Attach_5_-_Tulageak_Legacy_Well_Site_Delineation_and_Sampling_2019_Report.pdf

Tulageak #1 Legacy Well Site

Reserve Pit and Flare Pit Delineation and Field Sampling Report

NPRA Legacy Wells Remediation

Alaska

August 2019

Reserve and Flare Pit Delineation Report

North Slope, Alaska

IDIQ Contract L16PC00005

Task Order 140L0619R0013

Prepared for:

U.S. Bureau of Land Management Operations Center

Prepared by:

SLR International Corporation

2700 Gambell Street, Suite 200

Anchorage, Alaska 99503

Primary Authors:

Bret Berglund, C.P.G Brett Woelber, P.G.

Under Contract to:

Olgoonik Construction Services, LLC

3201 C Street, Suite 700

Anchorage, Alaska 99503

Project Manager:

James Nunley

Reserve Pit and Flare Pit Delineation and Field Sampling Report

Task Order -140L0619R0013 i August 2019

Table of Contents

Executive Summary ........................................................................................................................... E-1

1.0 Introduction

Project Objectives and Scope

Project Organization

Site Background and Potential for Environmental Contamination

1.3.1 Location and General Description

1.3.2 Drill Site History

1.3.3 Previous Inspection and Investigations

Potential Contaminants of Concern and Cleanup Levels

1.4.1 Soil

1.4.2 Water

Sampling Rationale and Approach

2.0 Summary of Project Activities and Methods

Deviations from the Work Plan

Subsurface Boring and Sampling

Sampling Protocols

2.3.1 Field Screening of Soil for VOCs

2.3.2 Discrete Soil Sample Collection

2.3.3 Surface Water Sampling

Sample Storage and Management

2.4.1 Waste Handling and Disposal

Surveying

Cross Sections and Volume Estimation

Laboratory Analysis, Data Validation, and Reporting

3.0 Results

Historical and Current Shoreline and Estimated Erosion

Site Conditions and Lithology

3.2.1 Reserve Pit

3.2.2 Flare Pit

3.2.3 Well Area

Analytical Results

3.3.1 Soil

3.3.2 Surface Water

Volume Calculations

4.0 Summary and Conclusions

5.0 References

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Figures

Figure 1 Project Location Map Figure 2 Site Map Figure 3 Borehole Sample Locations Figure 4 Reserve Pit Cross Section Figure 5 Flare Pit Cross Section

Tables

Table 1 Summary of Well Site History Table 2 Soil Reserve Pit Sample Results Table 3 Soil Flare Pit Sample Results Table 4 Soil Well Area Sample Results Table 5 Surface Water Sample Results Table 6 Volume Estimates

Appendices

Appendix A Photograph Log

Appendix B Field Notes, Field Forms, and Survey Coordinates

Appendix C Boring Logs

Appendix D Quality Assurance Review and Analytical Laboratory Data iii August 2019

Acronyms and Abbreviations

°C degrees Celsius AAC Alaska Administrative Code ADEC Alaska Department of Environmental Conservation

AMSL above mean sea level

AWQS Alaska Water Quality Standards bgs below ground surface

BLM Bureau of Land Management

BTEX benzene, toluene, ethylbenzene, total xylenes

CFR Code of Federal Regulations

COC contaminant of concern

DRO diesel-range organics

E&P exploration and production

EPA United States Environmental Protection Agency

FSP Field Sampling Plan ft foot/feet

GPS Global Positioning System

GRO gasoline-range organics

Husky Husky Oil NPR Operations, Inc.

LCS laboratory control sample

LOD Limit of Detection

LOQ Limit of Quantitation µg/L microgram per liter µS/cm microsiemens per centimeter mg/kg milligram per kilogram

MS/MSD matrix spike/matrix spike duplicate

NPRA National Petroleum Reserve-Alaska

OCS Olgoonik Construction Services, LLC

OPUS Online Positioning User Service

PAH polycyclic aromatic hydrocarbon

PID photoionization detector ppm parts per million

PWS Performance Work Statement

QA quality assurance

QAPP Quality Assurance Project Plan

QAR Quality Assurance Review

QC quality control

RCRA Resource Conservation and Recovery Act iv August 2019

RPD Relative Percent Difference

RRO residual-range organics

RTK Real-Time Kinematic

SGS SGS North America, Inc.

SIM selective ion monitoring

SLR SLR International Corporation

TAH Total Aromatic Hydrocarbons

TAqH Total Aqueous Hydrocarbons

TCLP Toxicity Characteristic Leaching Procedure

TPH total petroleum hydrocarbon

USGS United States Geological Survey

VOC volatile organic compounds yd3 cubic yards

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Executive Summary

This report documents the approach, methods, and results of environmental sampling performed in 2019 during the site assessment of the reserve pit and flare pit at Tulageak #1 Legacy Well Site.

The site is located 25 miles southeast of Utqiaġvik (formerly Barrow), Alaska. The well was drilled in 1981 in the National Petroleum Reserve – Alaska (NPRA), which is managed by the U.S. Bureau of Land Management (BLM).

The BLM contracted Olgoonik Construction Services, LLC (OCS) to complete the investigation in accordance with the Performance Work Statement (PWS) of BLM Contract L16PC00005. OCS is a subsidiary of Olgoonik Development, the Alaska Native Corporation owned by the natives of

Wainwright. SLR International Corporation (SLR) supported OCS with technical services, including plan development, field sample collection, laboratory management, and report preparation. SGS

North America, Inc. (SGS) in Anchorage, Alaska, provided analytical laboratory support.

