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Site Report: ADOT&PF Silvertip Highway Maintenance Station (Former location)

Site Name: ADOT&PF Silvertip Highway Maintenance Station (Former location)
Address: Mile 60 Seward Highway, 3 miles north of the Hope Junction, Anchorage, AK 99507
File Number: 2315.26.002
Hazard ID: 23444
Status: Active
Staff: Joshua Barsis, 9072697691
Latitude: 60.749200
Longitude: -149.371600
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.


During the removal of 4-500 gallon diesel tanks and one propane tank in 1986, and the removal of one 2,000 gallon diesel tank, and one 2,000 gallon gasoline tank removed in October 1989, diesel contamination from surface spills was encountered. The extent of the contamination has not yet been determined. Waiting for site assessment report. Updated 11-30-05 Alyce Hughey. Location described as on the nearly level alluvial flood plain westerly of the confluence of Silvertip Cr. & 6 Mi. Cr. update 2009: In 2006 two additional USTs (one 1,000 gallon gasoline and one 500 gallon diesel) were removed. Soil samples were taken during the excavation for confirmation, approximately 100 cubic yards were stored in Supersacks until May, 2008 when it was landspread on site. Monitoring wells were installed in May 2006 and sampled in 2006, 2007 and 2008. File number changed 10-09 to: 2315.26.002, which more closely reflects this site's location.

