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Site Report: Alyeska PS 09 Therminol Release


Site Name: Alyeska PS 09 Therminol Release
Address: Mile 258 Richardson Hwy., Pump Station 9, Delta Junction, AK 99737
File Number: 330.38.083
Hazard ID: 3113
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229 dec.icunit@alaska.gov
Latitude: 63.929978
Longitude: -145.766497
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

During scheduled maintenance in July 1998 to inspect and repair "boot liners," which form a seal between the underground liner and concrete footings that support aboveground piping, Alyeska personnel discovered Therminol impacted soil within the tank farm near Tanks 197 and 198 (both of which store therminol). An estimated 200 gallons of therminol were released at Tank 197 and less than 55 gallons at Tank 198. A municipal well (no longer Class C system) exists within 500 feet. 1st aquifer is approximately 110' BGS. Drinking water comes from an aquifer that is first encountered at approximately 390' BGS. Tanks 190, 197, and 198 are all within a secondary containment structure with a total capacity of 104,500 barrels (approx 4,389,000 gallons).

Action Information

Action Date Action Description DEC Staff
2/25/1999 Update or Other Action Date of final report by Emcon entitled "Pump Station 9 Tank Farm Therminol Release Soil Sampling". One excavation at Tank 197 and another at Tank 198. Confirmation samples collected at Tank 197 for DRO up to 4,650 mg/kg below liner estimated to be in a limited area but vertical extent below could not be determined because liner had already been repaired. Confirmation samples also collected along the sidewall of the excavation were up to 11,000 mg/kg DRO at Tank 197 perimeter. Samples collected along the sidewall near Tank 198 were up to 14,000 mg/kg DRO. Contaminated soil extending underneath each tank could not be determined without jeapordizing tank integrity. Keather McLoone
8/29/2000 Site Added to Database Therminol contamination. Bruce Wanstall
1/29/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Pam Clemens
2/1/2008 GIS Position Updated Updated using Arc GIS SPAR_StatewideLocator (ArcReader) Grant Lidren
11/7/2011 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 74088 AST 197 & 198. Keather McLoone
12/26/2012 Exposure Tracking Model Ranking Groundwater ingestion pathway has been reassessed (reduced) due to low volume of contaminant that was released, depth to 1st aquifer (~110' BGS), and depth/location of drinking water intake (~300' BGS), which is ~500' away. Richard Bernhardt
1/7/2013 Update or Other Action Updated coordinates based on Google Earth imagery. Richard Bernhardt
5/24/2013 Site Characterization Workplan Approved Received and approved a work plan to collect soil confirmation samples north of Tank 198. Previously contaminated soil northwest of Tank 197 was completely excavated to the liner and removed for offsite remediation in 2012, but additional sampling in this area (in support of a possible closure decision) was pre-approved at the discression of the RP/Consultant. Richard Bernhardt
1/2/2014 Update or Other Action On this date, ADEC received the 2013 Soil Sampling Report for PS 9 Tank 198 submitted by SLR dated December 2013. Two testpits were advanced at tank 198 to a depth of 2 feet bgs adjacent to the 1998 soil sample that contained 14,000 mg/kg DRO. Three soil samples collected from the two testpits contained DRO up to 2,570 mg/kg. Grant Lidren
4/9/2014 Cleanup Complete Determination Issued The Alaska Department of Environmental Conservation (ADEC), Contaminated Sites Program, has completed a review of the environmental records associated with the Alyeska PS 09 Therminol Release. Based on the information provided to date and the administrative record, the ADEC has determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment. No further remedial action will be required as long as the site is in compliance with established institutional controls Grant Lidren
4/9/2014 Institutional Control Record Established Institutional Controls established and entered into the database. Grant Lidren
5/9/2014 Update or Other Action On this date, ADEC received the signed CC-IC agreement from Alyeska. Grant Lidren
11/23/2015 Institutional Control Compliance Review IC compliance review conducted, staff changed from Lidren to IC unit, and reminder system set to review the site record in April 2019. Nathan Maxwell

Contaminant Information

Name Level Description Media Comments
DRO > Human Health/Ingestion/Inhalation Soil

Control Type

Type Details
Signed CS Determination

Requirements

Description Details
Advance approval required to transport soil or groundwater off-site.
Restricted to Industrial / Commercial Land Use
When Contaminated Soil is Accessible, Remediation Should Occur
Periodic Review Every five years
Groundwater Use Restrictions Installation of monitoring wells will require ADEC approval
Excavation / Soil Movement Restrictions In the future, if soil is removed from this site it must be characterized and managed following regulations applicable at that time

Missing Location Data

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