The work described in this report was conducted in accordance with the project’s Work Plan, including Field Sampling Plan: Tulageak #1 Legacy Well Site. The Work Plan contained multiple components, including a Field Sampling Plan (FSP) and Quality Assurance Project Plan (QAPP).

The primary purpose of the project was to characterize and delineate drilling waste, if present, within the reserve pit and flare pit at the Tulageak #1 Legacy Well Site. Eighteen boreholes were advanced at the Tulageak #1 Legacy Well Site to delineate the boundary between drilling waste and native material, estimate the total volume of drilling waste, and characterize the waste for disposal or treatment. Twelve borings were advanced within the reserve pit, three within the flare pit, and three around the well bore. Sampling was performed to document the site conditions and assess whether or not contamination was present that would merit further action, including additional investigation, removal, or remediation. Sampling was conducted from April 2 to April 4, 2019. At the time of sampling, the reserve pit had approximately 5 feet (ft) of ice overlying 3 ft of water. The flare pit had approximately 3 ft of ice overlying 4 feet of water.

Surveying was completed to document the location of boreholes, sample locations, and the

Beaufort Sea shoreline using a Trimble R10 real-time kinematic (RTK) base/rover global positioning system (GPS) capable of sub-foot accuracy.

Laboratory analysis was focused on the most probable contaminants of concern, considered to be diesel-range organics (DRO), residual-range organics (RRO) and Resource Conservation and

Recovery Act (RCRA) metals (particularly lead). However, samples were collected for other

E-2 August 2019 hazardous substances at a lesser frequency to verify their presence or absence. These analyses consisted of benzene, toluene, ethylbenzene, total xylenes (BTEX), polycyclic aromatic hydrocarbons, and hexavalent chromium. A subset of the samples from the reserve pit were also analyzed for toxicity characteristic leaching procedure (TCLP) RCRA metals. Water samples were analyzed for BTEX and polycyclic aromatic hydrocarbons (PAH) with selective ion monitoring (SIM).

The primary cleanup levels used to screen soil sample results and evaluate whether contamination was present were ADEC Method Two cleanup levels for the Arctic Zone, as listed in 18 AAC 75.341, Tables B1 and B2. There were no exceedances of ADEC Method Two soil cleanup levels, except arsenic.

Arsenic exceeded the ADEC Method Two soil cleanup level of 12 micrograms per kilogram (mg/kg) in approximately 80 percent of the samples collected from the well sites (29 of 36 primary samples). The detected arsenic concentrations were considered typical of the region and attributed to native soils, as opposed to an anthropogenic contaminant from past drilling activities. Detections of other metals were well below Method Two cleanup levels. In addition, TCLP RCRA metal concentrations in the reserve pit samples were well below the toxicity characteristic for a hazardous waste.

DRO exceeded the ADEC Method One soil cleanup level of 500 mg/kg in one borehole each within the reserve pit, flare pit, and well area. The maximum DRO concentrations detected were

2,730 mg/kg in the flare pit, 523 mg/kg in the reserve pit, and 726 mg/kg in the well area. There were no other Method One cleanup level exceedances.

Surface water samples from the reserve pit and flare pit were screened against the Alaska Water

Quality Standards (AWQS) contained in 18 AAC 70. No surface water samples exceeded AWQS for total aromatic hydrocarbons (TAH), total aqueous hydrocarbons (TAqH), or total metals for freshwater. Nickel concentrations slightly exceeded the marine AWQS in both pits but was well below the freshwater standard.

Based on the investigation, a significant volume of drilling mud and cuttings do not appear to be present within the reserve pit. This finding is supported by the lack of color or textural changes observed in the boring indicating the presence of a surficial layer of drilling mud within the reserve pit. In addition, metal concentrations in the samples were relatively uniform both laterally and vertically, and similar to the flare pit. Barium concentrations appeared slightly elevated in only a few boreholes within the reserve pit, limited to the surficial soils. The lack of a thick layer of mud being present in the reserve pit is consistent with the drilling records that indicated only 2,000 ft of

E-3 August 2019 drilling mud was displaced from a 9⅝" boring to finish the well, which is equivalent to approximately 87 cubic yards (yd3). Drilling mud was left in the borehole from 2,000 ft to bottom at 4,015 ft (Husky, 1982).

The reserve pit was estimated to contain 789 yd3 of water and 3,230 yd3 of ice at the time of sampling in April 2019, based on measurements of ice thickness and water depth. The flare pit was estimated to contain 450 yd3 of water and 157 yd3 of ice. The estimated volume of DRO-impacted soil above 500 mg/kg is 486 yd3 within the flare pit, 70 yd3 within the reserve pit, and 38 yd3 around the wellhead.

In April 2019, the eastern side of the reserve pit was measured to be is 330 ft from shoreline of the

Beaufort Sea. Assuming a constant rate of erosion, the reserve pit will begin to erode into the ocean in 19.7 years. However, the rate of erosion is likely accelerating due to longer ice-free summers in the Beaufort Sea. Additionally, shoreline erosion likely occurs in large, isolated events.

A large easterly storm during ice-free summer conditions has the potential to rapidly erode the ice-rich coastal bluff.

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1.0 Introduction

This report describes the approach, methods, and results of sampling performed to characterize and delineate the reserve pit, flare pit, and wellhead area at the Tulageak #1 Legacy Well Site. The site is located 25 miles southeast of Utqiaġvik (formerly Barrow), Alaska (Figure 1). The well was drilled in 1981 in the National Petroleum Reserve-Alaska (NPRA), which is managed by the U.S.

