A04_-_Attachment_-_Corrective_Action_Reports.pdf

DDepartmentt off Environmentall Conservationn

SPILL PREVENTION & RESPONSE

Contaminated Sites Program

610 University Avenue Fairbanks, Alaska 99709

Main: 907.451.2143 Fax: 907.451.2155 www.dec.alaska.gov

File No: 2612.38.009

March 27, 2019

Electronic Delivery Only Charles D. Grant Regional Environmental Compliance Coordinator USFWS Region 1, 7, 8 Division of Engineering 1011 East Tudor Road Anchorage, Alaska 99503

Subject: DEC Approval of Final Wollard House Soil Removal Corrective Action Report, United States Fish & Wildlife Service, McGrath, Alaska

Dear Mr. Grant, The Alaska Department of Environmental Conservation (DEC) has received and reviewed the final Wollard House Soil Removal Corrective Action Report for McGrath, Alaska. The report details the activities performed during the removal of contaminated soils at the Wollard House in McGrath, Alaska. DEC provided comments on a previous version of this report on February 28, 2019 and received the most recent response on March 27, 2019. All of DEC’s comments have been satisfactorily addressed and the report is approved.

If you have any questions, please contact me at (907) 451-5175 or via email at jamie.mckellar@alaska.gov.

Sincerely, Jamie McKellar Environmental Program Specialist

Enclosure: Comment Table for Wollard House CA Report, McGrath cc: Dumitru Radu, Tikigaq/AGVIQ Dean Camery, Tikigaq/AGVIQ David Leadenham, Tikigaq/AGVIQ Anthony Kuntz, USFWS Eric Breitenberger, DEC

Digitally signed by Jamie McKellar Date: 2019.03.27 10:06:41 -08'00'

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WOLLARD HOUSE SOIL REMOVAL

McGRATH, ALASKA

CORRECTIVE ACTION REPORT

FINAL

March 26, 2019

Prepared for:

United States Fish & Wildlife Services

Innoko Wildlife Refuge

Prepared by:

Signature of Qualified Environmental

Professional Responsible for Preparing the Report:

Dumitru Radu

Date: March 26, 2019

Contract No. F15PC00080/F17PD01978

ADEC File Number – 2612.38.009

Tikigaq Construction LLC, and Agviq Environmental Services, LLC

701 S. Knik Goose Bay Road

Wasilla, AK. 99654

PAGE INTENTIONALLY BLANK

Wollard House Contaminated Soils Removal, McGrath, AK Work Plan United States Fish & Wildlife Services

CES-AGVIQ of Alaska i 3/26/2019

TABLE OF CONTENTS

ACRONYMS AND ABBREVIATIONS ..................................................................................... ii

Executive summary

1. Introduction

1.1. Project Objectives

1.2. Summary of Field Activities

2. Field Work

2.1. Soils Removal

2.2. Indoor Air Quality Initial Assessment

3. Field methodology

3.1. Field Screening

3.2. Sample Handling

4. Results and findings

4.1. Field Screening

4.2. Analytical Results

4.3. Indoor Air Quality Assessment

4.4. Quality Control and Quality Assurance

4.5. Conceptual Site Model

5. Conclusions and Recommendations

6. REFERENCES

TABLES IN TEXT

1: Cleanup Levels

2: Field Screening Results

3: Tabulated Detectable Results

FIGURES

1: Site Location Map

2: Site Vicinity

3: Site Detail

4: Excavation and Sampling Locations

APPENDICES

A: Figures

B: Photographic Log

C: SGS Laboratory Report

D: ADEC Laboratory Data Review Checklist

E: Updated Conceptual Site Model

F: Field Log Book

G: Transportation and Disposal

CES-AGVIQ of Alaska ii 3/26/2019

ACRONYMS AND ABBREVIATIONS

AAC ................ Alaska Administrative Code

ADEC .............. Alaska Department of Environmental Conservation

AES…………...Agviq Environmental Services, LLC

AK ................... Alaska Method bgs ................... below ground surface

BTEX............... benzene, toluene, ethylbenzene, and xylenes

COC ................. contaminants-of-concern

CSM ................ Conceptual Site Model

DQO ................ data quality objectives

DRO ................ diesel range organics

GRO ................ gasoline range organics

HHO………….Home Heating Oil

IDW ................. investigation-derived waste

LCS/LCSD ...... laboratory control sample/ laboratory control sample duplicate mg/kg ............... milligrams per kilogram

MS/MSD ......... matrix spike/ matrix spike duplicate

PAH ................. polynuclear aromatic hydrocarbon

PID .................. photoionization detector

PPE .................. personal protective equipment

QA/QC............. quality assurance/quality control

RCRA .............. Resource Conservation and Recovery Act

RRO ................. residual range organics

SGS .................. SGS Environmental Services, Inc.

TCON…………Tikigaq Construction, LLC.

USFWS……….United States Fish and Wildlife Services

UST ................. underground storage tank

VOC ................ volatile organic compound yd3…………….cubic yards

AES of Alaska 3 3/26/2019

EXECUTIVE SUMMARY

On behalf of the U.S. Fish and Wildlife Service, Innoko Wildlife Refuge (USFWS), Tikigaq

Construction (TCON) and Agviq Environmental Services (AES) performed additional corrective action at the Wollard House in McGrath, Alaska on August 22 to August 24, 2018. This action is in response to the decommissioning of a 500-gallon underground storage tank (UST) that was found to have spilled/leaked an unknown quantity of Home Heating Oil (HHO). The removal of the tank was performed by Silver Mountain Construction with environmental support from North

Wind Site Services as a subcontractor.

Sixteen cubic yards (yd3) of HHO contaminated soils were excavated around the area of the former UST. Post excavation samples show that Diesel Range Organics (DRO) contamination remains above the Alaska Department of Environmental Conservation cleanup levels (ADEC, 2017a) at a depth below 6.5 ft to the north and east of the former excavation. A total of six samples and one duplicate were submitted to SGS Laboratories in Anchorage for analysis. Of these, three are above cleanup levels, one below, and two had non-detectable results for DRO.

