F10AK029804_05.09_0500_a.pdf

FT FINAL MMRP PROPOSED PLAN, OB/OD AREA (MRS-04) AND REMAINING OB/OD AREA (MRS-14), FORMER FORT GLENN, UMNAK ISLAND, ALASKA

DECISION DOCUMENT

OB/OD AREA (MRS-04)

MILITARY MUNITIONS RESPONSE PROGRAM

FORMER FORT GLENN, UMNAK ISLAND, ALASKA

FUDS PROJECT NUMBER: F10AK029804

September 2016

Environmental & Special Programs Branch 2204 3rd Street, P.O. Box 6898 Joint Base Elmendorf-Richardson, Alaska 99506-0898

F10AK029804_05.09_0500_a

1200C PERM

THIS PAGE INTENTIONALLY BLANK

DECISION DOCUMENT

OB/OD AREA (MRS-04)

FORMER FORT GLENN,

UMNAK ISLAND, ALASKA

FUDS # F10AK029804

Prepared for:

U. S. Army Engineering and Support Center Huntsville, Alabama and U. S. Army Corps of Engineers, Alaska District Elmendorf AFB, Alaska

Contract No. W912DY-09-D-0061 Task Order 0002

Table of Contents

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Table of Contents Section 1 Declaration ............................................................................................................................ 1-1

1.1 Site Names and Location ......................................................................... 1-1

1.2 Statement of Basis and Purpose ............................................................... 1-1

1.3 Assessment of Site ................................................................................... 1-1

1.4 Description of Selected Remedies ........................................................... 1-1

1.4.1 Remedy Components ................................................................... 1-1

1.4.2 Remedy Performance Criteria...................................................... 1-2

1.5 Statutory Determinations ......................................................................... 1-2

1.6 Data Certification Checklist ..................................................................... 1-2

1.7 Authorizing Signature .............................................................................. 1-3

Section 2 Decision Summary ................................................................................................................ 2-1

2.1 Site Name, Location, and Description ..................................................... 2-1

2.2 Site History and Regulatory Activities .................................................... 2-1

2.3 Previous Investigations ............................................................................ 2-2

2.3.1 Inventory Project Report .............................................................. 2-2

2.3.2 Archive Search Report ................................................................. 2-2

2.3.3 2001 Fort Glenn Remedial Investigation/Interim Removal

Action Report ............................................................................... 2-3

2.3.4 Disposal/Removal Action ............................................................ 2-3

2.3.5 Archives Search Report Supplement ........................................... 2-3

2.3.6 Site Inspection Report .................................................................. 2-3

2.3.7 Remedial Investigation ................................................................ 2-4

2.3.8 Feasibility Study .......................................................................... 2-4

2.3.9 Proposed Plan............................................................................... 2-4

2.4 Community Participation ......................................................................... 2-4

2.5 Scope and Role of Response Action ........................................................ 2-5

2.6 Site Characteristics................................................................................... 2-5

2.6.1 Climate ......................................................................................... 2-5

2.6.2 Topography .................................................................................. 2-5

2.6.3 Geology ........................................................................................ 2-6

2.6.4 Hydrogeology .............................................................................. 2-6

2.6.5 Hydrology .................................................................................... 2-6

2.6.6 Nature and Extent of Contamination ........................................... 2-7

2.6.7 Conceptual Site Model ................................................................. 2-8

2.7 Current and Potential Future Land and Resources Uses .......................... 2-9

2.8 Summary of Site Risks............................................................................. 2-9

2.8.1 Human Health Risks .................................................................... 2-9

2.8.2 Ecological Risks......................................................................... 2-10

2.9 Remedial Action Objectives and ARARs .............................................. 2-10

2.9.1 OB/OD Area (MRS-04) Remedial Action Objective ................ 2-11

2.9.2 ARARs ....................................................................................... 2-11

2.10 Description of Alternatives .................................................................... 2-11

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2.10.1 Alternative 1 – No Action .......................................................... 2-12

2.10.2 Alternative 2 – LUCs ................................................................. 2-12

2.10.3 Alternative 3 – Focused Surface Removal and LUCs ............... 2-13

2.10.4 Alternative 4 – Surface Removal and LUCs.............................. 2-14

2.10.5 Alternative 5 – Surface Removal, Focused Subsurface

Removal, and LUCs ................................................................... 2-15

2.10.6 Alternative 6 – Surface Removal, Subsurface Removal, and

LUCs ..................................................................................... 2-16

2.10.7 Alternative 7 – Surface Removal, Focused Soil Cover, and

LUCs ..................................................................................... 2-18

2.10.8 Alternative 8 – Focused Surface Removal, Focused

Subsurface Removal, and LUCs ................................................ 2-19

2.11 Summary of Comparative Analysis of Alternatives .............................. 2-21

2.11.1 Overall Protection of Human Health and the Environment ....... 2-21

2.11.2 Compliance with ARARs .......................................................... 2-22

2.11.3 Long-Term Effectiveness and Permanence ............................... 2-22

2.11.4 Reduction of Toxicity, Mobility, or Volume through

Treatment ................................................................................... 2-24