Bureau of Land Management (BLM). Project activities described in this report were conducted in

April 2019.

The work described in this report was conducted in accordance with the project’s Work Plan, entitled, Work Plan, including Field Sampling Plan Tulageak #1 Legacy Well Site Reserve and Flare

Pit Delineation North Slope, Alaska (Work Plan; OCS, 2019). The Work Plan contains a Field

Sampling Plan (FSP) and Quality Assurance Project Plan (QAPP).

Project Objectives and Scope

The primary objectives of the project were to characterize and delineate possible drilling wastes within the reserve pit, flare pit, and around the wellhead area at the Tulageak #1 Legacy Well Site.

Data were collected to estimate the volume of waste and associated impacted soil for potential treatment or disposal purposes. The area of investigation included the immediate well area, which borders the reserve pit, but did not include the entire drilling pad or surrounding areas.

The approach and methods used to complete these objectives included the following tasks:

• Mobilize and demobilize the necessary equipment, materials, and crew to the well site.

Travel on the tundra was conducted using off-road, approved vehicles pulling a Cat-train camp and tracked/skid sleighs with support equipment and supplies;

• Advance boreholes with a drill rig through the area of potential drilling waste within the reserve pit, flare pit, and well area to document the stratigraphy and collect samples for field screening and laboratory analysis;

• Collect water samples from the reserve pit and flare pit for laboratory analysis to characterize the fluids;

• Survey sample locations and a section of current shoreline adjacent to the reserve pit; and

• Report the activities and findings.

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The work was completed to meet the regulatory and performance requirements of the BLM and other agencies at their direction. Sampling and reporting methods were consistent with the requirements and guidance of the Alaska Department of Environmental Conservation (ADEC). This report includes a Quality Assurance Review (QAR). The QAR outlines the chemical data quality objectives, analytical methods, quality assurance (QA) and quality control (QC) requirements, and data validation procedures.

Project Organization

The BLM contracted Olgoonik Construction Services, LLC (OCS) to complete the investigation in accordance with the Performance Work Statement (PWS) of BLM Contract L16PC00005. OCS is a subsidiary of Olgoonik Development, the Alaska Native Corporation owned by the natives of

Wainwright. SLR International Corporation (SLR) supported OCS with technical services, including sample plan development, field sample collection, laboratory management, and reporting. SGS

North America, Inc. (SGS) in Anchorage, Alaska, provided analytical laboratory support that included receiving, analyzing, and providing a data report for all samples in accordance with the

QAPP.

Site Background and Potential for Environmental Contamination

1.3.1 Location and General Description

The Tulageak #1 Legacy Well Site is located approximately 25 miles southeast of Utqiaġvik, west of

Dease Inlet, and is about 350 feet (ft) west of the Beaufort Sea shoreline. The location of the well site is shown on Figure 1. The tundra at the well site is approximately 7 ft above sea level, with visually evident coastal erosion occurring. The well site is prone to inundation with salt water during storm tides (USGS, 1992). The area surrounding the well is tundra, with lagoons, lakes, small rivers, and ice wedge polygons disrupting the surface above continuous permafrost. Typical tundra vegetation of grasses, mosses, and sedges are found at the site and in the surrounding area.

This “test well” was drilled in 1981 by Husky Oil NPR Operations, Inc. (Husky) under contract to the

U.S. Geological Survey (USGS). The well’s purpose was to test the sandstone layers and units in the area. Based on the drilling records, the surface material is composed of silty clay with plant material and other organics, part of the Gubik Formation. The first unit of underlying bedrock consists of a shale of the Torok Shale unit, beginning approximately 100 ft below ground surface

(bgs). The unconsolidated material above the shale consisted of silt (Husky, 1982).

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Figure 2 presents a site map displaying the primary site features. The pad and pit area cover an area of about 720 ft north-south by 400 ft east-west. The pad area consists of an approximately

350 ft by 200 ft drill pad, and smaller camp pad to the north. The drill pad was built up 2 ft above the tundra and the camp pad was built up 3 ft. The pads were constructed using silty-clay excavated from the reserve and flare pits (Husky, 1982). The well was on the south side of the drill pad, almost in the center of the site. The reserve pit was located to the south of the drill pad, and the flare pit was constructed southwest of the reserve pit. Both pits were constructed without artificial walls or liners. Over time, the pits have filled with water, and thermokarsting has developed along the margins. The tundra has mostly reclaimed and revegetated the pad area and pit perimeter. The wellhead has been maintained in good working condition and is located in a wooden cellar (BLM, 2013).

1.3.2 Drill Site History

The report, History of Drilling Operations, Tulageak Test Well No. 1 (Husky, 1982) provides historical documentation on the well site and is summarized in this section. A site history summary highlighting equipment used and potential hazardous substances is presented in Table 1. Field operations at the site began on January 26, 1981, with the construction of the drilling pad and ice airstrip on a nearby lake. The drill rig and supporting equipment were moved to the Tulageak #1

Legacy Well Site from the nearby Walakpa #2 drill site beginning on February 16. The well was spudded on February 26, and drilling was conducted through March 20. The well was drilled to a depth of 4,015 ft.

Oil shows were slight to good in two formations encountered during drilling, but no gas was encountered. No oil or gas production was conducted from the well. The well was plugged with two cement plugs to seal off the lower formations. The upper 2,000 ft of the well was filled with diesel to facilitate USGS temperature monitoring. Below 2,000 ft bgs to the bottom at 4,015 ft, the well remained filled with drilling mud (Husky, 1982).