Two post-excavation wall samples taken from the northern wall indicate that a clean edge to a depth of 6.5 feet was established. Excavated soils were placed in one cubic yard super sacks and transported to Alaska Soil Recycling in Anchorage for final disposal. A reinforced 10-mil polyethylene liner was placed in the excavation prior to backfilling to existing grade.

AES of Alaska 4 3/26/2019

1. INTRODUCTION

This Corrective Action Report, developed by Agviq Environmental Services (AES) and Tikigaq

Construction, LLC of Alaska for the US Fish and Wildlife Services (USFWS), details the activities performed during the removal of contaminated soils at the Wollard House in McGrath, Alaska. The tasks performed are associated with Alaska Department of Environmental

Conservation (ADEC) Contaminated Sites Database file number 2612.38.009, under Prime

Contract Number F15PC00080/F17PD01978 for the US Fish and Wildlife Services.

McGrath is a remote village along the Kuskokwim River, accessible by commercial aircraft. The

Wollard House is a property of the US Fish and Wildlife Service, located at the corner of Chinana

Ave. and E Street. In 2016, a 500-gallon non-regulated UST was decommissioned by Silver

Mountain Construction, with environmental support from North Wind Site Services.

Contaminated soils are the result of the overfilling of the tank. This effort was conducted to further remediate contaminated soils that remained from the initial tank removal.

Site Location and Description

The Site is located at 101 Chinana Avenue, McGrath, Alaska, approximately 220 miles northwest of Anchorage, Alaska (Figures 1-3) with map coordinates of 62.9514 latitude and -155.5918 longitude. McGrath is located along the south bank of the Kuskokwim River, just south of the

Kuskokwim Mountain range and approximately 60 miles from the Alaska Range in western

Alaska. According to the United States Census Bureau, the village has total of area of 54.6 square miles, of which, 48.9 miles of it is land and 5.7 square miles of it is water. The area is considered to have a continental subarctic climate (Koppen Dfc). Temperatures range from an average low of -18o Fahrenheit (oF) to an average high of 70oF over the course of a yearly cycle.

McGrath receives an average of 18 inches of precipitation annually.

The Wollard House is a log sided building on a concrete slab foundation, used as an office space and temporary living quarters for USFWS personnel. The facility is used on a part time basis, typically having one employee there for a few days per week. The UST was located along the north side of the facility. The area consists of poorly to well sorted, poorly to moderately well-stratified deposits of alluvial, colluvial, lacustrine, eolian, and swamp deposits. Groundwater is believed to be between 15 to 20 feet below ground surface.

AES of Alaska 5 3/26/2019

Site History

Previous site activities were conducted in June of 2016 by Silver Mountain Construction, LLC with North Wind Site Services to remove and decommission a 500-gallon underground storage tank, located at the north corner of the facility. A tank closure report was submitted to ADEC in

September 2016.

1.1. Project Objectives

The objectives of this field effort were to delineate the horizontal and vertical extent of contamination and protection of human health and the environment by the removal of fuel impacted media caused by the incidental release of home heating oil to a 500-gallon underground storage tank. Results for diesel range organics (DRO), gasoline range organics (GRO), residual range organics (RRO), benzene, toluene, ethylbenzene and xylenes (BTEX), and polynuclear aromatic hydrocarbons (PAH) were compared against applicable ADEC criteria set forth in 18

AAC 75 Oil and Other Hazardous Substances Pollution Control (ADEC. 2017a, Tables B1 and

B2) and presented in tabular form below in Table 1. These levels are the most stringent under

Method Two, Under 40 Inch Zone, human health exposure or the Migration to Groundwater pathways. Samples were collected according to the approved Sampling and Analysis Plan, generally following ADEC Field Sampling Guidance (ADEC 2017b).

AES of Alaska 6 3/26/2019

Table 1: Cleanup Levels

Contaminants of Concern mg/kg

Petroleum Fractions

DRO 250

GRO 300

RRO 10000

VOCs

Benzene 0.022

Toluene 6.7

Ethylbenzene 0.13

Xylenes 1.5

PAHs

1-methylnaphthalene 0.41

2-methylnaphthalene 1.3

Acenaphthene 37

Acenaphthylene 18

Anthracene 390

Benzo(a)anthracene 0.28

Benzo(a)pyrene 0.27

Benzo(b)fluoranthene 2.7

Benzo(g,h,i)perylene 2300

Benzo(k)fluoranthene 20

Chrysene 82

Dibenzo(a,h)anthracene 0.2

Fluoranthene 590

Fluorene 36

Indeno(1,2,3-cd)pyrene 2

Naphthalene 0.038

Phenanthrene 39

Pyrene 87

Notes: Based on the Alaska Department of Environmental Conservation Method Two, Under 40-Inch Zone, most stringent exposure pathway cleanup level as stated in 18 AAC 75.341.

mg/kg = milligrams per kilogram

1.2. Summary of Field Activities

Excavation commenced on August 22, 2018 after utility locations were marked out, ensuring no conflicts with the area of concern. Upon determining the location of the former excavation, work began on the western side to find the lateral and vertical extent of contamination. Excavation continued generally north, guided by Photoionization Detector (PID) readings. Contaminated soils were placed directly into super sacks and staged on site until transported to the airport for final disposal in Anchorage at Alaska Soil Recycling. A total of 16 super sacks were generated during field activities, consisting of 16 yd3 of soils. Excavation limits for this field effort reached a depth of 6.5 ft, an overall length of 14.5 ft, and 7 ft wide (see Figure 4 of Appendix A). Post

AES of Alaska 7 3/26/2019 excavation sampling was conducted, collecting a total of 25 screening samples and seven confirmation samples (six samples plus one duplicate), which were sent to SGS North America

Laboratory in Anchorage, Alaska for off-site analysis. After sampling activities were concluded, a liner was placed in the excavation and backfilled to existing grade.

In addition to soil removal activities, an initial assessment of indoor air quality was done by using a PID to measure areas of the facility that would typically be inhabited by members of the

USFWS, as well as conduct an interview with an employee that most frequents the Wollard

House.

