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Site Report: Dutch Hbr-Humpy Cove Mess Hall UST

Site Name: Dutch Hbr-Humpy Cove Mess Hall UST
Address: Mile 8, Summer Bay Road, Unalaska Island, Unalaska, AK 99685
File Number: 2542.38.013
Hazard ID: 3065
Status: Cleanup Complete
Staff: No Longer Assigned, 9074655229 dec.icunit@alaska.gov
Latitude: 53.900556
Longitude: -166.431389
Horizontal Datum:

We make every effort to ensure the data presented here is accurate based on the best available information currently on file with DEC. It is therefore subject to change as new information becomes available. We recommend contacting the assigned project staff prior to making decisions based on this information.

Problems/Comments

Diesel contaminated soil at the former Mess Hall heating oil tank. This area is used for subsistence food gathering and fishing. The 300 gallon UST was removed 27 July 1998. Approximately 200 cubic yards of diesel impacted soil were excavated and transported offsite for treatment. Sampling indicated the excavation met Method II cleanup levels except for one sample at the bottom of the excavation (26 feet below ground surface), which contained 400 mg/kg DRO. After backfilling it was determined that the backfill had up to 890 mg/kg DRO. This site was the location of Fort Brumback and was a tactical artillery area during WWII. It included troop housing, a mess hall, latrines, power generation facilities, a dispensary and utilities. The U.S. Army Corps of Engineers had a contractor demolish and landfill the buildings and remaining debris in the mid - late 1980s. Underground fuel tanks were abandoned in place. In the mid-1990's the Corps of Engineers initiated further site investigation work to locate and address any remaining military contamination or sources of contamination.