2.11.5 Short-Term Effectiveness .......................................................... 2-24

2.11.6 Implementability ........................................................................ 2-25

2.11.7 Cost ..................................................................................... 2-25

2.11.8 Regulatory Agency Acceptance ................................................. 2-26

2.11.9 Community Acceptance ............................................................. 2-27

2.12 Principal Threat Wastes ......................................................................... 2-27

2.13 Selected Remedy .................................................................................... 2-27

2.13.1 Description of the Selected Remedy .......................................... 2-27

2.13.2 Remedy Cost Estimate Summary .............................................. 2-28

2.13.3 Expected Outcomes of Selected Remedy .................................. 2-28

2.14 Statutory Determinations ....................................................................... 2-28

2.15 Documentation of Significant Changes ................................................. 2-29

Section 3 Responsiveness Summary .................................................................................................. 3-1

3.1 Stakeholder Issues and Lead Agency Responses..................................... 3-1

3.2 Technical and Legal Issues ...................................................................... 3-2

Section 4 References ............................................................................................................................. 4-1

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List of Tables List of Tables Table 2-1 Detailed Analysis of Remedial Action Alternatives

Table 2-2 Cost Summary of Remedial Action Alternatives

List of Figures List of Figures Figure 2-1 Former Fort Glenn Location Map

Figure 2-2 OB/OD Area Details

Figure 2-3 OB/OD Area RI Visual Survey Results

Figure 2-4 OB/OD Area RI Results

Figure 2-5 MEC Conceptual Site Model, OB/OD Area (MRS-04)

Figure 2-6 MC Conceptual Site Model, OB/OD Area (MRS-04)

List of Appendices List of Appendices Appendix A Public Participation

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Acronyms and Abbreviations Acronyms and Abbreviations ADEC Alaska Department of Environmental Conservation

ARAR applicable or relevant and appropriate requirement

ASR Archive Search Report bgs below ground surface

BIP blown in place

BLM Bureau of Land Management

CAFB Cape Air Force Base

CELMS Corps of Engineers, St. Louis

CEPOA Corps of Engineers Pacific Ocean, Alaska

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980

CFR Code of Federal Regulations

COPC chemical of potential concern

CSM conceptual site model

DD Decision Document

DDESB Department of Defense Explosives Safety Board

DMM discarded military munitions

DoD Department of Defense

EOD Explosive Ordnance Disposal

ESS Explosives Safety Submission

FS Feasibility Study

DGM digital geophysical mapping

EM Engineering Manual

EMM earth moving machinery

INPR Inventory Project Report

LUC land use control

MC munitions constituents

MD munitions debris

MEC munitions and explosives of concern mm millimeter

MMRP Military Munitions Response Program

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MRS Munitions Response Site

MRSPP Munitions Response Site Prioritization Protocol

NCP National Oil and Hazardous Substances Pollution Contingency Plan

NWI National Wetlands Inventory

O&M operation and maintenance

OB/OD Open Burning/Open Detonation

PP Proposed Plan

RAC Risk Assessment Code

RAO remedial action objective

RCRA Resource Conservation and Recovery Act

RI Remedial Investigation

RRD range-related debris

SI Site Inspection

SUXOS Senior UXO Supervisor

TBC to be considered

TNT trinitrotoluene

TPP Technical Project Planning

URS URS Group, Inc.

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

UU/UE unlimited use and unrestricted exposure

UXO unexploded ordnance

UXOQCS UXO Quality Control Specialist

UXOSO UXO Safety Officer

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SECTIONONE Declaration

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1.1 SITE NAME AND LOCATION

Site Name: OB/OD Area (MRS-04)

Location: Umnak Island, Alaska

1.2 STATEMENT OF BASIS AND PURPOSE

In accordance with the Defense Environmental Restoration Program (DERP)-FUDS (10 USC 2700 et seq.), this Decision Document (DD) presents the United States (U.S.) Army Corps of Engineers (USACE) selected remedy for the Open Burning/Open Detonation (OB/OD) Area (Munitions Response Site [MRS]-04) at the former Fort Glenn, Umnak Island, Alaska. The selected remedial action was chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986, and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).

1.3 ASSESSMENT OF SITE

The selected remedy in this DD for the OB/OD Area (MRS-04) is necessary to protect the public health or welfare or the environment from actual or threatened releases of hazardous substances, pollutants, or contaminants from these sites, which may present an imminent and substantial endangerment to public health or welfare.

1.4 DESCRIPTION OF SELECTED REMEDIES

This DD addresses munitions and explosives of concern (MEC) at the OB/OD Area (MRS-04).

USACE will be responsible for implementing, maintaining, and monitoring the remedial actions identified for the duration of the remedies selected in this DD. With regard to the implementation of certain Land Use Controls (LUCs), USACE may only act within its authorities and may only assist with implementation of certain suggested controls as described below. It will exercise this responsibility under the DERP statute and in accordance with CERCLA and the NCP.

Based on information currently available, USACE believes the selected remedy meets the threshold criteria and provide the best balance of tradeoffs among the other alternatives with respect to the balancing and modifying criteria. USACE expects the selected remedy to satisfy the requirements of CERCLA by protecting human health and being cost-effective.

The selected remedy for the OB/OD Area (MRS-04) is Alternative 5 – Surface Removal, Focused Subsurface Removal, and LUCs.