The following data quality objectives were met:

• Collect accurate, precise and representative data

• Meeting 95% data completeness and usability goals

• Generate reproducible data

• Produce results that are comparable (use same sampling techniques, follow same procedures)

• Achieve sensitivity necessary to support action levels

• Meeting regulatory and guidance requirements

AES of Alaska 8 3/26/2019

2. FIELD WORK

On August 22, 2018 Mr. Dumitru Radu, a Qualified Environmental Professional with AES and

Mr. David Thomas of TCON mobilized to McGrath to perform site work. Mr. Tom Parker of the

City of McGrath Utility Service marked out all utilities that were within or near the work area prior to commencement of excavation activities. Upon determining the location of the former

UST, work commenced along the western edge. Soils were screened using a PID and the heated headspace method, as per ADEC Field Sampling Guidance, 2017a. Soils that screened above the

20 parts per million (ppm) action level were placed in one cubic yard super sacks for disposal.

Excavation continued in a generally north direction until PID readings indicated a clean edge had been achieved. An initial indoor air quality survey was conducted as well during this mobilization.

2.1. Soils Removal

Excavation did not start within the former excavation as this is a known area of contamination.

Instead, excavation work started along the western side of the former excavation in order to determine the horizontal extent of contamination. Historical results indicate that the southern end of the former UST excavation were below cleanup levels, contamination extended under the building to the east, therefore work proceeded generally north towards greater concentrations of contamination. Soils were field screened with a PID, analyzing every other bucket, as well as using olfactory senses. Soils that had results above the 20 ppm action level were placed directly into super sacks. Super sacks were filled close to the excavation, within the swing radius of the equipment. A 10’x12’ heavy duty tarp was used as a liner to prevent cross contamination from soils spilled during filling of the sacks. After a sack was filled, soils on the tarp were funneled back into the excavation.

After the first three sacks were filled, it was noted that approximately two less-than-level buckets and one-half bucket filled one super sack, therefore screening was adjusted to a rate equaling one screening per super sack. PID readings for the first day ranged from 76 ppm to 382 ppm for the six filled super sacks.

Excavation continued the next day, generally extending northward from the former UST area.

PID readings ranged from 44 ppm to 187 ppm, filling an additional 10 super sacks for a total of

16 sacks. Post excavation sampling was performed in accordance with the approved Sampling

Plan and the ADEC Field Sampling Guidance, 2017a. PID readings of the post excavation

AES of Alaska 9 3/26/2019 samples ranged from a low of 0 ppm to a high of 173 ppm. Table 2, in Section 4.1 below lists all excavation walls and floor PID results. A total of six confirmation samples (one for each sidewall plus two excavation floor) and one duplicate were collected for GRO, DRO, RRO, BTEX, and PAHs analysis. Samples were packaged and delivered to SGS Laboratories under appropriate chain-of-custody procedures. After sample collection, 10 mil polyethylene sheeting was placed in the excavation as a liner and backfilled.

All sixteen super sacks were transported to Northern Air Cargo at the McGrath airport for delivery to Anchorage and subsequently to Alaska Soil Recyclers (ASR) for final disposal.

Delivery tickets, ASR acceptance letter, and ADEC approval of waste disposal are in

Appendix G.

2.2. Indoor Air Quality Initial Assessment

The Wollard House is constructed of log siding on a concrete slab foundation. Chinking between log courses appears to be in good condition, providing an air tight seal along the walls. Due to the close proximity of the former UST to the building and the levels of contamination found in surface soils, an indoor air quality survey was conducted to assess the potential exposure to human health by inhalation from volatile petroleum vapors. A PID was used to measure ambient air in the northern end of the facility and the main area. The northern end of the building near the work area consists of two rooms, an empty office space currently being used for electronic devices, such as printers and routers, and a bedroom/living quarters for USFWS personnel. The building also consists of a second office area, a bathroom, utility room, and a multi-purpose main open area where there is a kitchen, dining/meeting/sitting area, and a merchandise/library area. A

USFWS employee, Mr. Ken Chase, was present during field work and interviewed as part of the air quality assessment. A detailed discussion of indoor air quality can be found in Section 4.3 of this report.

AES of Alaska 10 3/26/2019

3. FIELD METHODOLOGY

On August 22, 2018, TCON and AES mobilized to McGrath to perform site activities. Upon arrival, and after picking up the shipped supplies from Northern Air Cargo, the field crew meet with Utility Location of McGrath representatives were on site to mark out all utility that may be impacted by site activities. United Utilities Inc. of Alaska had previously indicated that they have no conflicts. A water line enters the Wollard House from the west, entering the building near the entryway on the west side of the building. A sewer line is on the south side of the building, extending to E Street. Neither of these are within the anticipated area of excavation.

3.1. Field Screening

The heated headspace field screening method with the use of a MiniRAELite PID was the primary method used during this removal, however, others include visual and olfactory senses to assist with determining if soils were contaminated. Field screening was conducted in accordance with the approved Sampling and Analysis Plan and the ADEC Field Sampling Guidance (ADEC, 2017). The PID was calibrated at the beginning of each day, prior to field activities. During excavation, screening of soils was done by taking a reading from the center of the equipment bucket. Overburden soils were determined by scraping an area with bucket, digging down at least six inches into the exposed soils and inserting the PID probe into the hole. Scraping continued in six to eight-inch cuts until PID readings indicated contaminates soils were reached. Excavation wall and floor samples were collected and screened utilizing the heated headspace method.

Screening results of greater than 20 ppm was considered contaminated and placed in super sacks.

Headspace samples were collected by filling a new sealable plastic bag one-third to one-half full of freshly uncovered soil. The bag was shaken for about 30 seconds and vapors allowed to develop for at least 10 minutes, but no longer than one hour. The bag was again agitated for about 15 seconds. The bag was partially opened to allow the PID probe to be inserted into the headspace of the bag, and re-sealed around the probe. The highest reading was recorded in the field log book.

3.2. Sample Handling

AES collected each soil sample for field screening or laboratory analysis utilizing clean stainless steel spoons and/or clean nitrile gloves. Laboratory samples were placed in clean glassware, preservative added if applicable, and placed in a cooler with gel ice to maintain sample temperatures between 00 and 60 Celsius. Sample, including one trip blank, were packaged and delivered to the laboratory under standard chain-of-custody procedures.