The drilling report includes a “staked and surveyed” plan for the well site with both a plan and cross-sectional view of the reserve and flare pit (Husky, 1982). When the site plan is overlain on a recent georeferenced aerial photograph (Figure 2), the plan appears to generally conform to current site features, indicating the well site was generally constructed to plan. The reserve pit and flare pit locations correlate with current surface water bodies. The perimeters of the pits appear to have expanded beyond the former pit boundaries due to thermokarsting and subsidence. The cross-sections in the drilling report indicate the flare and reserve pit were initially planned for equal depths, on the order of up to 12 ft deep, with a sidewall slope ratio of 2:1 horizontal to vertical. There is no documentation that the flare pit was used.

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1.3.3 Previous Inspection and Investigations

Analytical sampling was conducted by Tetra Tech in March 1981 and by Nuera Reclamation

Company in July 1984. A total petroleum hydrocarbon (TPH) concentration of 77 milligrams per kilogram (mg/kg) was identified in a single sediment sample collected from the reserve pit. No metals concentrations were reported. Specific conductance in the reserve pit was measured at

3,980 microsiemens per centimeters (μS/cm), indicating the contents had a higher content of dissolved solids (e.g., salts) than typical freshwater bodies (500 to 1500 μS/cm). Seawater has occasionally inundated the site during storms. Additionally, the drilling mud used at the well site was reported to have a high calcium chloride content (USGS, 1992).

The site was visited briefly by the USGS in 1989 and 1990 as part of reconnaissance visits to wells throughout the Arctic Coastal Plain. No sampling was conducted during the reconnaissance. The

USGS noted that dry conditions in 1990 may have been responsible for taller grass at the site and the presence of salt crusts.

The most recent publicly reported site inspection was performed in July 2012 by the BLM. The inspection noted that the wellhead was in operational condition and that there was no evidence of hydrocarbon contamination in the well cellar. No sampling was conducted during the inspection

(BLM, 2013).

The Tulageak #1 Legacy Well Site is not listed as a “contaminated site” in the ADEC contaminated sites database.

Potential Contaminants of Concern and Cleanup Levels

The potential contaminants of concern (COCs) and regulatory screening levels for site and waste characterization for subsurface soils and water are discussed in this section.

1.4.1 Soil

Based on the site history and knowledge of similar era NPRA drill sites, the potential COCs are limited to those associated with petroleum products and drilling muds, primarily diesel fuel and metals. Therefore, the primary potential COCs are diesel-range organics (DRO), residual-range organics (RRO) and Resource Conservation and Recovery Act (RCRA) metals (primarily lead and potentially chromium). Secondary potential COCs which have a lesser probability to be present but associated with petroleum products or crude oil are benzene, toluene, ethylbenzene, and total xylenes (BTEX) and gasoline-range organics (GRO).

5 August 2019 is present are ADEC Method Two cleanup levels for the Arctic Zone, as listed in Title 18 Alaska

Administrative Code (AAC) 75.341, Tables B1 and B2 (ADEC, 2018a). Method One petroleum soil cleanup levels for the Arctic Zone, as listed in 18 AAC 75.341, Table A2 (ADEC, 2018a), were used as secondary screening criteria. Method One cleanup levels for the Arctic Zone are specific to GRO, DRO, and RRO, are not risk-based and are only applicable to manmade gravel roads and pads.

In addition, soil sample results were screened against the RCRA criteria for a hazardous waste

(toxicity characteristic as listed in 40 Code of Federal Regulations [CFR] 261) to help classify the drilling waste for disposal in the event it was removed. However, the drilling waste within the reserve pit, flare pit, and immediate wellhead area would likely fit the criteria for RCRA-exempt exploration and production (E&P) waste.

1.4.2 Water

The intent of the water sampling was to collect samples that would characterize the ice and water in the reserve pit or flare pit, to evaluate the need for treating or managing water in the reserve and flare pits during future site remediation. The water results were screened against the Alaska

Water Quality Standards (AWQS) contained in 18 AAC 70 (ADEC, 2018b). The primary potential

COCs in surface water are those associated with petroleum hydrocarbons and drilling muds, which are regulated under 18 AAC 70. The target analytes are:

• Total aromatic hydrocarbons (TAH), which is the sum of BTEX compounds;

• Total aqueous hydrocarbons (TAqH), which is the sum of polyaromatic hydrocarbons by selected ion monitoring (PAH-SIM) and BTEX compounds; and

• Total metals.

For total metals, the AWQS for each metal was calculated in accordance with ADEC’s Alaska Water

Quality Criteria Manual for Toxic and Other Deleterious Organic and Inorganic Substances (ADEC, 2008). Sample results were screened against the AWQS freshwater and marine standards. The freshwater standard was considered most relevant due to the inland location of the water bodies

(impoundments). However, the impoundments are prone to inundation with salt water during storm tides and have brackish conditions based on specific conductivity measurements (USGS, 1992, and this report). In cases where the AWQS for a metal is hardness dependent, the standard was calculated based on the measured calcium and magnesium for the sample.

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Sampling Rationale and Approach

The primary data quality objective was to characterize and delineate the extent of drilling waste or impacted soil within the reserve pit and flare pit, and immediately around the well. The reserve pit was the primary focus of the investigation, in part due to its higher probability of containing significant volumes of drilling waste relative to other locations.

The investigative approach consisted of advancing boreholes over the reserve pit and flare pit footprints (Figure 2), with sufficient coverage that ensured the area of interest was delineated even if the actual pit footprints varied slightly from current estimates. Coordinates for each sample point were generated in advance using the georeferenced photographs so they could be located with a survey-grade real-time kinematic (RTK) global positioning system (GPS) during the plan execution under winter conditions.