1.4.1 Remedy Components

The remedy for the OB/OD Area (MRS-04) will include the following general components:

1 Declaration

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• MEC detection, demolition, and off-site disposal of munitions debris (MD) will reduce potential interaction with human receptors. In addition, LUCs will further reduce the potential for receptor interaction with potential MEC that may remain.

1.4.2 Remedy Performance Criteria

The remedy will have the following performance criteria at the OB/OD Area (MRS-04):

• Reduce the potential for direct contact with MEC by human receptors, considering the current and future land use.

Performance metrics for the remedy criterion will be included in the remedial design.

1.5 STATUTORY DETERMINATIONS

The selected remedy for the OB/OD Area (MRS-04) is protective of human health and the environment, complies with federal and state requirements that are legally applicable or relevant and appropriate to the remedial action, and utilizes permanent solutions to the maximum extent practicable.

Because the remedy at the OB/OD Area (MRS-04) will not remove all sources of hazardous substances (i.e., MEC below the depth of detection and MEC covered by lahar deposition) below levels that would allow unlimited use and unrestricted exposure (UU/UE), a statutory review will be completed within 5 years after initiation of the remedial action to ensure that the remedy remains protective of human health and the environment. Subsequent reviews will be conducted at least once every five years until the site is acceptable for UU/UE.

1.6 DATA CERTIFICATION CHECKLIST

The following information is addressed for the OB/OD Area (MRS-04) in Section 2 of this DD:

• How source materials constituting principal threats are addressed

• Current and reasonably anticipated future land use assumptions and current and potential future beneficial uses of groundwater

• Land and groundwater use that will be available at the site as a result of the selected remedy

• Total capital cost, annual and total operation and maintenance (O&M) cost, total periodic cost, overall total cost, total present value, and the number of years over which the remedy cost estimates are projected

• Key factors that led to selecting the remedy (i.e., describe how the selected remedy provides the best balance of trade-offs with respect to the balancing and modifying criteria, highlighting criteria key to the decision)

1.7 AUTHORIZING SIGNATURE

This DD presents the Selected Remedy of surface removal over 337 acres, a focused subsurface . removal over 30 acres, and LU Cs at the OB/OD Area (MRS-04) of the Fort Glenn Formerly Used Defense Site (FUDS) located on Umnak Island, Alaska. This DD will be incorporated into the Administrative File for the OB/OD Area, Fort Glenn FUDS which is available for public review.

The USA CE is the lead agency under the Defense Environmental Restoration Program at the Fort Glenn FUDS, and has developed this DD consistent with CERCLA, as amended, and the NCP.

This document, presenting a selected remedy with a present worth cost estimate of less than $10 million, is approved by the undersigned, pursuant to Memorandum, DAIM-ZA, September 9, 2003, Subject: Policies for Staffing and Approving Decision Documents (DDs) and Engineer Regulation 200-3-1, Formerly Used Defense Sites Program Policy.

For the United States Army Corps of Engineers:

Chief, Environm tal Division Directorate of Military Programs

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SECTIONTWO Decision Summary

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2.1 SITE NAME, LOCATION, AND DESCRIPTION

The former Fort Glenn is located on the eastern end of Umnak Island in the Fox Islands of the Aleutian Island Chain of Alaska (Figure 2-1). Umnak Island lies approximately 50 miles southwest of Dutch Harbor and 850 miles southwest of Anchorage, Alaska. The Fort Glenn installation has been abandoned since it was excessed to the Department of the Interior in 1955 as described in paragraph 2.2, and remnants of hundreds of structures are scattered over the 102,000 acres of the former installation. There is a system of cinder roads throughout the former installation, some of which are in reasonably good shape for vehicular traffic. Three cinder runways are also present, one of which was re-graded during the Remedial Investigation (RI) and is suitable for light aircraft. The only occupants at the former installation are employees of the Bering Pacific Ranches Limited, which has leased the property since 1993. Their ranch house and slaughtering facility is located in the middle of the former Fort Glenn installation. Although Umnak Island is remote with no towns or cities on the eastern end of the island, public access is not restricted and is open in many areas. There is a landing beach on the east coastline at Otter Bight.

The OB/OD Area is located in the southeastern portion of the former Fort Glenn installation (Figure 2-2). Based on the Remedial Investigation recommendations, USACE completed an administrative delineation of the Fort Glenn OB/OD Munitions Response Area (MRA) (2,076 acres) for project management purposes. The delineation supports the DoD requirement to maintain an accurate inventory of sites suspected of containing munitions and explosives of concern (MEC) or munitions debris (MD). The original OB/OD Area was divided into 2 separate projects consisting of the OB/OD Area (337 acres) which is the subject of this Decision Document, and the Remaining OB/OD Area (MRS-14) (1,739 acres) which is addressed under a separate Decision Document. The entire 2,076-acre OB/OD Area and Remaining OB/OD Area are currently owned by the State of Alaska Department of Transportation and Public Facilities. The site vicinity consists of small gently rolling hills on the northeast and southwest sides with a small valley in the center. Two distinct clusters of suspected demolition craters were identified in historical aerial photographs. The largest craters are located at approximately N 53° 22′ 56″ W 167° 56′ 51″, and the other craters are located approximately 0.5 mile to the southeast. These two clusters of demolition clusters are identified as the Focus Area and consist of approximately 30 acres (Figure 2-2).

