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Site Report: Alyeska PS 01 Tank 117

Site Name: Alyeska PS 01 Tank 117
Address: Spine Road, Pipeline Mile 0, Deadhorse, AK 99734
File Number: 330.38.028
Hazard ID: 1742
Status: Active
Staff: Grant Lidren, 9072698685
Latitude: 70.258652
Longitude: -148.620617
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.


In 1989, observations indicated Tank 117 had settled into the gravel pad. While evaluating the structural integrity of Tank 117, also in 1989, Alyeska discovered stained soil within 10 feet of the swing line outlet. It is suspected that a small leak in a flange on a pipeline carrying therminol was the source. In 1992, soil borings were advanced and surface and subsurface samples collected to determine the horizontal and vertical extent of contamination. An estimated 120 to 150 cubic yards of contaminated soils were estimated to be present in the area outside the tank's footprint. Ongoing monitoring reported under file number 330.38.019 (PS 01 Former Gas Tank area) also addressing this source area/release.

Action Information

Action Date Action Description DEC Staff
9/1/1992 Update or Other Action Site Assessment Report received by ADEC. The conclusions of the report were that impacted soils are present in the vicinity of the swing-line outlet on the south side of Tank #117. Therminol is the primary contaminant although diesel fuel and BTEX were also targeted as potential contaminants of concern. AN/E estimates approximately 120 to 150 cubic yards of impacted soils are present in the vicinity of the stained soils (exterior to the footprint of Tank #117). Maximum concentrations of 7,300 mg/kg Therminol and 5,700 mg/kg DRO were detected. Deborah Williams
1/5/1994 Update or Other Action Results of Soil Sampling and Analysis Report submitted to the department. Contaminated soils were left in place on the tank pad, due to concerns about undermining the tank, piping supports, and valve cabinets. Some of the contamination was excavated as a result of tank pad apron regrading work (Aug-September 1993). This sampling event included the advancement of four borings (1.5 feet in depth) and the collection of soil samples for laboratory analysis. The holes were hand augered at selected locations adjacent to 1992 borehole locations B6, B7, B8, and B12. Observations in June 1992 borings indicate that the pad in this area of PS-1 is approximately 2.2 to 3.5 feet in thickness and is underlain by frozen silt. The conclusions of the sampling determined that contamination migration is not observed. Alyeska recommends one more sampling event in 1994. Deborah Williams
10/27/1994 Update or Other Action Results of Soil Sampling and Analysis Report submitted to the department. Four borings were advanced adjacent to the 1992 boring locations (at 1.5 foot depth). Water was encountered between 0.8 and 1.5 feet below ground surface in each borehole. Conclusion: no evidence of migration of Therminol from previously defined limits into pad gravels south of the Tank 117 apron. Emcon recommends no further monitoring be performed. Deborah Williams
12/15/2000 Site Added to Database Therminol and Diesel contamination. Bruce Wanstall
12/15/2000 Site Ranked Using the AHRM Preliminary ranking. Deborah Williams
1/30/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Pam Clemens
11/2/2011 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 72720 Therminol spill Tank 117. Keather McLoone
2/26/2013 Report or Workplan Review - Other Groundwater monitoring data near Tank 117 are presented in the 2012 Water Monitoring Report for PS 01 Former Gas Tank Area (330.38.019). GRO concentrations are significantly elevated in MW-15 (206 mg/L) and MW-14 (64.5 mg/L) southeast and east of Tank 117, respectively. Richard Bernhardt
12/3/2013 Update or Other Action Ongoing monitoring reported under file number 330.38.019 (PS 01 Former Gas Tank area). Grant Lidren
11/15/2016 Offsite Soil or Groundwater Disposal Approved On this date, ADEC approved the transport of 8 cubic yards of DRO contaminated gravel to the Oxbow landfill. This contaminated gravel was generated October 2016 and is assumed historic. The contamination was encountered near Tank 117. Grant Lidren
2/15/2017 Report or Workplan Review - Other ADEC received the 2016 Pump Station 1 Tank 117 Historical Spill Site Sampling Report submitted by SLR dated December 29, 2016. Historical contamination was encounter on October 22, 2016 while performing an integrity dig within the tank farm, between crude tank 110 and turbine fuel tank 117. Eight cy of visibly impacted soil were removed and segregated by Alyeska until the intended final excavation depth for the project was achieved. The excavation measured 12 feet by 12 feet with sloped sidewalls to a depth of approximately 4 feet bgs SLR arrived on October 26, 2016 and observed petroleum impacts along the east excavation sidewall and beneath a diesel pipeline as evidenced by light staining/ strong odors and sheening on pooled water. Five confirmation samples collected from the bottom and excavation sidewalls did not contain contaminant concentrations above ADEC method one petroleum cleanup levels in the arctic zone. The 8 cy stockpile was transported to Oxbow Landfill. Grant Lidren
7/31/2018 Site Visit Visited site on this date with Alyeska and SLR. Grant Lidren

Contaminant Information

Name Level Description Media Comments

Control Type

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Description Details

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