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Site Report: Swanson River Tank Setting 1-27

Site Name: Swanson River Tank Setting 1-27
Address: Mi. 17.5 Swanson River Rd, Sterling, AK 99672
File Number: 2334.38.020
Hazard ID: 442
Status: Active
Staff: Peter Campbell, 9072623412 peter.campbell@alaska.gov
Latitude: 60.762500
Longitude: -150.832500
Horizontal Datum:NAD83

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

Petroleum contaminated soil and groundwater. Ethylene and triethylene glycol contaminated soil also encountered up to 12 feet below surface. Low levels of polychlorinated biphenyls (PCBs) were encountered near the ground surface. A flare stack is located adjacent to the tank setting which has contributed to soil and groundwater contamination. Light non-aqueous phase liquids (LNAPL) recovery systems installed. Annual groundwater monitoring. Plume appears stable and not expanding. Risk to human health and the environment is minimal. Due to the infrastructure related to oil field operations, major excavation and remediation of the contaminated soil will be completed at pad abandonment.

Action Information

Action Date Action Description DEC Staff
5/23/1990 Update or Other Action (Old R:Base Action Code = SI - Site Investigation). Arco sent in Phase II Investigation Report. All locations investigated except 1-9 have glacial drift which strongly limited the vertical/horizontal migration of hydrocarbons in subsurface soils. At 1-9 tank setting, permeable coarse grained soils have allowed hydrocarbons to migrate substantially in the subsurface soils/groundwater. Former Staff
11/1/1991 Update or Other Action (Old R:Base Action Code = TOTH - Treatment, Other). Results of Bioventing treatability test provided to the Department. Former Staff
7/15/1992 Update or Other Action (Old R:Base Action Code = TAS - Treatment Alternative Study (CS)). ARCO submitted results of evaluation remediation alternatives for SRF. Report identified numerous potential remediation methods for the contaminated soil and groundwater. Report concluded that in-situ bioventing was the optimum alternative for soil remediation, and disposal of contaminated groundwater at class II wells was optimum method for mitigating contaminated groundwater concern. Former Staff
8/24/1992 Update or Other Action (Old R:Base Action Code = RAPR - Remedial Action Plan Review (CS)). ADEC provided conditional approval of bioventing pilot study. Former Staff
12/6/1993 Site Added to Database Petroleum and ethylene and triethylene glycol contamination. Site broken out of Swanson River Field Tank Setting that was formerly inclusive of all Swanson River Field Tank Setting sites. Former Staff
12/6/1993 Site Ranked Using the AHRM Initial ranking. Former Staff
9/20/2000 Meeting or Teleconference Held Meeting at the oil field with Unocal, Chevron, USFWS to discuss past sampling results, improvements to sampling this year and approach to addressing problems. Will have meeting after this years monitoring report has been reviewed to discuss approach for the sites. Informed participants that in order to comply with USFWS regulations, Method 2 cleanup levels (Tables B and C) must be met, not 10 times or risk assessment. Donald Seagren
10/9/2000 Update or Other Action Re-reviewed the 1999 GW Monitoring Report. Final decision will wait until fall 2000 sampling event. At minimum, Unocal will have to determine extent of free product migration and begin free product recovery where needed. Donald Seagren
5/14/2001 Update or Other Action Review 2000 monitoring report; discuss free product recovery work plan with John Hammelman. Donald Seagren
4/24/2002 Meeting or Teleconference Held Annual meeting with ADEC, USFWS, BLM, Unocal and Oil Risk Consultants to discuss 01 work accomplished and 02 work planned. Discussed in detail additional MWs at all tanks settings and the free product recovery plan implementation. Donald Seagren
9/12/2002 Site Characterization Workplan Approved Review and approve Work Plan for monitoring well Installation. coordinate with USFWS. Donald Seagren