2.2 SITE HISTORY AND REGULATORY ACTIVITIES

Fort Glenn was established in 1942 as a 102,062-acre Army Airfield and defense garrison to support the United States Naval Base at Dutch Harbor. In June 1942, Fort Glenn helped defend Dutch Harbor against a Japanese attack. The Fort Glenn facility consisted of numerous structures including quonsets, revetments, metal sheds, hangars, reinforced concrete buildings, pump houses, ammunition magazines, and three runways. The main cantonment area included three volcanic cinder runways surrounded by hangars and hardstands to park planes. The hardstands were shielded from high winds by large horseshoe-shaped earthen berms and/or they were constructed below the surrounding grade. Most structures at Fort Glenn utilized one of these forms of wind

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protection. Twelve camps, north and east of the runways, were part of the main cantonment area.

These camps were used by infantry, field artillery, coast artillery, medical corps, finance department, ordnance department, quartermaster corps, chemical corps, chaplain corps, and the Army Air Forces. Warehouse storage, ammunition magazines, concrete bunkers, a Post Exchange, theater, hospital, and technical support facilities were also located within the main cantonment area.

Fort Glenn was placed in caretaker status by late 1944 after the Japanese were driven from the Aleutian Islands. On September 18, 1948, Fort Glenn was officially redesignated as Cape Air Force Base (CAFB). The new mission of CAFB was to provide facilities, services, and assistance for transient aircraft and personnel, air communications services, and weather squadrons.

Fort Glenn was relinquished to the Department of Interior, Bureau of Land Management between 1952 and 1955 and subsequently transferred to numerous owners including the State of Alaska, Department of Transportation and made available for selection by native entities under the Alaska Native Claims Settlement Act of 1981. Currently, the property is owned by the Aleut Corporation, the St. George Tanaq Corporation, the State of Alaska Department of Transportation and Public Facilities, and the United States Fish and Wildlife Service. The former Fort Glenn is currently listed on the National Register of Historic Places.

In 2008, an eruption of Mount Okmok resulted in lahar being deposited across the former Fort Glenn, including approximately 70 acres of the OB/OD Area. Lahar thickness ranges from a few inches to over 4 feet.

2.3 PREVIOUS INVESTIGATIONS

The following sections identify previous work completed at the former Fort Glenn and the OB/OD Area.

2.3.1 Inventory Project Report

The Inventory Project Report (INPR) was completed by the Corps of Engineers Pacific Ocean, Alaska (CEPOA), which established Formerly Used Defense Site eligibility on April 3, 1992 (USACE 1992). The INPR established a site boundary and assigned Property Number F10AK0298. The INPR states that 102,062 acres were acquired by transfer from the public to the War Department by Executive Order in April 1942. Improvements included quonsets, single and two-story wood framed buildings, reinforced concrete buildings, metal sheds, ammunition magazines, concrete bunkers, revetments, docks, hangars, fuel storage tanks, support facilities, and air strips.

2.3.2 Archive Search Report

The Archive Search Report (ASR) was completed by the Corps of Engineers, St. Louis (CELMS) in September 2001 following their review of available records, photographs, and site history reports. The ASR is the source of most available historical information pertinent to site operations

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and history. The ASR confirmed that the military occupied over 102,000 acres at Fort Glenn for defense purposes during World War II. Some of the property was relinquished to the BLM in 1952, and the remaining property was transferred to BLM in 1955. A field visit was conducted during the ASR. Practice bombs and .50-caliber ammunition were identified at several locations, and a large amount of ordnance-related scrap was found throughout the site.

2.3.3 2001 Fort Glenn Remedial Investigation/Interim Removal Action Report

The 2001 Fort Glenn RI/Interim Removal Action Report was completed by Jacobs Engineering Group, Inc. for CEPOA (Jacobs 2003). The RI presented results and findings of field activities performed during July, August, and October 2001. Field activities included site reconnaissance, RIs, and limited interim removal actions at eight operable units. The RI established ambient soil concentrations for metals in the Fort Glenn area based on seven samples.

2.3.4 Disposal/Removal Action

An Explosive Ordnance Disposal (EOD) response occurred in July 2002. The EOD team, comprised of Staff Sergeants Tom Ferris and John Bliven, recovered and disposed a number of MEC items. The list of MEC items, coordinates, and photographs are provided with the incident report (Ferris and Blivens 2002).

2.3.5 Archives Search Report Supplement

The ASR Supplement was completed in 2004 by the CELMS as an addition to the 2001 ASR (CELMS 2004). This document applied standard range configurations to the site, yielding specific range boundaries for each target area. The ASR Supplement also developed a list of MEC that may be found within each range area. No site visit was conducted in support of the ASR Supplement. Risk Assessment Code (RAC) scores in the ASR Supplement assigned each MRS a score from 1 to 5, indicating the highest and lowest hazard potentials, respectively. This document identified eight MRSs (with subranges) at the former Fort Glenn site, assigned their RAC scores, and listed the types of munitions potentially used at each MRS. The Demolition Area MRS (i.e., the OB/OD Area) was given a RAC score of 3 (medium risk).