AES of Alaska 11 3/26/2019

4. RESULTS AND FINDINGS

As PID readings decreased from the screening of equipment bucket soils, screening of sidewalls and the floor were taken to determine if limits were reached. Sidewall samples were taken from the west, north, and east wall. The south wall consists of the former excavation, with historical screening and laboratory results showing contamination, therefore this wall was not sampled. A total of 25 screening samples were collect and screened. Results indicate that horizontal extent at a 6.5-foot depth were reached on the north and west walls. Clean soils were also screened at locations near the northeast corner. Measurements of excavation are 14.5 feet at its longest along the west side, 7 feet wide along the north wall, and 8 feet along the east wall. Excavation limits with sample locations are shown in Figure 4 of Appendix A.

4.1. Field Screening

Field Screening samples collected during soils segregation were taken from the center of the equipment bucket. Readings from soils determined to be contaminated (>20 ppm PID) ranged from a low of 44 ppm to a high of 382 ppm. Overburden was removed by scraping along the surface, taking PID readings by digging into exposed soils at least six inches, inserting the PID nozzle into the hole and covering the hole. All readings from soils considered overburden ranged from 0 to 1.5 ppm.

As readings for contaminated soils decreased, the excavation was assessed to determine if clean boundaries were achieved. A total of 25 field screening samples were collected and analyzed via the headspace method. Results from the sidewalls on the northwest and north walls indicate clean limits have been reached to a depth of 6.5 feet. Based on approximately 77 square feet of excavation floor, five floor samples were collected for field screening, with readings between 32 and 127 ppm.

PID readings from the east wall show contamination near the former excavation, with other readings toward the northeast corner indicating clean soils, with 0 ppm results from each of the four various depths (2, 4, 5.5, and 6.5 ft bgs). PID results with sample locations are shown in

Figure 4 of Appendix A.

AES of Alaska 12 3/26/2019

TABLE 2 - Field Screening PID Results

Excavated Soils Post-Excavation Sampling

Sample ID

PID

(ppm) Sample ID PID (ppm) Sample ID PID (ppm)

S1 138 PE-1-2 173 PE-5-2 0.8

S2 178 PE-1-4 155 PE-5-4 3.6

S3 254 PE-1-6.5 80 PE-5-6.5 14.8

S4 307 PE-2-2 0.0 PE-5-3 0.9

S5 382 PE-2-4 71.1 PE-5-5 10.1

S6 187 PE-2-6.5 81 PE-6-2 0.0

S7 234 PE-3-2 1.0 PE-6-4 0.0

S8 193 PE-3-4 1.4 PE-6-6.5 0.0

S9 149 PE-3-6.5 141 PEF-1 113

S10 93 PE-4-2 0.4 PEF-2 32

S11 105 PE-4-4 3.0 PEF-3 127

S12 113 PE-4-6.5 48 PEF-4 92

S13 126 PEF-5 111

S14 94 S15 58 S16 76 S17 75 S18 87 S19 44

4.2. Analytical Results

AES collected a total of seven soil samples (one from each side sidewall, two from the floor, and one duplicate) for analysis of GRO, DRO, RRO, BTEX, and PAHs at SGS Laboratories, an

ADEC approved laboratory. A summary of detectable results is found in Table 3 below, with the full laboratory report in Appendix C. In consideration of screening results, sidewall confirmation samples were collected at the 6.5 foot bgs depth to evaluate contaminant concentrations that may still be present. Of the four sidewall samples, two samples with highest PID readings were collected from the west wall, one sample from the north wall that had a PID reading of 14.8 ppm, and one from the east side wall with a PID reading of 0 ppm were submitted for analysis. The two floor samples were chosen to show concentrations remaining along the west wall and possibly clean soils in the northeast corner.

AES of Alaska 13 3/26/2019

TABLE 3 - Detectable Results

PE-2-6.5 PE-3-6.5 PE-5-6.5 PE-6-6.5 PE-6-6.5D PEF-3 PEF-5

Sample Depth (ft bgs)

6.5 6.5 6.5 6.5 6.5 6.5 6.5

Field Screening Reading (ppm) 81 141 14.8 0.0 --- 127 111

Analyte ADEC Cleanup Level (mg/Kg)

Petroleum Fractions mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg

Diesel Range Organics 250 1170 1280 13.3 U 13.4 U 12.7 J 422 229

Residual Range Organics 10,000 10.8 U 43.0 30.7 42.1 42.8 32.2 28.1

Gasoline Range Organics 300 8.52 15.4 2.20 U 2.39 U 2.40 U 17.2 7.73

Volatiles (BTEX) µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg

Benzene 22 6.85 U 7.70 U 11.0 U 11.9 U 12.0 U 9.25 U 12.9 U

Ethylbenzene 130 23.0 J 21.8 J 22.0 U 23.9 U 24.0 U 15.9 J 25.8 U

P & M -Xylene 111 102 44.0 U 47.9 U 48.0 U 79.9 35.1 J o-Xylene 39.2 346 22.0 U 23.9 U 24.0 U 447 184

Xylenes (total) 1,500 150 448 66.0 U 71.5 U 72.0 U 527 219

Toluene 6,700 22.7 J 10.8 J 22.0 U 23.9 U 24.0 U 19.6 J 25.8 U

PAHs µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg µg/Kg

Chrysene 600,000 26.6 17.4 J 16.6 U 16.7 U 16.4 U 14.5 U 10.2 J

Fluoranthene 590,000 112 38.6 16.6 U 16.7 U 16.4 U 10.3 J 19.6 J

Pyrene 87,000 51.0 34.4 16.6 U 16.7 U 16.4 U 11.4 J 17.0 J

Key: BOLD indicat results exceed ADEC Method Two, Under 40-inch Zone Cleanup Levels mg/Kg= milligrams per kilogram µg/Kg= micrograms per kilogram ppm= parts per million PAH= polycyclic aromatic hydrocarbons

Flag Definition: J= quantitation is an estimate U= analyte not detected at the detection limit listed

DRO was the only analyte reported with concentrations in exceedance of ADEC cleanup criteria, based on the Method Two, Under 40 Inch Zone limit of 250 mg/kg. Analytical results were 1,170 mg/kg and 1,280 ppm for PE-2-6.5 and PE-3-6.5 respectively, both at the base of the west wall.

