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Site Report: ADOTPF - 7 mile Maintenance Station

Site Name: ADOTPF - 7 mile Maintenance Station
Address: 7 mile/mile post 62 Dalton Highway, Fairbanks, AK 99701
File Number: 330.26.003
Hazard ID: 24594
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229
Latitude: 65.939476
Longitude: -149.854733
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.


A 500 gallon used oil UST was removed when the roof of the maintenance shop that it serviced collapsed due to snow load. The ADOT&PF requested removal of the UST to accommodate construction of a new vehicle repair/storage bay. The UST had passed a tightness test in 1992 and was removed in May, 1995. ADOT had reported a 6,000 gallon diesel fuel spill along the southwest wall of the facility almost directly over the UST in 1988. Approximately 60 cubic yards of contaminated soil was removed during the excavation of the UST which was terminated just above the water table at a depth of 14 feet. The close proximity of the building foundation, the access road, and sewer lines prohibited further excavation. The exposed soil excavation wall adjacent to the exterior fill spout of the UST, and the soil between the tank and the building foundation were darkly stained with used oil, either from piping leaks, or surface spills while emptying the used oil tank. Contamination beneath the UST and on the sidewalls of the excavation contained up to 20,000 TPH, 2,200 DRO, and 260 GRO, (concentrations listed in mg/kg). The report suggests that the contamination does not extend far beyond the limits of the excavation, but groundwater may have been impacted. The stockpiled soils were thermally remediated at OIT in September 1995.

Action Information

Action Date Action Description DEC Staff
1/3/1995 Leaking Underground Storage Tank Release Confirmed - Petroleum LUST Site created in CSP for source area ID 77848 Please Edit the release date. Did not have julian date conversion chart. * Not Assigned
1/3/1995 Site Added to Database * Not Assigned
7/24/1995 Underground Storage Tank Site Characterization or Assessment Dames & Moore conduct SA. Petroleum impacts detected to 14,000 TPH, 2,100 DRO, 250 GRO and 96 ppm benzene remaining in place. Recommend GW monitoring with 3 wells. Rec. excavated soil be treated as well as the tank sludge. * Not Assigned
9/1/1995 Leaking Underground Storage Tank Cleanup Initiated - Petroleum Remove about 65 cubic yards of soil and have thermally treated at OIT in Moose Creek. * Not Assigned
12/26/1997 Update or Other Action ADEC sends standard letter to Mr. Ralph Swarthout, Director of Maintenance & Operations requesting RI and registration forms. * Not Assigned
1/28/2004 Update or Other Action Transferred DEC staff lead from John Carnahan Cynthia Pring-Ham
1/3/2006 Update or Other Action File review, update problem statement. Update GIS using Topozone Pro and file maps. Kim DeRuyter
5/8/2007 Exposure Tracking Model Ranking source area was an used oil tank that was pulled and the area subsequently covered by the shop building. Soil contamination remained in the ground Jim Frechione
5/18/2007 Underground Storage Tank Site Characterization or Assessment Shannon & Wilson installed 3 soil borings - that were converted to monitor wells. Possible source areas include: used oil UST that was removed in 1995 and now area is covered by shop building and numerous fuel releases in 1980s. Soil sample data indicated soil contamination above migration to GW but below ingestion/inhalation levels. The groundwater at the site consists of a perched (shallow) aquifer underlain by bedrock and/or permafrost. Deeper aquifer is reportedly artesian and used as drinking water source. Extent of soil contaminastion not fully defined but risks to human health and migration to deeper aquifer appear to be minimal. The site information will be evaluated and a decision document prepared regarding the environmental status of the site. Jim Frechione
6/6/2007 Conditional Closure Approved record of decision issued for conditional closure. Soil contamination remains above MTG levels and suprapermafrost groundwater impacted by DRO. Drinking water aquifer is artesian and separated from contamination by permafrost and bedrock. Jim Frechione
6/6/2007 Institutional Control Record Established conditional closure requires ADOTPF to contact ADEC when contaminated soil associated with former used oiol tank is accessible. It currently is beneath the shop building. Drinking water well should periodically be monitored to ensure no contamination migrates into deeper aquifer. Jim Frechione
12/20/2011 Update or Other Action Site management staff changed to IC Unit. Evonne Reese
12/20/2011 Institutional Control Compliance Review IC review conducted, closure details completed in the database, follow up requirements added, and reminder system updated. Evonne Reese
1/3/2013 Update or Other Action Site symbol adjusted visually using, Google satellite imagery, and topographic maps from the file. This file cross referenced with file 330.38.111. Laurel Gale
5/27/2014 Institutional Control Update An IC reminder letter was issued to the responsible party on this date. Kristin Thompson

Contaminant Information

Name Level Description Media Comments
DRO Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation Soil
DRO > Table C Groundwater

Control Type

Type Details
Other Database QC update 12/20/11


Description Details
Groundwater Use Restrictions
Advance approval required to transport soil or groundwater off-site.
Excavation / Soil Movement Restrictions
Periodic Review Every 5 years contact the RP regarding site conditions and to verify that the shallow groundwater aquifer is not being used as a drinking water source.

Missing Location Data

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