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Site Report: Unalakleet Air. Warning - Generator Hill

Site Name: Unalakleet Air. Warning - Generator Hill
Address: 3.5 Miles NNE of Unalakleet, Unalakleet, AK 99684
File Number: 630.38.003
Hazard ID: 4296
Status: Cleanup Complete
Staff: No Longer Assigned, 9074655229 dec.icunit@alaska.gov
Latitude: 63.921091
Longitude: -160.753144
Horizontal Datum:WGS84

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 was found associated with a day tank in the middle 1990s during building demolition. Approximately 550 cubic yards of contaminated soil were excavated and treated at the former main radar installation (see “comments” below). Additional site characterization in 2005 documented that DRO contaminated soil remains above Method 2 cleanup levels (up to 7,100 mg/kg). No BTEX was detected above cleanup levels. For more background on the U.S. Army Corps of Engineers environmental restoration of formerly used defense sites in Unalakleet, see the “Unalakleet Air. Warning - Main Radar Site” database entry. During removal actions (RAs) in 1993 and 2005, the Generator Building, storage tanks, and aboveground fuel line were demolished; the military drums were removed; and approximately 678 cubic yards of contaminated soil was excavated from the site. Excavation during the 2005 RA also remediated the 100,000 mg/kg RRO concentration detected during the 2002 preliminary assessment. RRO was not detected above the cleanup level in confirmation samples. Update 2012 - The 2010 remedial action objective at Site 22, Generator Hill, was to excavate approximately 200 cubic yards (~300 tons) of DRO-contaminated soil located north of the former generator. 2010 Remedial Action Work Plan, bedrock at the site constitutes a compliance point for soil excavation. If bedrock was encountered and verified laterally as a confining geologic feature, then confirmation samples following excavation were not collected from residual soil remaining atop the bedrock. Excavation sidewall samples were collected and used for lateral remedial action confirmation in locations where previous confirmation sampling had not occurred. The following list of activities summarizes 2010 remedial action at Site 22. • Used test pits and a PID to field screen for DRO contaminated soil • Correlated field screening data with off-site laboratory data • Excavated 436 tons (approximately 291 cubic yards) of petroleum contaminated soil, reaching bedrock • Screened excavated material using a 2-inch screen plant to segregate debris and large rocks from the petroleum contaminated soil • Collected 11 side-wall confirmation samples for off-site analysis for DRO • Surveyed, backfilled and graded excavated areas Only one of the 11 soil samples (ten samples plus a duplicate) analyzed contained contaminants of concern at concentrations exceeding Decision Document cleanup levels. Sample number SITE22-GB-11-2.5-SO contained 262 mg/kg of DRO at a depth of 2.5 feet below ground surface, slightly above the cleanup level of 250 mg/kg. No Further action is recommended for Site 22, Generator Hill, in the Remedial Action Report. ADEC visited the site on June 21, 2012 and found no evidence of contamination remains. The site has been graded, is clean and no odor or soil staining was observed.

Action Information

Action Date Action Description DEC Staff
9/13/2006 Site Added to Database Site added to the database. Mitzi Read
4/2/2007 Update or Other Action Project Closure fsigned by DEC and Air Force for the Contaminerized Hazardous, Toxic, or Radiological Waste (CONHTRW) for the Unalakleet Air Force Station FUDS project. This closure decidion involves only the structures left by Air Force, not removal of contaminated soil. Lisa Maserjian
6/18/2008 Update or Other Action A draft Feasibility Study and Draft Proposed Plan were received May 16 and June 2, 2008. Three source areas were associated with the Generator Hill site: Drums along the hillside, a fuel release associated with the low point drain in a fuel line, and the Generator Building at the hill top. The fuel line and drums were removed, contaminated soil was excavated from beneath the drums, DRO remains along the hillside to 740 mg/kg. Initial samples of the low point drain exceeded cleanup levels, but further characterization efforts failed to find the contaminated soil. DRO to 7,100 mg/kg remains in soil on the north side of the former Generator Building. Kim DeRuyter
7/7/2008 Site Visit A site visit was conducted to most of the source areas prior to the RAB meeting. The Communication Building site which had DRO Contamination up to 14,000 ppm could not be located, it appears to have been covered with pavement by ADOT during improvements to the access road to the airport. The consultant will review the records to determine if GPS data is available for the site. An additional drum with product, and numerous lead-acid batteries and a compressed gas tank were found near one of the Musk Ox Farm buildings. It is unclear if this potential source area is of military origin. Kim DeRuyter
6/10/2011 Document, Report, or Work plan Review - other ADEC received a Draft Workplan for Remedial Action Addendum. This workplan addressed remaining work to be completed at the Generator hill site. Amanda Loomis
7/27/2011 Document, Report, or Work plan Review - other ADEC provided comments on the Work Plan for Remedial Action Addendum Formerly Used Defense Site Unalakleet, Alaska (Work Plan Addendum). Amanda Loomis
2/6/2012 Document, Report, or Work plan Review - other ADEC received a copy of the draft document, 2010-2011 Remedial Action Report, Formerly Used Defense Site, Unalakleet, Alaska. The Generator hill Site was recommended No Further Action. Dennis Shepard
2/29/2012 Document, Report, or Work plan Review - other ADEC submitted preliminary comments on the draft document, 2010-2011 Remedial Action Report, Formerly Used Defense Site, Unalakleet, Alaska. Dennis Shepard
3/6/2012 Update or Other Action Project manager changed from Vreeman to Shepard. Rebecca Bryan
6/20/2012 Meeting or Teleconference Held On June 20, 2012, a public meeting was held in Unalakleet to discuss the remedial actions and remaining concerns for contaminated sites at the Unalakleet FUDS Aircraft Warning Site. The Unalakleet Public meeting was attended by U.S. Army Corps of Engineers (USACE), the USACE consultants, BSI- OASIS, ADEC Project Manager, and members of the Unalakleet community. Dennis Shepard
6/21/2012 Site Visit Alaska Department of Environmental Conservation (ADEC) Project Manager, conducted a site visit on June 21, 2012. The site appeared graded and clean. No evidence of contamination was observed (no odor, staining or debris)at the Generator Hill Site. Dennis Shepard
8/17/2015 Cleanup Complete Determination Issued The available data indicate that residual contamination does not remain above Decision Document cleanup levels and institutional controls are not required Joy Whitsel

Contaminant Information

Name Level Description Media Comments
DRO < Method 2 Most Stringent Soil The available data indicate that residual contamination does not remain above Decision Document cleanup levels and institutional controls are not required
RRO < Method 2 Most Stringent Soil The available data indicate that residual contamination does not remain above Decision Document cleanup levels and institutional controls are not required

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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State of Alaska Department of Environmental Conservation

P.O. Box 111800
Juneau, AK 99811-1800
Phone: 907-465-5066
Fax: 907-465-5245
TDD: 800-770-8973
Physical Location: 410 Willoughby