting limits and completeness.

All water sample results were within quality control limits and none were qualified.

Several soil samples have been qualified as estimated based on the following QC criteria:

PAH samples were analyzed outside of the method holding time. The associated results are flagged J-H for positive results and UJ-H for non-detect (ND) results.

The field duplicate relative percent differences (RPD’s) for the duplicate pair collected from test pit C7 were outside control limits for GRO, benzene, and xylenes; the associated results are flagged JD.

Laboratory duplicate RPDs were outside control limits for DRO, GRO, and xylenes; the associated results are flagged J for positive results and UJ for ND results.

LCS/LCSD RPDs were outside control limits for BTEX; the associated results are flagged JL for positive results and UJL for ND results.

Surrogate recoveries were outside control limits for GRO, BTEX, and PAH; the associated results are flagged JS.

Sample results are considered usable for project objectives. The full QA/QC report and DEC Laboratory Data Review Checklists are included in Appendix C with the laboratory reports.

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17 2/13/2012

5. CONCEPTUAL SITE MODEL

This section presents a human health CSM for the site. CSM Scoping forms are included in Appendix D. This CSM is based on the assumption of continuing soil impacts in this area.

5.1. Receptor Profile

Receptors for the current scenario include residents, construction workers, subsistence harvesters and consumers, and site visitors and trespassers. The LKSD has plans to build a new school on the former BIA School site in 2012, so school children, faculty, and staff can be included as potential future receptors.

5.2. Exposure Pathways

At areas A, B, C, and D contamination is present in surface soils. The distribution of contamination at Area C also includes contamination as deep as 8 feet bgs. Increasing concentrations with depth at Area C suggest that contamination may have migrated to the groundwater table and then spread as a light non-aqueous phase liquid (LNAPL).

Due to the shallow and deeper depth of soil contamination, and the possible presence of both volatiles and PAH compounds, the soil ingestion, dermal contact, and outdoor air inhalation pathways are potentially complete. Napaskiak residents are living in the buildings near the site and a new school is planned for this area, so the indoor air pathway is also potentially complete.

The presence of shallow groundwater and present groundwater use in the area make the groundwater ingestion, contact and inhalation of volatile compounds potentially complete exposure pathways.

Assuming subsistence activities in this area, potential exposure to harvesters and consumers could occur.

While the site is close to Napaskiak Slough, the river is silty and very cold and would be unlikely to be used for drinking water or swimming making the surface water ingestion/contact and sediment contact pathways incomplete. Table 9 summarizes the potential exposure pathways.

Table 9: POTENTIAL EXPOSURE PATHWAYS

Exposure Pathway Pathway

Complete?

Discussion

Incidental soil ingestion Yes Soil contamination near and beneath former ASTs between 0 and 3 feet bgs.

Dermal absorption Yes Contaminated soil and groundwater above 15 feet bgs.

Ingestion of groundwater No Drinking water wells in the area were not impacted during the 2011 sampling event.

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Exposure Pathway Pathway

Complete?

Discussion

Ingestion/contact of surface water/sediment

No Silty water in slough is not used for drinking water. Swimming unlikely due to water temperature.

Ingestion of wild food Yes Further data would be needed to evaluate.

Inhalation of outdoor air Yes

Soil is impacted between the surface and 15 feet bgs. BTEX compounds exceed cleanup levels in Area C.

Inhalation of indoor air Yes New school to be built on the site

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6. CONCLUSIONS

A discussion of the project findings is presented in this section. The results from the drinking water, groundwater, and soil assessments were used to update the conceptual site model and to estimate the volume of contaminated soil that may need to be removed before building the new school.

6.1. Groundwater and Drinking Water

During normal to low water flow on the Kuskokwim River, it would be reasonable to assume that the groundwater would flow to the northwest toward the river and downstream. During high water on the Kuskokwim River, however, the groundwater flow may reverse and groundwater could flow toward the southwest as the Kuskokwim River became a losing stream.