Action Information

Action Date Action Description DEC Staff
5/16/1990 Leaking Underground Storage Tank Release Confirmed - Petroleum LUST Site created in CSP for source area ID 77635 ADD; Petroleum contaminants. * Not Assigned
5/16/1990 Site Added to Database * Not Assigned
12/24/1991 Update or Other Action Letter from Don Fritz sent requesting a site assessment and the location of the contaminated soils. Alyce Hughey
2/15/1994 Release Investigation RELR; Reviewed a release investigation report. * Not Assigned
8/9/1995 Underground Storage Tank Site Characterization or Assessment SA1A; Reviewed a phase 1 site assessment report. * Not Assigned
9/9/1995 Update or Other Action CAPR; Reviewed a remedial action report. * Not Assigned
9/9/1995 Release Investigation SA2A; Reviewed a phase 2 site assessment report. * Not Assigned
9/18/1995 Leaking Underground Storage Tank Cleanup Initiated - Petroleum LCAU; * Not Assigned
5/6/1997 Update or Other Action E-Mail sent by Monica English requesting a Site Assessment form Dan Breeden, ADOT&PF. Alyce Hughey
6/1/2004 Leaking Underground Storage Tank Corrective Action Underway Staff reviewed and provided comments to a Soil Remediation work plan and a thermal operations plan. Monica English
6/9/2004 Update or Other Action File number assigned and entered into the Fileroom DB and LUST DB. Alyce Hughey
7/8/2005 Update or Other Action Reviewed file to organize and figure out what was done. It was determined that this site is for the former location. Information was conflicting so a copy of the file was sent to ADOT in Anchorage for their assistance in determining what additional action may be required for site closure. Donald Seagren
11/30/2005 Update or Other Action Using Figure 1 from an Environmental Assessment and Cleanup Services, ADOT&PF Silvertip, from Shannon & Wilson, Dated December 2000, 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 1:10,000, Coordinate Datum NAD83. High degree of confidence in accuracy of location. Alyce Hughey
5/8/2006 Underground Storage Tank Site Characterization or Assessment Approved site investigation work plan. Addiitonal assessment/cleanup actions will depend on report findings. At a minimum, 2 USTSs remaining on site will be removed. Donald Seagren
6/23/2006 Report or Workplan Review - Other Reviewed draft assessment/monitoring report. Provided comments and approval to finalize. Requested electronic copy on entire final report for ease of distribution to DOT. Donald Seagren
7/12/2006 Underground Storage Tank Site Characterization or Assessment Final report showed soil contamination exists but is below Table B levels. GW DRO contamination exceeding Table C levels. 1 UST remaining in ground. Seeking approval for CIP funds for additional assessment & removal of remaining UST. Copy of the report sent to Ron Stroman, DOT. Donald Seagren
9/11/2006 Leaking Underground Storage Tank Corrective Action Underway Reviewed and approved, with minor corrections the draft work plan for UST removal and closure assessment and GW monitoring in 07 Donald Seagren
10/12/2006 Update or Other Action One UST was found to contain fluid, presumably water & residual fuel. It will be pumped out prior to UST removal. More contaminated soil was found than expected. 50yds3 will be stored in supersacks as planned. The rest will be placed on a liner and covered for the winter, pending analytical data to determine disposal options. Donald Seagren
2/14/2007 Exposure Tracking Model Ranking * Not Assigned
7/11/2007 Report or Workplan Review - Other Reviewed monitoring report, no contaminats exceeding cleanup levels detected. Discussed soil remediation with HC Donald Seagren
7/20/2007 Update or Other Action reviewed and approved proposal for LTM and landspreading stockpiled soil Donald Seagren
8/10/2007 Update or Other Action After discussing with ADOT, the work plan for GW monitoring and landspreading the stockpiled contaminated soil was approved. Donald Seagren
6/13/2008 Update or Other Action Site transferred from Don Seagren to Paul Horwath per Linda Nuechterlein. Alyce Hughey
7/3/2008 Report or Workplan Review - Other Received and reviewed the Groundwater Monitoring Report prepared by term contractor Clarus Technologies, LLC, dated June 2008. Approximately 100 cubic yards of GRO and DRO contaminated soil was landspread onsite. Five GW monitoring wells were sampled and MW-5 exceeded ADEC GW cleanup levels for DRO. All other MWs met ADEC groundwater cleanup levels. MW-5 is the downgradient MW and should be resampled again during the 2009 field season. The landspread soils could also be resampled at that time to see if the GRO and DRO contaminant concentrations meet the ADEC soil cleanup levels. Paul Horwath
5/29/2009 Update or Other Action File transferred from Soldotna to Anchorage 6-1-09. Project Manager changed from Paul Horwath to Linda Nuechterlein. Alyce Hughey
5/24/2010 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 77635 name: ust Pam Clemens
8/4/2010 Update or Other Action Site transfered to Pam Clemens. Pam Clemens
12/3/2010 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 77635 Underground Storage Tank. Pam Clemens
1/5/2011 Update or Other Action Groundwater monitoring has shown a decreasing trend in all but one monitoring well (MW5). Monitoring wells need to be decommissioned, this site is being evaluated for closure. Pam Clemens
5/28/2014 Site Visit On this day, the CSP observed soil and groundwater sampling at this site. Monitoring Well MW5 was purged and sampled. A petroleum odor was noted during the purging activities and a sheen was observed while filling the sample jars. MW5 purged dry while filling the final sample jar. In addition to sampling MW5, the formerly land spread soils were screened and sampled. Because the ADOT had grated the entire area, the edges of the former land spread soils were not located. Four screening and one analytical sample were collected from the approximate location of land spread soils. All soil and groundwater samples were submitted for GRO, DRO, RRO, and BTEX. Analytical results were received on June 9, 2014. The water sample exhibited a concentration of DRO at 10.8 mg/L; which exceeds the ADEC cleanup criterion of 1.5 mg/L. The soil sample did not exhibit any contaminants exceeding ADEC cleanup levels. Joshua Barsis
6/9/2014 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 77635 Underground Storage Tank. Joshua Barsis
12/31/2015 Update or Other Action File review on this day; no new information. Joshua Barsis
10/25/2016 Update or Other Action Letter sent on this day with a brief site history and to outline existing data gaps that need to be addressed before this site could be considered for closure. Joshua Barsis

Contaminant Information

Name Level Description Media Comments

Control Type

Type Details


Description Details

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