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Site Report: ADOT&PF SREB - Unalakleet


Site Name: ADOT&PF SREB - Unalakleet
Address: Near FAA station, Unalakleet, AK 99684
File Number: 630.38.010
Hazard ID: 4109
Status: Active
Staff: Sammi Castle, sammi.castle@alaska.gov
Latitude: 63.879389
Longitude: -160.797237
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

FAA removed a heating oil tank in 1997 near building 205. The site was closed, but DRO contamination was found to exist upgradient, in increasing concentrations. The upgradient well MP001, located down gradient to ADOT property, contained up to 0.55 feet of free product. This indicates that the contamination would not be caused by the FAA tank. Further investigation/removal of free product is warranted. In 2009, a Site Characterization was conducted to evaluate an abandoned pipeline as the source of contamination. Pipeline located between the FAA Building and ADOT&PF SREB Building - estimated to be approximately 3-5 feet below ground surface. No signs of hydrocarbon contamination were present until depths at or slightly above the saturated soil surface (14 to 15 feet bgs). In the vicinity of saturation, soil contained noticeable levels of petroleum contamination, including hydrocarbon odors and product-stained soil. This phase of characterization did not provide evidence of the underground pipeline as the source of the initial release.

Action Information

Action Date Action Description DEC Staff
11/7/2002 Update or Other Action Release Investigation Report Unalakleet FAA Station Fuel Storage Tank Management Program Unalakleet, Alaska, dated January 2002,submitted by CH2-OH, and recieved by ADEC on this date. Four soil samples and four groundwater samples were analyzed. Groundwater samples indicate DRO contamination up to 5.7 mg/L and benzene contamination up to 0.024 mg/L. Soil samples at 14 feet bgs indicate DRO up to 2,600 mg/kg and benzene up to 0.06 mg/kg. Free product was found upgradient of former AST location and clean native soil was found below AST location. It is believed the soil and water contamination is from an unconfirmed upgradient source. Grant Lidren
11/2/2004 Site Added to Database DRO. Sarah Cunningham
11/29/2006 Update or Other Action Staff transferred from Pikul to Jaynes. Aggie Blandford
4/18/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Grant Lidren
12/4/2008 Update or Other Action Site name changed from "ADOT&PF Unalakleet" to "ADOT&PF SREB - Unalakleet" Grant Lidren
4/27/2009 Site Characterization Workplan Approved The ADEC has no objections to the Work Plan For the Site Characterization- ADOT&PF SREB Unalakleet, submitted by Oasis, dated April 20, 2009. The field work will occur during the week of May 25, 2009. Grant Lidren
10/14/2009 Report or Workplan Review - Other ADEC reviewed Report for Site Characterization ADOT&PF SREB Unalakleet, Alaska dated October 2, 2009 and submitted by Oasis. Work performed at the site included evaluation of an historic underground pipeline and to determine the source of free-phase petroleum hydrocarbons and groundwater contamination at the site. Analysis of the sample data indicates the HC contamination at the site begins at or slightly above the GW interface at 8 ft. bgs. Samples collected at the pipeline depth, at 3 to 5 ft. bgs, contained little or no petroleum impact; therefore the pipeline does not appear to be a source of contamination. Subsurface soil samples collected, at 8 to 15 ft. bgs, contained DRO up to 10,200 mg/kg, and benzene up to 0.072 mg/kg. Five water samples collected from 5 monitoring wells contained benzene up to 0.0951 mg/L, GRO up to 3.13 mg/L, DRO up to 17.0 mg/L, and RRO up to 3.21 mg/L. GW flows to the north, north easterly direction depending on the tides. Source of contamination remains unknown. Grant Lidren
12/2/2013 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 75082 unknown spill. Joshua Barsis
11/13/2015 Update or Other Action File review; no new information. Joshua Barsis
5/18/2016 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 75082 unknown spill. Nathan Maxwell
5/26/2016 Update or Other Action Sent a letter on this date detailing site history and existing data gaps which need to be addressed for the site to be considered for closure. Requested contact to discuss site's future. Nathan Maxwell
6/16/2017 Update or Other Action Letter sent to ADOT&PF detailing site history, existing data gaps, and requesting a work plan prior to conducting any work at this site. Sammi Castle

Contaminant Information

Name Level Description Media Comments

Control Type

Type Details

Requirements

Description Details

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