PEF-3, a floor sample has a result of 422 mg/kg, above ADEC cleanup criteria, while PEF-5 had a result of 229 mg/kg. All other results are either Non-Detected or well below Method Two cleanup criteria. PE-5-6.5 had a PID reading of 14.5 ppm but laboratory DRO results were below detection limits. PEF-5 had an analytical result of 229 mg/kg, below cleanup levels, but a PID reading of 111 ppm. All samples submitted for laboratory analysis had a depth of 6.5 ft bgs.

These results are indicative of soil gas within the screening samples. Therefore, these locations may be in close proximity to the DRO contaminant plume.

Although GRO concentrations range from Non-Detect to 15.4 mg/kg, all detectable results are correlated to samples with concentrations of DRO. DRO has constituents that are within the

GRO range (C6-C10), therefore, the middle distillate (DRO) is contributing to the GRO results.

This would be consistent with reports of heating oil spilled/leaked to the ground, not gasoline.

AES of Alaska 14 3/26/2019

4.3. Indoor Air Quality Assessment

Indoor air quality was assessed due the close proximity of contaminated soils to the Wollard

House. The conceptual site model completed prior to field work indicated that the inhalation of indoor air pathway is complete and further assessment is required. A PID was used to as an initial assessment of air quality, with other considerations given to building design, room locations and occupation frequency, and interviewing an employee of the USFWS that was at the

Wollard House but is not there on a fulltime basis. PID readings ranged from 0 to 0.1 ppm. The

0.1 ppm reading was located in the north unoccupied office next to the work area, but the room also had other electronics such as a printer/copier. All other results were 0 ppm.

The Wollard House is log sided structure with the chinking in good condition, on a concreate slab foundation. Upon entering the building, no noticeable petroleum odors were noted, nor was it present in any area of the building. Mr. Ken Chase of the USFWS was interviewed for further information. Mr. Chase has work for the USFWS for several years and travels to the Wollard

House as part of his rotation, with stays as long as two weeks. During his stays at the site, he has never noted any petroleum odors within the building, even during the timeframe of the UST removal.

4.4. Quality Control and Quality Assurance

The Analytical data was reviewed for quality including completeness, compliance with method procedures, correctness, and quality control field duplicate sample was collected and submitted blind to the laboratory for analysis of each analyte. Laboratory Data was reviewed utilizing the

ADEC Laboratory Data Review Checklist, found in Appendix D. Sample PE-6-6.5 was used as a duplicate. Though this sample had low results, it was chosen to confirm the low readings from field screening.

Based on the LDRC, all analytical data is considered usable for the purpose of evaluating the presence or absence of petroleum contamination. The precision, accuracy, comparability, completeness, sensitivity, and representativeness were evaluated as part of the LDRC.

4.5. Conceptual Site Model

An ADEC Conceptual site model (CSM) scoping forms have been completed and is included as

Appendix E. Though changes to site conditions occurred from the removal event and new laboratory data is available, the CSM indicates the same exposure pathways of incidental soil ingestion, dermal absorption, ingestion of groundwater, and the inhalation of outdoor and indoor air. However, indoor air quality was assessed during this field effort and does not currently

AES of Alaska 15 3/26/2019 affect inhabitants of the Wollard House. In addition, prior to commencement of work and after the excavation was backfilled, no petroleum odors were noted.

AES of Alaska 16 3/26/2019

5. CONCLUSIONS AND RECOMMENDATIONS

On August 22nd and 23rd, AES provided environmental support to TCON during the removal of contaminated soils located at the Wollard House in McGrath, Alaska. A total of 25 post excavation field screening samples and seven confirmation samples were collected during site activities. Laboratory results indicate DRO contamination extends beyond 6.5 feet bgs in the area that was excavated. PID field screening and laboratory results indicate that clean sidewalls were accomplished on the northern end of the excavation, including the northern portion of the east wall, down to a depth of 6.5 feet.

As contamination is still present at depth, AES recommends further characterization of the site to delineate the vertical extent of contamination. Considering the silty sands present in the area and the passage of time since the UST was removed, migration of contaminants may extend down to groundwater. Delineation of soils can be accomplished via soil borings that extend into the groundwater table, followed by installation of groundwater monitoring wells. Monitoring would then consist of multiple sampling events over the course of several months, requiring multiple mobilizations.

An alternative to this would be the utilization of Direct Sensing technologies such as a Membrane

Interface Probe or an Ultra Violet Optical Screening Tool. Both require the use of direct push technology. When used to their full potential, these technologies are capable of delineating both soil and groundwater contaminant plumes within one mobilization. Though these technologies are usually costlier on a first mobilization basis, historically, the cost of direct sensing versus traditional methods of characterization are found to be approximately equal.

Based on PID results and the interview with Mr. Chase, indoor air quality does not appear to be a hazard to human health at the Wollard House. AES recommends no further action along this pathway.

AES of Alaska 17 3/26/2019

6. REFERENCES

Alaska Department of Environmental Conservation (ADEC). 2017a. 18 AAC 75, Oil and Other

Hazardous Substances Pollution Control. As amended through October 27, 2018.

ADEC. 2017b. Field Sampling Guidance for Contaminated Sites and Leaking Underground

Storage Tank Sites. August 2017.

ADEC. 2017c. Site Characterization Work Plan and Reporting Guidance for Investigation of

Contaminated Sites. March 2017.

ADEC. 2017e. Underground Storage Tanks Procedures Manual. March 2017.

ADEC. 2017g. Guidance on Developing Conceptual Site Models January 2017.

ADEC. 2017h. Technical Memorandum. Data Quality Objectives, Checklists, Quality Assurance

Requirements for Laboratory Data, and Sample Handling. March 2017.

ADEC. 2016. Transitioning to the New Cleanup Levels Memorandum. October 11, 2016.

North Wind 2016 UST Removal Report. Wollard House U.S. Fish and Wildlife Service, McGrath, Alaska. September 2016.

PAGE INTENTIONALLY BLANK

APPENDIX A:

FIGURES

APPENDIX B:

PHOTOGRAPHIC LOG

Wollard House, McGrath Photographic Log US Fish & Wildlife Service

AES, LLC 1 9/7/18

Photo 1: View looking east of start of excavation activities with a cut west of former UST excavation.

Photo 2: View of liner from former UST removal.

AES, LLC 2 9/7/18

Photo 3: View looking west of excavation. Super sacks were hold open with the forks of the all-terrain forklift.