As there is no way to determine an absolute upgradient direction from the site, it is possible that the groundwater impacts in both WP-2 and WP-3 may be associated with releases from the project area. As WP-1 did not produce enough water to collect a sample, it is unknown whether the groundwater between the school and the site is impacted. As mentioned in Section 3.1, no VOCs were detected in the school or community wells.

No DRO samples were collected from the drinking water wells. Diesel contains both volatile and semi-volatile components. Though VOCs were not detected in the drinking water, the VOC analysis does not cover semi-volatile components. OASIS recommends that the wells be sampled for DRO during one of the regular drinking water sampling events.

6.2. Soil Impacts

Figure 8 presents the estimated extents of soil that exceeds the DEC migration to groundwater cleanup level for DRO and which would be slated for excavation if the new school were to be built at this site.

Many test pit samples exceeded the DRO ingestion and inhalation cleanup levels as well as the MTG cleanup levels. OASIS recommends removing the top 2 feet of soil from the impacted areas. This will eliminate the dermal contact and ingestion pathways.

The school is designed to be constructed on pilings and the area beneath the school will not be enclosed. This should reduce vapor intrusion into the buildings and minimize the indoor air inhalation pathway. OASIS recommends enclosing the space beneath the school with chain link fence to keep receptors out. Institutional controls may also be required to prevent soil excavation between 2 feet bgs without appropriate safeguards.

The proposed excavations have been partitioned into areas containing greater than 1000 mg/kg DRO and those containing less than 1000 mg/kg DRO in the top two feet of soil. These divisions are predicated on approval from the DEC to remove only the top 2 feet of soil from the site and on the SPLP results. Based on the two SPLP samples, 20 2/13/2012

OASIS estimates that DRO in soil at concentrations greater than 1,000 mg/kg may leach into the substrate. In order for contaminated soil to be transported to a landfill for disposal, the contaminant must not be leachable.

The excavation areas are based on DRO analytical results or PID screening results where the top two feet of a test pit was not analyzed. OASIS compared DRO and PID results from samples that were sent for analysis to estimate DRO concentrations for these test pits.

The proposed excavations in Areas A and B are in areas containing greater than 1,000 mg/kg DRO and comprise estimated volumes of 110 and 30 loose cubic yards (LCY), respectively. The term LCY is used to describe the expansion of soil after it is removed from the ground (fluff factor). The single proposed excavation covering Areas C and D has been divided into two areas containing less than and greater than 1,000 mg/kg each. The total volume of the excavation is estimated at 850 LCY. The estimated volume containing greater than 1,000 mg/kg DRO is 485 LCY and the estimated volume containing less than 1,000 mg/kg DRO is 365 LCY. A fluff factor of 1.25 was used to estimate soil volumes.

6.3. Abandoned Sewage Lagoon Assessment

The COD and BOD results indicate that the sewage lagoon contains sewage solids.

The Sludge Judge® samples were collected from the edges of the lagoon rather than throughout the entire lagoon, making accurate volume estimation difficult. For this reason, an uncertainty factor of 2 was applied to the bio-solid and water volume estimates shown in Table E1 in Appendix E.

Based on an area of 25 feet by 34 feet and an average thickness of 0.33 feet (4 inches), the sewage lagoon contains approximately 21 cubic yards of sewage solids. Based on an average water depth of 1.4 feet, the sewage lagoon contains approximately 18,000 gallons of water.

In order to leave the sewage solids in place, the lagoon must be de-watered and the sewage solids must be treated. OASIS proposes that the most feasible in-situ treatment for the lagoon is the addition of quicklime to raise the pH of the sewage solids.

Table E2 in Appendix E applies the dose rate of hydrated lime, used in the bench-scale study, to the estimated volume of sewage solids. These calculations indicated that approximately 1,144 pounds of hydrated lime would be required to treat all the sewage solids present in the sewage lagoon.

