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Site Report: ADOT&PF Skagway Maintenance Station


Site Name: ADOT&PF Skagway Maintenance Station
Address: 2.5 Mile Klondike Highway, Skagway, AK 99840
File Number: 1526.38.017
Hazard ID: 26058
Status: Active
Staff: Eileen Olson, 9072697527 eileen.olson@alaska.gov
Latitude: 59.481111
Longitude: -135.291111
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.

Problems/Comments

On October 10, 2012, ADOT closed Class V Injection Well drain field at the Skagway Maintenance Station. The drain field received discharge from a oil-water seperator system in which a waste oil storage tank was not installed according to the original design. All parts of the Class V Injection Well were decommissioned and an estimated volume of 200 cubic yards of contaminated soil was removed and remediated off-site. Contamination above soil cleanup levels remains inaccessible in subsurface soil below 16 feet below ground surface. Investigation into the extent of soil and groundwater contamination by gasoline, diesel, and residual range hydrocarbons and volatile (VOC) and semi-volatile hydrocarbon compounds continued in 2014, 2015 and, 2016. Soil DRO, RRO, PCE, TCE, and n-propylbenzene contamination detected during the 2012 investigation does not appear to be significantly migrating to groundwater or is rapidly breaking down in the subsurface. Low-level groundwater DRO and RRO contamination detected during the 2014 investigation appears to be the result of laboratory contamination due to the low levels detected and the similarity in concentration between hydrologic and spatially separated sampling point. TCE, PCE, or their breakdown products, have not been detected in the shallow or deep monitoring wells by the 2014, 2015, or 2016 sampling events, indicating that a dense non-aqueous phase liquid (DNAPL) plume does not exist in the subsurface.