2.3.6 Site Inspection Report

The Site Inspection (SI) report was completed as a Revised Final version by Parsons on September 5, 2008 (Parsons 2008). The SI was conducted from May 17 through May 23, 2007. The objective of the SI was to discern the presence or absence of MEC and munitions constituents (MC) within the eight designated MRSs, one of which was the OB/OD Area. The OB/OD Area was identified as the “Demolition Area” in the SI. The SI work included gathering samples and analysis for MC.

The SI team also conducted a qualitative reconnaissance by traversing the sites to gather general information about potential surficial presence of MEC and to assess the overall site conditions with regard to the logistical requirements for implementation of a potential RI/Feasibility Study (FS). In addition to the eight MRSs, three additional Areas of Concern were identified for SI field

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evaluation by the Technical Project Planning (TPP) team. The SI recommended an RI/FS for the Demolition Area (i.e., the OB/OD Area).

2.3.7 Remedial Investigation

In June and July 2011, a Remedial Investigation (URS 2012) was completed at the OB/OD Area to determine the nature and extent of MEC and MC contamination, and to assess the potential risks to human health and the environment. The RI fieldwork included a visual reconnaissance survey, a lahar boundary survey to determine areal extent, digital geophysical mapping (DGM) of 9.04 acres, intrusive investigation of 293 anomalies, and collection of 68 soil samples and one groundwater seep sample. During the RI, 102 MEC items were found and demolished (including the nine unfired 75 millimeter (mm) projectiles identified during the SI), and 425 MD items were found and shipped off-site for destruction by smelting.

Based on the RI results, it was recommended that the boundary of the OB/OD Area should be reduced from 2,076 acres to 337 acres, and an FS for MEC/MD and MC at the OB/OD Area should be completed using the proposed new boundary.

2.3.8 Feasibility Study

The FS (URS 2014a) evaluated the possible alternatives in detail and completed a comparative analysis based on criteria outlined in the NCP.

During the development of the FS report, further clarifications to the recommended OB/OD Area boundary were made. The 2,076-acre OB/OD Area was recommended to be split into two new MRSs. The OB/OD Area (MRS-04) (337 acres) was recommended for a response action and the Remaining OB/OD Area (MRS-14) (1,739 acres) was recommended for no further action. Further incidental MC investigation at OB/OD Area (MRS-04) was not recommended in the FS report because MC risks to current or future residential receptors were determined to be biased high and resulted from localized detections around discovered MEC items.

2.3.9 Proposed Plan

A Proposed Plan (PP) (URS 2014b) was completed for the OB/OD Area (MRS-04) and the Remaining OB/OD Area (MRS-14). The PP documented the preferred alternatives for each MRS to address MEC/MD hazards.

2.4 COMMUNITY PARTICIPATION

The FS (URS 2014a) and PP (URS 2014b) were made available to the public in April 2014 at the Alaska Resources Library and Information Services in Anchorage, Alaska and at the Unalaska Public Library in Unalaska, Alaska. URS Group, Inc. (URS) published a public notice of availability for documents in the Anchorage Daily News on April 27, 2014 and in the Bristol Bay Times/Dutch Harbor Fisherman on May 1, 2014. A public comment period was held from May 1 to June 2, 2014. In addition, public meetings were held at the Z.J. Loussac Public Library on May

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6, 2014, and at the Unalaska Public Library on May 7, 2014, to present the PP to a broader community audience than those who had already been involved at the site. At these meetings, representatives from USACE, Alaska Department of Environmental Conservation (ADEC), and URS were available to answer questions about the sites and the proposed remedial alternatives/remedies. One public comment was received via e-mail during the public review period. Summaries of the public meetings and the e-mail correspondence during the public comment period are included in Appendix A.

2.5 SCOPE AND ROLE OF RESPONSE ACTION

This DD documents the selected response action for the OB/OD Area (MRS-04). USACE intends to reduce the explosive hazards at the OB/OD Area (MRS-04) by removing MEC to prevent potential future exposure. LUCs will also be implemented at the OB/OD Area (MRS-04) to increase awareness of potential risks remaining in the subsurface and greater area through administrative and institutional controls.

2.6 SITE CHARACTERISTICS

This section summarizes site characteristics for Umnak Island and the former Fort Glenn, including climate, topography, geology, hydrogeology, and hydrology. This section also documents the nature and extent of MEC and MC and presents the conceptual site model (CSMs) for the OB/OD Area (MRS-04).

2.6.1 Climate

The climate on Umnak Island is characterized by persistently overcast skies, high winds, and frequent, often violent cyclonic storms originating in the northern Pacific Ocean and Bering Sea.

Weather can be localized, with conditions of fog, low ceilings, precipitation, and clear weather all possible concurrently within a distance of a few miles. Storms occur all year, with the most frequent and severe storms during the winter. Wind speeds during the winter storms can reach 100 knots. Summer wind speeds average 13 knots. High temperatures in the summer range from 50 to 55 degrees Fahrenheit and during the winter range from 20 to 36 degrees Fahrenheit. The average annual rainfall at Nikolski (west end of Umnak Island) is approximately 57 inches and at Unalaska is approximately 60 inches.