Photo 4: View looking north of the temporary staging area of the filled super sacks.

AES, LLC 3 9/7/18

Photo 5: View looking west of secured excavation after first day of activities.

Photo 6: View of excavation looking generally southwest. The liner of the former UST excavation can be seen in the upper left of photo.

AES, LLC 4 9/7/18

Photo 7: View looking generally southwest of excavation as liner was being placed prior to backfilling.

Photo 8: View looking generally north at the backfilled excavation before final grading.

Rainy conditions delayed final grading.

APPENDIX C:

SGS LABORATORY REPORT

Report Number: 1184766

Client Project: USFWS McGrath Job 5010

Laboratory Report of Analysis

Dear Dumitru Radu, Enclosed are the results of the analytical services performed under the referenced project for the received samples and associated QC as applicable. The samples are certified to meet the requirements of the National

Environmental Laboratory Accreditation Conference Standards. Copies of this report and supporting data will be retained in our files for a period of ten years in the event they are required for future reference. All results are intended to be used in their entirety and SGS is not responsible for use of less than the complete report. Any samples submitted to our laboratory will be retained for a maximum of fourteen (14) days from the date of this report unless other archiving requirements were included in the quote.

If there are any questions about the report or services performed during this project, please call Chuck at (907)

562-2343. We will be happy to answer any questions or concerns which you may have.

Thank you for using SGS North America Inc. for your analytical services. We look forward to working with you again on any additional analytical needs.

Sincerely, SGS North America Inc.

Chuck Homestead Date

Project Manager Charles.Homestead@sgs.com

To: AGVIQ Environmental Services (AES)

701 S. Knik Goodse Bay Rd., B

Wasilla, AK 99654

(907)980-9936

Print Date: 08/30/2018 4:19:02PM

Member of SGS Group

SGS North America Inc. 200 West Potter Drive, Anchorage, AK 99518 t 907.562.2343 f 907.561.5301 www.us.sgs.com

Results via Engage

Case Narrative

SGS Client: AGVIQ Environmental Services (AES)

SGS Project: 1184766

Project Name/Site: USFWS McGrath Job 5010

Project Contact: Dumitru Radu

Refer to sample receipt form for information on sample condition.

*QC comments may be associated with the field samples found in this report. When applicable, comments will be applied to associated field samples.

Print Date: 08/30/2018 4:19:03PM

Member of SGS Group

SGS North America Inc.

200 West Potter Drive, Anchorage, AK 99518

Laboratory ID Client Sample ID Analytical Batch Analyte Reason

Report of Manual Integrations

8270D SIM (PAH)

PE-3-6.5 XMS11026 Phenanthrene BLC1184766002

PEF-5 XMS11026 Phenanthrene BLC1184766007

Manual Integration Reason Code Descriptions

Code Description

O Original Chromatogram

M Modified Chromatogram

SS Skimmed surrogate

BLG Closed baseline gap

RP Reassign peak name

PIR Pattern integration required

IT Included tail

SP Split peak

RSP Removed split peak

FPS Forced peak start/stop

BLC Baseline correction

PNF Peak not found by software

All DRO/RRO analysis are integrated per SOP.

Print Date: 08/30/2018 4:19:04PM

Member of SGS Group

SGS North America Inc.

Laboratory Qualifiers

Enclosed are the analytical results associated with the above work order. All results are intended to be used in their entirety and SGS is not responsible for use of less than the complete report. This document is issued by the Company under its General Conditions of Service accessible at <http://www.sgs.com/en/Terms-and-Conditions.aspx>.

Attention is drawn to the limitation of liability, indenmification and jurisdiction issues defined therein.

Any holder of this document is advised that information contained hereon reflects the Company's findings at the time of its intervention only and within the limits of Client's instructions, if any. The Company's sole responsibility is to its Client and this document does not exonerate parties to a transaction from exercising all their rights and obligations under the transaction documents. Any unauthorized alteration, forgery or falsification of the context or appearance of this document is unlawful and offenders may be prosecuted to the fullest extent of the law.

SGS maintains a formal Quality Assurance/Quality Control (QA/QC) program. A copy of our Quality Assurance Plan

(QAP), which outlines this program, is available at your request. The laboratory certification numbers are AK00971

(DW Chemistry & Microbiology) & 17-021 (CS) for ADEC and 2944.01 for DOD ELAP/ISO17025 (RCRA methods:

1020B, 1311, 3010A, 3050B, 3520C, 3550C, 5030B, 5035A, 6020A, 7470A, 7471B, 8015C, 8021B, 8082A, 8260C, 8270D, 8270D-SIM, 9040C, 9045D, 9056A, 9060A, AK101 and AK102/103). Except as specifically noted, all statements and data in this report are in conformance to the provisions set forth by the SGS QAP and, when applicable, other regulatory authorities.

The following descriptors or qualifiers may be found in your report:

* The analyte has exceeded allowable regulatory or control limits.

! Surrogate out of control limits.

B Indicates the analyte is found in a blank associated with the sample.

CCV/CVA/CVB Continuing Calibration Verification

CCCV/CVC/CVCA/CVCB Closing Continuing Calibration Verification

CL Control Limit

DF Analytical Dilution Factor

DL Detection Limit (i.e., maximum method detection limit)

E The analyte result is above the calibrated range.

GT Greater Than

IB Instrument Blank

ICV Initial Calibration Verification

J The quantitation is an estimation.

LCS(D) Laboratory Control Spike (Duplicate)

LLQC/LLIQC Low Level Quantitation Check

LOD Limit of Detection (i.e., 1/2 of the LOQ)

LOQ Limit of Quantitation (i.e., reporting or practical quantitation limit)

LT Less Than

MB Method Blank

MS(D) Matrix Spike (Duplicate)

ND Indicates the analyte is not detected.

RPD Relative Percent Difference

U Indicates the analyte was analyzed for but not detected.

Note: Sample summaries which include a result for "Total Solids" have already been adjusted for moisture content.

All DRO/RRO analyses are integrated per SOP.