4/23/2003 Meeting or Teleconference Held Annual meeting to discuss 2002 work and plans for 2003. Donald Seagren
4/29/2003 Update or Other Action Reviewed 2002 MW installation report. Donald Seagren
4/30/2004 Update or Other Action File number assigned and entered into the Fileroom DB and CS DB. Alyce Hughey
5/27/2004 Meeting or Teleconference Held Monthly progress meeting. Revised NAPL recovery plan to be submitted by 30 June 04. Donald Seagren
3/21/2005 Update or Other Action reviewed 2004 GW monitoring report. No appreciable change in the risk to human health or the environment. Donald Seagren
10/7/2005 GIS Position Updated Using a Swanson River Layout Map, from Unocal, in conjunction with TopoZone Pro and the KPB Parcel Lookup, entered the coordinates for this site. Metadata includes No Topo Basemap, TopoZone Pro Street Maps, Black and White Aerial Photo, on a Medium Size Map, View Scale 1:24,000, Coordinate Datum NAD83. High degree of confidence in accuracy of location. Alyce Hughey
3/9/2006 Update or Other Action Reviewed 05 monitoring report. No significant change to risk to human health or the environment. Annual monitoring and LNAPL recovery to continue Donald Seagren
4/2/2007 Update or Other Action Reviewed 06 monitoring report. No significant change to risk to human helath or the environemnt. Annual monitoring and LNAPL recovery will continue Donald Seagren
5/7/2007 Exposure Tracking Model Ranking Donald Seagren
6/11/2008 Update or Other Action Site transferred from Don Seagren to Paul Howath per Linda Nuechterlein. On 6-30-08 transferred from Paul Horwath to Don Fritz per Paul Horwath. Alyce Hughey
9/28/2011 Document, Report, or Work plan Review - other Reviewed the 2010 Groundwater Monitoring Report Swanson River Field Tank Settings and Flare Pits, dated July 2011 and prepared by OilRisk Consultants. During the 2010 groundwater sampling event conducted at Tank Setting 1-27 on November 10, 2010, all seven of the monitoring wells were sampled for BTEX. Analytical results detected Benzene in only one of the monitoring wells above the groundwater cleanup levels at a concentration of 0.0758 mg/L. Alyce Hughey
11/16/2011 Update or Other Action Site transferred from Don Fritz to Peter Campbell per Paul Horwath. Alyce Hughey
9/25/2015 Meeting or Teleconference Held Meeting held to discuss long term sampling strategy and removing some wells from the sampling suite that have been clean for years. Peter Campbell
9/19/2017 Document, Report, or Work plan Review - other SRF Tank Setting 1-27 groundwater wells are monitored on a biennial and a four-year schedule. All viable wells are gauged during each sampling event. 2017 field activities will include: Sample four monitoring wells for 8260C and PAH: TS1-27G, TS1-27K, TS1-27L, and TS1-27M. Well FS1-27C is sampled for 8260C every four years and will be sampled next in 2019. See 2017 Kenai Groundwater Monitoring Program Work Plan. Peter Campbell
11/7/2019 Document, Report, or Work plan Review - other Reviewed the 2017 Groundwater Monitoring Program Report. No LNAPL was detected in the site monitoring wells. There were exceedances for trimethylbenzene, BTEX and naphthalene. PAH sampling will be reduced to once every four years. Peter Campbell
3/25/2020 Document, Report, or Work plan Review - other Reviewed the 2019 Groundwater Monitoring Report. No significant changes from previous sampling events. Peter Campbell
7/21/2021 Document, Report, or Work plan Review - other 2021 Groundwater Monitoring Program Work Plan ADEC Approval Letter Peter Campbell
8/1/2022 Document, Report, or Work plan Review - other 2021 Groundwater Monitoring Program Report ADEC Report Plan Approval Peter Campbell
6/1/2023 Long Term Monitoring Workplan or Report Review Review and approve 2023 Groundwater Monitoring Program Work Plan Addendum Peter Campbell

Contaminant Information

Name Level Description Media Comments

Control Type

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Description Details

No associated sites were found.

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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
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