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Site Report: Swanson River Tank Setting 3-4

Site Name: Swanson River Tank Setting 3-4
Address: Mi. 17.5 Swanson River Rd, Sterling, AK 99672
File Number: 2334.38.023
Hazard ID: 445
Status: Active
Staff: Peter Campbell, 9072623412 peter.campbell@alaska.gov
Latitude: 60.723611
Longitude: -150.881944
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

Significant petroleum contamination of soil and groundwater below this tank setting. Light non-aqueous phase liquid (LNAPL) recovery and annual groundwater monitoring on-going. Contaminant plume appears stable and not expanding. Under current site conditions, risk to human helath and the environment is minimal. Due to the facility infrastructure, it is not currently feasible to access the conatmination and complete a cleaup. Site cleanup will be accomplished 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 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 Reviewed 2000 monitoring report; discussed free product recovery work plan with John Hammelman. 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 2003 plans. 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
6/18/2004 Cleanup Plan Approved reviewed and approved NAPL recovery plan. 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 human health or the environment. LNAPL recovery and annual monitoring to continue. Donald Seagren
4/2/2007 Update or Other Action reviewed 06 monitoring report. No significan change to the risk to human health or the environment. Annual monitoring & LNAPL recovery to continue Donald Seagren
5/8/2007 Exposure Tracking Model Ranking Donald Seagren
6/11/2008 Update or Other Action Site transferred from Don Seagren to Paul Horwath per Linda Nuechterlein. On 6-30-08 transferred from Paul Horwath to Don Fritz per Paul Horwath. Alyce Hughey
9/30/2011 Document, Report, or Work plan Review - other Reviewed the 2010 Groundwater Monitoring Report Swanson River Tank Setting and Flare Pit, dated July 2011, from OilRisk Consultants. During the 2010 groundwater sampling event conducted at Tank Setting 3-4 in November through December, eleven of the twelve monitoring wells were sampled for BTEX. Well TS3-4CC was not sampled because not enough water was within the well for sampling. Analytical results detected Benzene in three of the monitoring wells above the groundwater cleanup levels at concentrations of 0.0276 mg/L to 2.15 mg/L. Alyce Hughey
11/16/2011 Update or Other Action Site transferred from Don Fritz to Peter Campbell per Paul Horwath. Alyce Hughey
7/2/2015 Update or Other Action Delayed status: Contaminant plume appears stable and not expanding. Peter Campbell
9/25/2015 Meeting or Teleconference Held Meeting with Hilcorp to determine long term sampling strategy. Plan is to discontinue sampling wells Z, NN and PP. Sample wells MM, OO, and B every four years. Sample wells P, CC, A and F every other year. Peter Campbell
9/19/2017 Document, Report, or Work plan Review - other SRF Tank Setting 3-4 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: Remove LNAPL and replace LNAPL-absorbent socks in two wells: TS3-4D and FS3-4D. If LNAPL is not present, sample wells for 8260C and PAH. Sample four wells for 8260C and PAH: TS3-4P, TS3-4CC, FS3-4A, and FS3-4F. Three wells are sampled for 8260C every four years and will be sampled next in 2019: TS3-4MM, TS3-4OO, and FS3-4B. See 2017 Kenai Groundwater Monitoring Program Work Plan. Peter Campbell
11/12/2019 Document, Report, or Work plan Review - other Reviewed the 2017 Groundwater Monitoring Program Report for the Swanson River Field. There was an obstruction in monitoring well TS3-4D, the product absorption sock could not be placed, and no product was bailed from the well. The well was not gauged. Concentrations in monitoring well TS3-4CC increased, with a first sheen noted on the water. Down gradient monitoring may be incomplete on the pad. Peter Campbell
3/25/2020 Document, Report, or Work plan Review - other Review the 2019 Groundwater Monitoring Report. ADEC had issues with the way groundwater contours were presented, not honoring groundwater elevations at several wells. There is significant free product in well TS3-4D, which may have the potential to migrate toward the wetlands. ADEC has asked Hilcorp to evaluate the potential. 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

Type Details

Requirements

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
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