Either of two types of lime could be used to treat the sewage solids: hydrated lime or quicklime. Hydrated lime was used in the bench-scale study. Quicklime is commonly used to treat sewage solids and to dry muddy construction sites. Because of high shipping costs to Napaskiak, use of quicklime would likely be less expensive because it avoids shipping the water entrained in hydrated lime. Quicklime has two advantages:

It absorbs a significant amount of water, improving the handleability of the sewage solids; and

21 2/13/2012

When quicklime is mixed with sewage solids, an exothermic reaction occurs resulting in water evaporation, reducing sewage solids volume.

As shown Table E2, approximately 900 pounds of quicklime would be required to treat the estimated volume of the sewage solids in the lagoon.

6.4. Proposed Cleanup Technique

The applicable regulation (18 AAC 75.335(c)(5)) requires that a site characterization report: “proposes cleanup techniques for the site.”

6.4.1. Alternatives Considered

To that end, a variety of remediation alternatives were considered:

Alternative 1: Excavation and Offsite Disposal

Alternative 2: Onsite Treatment and Disposal

Alternative 3: Aggressive Onsite Treatment

Alternative 4: In Place Landfarming

In addition to the four alternatives listed above, use of chemical oxidation was also considered. The available literature indicates that that potassium permanganate is the oxidant most likely to be effective in treating the petroleum contaminants present at the site (Interstate Technology & Regulatory Council, 2005). For each of a variety of oxidants, the guidance document categorizes contaminants of concern as being amenable, reluctant, or recalcitrant to oxidation. Fuel components such as PAHs, toluene, ethylbenzene, and xlyenes are considered amenable to treatment with potassium permanganate. Benzene is considered a reluctant contaminant of concern to treat with potassium permanganate. In addition, potassium permanganate is a solid (which would make transportation easier) and relatively safe to handle. However, high contaminant concentrations would drive extremely high oxidant demand, and make chemical oxidation cost prohibitive. Thus, chemical oxidation was not developed further as an alternative.

Appendix F presents cost estimates for each of the evaluated remedial alternatives, along with a detailed basis of estimate and list of cost assumptions. Table 10 compares the four alternatives.

Table 10: SUMMARY EVALUATION OF ALTERNATIVES

Alternative Advantages Disadvantages

Estimated Cost

Alternative 1:

Excavation and Offsite Disposal

Highly contaminated soil would be shipped off site

Logistically complex

High Cost $1.6M

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Alternative Advantages Disadvantages

Estimated Cost

Alternative 2:

Onsite

Treatment and Disposal

100 tons of the most highly contaminated soil would be shipped off site

Two field seasons required for treatment

Would require pilot testing to ensure feasibility

$934K

Alternative 3:

Aggressive

Onsite Treatment

Less complex than Alternatives 1 or 2

Highly contaminated soils can be difficult to biodegrade Would require pilot testing to ensure feasibility

$498K

Alternative 4:

In Place

Landfarming Logistically simple

No commitment made to attain specific cleanup levels

$219K

All of the alternatives considered would limit soil to be excavated and/or treated to soil within 2 feet of ground surface. In addition, none of the alternatives considered would address smear zone contamination that is present at the site. The cost estimates include funds to treat sewage solids with quicklime and to backfill the sewage lagoon.

Alternative 1 was the most aggressive alternative considered. Under Alternative 1, soil contaminated at a concentration greater than 1,000 mg/kg would be shipped off site for disposal. This would necessitate mobilizing shipping containers to the site, excavating, manifesting, packaging, and shipping this contaminated soil to a Resource Conservation and Recovery Act (RCRA) Subtitle D landfill. The remainder of the soil would be used as cover material at the Napaskiak landfill. This alternative would rapidly address the most contaminated soil, but would be logistically challenging and cost-prohibitive.

Under Alternative 2, the volume of soil to be shipped off site would be limited to 100 tons of the most highly…