Action Information

Action Date Action Description DEC Staff
5/13/2013 Report or Workplan Review - Other DEC letter approved the R&M Report on dismantling the oil water separator and site assessment of the Class V drain field system at the DOT Skagway Highway Maintenance Shop in accordance with 18 AAC 75.335(d). In the letter DEC requested that DOT submit a work plan for DEC approval to investigate groundwater for contamination from inaccessible contamination that remains in subsurface soil at the former C5 Well site and south of test pits TP-2, TP-2 and TP-3. Contaminants of concern are those named in the Report except for total metals which the data show are at levels within the range of background for the area. The investigation will include an evaluation of potential human and ecological receptors and pathways that could present an exposure risk for those receptors to contaminants of concern reflected in the results of the site characterization Report: GRO, DRO and RRO range hydrocarbons and VOC and SVOC hydrocarbon compounds. Bruce Wanstall
5/21/2013 Site Added to Database A new site has been added to the database Mitzi Read
5/21/2013 Spill Transferred from Prevention Preparedness and Response Program Spill transferred by PERP staff Crystal Smith. Spill number 12119928402; spill date = 10/10/12; substance = unknown; quantity = unknown; source = Class V injection well. Mitzi Read
5/22/2013 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 79461 name: Class V Injection Well Mitzi Read
7/12/2013 Report or Workplan Review - Other In the approval letter for the R&M Report of site assessment in conjunction with demolition of the oil water separator and drain field, DEC requested that DOT investigate the extent of solvent and petroleum contamination in subsurface soil under the former OWS drain field. DEC prepared an ArcGIS map display of possible well locations and suggestions for drill boring & monitoring well plan for the DOT RFP. Bruce Wanstall
1/27/2014 Report or Workplan Review - Other DEC sent approval with several requested changes by electronic and regular mail today for a work plan submitted by R&M Anchorage for ADOT. The investigation will include detection and characterization of dense non-aqueous petroleum liquids (DNAPLs) and light non-aqueous petroleum liquids (LNAPLs). If no groundwater is encountered on site, then the investigation will focus on characterizing the remaining soil contamination and locating the nearest underlying confining layer. Bruce Wanstall
3/3/2014 Cleanup Level(s) Approved DEC evaluated a Site Investigation Work Plan by R&M for DOT dated February 24, 2014. In January DEC requested additional borings and analytical testing of off-site tap water well at the White Pass RV Park for site contaminants of concern. Approval of the new version was sent today by email to DOT. The hazardous chemical cleanup level requirements at this site for soil are those established under 18 AAC 75.341(d) Method Two for the Under 40-inch zone as chemicals in Table B1 and as petroleum hydrocarbon ranges in Table B2. Groundwater cleanup levels are those established in 18 AAC 75.345(b)(1) Table C and surface water cleanup levels are those established in 18 AAC 70 Water Quality Standards for surface water. Bruce Wanstall
6/11/2014 Site Visit DEC performed a brief inspection of the drainfield excavation and contaminated soil removal site at the maintenance facility. Monitor wells are scheduled to be installed in 2014 Bruce Wanstall
2/3/2015 Site Characterization Report Approved DEC approved by letter Site Monitoring Report – Skagway Highway Maintenance Station Former Class V Injection Well Skagway, Alaska (Report), completed in January 2015 by R&M Consultants Inc. documenting investigation of soil and groundwater contamination in 2014. The Report concludes bulk of soil contamination was removed during the 2012 Class V well decommissioning. Remaining contamination above cleanup levels is stable and limited to the area near the former class V well. Recommended cleanup remedy is monitored natural attenuation (MNA). DEC requested groundwater sampling in spring 2015 to establish MNA trends in contaminant concentrations detected in groundwater. Bruce Wanstall
2/4/2015 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 79461 Class V Injection Well. The source of soil and groundwater contamination was removed during the 2012 Class V well closure and removal action. There is no indication that soil and groundwater contamination exceeding cleanup levels is migrating off site. Remaining contamination is currently limited to the former drain field. On-site land use is commercial/industrial. The remaining soil and groundwater contamination is at least 500 feet from occupied residential properties that are cross-gradient to groundwater flow direction. The site is within the UNDER 40-inch Soil Cleanup Zone. Bruce Wanstall
12/17/2015 Report or Workplan Review - Other DEC reviewed and approved by letter Draft Groundwater Monitoring Spring 2015 – Skagway Highway Maintenance Station Former Class V Injection Well Skagway, Alaska (Report), submitted in September 2015 and completed by R&M Consultants Incorporated documenting the analytical groundwater sample monitoring at the referenced Site in June 2015. DEC concurred with Report conclusions that data indicate soil contamination is stable and not migrating in groundwater and the Report recommendation that DOT perform additional analytical sampling of the wells in 2016 to confirm MNA is the appropriate cleanup remedy. Bruce Wanstall
4/4/2016 Update or Other Action DEC unable to attend well sampling this week at the maintenance facility in Skagway; sent by email approval for R&M Consultants Inc. to proceed with the sampling and analysis plan. Bruce Wanstall
5/3/2016 Update or Other Action Spring 2016 Sampling Report arrived by electronic mail. Analytical results are again below cleanup levels; ADOT&PF requested in-house closure of the monitoring wells and a cleanup complete determination. Bruce Wanstall
5/5/2016 Site Characterization Report Approved DEC reviewed and approved by letter sent regular and electronic mail today to ADOT&PF (DOT) the R&M Report on 2016 well sampling and analysis at the Skagway Highway Maintenance Facility Class V Injection Well decommissioning Site. The results from this year mirrored the 2015 results indicating no groundwater contamination above cleanup levels in either the shallow or the deep well samples. The remaining DRO and RRO soil contamination is stable, not migrating to groundwater and, by all indications, is present to a limited extent in the subsurface following the 200 cubic yard removal cleanup. DEC requested DOT submit for approval a scheduled plan to decommission the monitoring wells at the Site in accordance with DEC methodology in the Monitoring Well Guide dated September 2013. Bruce Wanstall
5/6/2016 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 79461 Class V Injection Well. Contaminant of concern groundwater analytical data clearly show there are no signs contamination migrating from the Source Area in groundwater at the soil interface or at bedrock depth. The facility wash-down water well is located upgradient and is not affected by contamination in the Source Area. Bruce Wanstall
10/10/2017 Update or Other Action Staff assigned changed from Sally Schlichting to Eileen Olson. Kathryne Roldan

Contaminant Information

Name Level Description Media Comments

Control Type

Type Details

Requirements

Description Details

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