Action Information

Action Date Action Description DEC Staff
8/25/1999 Interim Removal Action Approved ADEC received the final report titled "1998 SI, RI, IRA Amaknak and Unalaska Islands" dated August 1999, by Jacobs Engineering. The report documents site investigation work, locating buried fuel tanks at the former mess hall, dispensary, power plant and two latrines. The fuel, tanks and contaminated soil were excavated. Contaminated soil was thermally treated in Unalaska. A fifth UST was located but not removed due to the isolated location and inability to remove it. Three of the four sites where tanks were removed have residual soil contamination at levels higher than ten times the method two migration to groundwater levels and soil was excavated to the water table. Visible groundwater contamination was present in two excavations. Well points were installed, but subsequent water level measurements indicate they may not be downgradient. Further investigation and possibly cleanup are needed. John Halverson
2/11/2000 Update or Other Action Staff reviewed and commented on the draft Comprehensive Remedial Investigation Report for Amaknak and Unalaska Islands, dated December 1999. The report evaluated cleanup levels for this area using an assumption that groundwater is not a potential future drinking water source, however, the necessary steps to make such a determination have not been undertaken. ADEC requested the report be revised to consider groundwater as a drinking water source or that steps in 18 AAC 75.350 be addressed. Further groundwater monitoring was recommended and is necessary. John Halverson
6/5/2000 Site Characterization Report Approved ADEC received the final Comprehensive Remedial Investigation Report, dated May 2000, by Jacobs Engineering under contract to the Corps. Humpy Cove Mess Hall UST - a 300 gallon heating oil tank and ~200 cubic yards of diesel contaminated soil were removed. Contaminated soil was removed to a depth of 26 feet below the ground surface (bgs). Contaminated soil was thermally treated off-site. A sample from 26' bgs contained 400 mg/kg DRO. Sidewall samples met the cleanup levels. Approximately 50 cubic yards of soil used to backfill the excavation contained up to 890 mg/kg DRO. An alternative soil cleanup level, based on the migration to groundwater pathway, may be proposed later. Dispensary UST - a 680 gallon UST and ~430 cubic yards of contaminated soil were removed. DRO contaminated soil extended to the water table with the highest concentration measured being 7100 mg/kg at ~13' bgs. Groundwater was encountered at 13' bgs. Three well points were installed and sampled; no groundwater contamination was found above the Table C levels, however, none of the well points were directly downgradient from the source area. Additional groundwater monitoring is planned. Power Plant - a 1600 gallon UST and ~540 cubic yards of petroleum contaminated soil were removed. Diesel range organics (DRO) contaminated soil extends to the water table at ~14' bgs. A soil sample from 14' bgs contained 11,000 mg/kg DRO. Well points installed at the site did not contain contaminants above regulatory levels, however, no well points were installed within or directly downgradient of the source area. Further groundwater characterization is recommended. Latrine #3 - a 300 gallon UST and ~35 cubic yards of petroleum contaminated soil were removed. Soil containing up to 3,800 mg/kg DRO was used to backfill the excavation. Confirmation samples collected from the limits of the excavation contained up to 3,400 mg/kg DRO at a depth of 9' bgs. Groundwater characterization is recommended. Latrine #1 - a UST estimated to be ~300 gallons in capacity, was located about 250' up a vegetated hillside from the road. A soil sampled collected from ~5' bgs and 5' downhill from the tank contained 10,000 mg/kg DRO. Another sample collected about 10' further downhill and 5' bgs did not contain measurable DRO. The tank was emptied and left in place due to limited access (would need to cut in a road). The report recommends in-place closure of this UST. John Halverson
9/5/2001 Update or Other Action DEC received the final 2000 Island-wide SI/IRA/RI Report for Amaknak/Unalaska Islands, dated August 2001, by Jacobs Engineering. It documents the following work in the Humpy Cove area: Power Plant site - one soil boring was drilled to 24.5' and did not encounter water. A second boring was drilled to ~30' and groundwater rose to ~21.5' bgs in the well. Field screening indicated contaminated soil between 18 and 30' bgs. The water sample from MW1 did not contain measurable levels of DRO and only 640 ug/l RRO. The report recommends no further action with institutional controls. Dispensary - two soil borings were drilled to refusal at ~11' bgs, no water was observed in either and the borings were backfilled. The report recommends no further action. Latrine 1 - a soil boring was installed to 28.5' bgs. The boring was dry, but a MW was installed. The well remained dry in September and October, but did contain water in December. A water sample from the well contained 230 ug/l DRO and PAHs below applicable cleanup levels. The UST was emptied and filled with gravel. The report recommends no further action. Latrine #3 - two soil borings were installed to 8 and 9 feet bgs. Neither well encountered water or evidence of soil contamination. A soil sample from 7.5' bgs contained only 2.9 mg/kg DRO. The report recommends no further action. John Halverson
1/23/2003 Site Added to Database Humpy Cove expanded into five unique sites from one. John Halverson
1/23/2003 Site Ranked Using the AHRM Initial ranking. Debra Caillouet
11/21/2003 GIS Position Updated Using Topozone, NAD 27. Debra Caillouet
12/8/2003 Site Number Identifier Changed Changed reckey to represent tank removal date. Old Reckey was 199925X120602. Former Staff
6/10/2005 Update or Other Action File number issued 2542.38.013. Aggie Blandford
6/3/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Jill Taylor
9/14/2010 CERCLA Proposed Plan ADEC received Proposed Plan # 8 which addressed the Summer Bay Management Area 13. The plan recommends Alternative 1 (Corrective Action Complete/Cleanup Complete with NDAI)for the Mess Hall becuase the primary source was removed from the site and remaining DRO is below the method 3 ACLs. Meghan Dooley
1/25/2024 Document, Report, or Work plan Review - other Bulk action entry for review of the Draft Restoration Summary Report Containerized Hazardous, Toxic, and Radioactive Waste, Amaknak Formerly Used Defense Sites, recommending closure at 53 sites. DEC received the draft summary report on April 2023, and provided comments on June 2023. On January 15, 2024, FUDS submitted a final summary report. Comment resolution has not been performed and is not complete. Further coordination is necessary with FUDS. Cascade Galasso-Irish
2/21/2024 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 74040 300 Gallon UST. Cascade Galasso-Irish
2/22/2024 Document, Report, or Work plan Review - other On this date, DEC reviewed and approved the redline final, RTCs, and final Restoration Summary Report for the Amaknak Formerly Used Defense Sites F10AK0841-13, -14, -15, -16, -18, -20, Unalaska Valley, Pyramid Valley-Port Levashef, Summer Bay-Humpy Cove, Margaret Bay-Airport, Mount Ballyhoo, and Little South America in Unalaska, Alaska. Of the 53 sites included in this report, 39 of these sites are either closed in the Contaminated Sites database or are not eligible active sites. Fourteen (14) sites remain open in the CS database, either pending further coordination on the pathway to closure or are currently with DEC management for closure decision. This letter is documenting the approval of the final document but does not preclude the need for further investigation of sites included in the report. Cascade Galasso-Irish
4/19/2024 Cleanup Complete Determination Issued The Alaska Department of Environmental Conservation, Contaminated Sites Program (DEC) has completed a review of the environmental records associated with the Dutch Hbr-Humpy Cove Mess Hall UST, located Summer Bay Road in Unalaska, Alaska. Based on the information provided to date, it has been determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment, and no further remedial action will be required unless information becomes available that indicates residual contaminants may pose an unacceptable risk. This Cleanup Complete determination is based on the administrative record for the Dutch Hbr-Humpy Cove Mess Hall UST, which is located in the DEC office in Anchorage, Alaska. This decision letter summarizes the site history, cleanup actions and levels, and standard site closure conditions that apply. Sarah Bernhardt

Contaminant Information

Name Level Description Media Comments
DRO Other Soil The applicable cleanup levels at the site are the calculated method three site-specific alternative cleanup level (ACL) under 18 AAC 75.340 (e). A site-specific organic carbon content of soil (foc) value of 0.06 grams per gram (g/g) was used in the Petroleum Cleanup Level Calculator, as opposed to the default Method Two foc value of 0.001 g/g. The approved cleanup level for the contaminant DRO in soil is 8,300 mg/kg for this site.

Control Type

Type Details
No ICs Required

Requirements

Description Details
Advance approval required to transport soil or groundwater off-site.
Movement or use of contaminated material (including on site) in a manner that results in a violation of the water quality standards is prohibited (18 AAC 70)

No associated sites were found.

Missing Location Data

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