Within the reserve pit, a boring/sample grid network was established on 50-ft centers, with slightly tighter spacing along the probable pit boundaries. In addition, three borings (W-02, W-03, and W-

04) were planned to be advanced roughly equidistant from the well, and one boring (W-01) was planned to be advanced within the well cellar. Three borings were planned to be advanced within the flare pit on the northeast corner (F-01), center (F-02), and southwest corner (F-03).

A variety of sample collection, screening and analytical methods were used to support the cleanup activities. Sampling activities were documented in field logs, notebooks, and with photographs.

Laboratory sample locations and relevant site features were mapped with a Trimble R10 RTK GPS survey system.

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2.0 Summary of Project Activities and Methods

The work was conducted in accordance with the Work Plan and FSP (OCS, 2019), unless otherwise noted. Field sampling was performed by ADEC-Qualified Environmental Professionals (per 18 AAC

75.333 criteria), consisting of SLR employees Brett Woelber and Nick Wells. Photographs of the sites and field activities are included in the Photograph Log (Appendix A). Field notes and forms are included as Appendix B. Variances in the sample approach or methods in response to field conditions were documented in the field notes.

Samples collected during the April 2019 fieldwork included advancing and sampling soil borings adjacent to the wellhead, and within the reserve pit and flare pit. In addition, surface water samples were collected from the reserve pit and flare pit.

Deviations from the Work Plan

Two variances to the planned sampling approach occurred in response to field conditions, as summarized below:

• Surface water samples were collected instead of ice samples because the reserve pit and flare pits were not completely frozen to the bottom. An ice auger opened a hole in the ice large enough to directly sample the water. Directly sampling water was considered preferable to collecting and thawing ice samples because the results would be more representative of water quality, especially for volatile organic compounds (VOCs).

• A boring was initially advanced within the well cellar at W-01, as planned, but it was abandoned after a drill depth of 2 inches, when the wooden well floor was encountered and drilling resulted in refusal.

Subsurface Boring and Sampling

Subsurface soil borings were advanced to delineate the possible extent and impact of drilling waste within the reserve pit, flare pit, and around the wellhead. Borings were advanced with a tracked Simco® Earthprobe 200 drill rig, equipped with a 4-inch, solid-stem auger. Auger cuttings were logged continuously to produce a complete lithographic profile. The soil intervals to be sampled within each boring were determined at the judgement of the field crew, dependent on the observations of adjacent borings and location within the respective pit. Samples were collected by raising the auger and collecting cuttings from the auger flight at discrete depths measured from the top of the ice or ground surface, where applicable. As indicated above, liquid water existed below frozen ice in both the reserve pit and flare pit. Therefore, in all borings except those located at the reserve pit perimeter, the auger flights were lifted through liquid water before a sample could be taken.

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All borings advanced within the reserve pit, flare pit, and in the wellhead area during the field effort were logged for lithology, field screened for volatiles, and sampled for laboratory analysis.

Sampling Protocols

Field sampling was conducted in accordance with the FSP section of the Work Plan, which included specific protocols for the collection of soil and water samples. Sampling methods were consistent with the ADEC Field Sampling Guidance (ADEC, 2017a).

Field duplicates were collected at a frequency of no less than one field duplicate per ten primary samples. Field duplicates were submitted as blind samples to the laboratory. Matrix spike (MS) and matrix spike duplicate (MSD) samples were each collected at an approximate frequency of no less than 1 per 20 samples. For volatiles analysis, MS and MSD samples were analyzed using the same aliquot of soil provided for the primary analysis. For non-volatiles analyses, triplicate sample volume was collected to ensure that adequate soil was provided to the laboratory for this purpose.

A variety of sample collection, screening, and analytical methods were used to support the cleanup activities as summarized below.

2.3.1 Field Screening of Soil for VOCs

Field screening with a photoionization detector (PID) for VOCs was used to screen soil on the auger flights at each boring. Heated headspace PID-screening was typically employed at the same interval from which analytical samples were collected. Frozen samples were collected in Ziplock bags and heated to thaw prior to screening. The field team recorded PID readings on boring logs, now digitized and included as Appendix C.

2.3.2 Discrete Soil Sample Collection

Discrete soil samples were collected for site characterization purposes. One shallow and one deep soil sample was collected from each boring, when practicable. Soil samples were collected by removing a sufficient quantity of soil directly from the auger flight with a stainless steel spoon and placing the soil directly into a sample container.

2.3.3 Surface Water Sampling

Surface water sampling was conducted at the reserve pit and flare pit. A discrete grab sample was collected by submerging sample bottles in a hole drilled through surface ice with an ice auger. A transfer bottle was used to collect and pour surface water into each preserved bottle.

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Sample Storage and Management

Procedures to ensure the custody and integrity of samples collected for the laboratory began at the time of collection and continued until analysis. Documentation concerning the custody and condition of the samples were maintained in field and laboratory records.

A bound and sequentially numbered field logbook, as well as sample collection forms and field logs, were consistently maintained to document field activities, including the collection of each sample. Samples were assigned a unique identifier consisting of its matrix (soil or water), collection point (boring/location), and the depth of collection. Field notes in indelible ink provided a record of information such as team members, sample locations, field screening results, site observations, and work directives.

At the time of collection, sample containers appropriate for the specified analysis were filled, capped, and labeled. A blind sample designation was assigned to duplicate samples, and the collection time for these samples corresponded with the collection time of the primary sample. A trip blank was included in each cooler that contained samples to be analyzed for volatiles (BTEX and GRO). Labels indicating sample identification, date, time, and the sampler’s initials were affixed on the sample containers.