2.6.2 Topography

The former Fort Glenn is situated in the United States Geological Survey Umnak and Unalaska quadrangles. The site lies just southeast of the Mount Okmok, which reaches a rim height of 3,516 feet. The topography surrounding Mount Okmok slopes radially away from the rim. The former Fort Glenn property is generally situated between 0 feet (sea level) to approximately 1,000 feet above sea level at its northwestern edge. The terrain ranges from flat with gentle slopes to sheer rock faced bluffs, and is bisected by streams with very steep banks. Some streams have cut ravines into the easily eroded surface to depths of 100 feet and greater.

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2.6.3 Geology

Umnak Island is part of the Alaska-Aleutian physiographic province. Umnak Island is the third largest island in the Aleutian Arc, a narrow belt of east-west trending ridges that extend from the Alaskan Peninsula to Attu Island. Approximately 80 major volcanoes lie in this arc, of which at least 36 have been active since 1760.

Umnak Island was formed by volcanoes including Okmok Volcano, which now stands as a caldera after the collapse of its summit. Okmok Volcano lies on Tertiary volcanic rocks and consists of three basic rock layers. The pre-caldera shield complex (the bottom layer) contains basalt, andesite, rhyolite, tuff, tuff-breccia, and pyroclasts. The middle layer consists of pyroclastic deposits, including ash-flow tuffs, airfall ash, and pumice from the two major caldera forming eruptions. The upper layer consists of ash and basalt from the post-caldera field of small cinder cones and lava flows that include historically active vents within the caldera. The rim of the Mount Okmok caldera is approximately 6 miles in diameter and reaches an elevation of over 3,000 feet.

Over time, the land has been eroded by glacier action and streamflow.

A thin mantle of till, volcanic ash, humus, and soil discontinuously veneers the island surface. In general, the soils are progressively less compact and humic upward and more clayey downward.

The clay layers range in color from yellowish gray to orange, reddish brown, olive gray, and bluish gray. Bluish-gray clays are commonly associated with till in the region. The ash and cinder layers are medium gray to yellowish gray to orange (CELMS 2001).

The latest eruption from Mount Okmok was in 2008, with resulting lahar impacting the former Fort Glenn area, including the OB/OD Area.

2.6.4 Hydrogeology

Approximately 50 percent of the groundwater needs on many of the larger Aleutian Islands, including Umnak Island, can be met with wells drilled into unconsolidated deposits. The remaining groundwater is derived from bedrock aquifers. Bedrock aquifers could supply water to a significant number of wells on Umnak Island. The water from these wells would typically be of a chemical quality suitable for most uses (CELMS 2001).

According to the Alaska Department of Natural Resources Well Log Tracking System (http://www.navmaps.alaska.gov/welts), the only well listed for Umnak Island is a 6-foot deep well in Umnak Lake, Nikolski Village. There are no listed wells on the eastern side of Umnak Island. The residents of the Bering Pacific Ranch obtain their drinking water from a spring located north of the ranch house; they use the same spring and distribution system from which the former Fort Glenn received its potable water.

2.6.5 Hydrology

Surface water in eastern Umnak Island consists of swift moving streams that drain radially off the Mount Okmok and Tulik Volcano. Thirty Three Creek runs easterly along the northern edges of

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the OB/OD Area, eventually draining into Idak Cove. Average estimated flow for Thirty Three Creek is 10 cubic feet per second. Marsh Creek is located north of the main runway and runs easterly for approximately 2.5 miles before joining with Thirty Three Creek. Camp Creek runs southeasterly along the southwestern edge of the OB/OD Area and drains into the Pacific Ocean southwest of the main runway. Lake Manila is a predominant surface water feature on the east side of the installation.

The United States Fish and Wildlife Service Wetlands Online Mapper (USFWS 2006), through the National Wetlands Inventory (NWI), was used to identify if wetlands have been defined at the former Fort Glenn site. Currently, no wetlands data is available through the NWI; however, during the ASR site visit it was noted that vegetation in many areas was indicative of wetlands and that the soil remains saturated most of the year. Thirty Three Creek and Marsh Creek would likely be classified as Palustrine moss-lichen wetlands (CELMS 2001).

2.6.6 Nature and Extent of Contamination

This section presents the nature and extent of MEC and MC contamination in the OB/OD Area.

2.6.6.1 Nature and Extent of MEC

The OB/OD Area (MRS-04) boundary encompasses the estimated extent of MEC contamination, and is based on visual reconnaissance, surface clearance, geophysical data, and intrusive investigations. The results of the visual survey completed during the RI are shown in Figure 2-3.

The boundary covers two distinct areas, the main area that includes the OB/OD craters and kick-outs and a smaller area to the northeast that includes an erosional feature found to contain range-related debris (RRD). The MRS boundary around the main area (approximately 332 acres) was established by first plotting the MD identified within the OB/OD Area. Based on discussion with the TPP Team, the southern portion of this boundary was set at the northern edge of a steep embankment of an incised perennial stream. This stream and associated topography is a significant barrier to DGM activities and also reduces access to the south and west. MD finds past this barrier were infrequent and widely scattered. The western, eastern, and northern portions of the boundary were chosen to encompass all of the higher concentrations of MD throughout the MRS, while maintaining an overall smooth outline. The main area boundary has been extended to the north beyond a cache of discarded military munitions (DMM) (high explosive incendiary 20mm MK 3 projectiles) identified during the RI field activities and a 200-foot buffer around that cache. The boundary around the smaller area (approximately 5 acres) covers a 25-foot-wide swath centered on an erosional feature where temporary storm water flows have exposed a partially buried pile of M106 fuze shipping containers (identified as RRD) and washed some of the fuze containers downstream. The total area encompassed by the OB/OD Area (MRS-04) boundary is approximately 337 acres.

