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Site Report: Swanson River Tank Setting 1-4

Site Name: Swanson River Tank Setting 1-4
Address: Mi. 17.5 Swanson River Rd, Sterling, AK 99672
File Number: 2334.38.018
Hazard ID: 441
Status: Active
Staff: Peter Campbell, 9072623412 peter.campbell@alaska.gov
Latitude: 60.732222
Longitude: -150.863056
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

Numerous spills at this site with contaminated soils present. Impact to human health or total extent of contamination unknown. Groundwater contamination present. Numerous monitoring wells have floating product. Light non-aqueous phase liquid (LNAPL) recovery and annual groundwater monitoring in effect. Plume appears stable and not expanding. Risk to human health and the environment is minimal under current site conditions. Due to oil field infrastructure, excavation and remediation of the contaminated soil is not feasible at present. This will be delayed until 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
6/4/1991 Site Added to Database Petroleum contamination. Former Staff
11/1/1991 Update or Other Action (Old R:Base Action Code = TOTH - Treatment, Other). Results of Bioventing treat ability 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
3/8/1993 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
1/24/2001 Update or Other Action Site broken out of Swanson River Field Tank Setting that was formerly inclusive of all Swanson River Field Tank Setting sites. 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 the 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, by 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 1:25,000, 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 & LNAPL recovery to continue Donald Seagren
4/2/2007 Update or Other Action Reviewed 06 monitoring report. No significan change to risk to human health or the environment. Annucla monitoring and LNAPL recovery to 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 Horwath per Linda Nuechterlein. On 6-30-08 transferred from Paul Horwath to Don Fritz per Paul Horwath. Alyce Hughey
9/23/2011 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 in November through December, all eight of the monitoring wells located at pad 1-4 were sampled for BTEX. Analytical results detected Benzene in five of the monitoring wells above the groundwater cleanup levels at concentrations of 0.00818 mg/L to 0.758 mg/L. Alyce Hughey
11/16/2011 Update or Other Action Site transferred from Don Fritz to Peter Campbell per Paul Horwath. Alyce Hughey
12/20/2013 Update or Other Action On November 20, 2013 while trenching for the 21A-4 flow line, historical contamination was found northwest of the Tank Setting Building and northeast of the Lact Unit along the road way. Approximately 1.5 cubic feet of contaminated material was placed in super sacks and moved to the solid waste cell. Alyce Hughey
9/24/2015 Meeting or Teleconference Held Meeting held to discuss monitoring well sampling frequency and the path forward for this pad. Hilcorp has purchased the facility and the adjoining contaminated site known as the Electrical Shop. We requested that these two sites be managed together to better under stand site groundwater flow patterns and the extent of contamination. Peter Campbell
10/1/2015 Site Visit A release of glycol was reported to the Spill Response section. Observed cleanup activities which involved moving the glycol unit, excavating impacted soils which had commingled with historically impacted hydrocarbon impacted soils. the release occurred near monitoring well TS1-4G, which will be sampled for glycol to determine if there have been impacts to groundwater. Peter Campbell
6/7/2016 Update or Other Action Reviewed 2015 Groundwater Monitoring Report. Monitoring well TS1-4G was blocked and could not be sampled. The well is to be replaced and sampled for glycol. Four of the monitoring wells have benzene concentrations that exceed ADEC cleanup levels. Benzene is an indicator compound for the hydrocarbon impacts. One well, TS1-4J, has measureable separate phase product on the water surface. Peter Campbell
9/18/2017 Document, Report, or Work plan Review - other SRF Tank Setting 1-4 groundwater wells are monitored on a biennial schedule. All viable wells are gauged during each sampling event. 2017 field activities include: Monitor and remove LNAPL in TS1-4J and replace LNAPL-absorbent sock. If LNAPL is not observed, sample well for 8260C and PAH. Replace the LNAPL-absorbent sock in TS1-4F. Decommission and replace TS1-4G. This monitoring well has an obstruction and was unable to be sampled in 2014; however, it has historically contained benzene exceeding the cleanup level and is located near a potential source area. Survey to establish coordinates and top-of-casing elevations for the replacement well. Cut the PVC well casing on FS1-4E in order to properly close and lock the steel casing. Sample five monitoring wells for 8260C and PAH: TS1-4EE, TS1-4F, FS1-4E, FS1-4H, and TS1-4GR (replacement well for TS1-4G). Sample two monitoring wells for ethylene glycol: TS1-4EE and TS1-4GR (replacement well for TS1-4G). Gauge groundwater levels in all monitoring wells within a 24-hour period in order to determine groundwater elevation and flow direction. 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. Elevated levels of Glycol was detected in TS1-4GR. The consultant has recommended a new monitoring well south of the flare pit. Separate phase product was present in TS1-4F. Peter Campbell
3/25/2020 Document, Report, or Work plan Review - other Review the 2019 Groundwater Monitoring Report, No significant change at Pad 1-4. Only four of the wells were sampled during this event. 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 Approve an addendum for 2023 field sampling to include the addition of sampling 1,4 Dioxane in surface water if present. 1,4 Dioxane may be present where glycol has been released. Peter Campbell

Contaminant Information

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Description Details

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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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