Chain-of-custody forms were completed when the samples were packaged into coolers for transport to the laboratory. Trip blanks, temperature blanks, and frozen ice packs were added as required. The samples were maintained at a temperature of 0 to 6 degrees Celsius (°C) from the time of collection until arrival at the laboratory. The samples were always stored in a chilled cooler under a person’s custody and sealed with custody seals. The samples were shipped with enough time for the laboratory to extract the sample within the test method holding time requirements.

The sample coolers were sealed and shipped to Anchorage under proper chain-of-custody documentation, then hand-delivered to the laboratory. Compliance with the project’s sample storage and management criteria are noted in the QAR (Appendix D). There were no issues impacting data quality, with respect to sample receipt, holding times, or preservation.

2.4.1 Waste Handling and Disposal

As stated in the Work Plan, due to the winter conditions and the remote conditions, full wet decontamination of the drilling equipment was not practical between borings. A hammer was first used to break frozen soil and water from the drill augers. The drill augers were then dry-brushed between borings with a stiff-bristled brush to remove any remaining solids.

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Investigation-derived waste was managed appropriately to contain waste materials and reduce the potential spreading of contaminants. Excess soil from sampling or PID-screening samples was returned to the same boring from which it was collected. Solid waste (trash) generated from sampling activities was classified as non-hazardous waste and was disposed of in appropriate receptacles for incineration or landfill disposal in Prudhoe Bay.

Surveying

Surveying was completed to document the location of sample points and other relevant site features. Survey coordinates were obtained with a Trimble R10 RTK GPS, capable of sub-foot accuracy. A temporary benchmark was established north of the wellhead as the basis for survey control. The temporary benchmark consisted of a rebar stake driven into the drill pad. Benchmark positioning data were obtained by using the National Geodetic Survey’s (NGS) Online Positioning

User Service (OPUS), providing coordinates from the National Spatial Reference System. Survey coordinates were collected in Alaska State Plane Coordinates, NAD83, Zone 5, in U.S. survey ft.

Features surveyed included boring locations, surface water sample points, well location, and the shoreline. The shoreline was mapped by walking along the edge shoreline bluff in the vicinity of the reserve pit and pad and recording points with the GPS unit. A table with survey coordinates of sample locations and other areas of interest are included in Appendix B.

Cross Sections and Volume Estimation

Auger cuttings were logged continuously to produce a complete lithographic profile. Digital borelogs were generated using information recorded on boring logs in the field. Lithographic information contained in borelogs was used to generate a north-south cross section and east-west cross section. Three primary lithographic units were identified after a borehole was logged: 1) ice,

2) liquid water, and 3) native silt. After analytical results were received, the volume of soil exceeding screening criteria was calculated using geometrical shapes or using elevation models generated by AutoCAD®, as described in Section 3.4.

Laboratory Analysis, Data Validation, and Reporting

SGS in Anchorage, Alaska, provided analytical support for this project. SGS maintains current ADEC

Contaminated Sites approval for the methods of interest (approval number UST-005). Samples analyzed for site characterization and confirmation purposes were analyzed for the following analytes by the following methods:

• GRO by Alaska Method AK101;

• DRO by Alaska Method AK102;

• RRO by Alaska Method AK103;

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• BTEX by U.S. Environmental Protection Agency (EPA) Method SW8021B and SW8260C for soils and waters, respectively;

• Total RCRA metals by EPA Method SW6020A;

• Toxicity Characteristic Leaching Procedure (TCLP) RCRA metals by EPA Method SW6020A

TCLP;

• Hexavalent chromium by EPA Method SW7196A; and

• PAH-SIM by EPA Method SW8270D.

For comparison to the AWQS, the sum of the detected BTEX compounds was used to calculate the

TAH, and the sum of TAH and PAH-SIM compounds were used to calculate TAqH.

Following receipt of sample results, the data were reviewed to ensure that the data set met project data quality objectives and was usable for purposes of the project. Sample results were given a full data review as described in this section. The analytical data were reviewed for consistency with the project Work Plan FSP and with ADEC’s Technical Memorandum: Data Quality

Objectives, Checklists, Quality Assurance Requirements for Laboratory Data, and Sample Handling

(ADEC, 2017b) requirements. The review was documented in a QAR (Appendix D). In addition to the QAR, Appendix D presents ADEC Laboratory Data Review Checklists for each work order, and analytical laboratory data packages.

The QAR includes a list of all work order numbers for the project, a brief description of the type of samples analyzed, a quality assurance (QA) summary for the associated data set and an ADEC

Laboratory Data Review Checklist for each work order reviewed in the QA summary. The following data quality indicators were included in the review in order to evaluate the data against precision, accuracy, representativeness, completeness, and sensitivity requirements established for the project.

• Chain-of-custody paperwork and custody seals;

• preservation (thermal 4 ± 2 °C and chemical);

• analytical method hold times;

• blanks (trip blanks and method blanks);

• continuous calibration verifications;

• internal standards;

• surrogate recoveries;

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• laboratory control sample and laboratory control sample duplicate recoveries as percent recovery and precision as relative percent difference (RPD);

• MS/MSD recoveries as percent recovery, and precision as RPD;

• field duplicates as RPD; and

• laboratory method detection and reporting limits.