Within the MRS boundary, the Focus Area (encompassing the northwest and southeast craters) was delineated during the RI as shown in Figure 2-4. The Focus Area covers approximately 30 acres and encompasses all the craters and the immediately surrounding areas with the highest

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estimated anomaly densities. All of the craters were plotted and a 200-foot buffer was then drawn around each OB/OD crater, resulting in a boundary for the Focus Area. This boundary was visually inspected and smoothed resulting in minor adjustments of the boundaries outward. The intention of defining the Focus Area is to group together the locations most likely to have MEC hazards associated with former OB/OD activities at the OB/OD craters. A 200-foot buffer around each crater was chosen because it aligns well with MEC and MD finds identified through intrusive investigations during the RI field effort. It also is similar to buffers used on other OB/OD sites and Military Munitions Response Program (MMRP) sites elsewhere in the Aleutian Islands. All but one of the intrusive investigations that resulted in a MEC find lies within the Focus Area. This sole exception is a cache of DMM that is not related to the OB/OD activities associated with the

MRS.

2.6.6.2 Nature and Extent of MC

In MC screening at the OB/OD Area (MRS-04), three constituents (trinitrotoluene [TNT], copper, and lead) were identified as a COPC for human health and three constituents (copper, lead, and zinc) were identified as a chemical of potential ecological concern for ecological evaluation. All were from discrete sampling locations. No chemicals of concern were identified in incremental sampling locations.

Discrete samples were focused on specific locations where MEC was identified. These are localized areas, so contamination is expected to be localized around the MEC item and not widespread. TNT was detected in two of 14 discrete samples, only one of which exceeded a screening level (OBOD-SB010-3.0). For metals in surface soils, concentrations above background and screening levels were associated with the following locations:

• Copper - OBOD-SS003-2.0, OBOD-SB009-3.0

• Lead - OBOD-SS003-2.0

• Zinc - OBOD-SS003-2.0, OBOD-SB006-1.5, OBOD-SS007-0.5

These represent locations where concentrations exceeded screening levels and background levels.

TNT, copper, and lead were determined to be COPCs for human health receptors based on a future residential scenario. Risks associated with TNT, copper, and lead are considered to be low for future residential receptors and result from localized detections around discovered MEC items.

Copper, lead, and zinc were detected above ecological screening levels, but were considered unlikely to pose potential risk to ecological receptors.

2.6.7 Conceptual Site Model

A CSM is a representation of a site and its environment that is used to facilitate understanding of the site and the potential contaminant exposure pathways that might be present. The CSM describes potential contamination sources and their known or suspected locations, human and/or ecological receptors present, and the possible interactions between them. The CSM summarizes which potential receptor “exposure pathways” for contamination are (or may be) “complete” and

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which are (and are likely to remain) “incomplete.” An exposure pathway is considered incomplete unless all of the following elements are present: (a) contamination; (b) a receptor that might be affected by that contamination; and (c) a method for the receptor to be exposed to (i.e., come into contact with) the contamination. If all of these elements are present, an exposure pathway is considered complete.

The MEC and MC CSMs for the OB/OD Area (MRS-04) are shown on Figure 2-5 and Figure 2- 6, respectively. Because MEC in surface and subsurface soil was observed at OB/OD Area (MRS-

04) during previous investigations, complete pathways exist for current and future residents, site workers, and recreational users. Because potential sources of MC contamination exist (e.g., MEC), pathways for current and future residents, site workers, recreational users, and ecological receptors are considered potentially complete.

2.7 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCES USES

Current activities at the site include agricultural (free range cattle grazing), recreational (hunting), and nearby residential. Potential future activities are the same, with the addition of residential use within the site boundary. For the current activities, potential exposure to MEC or MC would primarily be at the surface. For the future residential scenario, exposure to subsurface soil or MEC items during excavation activities is also possible.

2.8 SUMMARY OF SITE RISKS

2.8.1 Human Health Risks

Based on historical data and RI field observations, potential MEC hazards have been identified at the OB/OD Area (MRS-04) (337 acres).

Risks were evaluated for human receptors (site worker, recreational user, and future resident) scenarios. COPCs included TNT, copper, and lead in soils. For the site worker and recreational user, carcinogenic risk did not exceed 1x10-6, and noncarcinogenic hazard was less than 1.0. For the future resident, potential carcinogenic risks of 3.3x10-5 were estimated based on detection of TNT at a single sample location, a noncarcinogenic hazard of 2.7 also was estimated based on copper at a single sample location, and lead slightly exceeded the residential soil cleanup level of 400 milligrams per kilogram at a single location. The TNT and copper results were deeper than

2.0 feet below ground surface (bgs), so the exposure is beyond the typical residential contact with surface soils (0 to 2 feet bgs). Therefore, risk is considered unlikely.

