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Site Report: Alyeska PS 12 Mainline Turbine Sump

Site Name: Alyeska PS 12 Mainline Turbine Sump
Address: Mile 64.7 Richardson Hwy., Pipeline Mile 735, Copper Center, AK 99573
File Number: 330.38.073
Hazard ID: 1732
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229
Latitude: 61.475900
Longitude: -145.145300
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.


During excavation activities related to the removal of the MLT sump located outside of the Main Pump Enclosure at PS12, Alyeska personnel encountered petroleum-impacted soils. Soil impact probably occurred from leakage associated with a loose vent flange noted on the west-end of the MLT sump during removal. The MLT sump may have periodically contained turbine fuel discharged from the MLT during startup and shutdown of the unit and/or from a "blowdown" tank. The release was reported as 30 gallons of turbine fuel.

Action Information

Action Date Action Description DEC Staff
12/19/1996 Update or Other Action Alyeska submitted a report entitled PS12 Mainline Turbine Sump Soil Sampling and Analysis Report. Field observations and analytical data indicates that Level B target cleanup standards for all regulated contaminants were exceeded in the western section of the excavation. Further excavation of the contamination was not possible without threatening the stability of nearby buildings and underground utilities. EMCON recommends further site assessment activities. Deborah Williams
7/18/1997 Update or Other Action Alyeska submitted a Contamination Assessment Workplan. The objectives of the workplan were to assess the extent of subsurface impact by drilling in the locations of the two corrugated metal piping. An additional soil boring will be advanced to the southwest of the footprint of the former excavation if possible. Also, to prepare a contamination assessment report documenting the findings of the soil boring installations and summarizing analytical findings from the acquired data. Deborah Williams
7/24/1997 Update or Other Action Frechione approved the July 1997 Contamination Assessment Workplan. Deborah Williams
12/3/1997 Update or Other Action ADEC received the November 1997 PS 12 MLT Sump Contamination Assessment Report. During the assessment, DRO levels up to 16,000 ppm were detected in the sidewall of the excavation. Excavation was limited in order to protect the structural integrity of adjacent buildings and utilities. Two soil borings were later installed through the excavation down to 27 and 36.3 feet bgs. Groundwater was encountered at 32.8 feet. There was no odor or other indication that groundwater was impacted from the drill rods or the sample collected at 35 feet bgs. One sample collected at 12 feet bgs had levels up to 6,500 ppm DRO, but all the other samples collected deeper were non-detect for all compounds. Deborah Williams
11/6/2000 Site Added to Database Petroleum contamination. Bruce Wanstall
11/6/2000 Site Ranked Using the AHRM Preliminary ranking. Deborah Williams
1/2/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Keather McLoone
2/1/2008 GIS Position Updated Updated using Arc GIS SPAR_StatewideLocator (ArcReader) Grant Lidren
12/22/2009 Conceptual Site Model Submitted Date of receipt of Pump Station 12 Mainline Turbine Sump Conceptual Site Model submitted by SLR on behalf of Alyeska. Keather McLoone
2/17/2010 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 12 Mainline Turbine Sump. Based on the information provided to date, the ADEC has determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment, and no further remedial action will be required as long as the site is in compliance with established institutional controls. This decision is based on the administrative record for Alyeska PS 12 Mainline Turbine Sump, which is located in the offices of the ADEC in Anchorage, Alaska. Keather McLoone
2/18/2010 Institutional Control Record Established Institutional Controls established and entered into the database. Keather McLoone
4/20/2010 Update or Other Action Receipt via email from Alyeska of letter written by JPO in response to decision letter recently written. It would appear that JPO feels that the decision may meet state requirements but not other requirements. Keather McLoone
12/1/2011 Update or Other Action The current project manager chose to retain management of this site with the Cleanup Complete Determination that has Institutional Controls. Kristin Thompson
11/12/2013 Institutional Control Compliance Review IC compliance review conducted and staff changed from Linda Nuechterlein to IC unit. Reminder system set-up to follow-up with the responsible party in 2015. Kristin Thompson
3/9/2015 Institutional Control Update An IC reminder letter was issued to the responsible party on this date. Kristin Thompson
10/12/2015 Institutional Control Periodic Reporting The responsible party informed ADEC that there have been no changes in land use or ownership at this site since the 2010 Record of Decision. Reminder system re-set to follow up in another five years. Kristin Thompson
6/19/2018 Institutional Control Compliance Review IC compliance review conducted. Closure/IC Details updated. Reminder system already set for follow-up in 2020. Kristin Thompson

Contaminant Information

Name Level Description Media Comments
DRO > Human Health/Ingestion/Inhalation Soil GRO and DRO concentrations remaining in the soil may be above cleanup levels for ingestion, direct contact and inhalation pathways, and migration to groundwater. However the exposure risk for these pathways is considered acceptable, primarily because the amount of contaminated soil was determined to be de minimis in extent. The groundwater ingestion exposure pathway is further protected by the use of a much deeper aquifer at PS 12 below silt and clay confining layers
GRO > Human Health/Ingestion/Inhalation Soil see DRO comment

Control Type

Type Details
Signed CS Determination


Description Details
Advance approval required to transport soil or groundwater off-site. Standard condition.
When Contaminated Soil is Accessible, Remediation Should Occur Soil contamination is located in the area of the MLT sump. When the soil in this area becomes accessible and the utilities in this area are no longer necessary, the soil must be evaluated and contamination addressed in accordance with an ADEC approved work plan.
Other Alyeska shall report to ADEC every five years to document land use, or report as soon as they become aware of any changes in land ownership and/or use.
Movement or use of contaminated material (including on site) in a manner that results in a violation of the water quality standards is prohibited (18 AAC 70) Standard condition.

Missing Location Data

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