Anomalies identified are discussed in the QAR. Where applicable, the associated data were qualified by applying flags based on the EPA National Functional Guidelines (EPA, 2014). The rationale for applying qualifiers to specific data sets is detailed in the QAR (Appendix D). Data flags used are presented below:

U - The analyte was analyzed for, but was not detected above the limit of detection (LOD).

This qualifier is appended by the laboratory.

J - The analyte has been “tentatively identified” or is “presumptively present” and the associated numerical value is the estimated concentration in the sample between the limit of quantitation (LOQ) and the LOD. This qualifier is appended by the laboratory.

UJ - The analyte was analyzed for, but was not detected. The reported quantitation limit is approximate and may be inaccurate or imprecise.

Q - The result is an estimated quantity. The associated numerical value is the approximate concentration of the analyte in the sample, due to one or more laboratory quality control criteria failures (e.g., laboratory control sample [LCS] recovery, surrogate spike recovery) or a matrix effect. Where applicable, a “+” or “-″ was appended to indicate a high bias or low bias, respectively.

B - Blank contamination: The analyte was positively identified in the blank (e.g., trip blank and/or method blank) associated with the sample and the concentration reported for the sample was less than five times that of the blank (ten times for metals and common laboratory contaminants methylene chloride and acetone). Where applicable, “U” was appended prior to the “B” to indicate the blank detection is greater than the sample detection and the result is likely a false positive.

The project data review indicated that the reported laboratory data met the data quality objectives. All data were usable as qualified. No data were rejected, and thus the overall project completeness goal of 85 percent was exceeded.

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3.0 Results

The following sections discuss findings of the investigation based on the activities completed.

Historical and Current Shoreline and Estimated Erosion

The current and historical (2012) shoreline locations are shown in Figure 2. Based on a review of the July 2012 site visit photographs (BLM, 2013), the shoreline at the Tulageak #1 Legacy Well Site consists of an approximately 5-ft-high bluff, with no exposed beach seaward of the bluff. Thus, the bluff line surveyed in April 2019 is representative of the current coastline.

To measure the amount of coastal erosion since 2012, orthorectified aerial imagery downloaded from DigitalGlobe showing the shoreline location in June 2012 was compared to the location of the bluff surveyed by SLR in April 2019. The distance from the 2012 to the 2019 shoreline varies from 89 to 118 ft across the drill site. Near the reserve pit, the shoreline eroded 118 ft between

2012 and 2019, or approximately 16.7 ft per year.

The 2019 shoreline is 330 ft from the eastern side of the reserve pit. Assuming a constant rate of erosion, the reserve pit will begin to erode into the ocean in 19.7 years. However, the rate of erosion is likely accelerating due to longer ice-free summers in the Beaufort Sea. Additionally, shoreline erosion likely occurs in large, isolated events. A large easterly storm during ice-free summer conditions has the potential to rapidly erode the ice-rich coastal bluff.

Site Conditions and Lithology

Borehole elevations varied across the site. Ice surface elevations were typically slightly greater than 7 ft above mean sea level (AMSL). Borings advanced through the ice in both the flare pit and reserve pit terminated anywhere between 0 and -10 ft AMSL. Ground surface elevations of the wellhead borings were approximately 10 ft AMSL. All wellhead area borings were advanced 4 ft to approximately 6 ft AMSL.

Location-specific reserve pit, flare pit, and wellhead site conditions and lithology are discussed in the following subsections.

3.2.1 Reserve Pit

In general, borings within the reserve pit were advanced through approximately 5 ft of ice, then through approximately 3 ft of liquid water, and then into native soil. Typically, two soil samples were collected, one near the ground surface and one deeper. Perimeter reserve pit borings R-03 and R-18 were shallow and intersected frozen native soil, so only one analytical sample was collected at these locations. Boring R-18 intersected massive ice. In reserve pit boring R-10, three

14 August 2019 analytical samples were collected to examine three distinct zones of interest. In reserve pit boring

R-05, three analytical samples were collected to better define potential contamination within the boring.

Observed lithology consisted of gray, unfrozen, silt with occurrences of black or brown silt at higher elevations in some boreholes. The silt in all boreholes appeared to be unfrozen, with the exception of reserve pit borings R-03, R-14, and R-18. Apparent diesel odors were observed in reserve pit boring R-06. Petroleum sheens were observed in surface water at borings R-04 and

R-06 after the boring was advanced and the auger was retrieved through the water column. There were no sheens observed on surface water in the reserve pit prior to drilling and disturbing sediments. Therefore, the sheen was attributed to the soils on the auger. No color or textural changes indicate the presence of drilling mud within the reserve pit. Sample locations are shown on Figure 3.

The lack of apparent observable drilling mud in the reserve pit may in part be explained by the site history. As noted in Section 1.3.2, the borehole was left filled with drilling mud from 2,000 to 4,015

ft. The upper 2,000 ft of the well was filled with diesel to facilitate USGS temperature monitoring.

Below 2,000 ft bgs, the well remained filled with drilling mud (Husky, 1982). The volume of cutting displaced from a 9⅝” borehole over a 2,000 ft interval is approximately 87 cubic yards (yd3). If this volume of material was spread evenly across the bottom of the reserve pit (approximately 29,435 square ft) the thickness would be approximately 1 inch.

3.2.2 Flare Pit

Borings within the flare pit were advanced through approximately 3 ft of ice. Water depth at the perimeter borings (F-01 and F-03) was approximately 1 ft. Water depth at the central flare pit boring F-02 was advanced through approximately 4 ft of liquid water. Two soil samples were collected in each boring, one in shallow native material, and one in deep native material.