Print Date: 08/30/2018 4:19:05PM

Member of SGS Group

SGS North America Inc. 200 West Potter Drive, Anchorage, AK 99518 t 907.562.2343 f 907.561.5301 www.us.sgs.com http://www.sgs.com/terms_and_conditions.htm http://www.sgs.com/terms_and_conditions.htm

Sample Summary

Client Sample ID Lab Sample ID Collected Received Matrix

PE-2-6.5 1184766001 08/23/2018 08/27/2018 Soil/Solid (dry weight)

PE-3-6.5 1184766002 08/23/2018 08/27/2018 Soil/Solid (dry weight)

PE-5-6.5 1184766003 08/23/2018 08/27/2018 Soil/Solid (dry weight)

PE-6-6.5 1184766004 08/23/2018 08/27/2018 Soil/Solid (dry weight)

PE-6-6.5D 1184766005 08/23/2018 08/27/2018 Soil/Solid (dry weight)

PEF-3 1184766006 08/23/2018 08/27/2018 Soil/Solid (dry weight)

PEF-5 1184766007 08/23/2018 08/27/2018 Soil/Solid (dry weight)

TRIP BLANK 1184766008 08/23/2018 08/27/2018 Soil/Solid (dry weight)

Method DescriptionMethod

8270 PAH SIM Semi-Volatiles GC/MS8270D SIM (PAH)

AK101/8021 Combo. (S)AK101

AK101/8021 Combo. (S)SW8021B

Diesel/Residual Range OrganicsAK102

Diesel/Residual Range OrganicsAK103

Percent Solids SM2540GSM21 2540G

Print Date: 08/30/2018 4:19:05PM

Member of SGS Group

SGS North America Inc.

Detectable Results Summary

Client Sample ID: PE-2-6.5

Lab Sample ID: 1184766001 UnitsParameter Result

Benzo[b]Fluoranthene ug/Kg19.3JPolynuclear Aromatics GC/MS

Chrysene ug/Kg26.6

Fluoranthene ug/Kg112

Phenanthrene ug/Kg20.0J

Pyrene ug/Kg51.0

Diesel Range Organics mg/Kg1170Semivolatile Organic Fuels

Ethylbenzene ug/Kg23.0JVolatile Fuels

Gasoline Range Organics mg/Kg8.52 o-Xylene ug/Kg39.2

P & M -Xylene ug/Kg111

Toluene ug/Kg22.7J

Xylenes (total) ug/Kg150

Client Sample ID: PE-3-6.5

Lab Sample ID: 1184766002 UnitsParameter Result

Benzo[b]Fluoranthene ug/Kg19.3JPolynuclear Aromatics GC/MS

Benzo[g,h,i]perylene ug/Kg9.99J

Chrysene ug/Kg17.4J

Fluoranthene ug/Kg38.6

Indeno[1,2,3-c,d] pyrene ug/Kg9.77J

Phenanthrene ug/Kg16.8J

Pyrene ug/Kg34.4

Diesel Range Organics mg/Kg1280Semivolatile Organic Fuels

Residual Range Organics mg/Kg43.0

Ethylbenzene ug/Kg21.8JVolatile Fuels

Gasoline Range Organics mg/Kg15.4 o-Xylene ug/Kg346

P & M -Xylene ug/Kg102

Toluene ug/Kg10.8J

Xylenes (total) ug/Kg448

Client Sample ID: PE-5-6.5

Lab Sample ID: 1184766003 UnitsParameter Result

Residual Range Organics mg/Kg30.7Semivolatile Organic Fuels

Client Sample ID: PE-6-6.5

Lab Sample ID: 1184766004 UnitsParameter Result

Residual Range Organics mg/Kg42.1Semivolatile Organic Fuels

Client Sample ID: PE-6-6.5D

Lab Sample ID: 1184766005 UnitsParameter Result

Diesel Range Organics mg/Kg12.7JSemivolatile Organic Fuels

Residual Range Organics mg/Kg42.8

Print Date: 08/30/2018 4:19:06PM

Member of SGS Group

SGS North America Inc.

Detectable Results Summary

Client Sample ID: PEF-3

Lab Sample ID: 1184766006 UnitsParameter Result

Fluoranthene ug/Kg10.3JPolynuclear Aromatics GC/MS

Pyrene ug/Kg11.4J

Diesel Range Organics mg/Kg422Semivolatile Organic Fuels

Residual Range Organics mg/Kg32.2

Ethylbenzene ug/Kg15.9JVolatile Fuels

Gasoline Range Organics mg/Kg17.2 o-Xylene ug/Kg447

P & M -Xylene ug/Kg79.9

Toluene ug/Kg19.6J

Xylenes (total) ug/Kg527

Client Sample ID: PEF-5

Lab Sample ID: 1184766007 UnitsParameter Result

Benzo[b]Fluoranthene ug/Kg12.3JPolynuclear Aromatics GC/MS

Chrysene ug/Kg10.2J

Fluoranthene ug/Kg19.6J

Phenanthrene ug/Kg9.28J

Pyrene ug/Kg17.0J

Diesel Range Organics mg/Kg229Semivolatile Organic Fuels

Residual Range Organics mg/Kg28.1

Gasoline Range Organics mg/Kg7.73Volatile Fuels o-Xylene ug/Kg184

P & M -Xylene ug/Kg35.1J

Xylenes (total) ug/Kg219

Print Date: 08/30/2018 4:19:06PM

Member of SGS Group

SGS North America Inc.

Client Project ID: USFWS McGrath Job 5010

Lab Sample ID: 1184766001

Lab Project ID: 1184766

Collection Date: 08/23/18 11:50

Received Date: 08/27/18 08:08

Matrix: Soil/Solid (dry weight)

Solids (%):92.1

Results by Polynuclear Aromatics GC/MS

Results of PE-2-6.5

Location:

Date AnalyzedParameter DFUnitsResult LOQ/CL DL Allowable

LimitsQual

1-Methylnaphthalene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

2-Methylnaphthalene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Acenaphthene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Acenaphthylene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Anthracene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Benzo(a)Anthracene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Benzo[a]pyrene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Benzo[b]Fluoranthene 19.3 ug/Kg 126.6 6.65 08/28/18 15:27J

Benzo[g,h,i]perylene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Benzo[k]fluoranthene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Chrysene 26.6 ug/Kg 126.6 6.65 08/28/18 15:27