All discrete sample concentrations were measured at the source of MEC items (i.e., adjacent to or directly below the MEC item, with the exception of 3 demolition craters that were not sampled due to safety concerns), any surrounding concentrations would be reduced via attenuating transport mechanisms. Sampling in conjunction with isolated MEC items indicates a highly localized source, with the exposure concentration (maximum detected) biased high because the sample collected was in association with a small, single source item at depth. The actual exposure

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concentration can reasonably be expected to be substantially lower than the maximum concentration detected, and similarly, the associated risk or hazard would be substantially lower as well. As a result, because the exposure concentration is biased high, and would be much less if combined with surrounding samples consistent with a representative residential exposure, no further action for MC in soil is warranted.

Exposure pathways to groundwater in the OB/OD Area are considered to be potentially complete but insignificant based on both the screening results from the groundwater seep and the low frequency/localized nature of detected soil contamination that could be the source of groundwater contamination. Therefore, groundwater is no longer considered a medium of concern.

A MEC hazard assessment was completed using the United States Environmental Protection Agency (USEPA) 2008 method, which takes into account the severity, accessibility, and sensitivity of potential explosives hazards. The OB/OD Area (MRS-04) has a baseline MEC hazard assessment score of 865 (out of 1,000), which results in a Hazard Level of 1 (the highest hazard level out of four levels). The primary factors leading to this high level are the presence of high and low explosive filler in fragmenting bombs, the accessibility of the site, the former use of the site for OB/OD, and the possibility of MEC including unexploded ordnance (UXO) items at the surface.

Data used to complete the USEPA MEC hazard assessment and human health and ecological risk assessments were also used to complete Munitions Response Site Prioritization Protocol (MRSPP) tables. In 2005, the DoD published the MRSPP as a Federal Rule (32 CFR Part 179) to assign a relative risk priority to each defense site in the MMRP Inventory for response activities. Risk is based on the overall conditions at each MRS taking into consideration various factors related to explosive safety (i.e., MEC hazards) and environmental hazards (i.e., MC contamination). In accordance with the DoD MRSPP Primer (DoD 2007), each MRS is assigned an MRSPP Priority ranging from 1 to 8. Priority 1 indicates the highest potential hazard and Priority 8 indicates the lowest potential hazard. The overall MRSPP priority score is 3 for the OB/OD Area (MRS-04) (337 acres).

2.8.2 Ecological Risks

Potential ecological risks were also evaluated during the RI, and it was concluded that it is unlikely that MC pose potential risks to ecological receptors.

2.9 REMEDIAL ACTION OBJECTIVES AND ARARS

A remedial action objective (RAO) is a site-specific goal to protect human health and the environment. RAOs specify the contaminants and media of interest, exposure pathways, and preliminary remediation goals, which are developed on the basis of chemical-specific applicable or relevant and appropriate requirements (ARARs) or site-specific risk factors.

ARARs are identified on a site-specific basis. Based on USEPA guidance (USEPA 1988), ARARs are categorized as chemical-specific, action-specific, or location-specific:

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• Chemical-specific ARARs are based on health- or risk-based concentration limits or discharge limitations in environmental media (i.e., air, soil, or water) for specific hazardous chemicals.

The requirements may be used to set cleanup levels for the chemicals of concern in the designated media, or to set a safe level of discharge (e.g., air emission or wastewater discharge) where a discharge occurs as a part of the remedial action.

• Action-specific ARARs generally set performance, design, or other similar operational controls or restrictions on particular activities related to management of hazardous substances or pollutants. These requirements address specific activities that are used to accomplish a remedy. Action-specific requirements do not in themselves determine the remedial action;

rather, they indicate how a selected remedial action alternative must be designed, operated, or managed.

• Location-specific ARARs are restrictions placed on the types of activities that may occur in particular locations. The location of a site may be an important characteristic in determining its impact on human health and the environment. Location-specific ARARs include federal requirements for wetlands protection and floodplain restrictions on management of hazardous waste.

2.9.1 OB/OD Area (MRS-04) Remedial Action Objective

The RAO for OB/OD Area (MRS-04) is to reduce the potential for direct contact with MEC by human receptors, considering the current and future land use.

2.9.2 ARARs

The Resource Conservation and Recovery Act (RCRA) Subpart X – Miscellaneous Units, Section 264.601 Environmental Performance Standards (40 CFR 264) is a relevant and appropriate requirement for the use of consolidated shots to dispose of MEC at the OB/OD Area (MRS-04). Following pursuit of RCRA Subpart X, soil confirmation samples will be collected after disposal/removal/treatment of damaged MEC items and analyzed for TNT, copper, lead, and zinc. Analytical results will be compared to 18 AAC 75.341, Table B1, direct contact, over 40 inch zone cleanup levels to evaluate if soil cleanup may be required.

2.10 DESCRIPTION OF ALTERNATIVES

A range of general response actions were identified, evaluated, and screened to develop a list of possible remedial alternatives for the OB/OD Area (MRS-04). These general response actions were (a) LUCs, (b) MEC removal, (c) containment, (d) demolition, and (e) disposal.