Observed lithology consisted of gray, unfrozen, high-plasticity silt. Apparent diesel odors were observed in flare pit boring F-01. Frozen soil was encountered near the base of boring F-03. No color or textural changes indicate the presence of drilling mud within the flare pit. Sample locations are shown on Figure 3.

3.2.3 Well Area

Three borings (W-02, W-03, and W-04) were advanced roughly equidistant around the wellhead. A fourth boring, W-01, was attempted within the well cellar but was discontinued after drilling through ice to a depth of 2 inches and encountering a wood floor.

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Lithology consisted of frozen, gray silt. Massive ice was encountered in borings W-03 and W-04 in the deepest 0.5 ft of the borehole. No hydrocarbon odors were observed in the well area. No color or textural changes indicate the presence of drilling mud in the well area. Sample locations are shown on Figure 3.

Analytical Results

3.3.1 Soil

Soil sample results for the reserve pit, flare pit, and wellhead area are shown on Tables 2, 3, and 4, respectively. There were no ADEC Method Two soil cleanup level exceedances, except arsenic.

Arsenic exceeded the Method Two cleanup level of 12 mg/kg in approximately 80 percent of the samples collected from the well site (29 of 36 primary samples). The concentrations ranged from

7.52 to 35.3 mg/kg, with the majority in the 10 to 20 mg/kg range. The two samples with the highest arsenic detections (35.3 and 23 mg/kg) did not display elevated petroleum hydrocarbons or barium, suggesting the two samples were not impacted by drilling muds or waste. The detected arsenic concentrations in all of the samples are considered typical of the region and attributed to native soils, as opposed to an anthropogenic contaminant from past drilling activities. The other metal concentrations were well below Method Two cleanup levels. In addition, the TCLP metal concentrations in the reserve pit samples were well below the RCRA toxicity characteristic for a hazardous waste. Hexavalent chromium concentrations in the reserve and flare pit were non-detectable or detected at trace concentrations well below the Method Two cleanup level of 4.9 mg/kg.

No soil samples exceeded the primary DRO screening level (Method Two) of 12,500 mg/kg. DRO exceeded the ADEC Method One soil cleanup level of 500 mg/kg in 4 of the 36 primary sample locations. BTEX concentrations were less than 15 mg/kg, and benzene concentrations were less than 0.5 in all samples, so the 500 mg/kg cleanup level was considered the appropriate criteria for

DRO under Method One (as opposed to 200 mg/kg). The exceedances of the 500 mg/kg Method

One cleanup level were detected at the flare pit (2,730 and 600 mg/kg), reserve pit (523 mg/kg) and wellhead area (726 mg/kg). The location of the exceedances is shown on Figure 2. The presence of elevated DRO generally correlated with elevated PID readings, as shown on Tables 2, 3, and 4. However, the PID reading were all generally low, with a maximum reading of 37.6 parts per million (ppm). GRO and DRO did not exceed Method One cleanup levels.

The soil boring with the highest DRO detection (F-01 in the flare pit) did not have elevated barium concentrations relative to the other samples, suggesting it was not associated with the presence of drilling muds. Barium is common component of drilling muds. The GRO and RRO were also low

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(40.9 and 422 mg/kg, respectively), further suggesting the impacts were associated with diesel fuel.

Barium concentrations in the reserve pit and flare pit were typically less than 500 mg/kg. However, several borings in the reserve pit (R-06, R-07, R-09, R-10, R-13, R-14, and R-15) had barium concentrations in excess of 500 mg/kg, with a maximum detected value of 2,970 mg/kg. The elevated barium concentrations were detected in the upper (surficial) sample of each boring and not at depth. The elevated concentrations may have been caused by the presence of drilling muds.

However, the detected barium concentrations were well below the Method Two cleanup level of

25,000 mg/kg.

3.3.2 Surface Water

Surface water analytical results are shown in Table 5. No surface water samples exceeded AWQS for TAH or TAqH. BTEX concentration were non-detectable. PAH concentrations were either non-detectable or very low. Total metal concentrations did not exceed the AWQS for freshwater;

however, nickel exceeded the marine water AWQS of 8 micrograms per liter (µg/L). Nickel exceedances were detected in both reserve pit and flare pit samples, with concentrations of 17.2 and 16.7 µg/L, respectively. The nickel concentrations in the two pits were well below the freshwater AWQS of 200 µg/L.

Volume Calculations

Cross sections were created to illustrate ice thickness, water depth, site lithology, and the locations of DRO-impacted soil above 500 mg/kg. One reserve pit cross section was developed showing an E-W transect, and another reserve pit cross section was developed showing a N-S transect (Figure 4). The N-S reserve pit cross section also includes borings advanced around the well cellar. One flare pit cross section was developed along a SW-NE transect (Figure 5). The locations of transects are also shown in plan view (Figure 3).

For both flare pit and reserve pit cross sections, approximate locations of soil impacted with DRO in excess of 500 mg/kg is shown in red. The extent of DRO-impacted soil was estimated conservatively. Assumptions were as based on the site conditions and available sample points. For example, it is assumed that DRO-impacted soil is present within the well cellar footprint, although no samples were collected within the cellar due to the presence of wood flooring. It is assumed

DRO-impacted soil is present based on the DRO detected concentration above 500 mg/kg in one of the borings outside the cellar and likelihood that there was a diesel release around the well casing, either during drilling or when filling the casing for freeze protection to diesel to facilitate USGS temperature monitoring.

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Estimated volumes of ice, water, and DRO-impacted soil present at the site are provided in Table

6. The volume of ice and water was based on the measurements of ice thickness and water depth…