Dibenzo[a,h]anthracene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Fluoranthene 112 ug/Kg 126.6 6.65 08/28/18 15:27

Fluorene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Indeno[1,2,3-c,d] pyrene 13.3 ug/Kg 126.6 6.65 08/28/18 15:27U

Naphthalene 10.7 ug/Kg 121.3 5.32 08/28/18 15:27U

Phenanthrene 20.0 ug/Kg 126.6 6.65 08/28/18 15:27J

Pyrene 51.0 ug/Kg 126.6 6.65 08/28/18 15:27

Surrogates

2-Methylnaphthalene-d10 (surr) 83.1 % 158-103 08/28/18 15:27

Fluoranthene-d10 (surr) 75.2 % 154-113 08/28/18 15:27

Batch Information

Prep Batch: XXX40314

Prep Method: SW3550C

Prep Date/Time: 08/28/18 08:51

Prep Initial Wt./Vol.: 22.966 g

Prep Extract Vol: 5 mL

Analytical Batch: XMS11026

Analytical Method: 8270D SIM (PAH)

Analyst: BMZ

Analytical Date/Time: 08/28/18 15:27

Container ID: 1184766001-A

Print Date: 08/30/2018 4:19:07PM

Member of SGS Group

SGS North America Inc.

200 West Potter Drive Anchorage, AK 95518

J flagging is activated

Lab Sample ID: 1184766001

Lab Project ID: 1184766

Collection Date: 08/23/18 11:50

Received Date: 08/27/18 08:08

Matrix: Soil/Solid (dry weight)

Solids (%):92.1

Results by Semivolatile Organic Fuels

Results of PE-2-6.5

Location:

Date AnalyzedParameter DFUnitsResult LOQ/CL DL Allowable

LimitsQual

Diesel Range Organics 1170 mg/Kg 121.5 6.66 08/28/18 13:03

Surrogates

5a Androstane (surr) 95.5 % 150-150 08/28/18 13:03

Batch Information

Prep Batch: XXX40311

Prep Method: SW3550C

Prep Date/Time: 08/28/18 07:18

Prep Initial Wt./Vol.: 30.344 g

Prep Extract Vol: 5 mL

Analytical Batch: XFC14546

Analytical Method: AK102

Analyst: VDL

Analytical Date/Time: 08/28/18 13:03

Container ID: 1184766001-A

Date AnalyzedParameter DFUnitsResult LOQ/CL DL Allowable

LimitsQual

Residual Range Organics 10.8 mg/Kg 121.5 6.66 08/28/18 13:03U

Surrogates n-Triacontane-d62 (surr) 84.8 % 150-150 08/28/18 13:03

Batch Information

Prep Batch: XXX40311

Prep Method: SW3550C

Prep Date/Time: 08/28/18 07:18

Prep Initial Wt./Vol.: 30.344 g

Prep Extract Vol: 5 mL

Analytical Batch: XFC14546

Analytical Method: AK103

Analyst: VDL

Analytical Date/Time: 08/28/18 13:03

Container ID: 1184766001-A

Print Date: 08/30/2018 4:19:07PM

Member of SGS Group

SGS North America Inc.

200 West Potter Drive Anchorage, AK 95518

Lab Sample ID: 1184766001

Lab Project ID: 1184766

Collection Date: 08/23/18 11:50

Received Date: 08/27/18 08:08

Matrix: Soil/Solid (dry weight)

Solids (%):92.1

Results by Volatile Fuels

Results of PE-2-6.5

Location:

Date AnalyzedParameter DFUnitsResult LOQ/CL DL Allowable

LimitsQual

Gasoline Range Organics 8.52 mg/Kg 12.74 0.822 08/28/18 15:49

Surrogates

4-Bromofluorobenzene (surr) 97.5 % 150-150 08/28/18 15:49

Batch Information

Prep Batch: VXX33001

Prep Method: SW5035A

Prep Date/Time: 08/23/18 11:50

Prep Initial Wt./Vol.: 58.779 g

Prep Extract Vol: 29.6597 mL

Analytical Batch: VFC14382

Analytical Method: AK101

Analyst: ST

Analytical Date/Time: 08/28/18 15:49

Container ID: 1184766001-B

Date AnalyzedParameter DFUnitsResult LOQ/CL DL Allowable

LimitsQual

Benzene 6.85 ug/Kg 113.7 4.38 08/28/18 15:49U

Ethylbenzene 23.0 ug/Kg 127.4 8.55 08/28/18 15:49J o-Xylene 39.2 ug/Kg 127.4 8.55 08/28/18 15:49

P & M -Xylene 111 ug/Kg 154.8 16.4 08/28/18 15:49

Toluene 22.7 ug/Kg 127.4 8.55 08/28/18 15:49J

Xylenes (total) 150 ug/Kg 182.2 25.0 08/28/18 15:49

Surrogates

1,4-Difluorobenzene (surr) 98.1 % 172-119 08/28/18 15:49

Batch Information

Prep Batch: VXX33001

Prep Method: SW5035A

Prep Date/Time: 08/23/18 11:50

Prep Initial Wt./Vol.: 58.779 g

Prep Extract Vol: 29.6597 mL

Analytical Batch: VFC14382

Analytical Method: SW8021B

Analyst: ST

Analytical Date/Time: 08/28/18 15:49

Container ID: 1184766001-B

Print Date: 08/30/2018 4:19:07PM

Member of SGS Group

SGS North America Inc.

200 West Potter Drive Anchorage, AK 95518

Client Sample ID: PE-3-6.5

Lab Sample ID: 1184766002

Lab Project ID: 1184766

Collection Date: 08/23/18 11:56

Received Date: 08/27/18 08:08

Matrix: Soil/Solid (dry weight)

Solids (%):85.2

Results by Polynuclear Aromatics GC/MS

Results of PE-3-6.5

Location:

Date AnalyzedParameter DFUnitsResult LOQ/CL DL Allowable

LimitsQual

1-Methylnaphthalene 14.4 ug/Kg 128.9 7.22 08/28/18 15:47U

2-Methylnaphthalene 14.4 ug/Kg 128.9 7.22 08/28/18 15:47U

Acenaphthene 14.4 ug/Kg 128.9 7.22 08/28/18 15:47U

Acenaphthylene…