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Site Report: ADOTPF - Sitka Airport Maintenance Station


Site Name: ADOTPF - Sitka Airport Maintenance Station
Address: 605 Airport Road, Sitka, AK 99835
File Number: 1525.26.023
Hazard ID: 23179
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229 dec.icunit@alaska.gov
Latitude: 57.053291
Longitude: -135.366648
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

During closure by removal of regulated underground storage tanks, diesel range hydrocarbons (DRO) and gasoline hydrocarbons (GRO) were detected in soil samples collected at the water table interface three feet below the ground surface. The highest DRO and GRO concentrations detected in soil were stated as 16,000 mg/kg and 640 mg/kg respectively, however benzene was not detected. The ADEC cannot validate the data; a laboratory report for this data is not available. The fall 2007 investigation re-assessed residual soil contamination next to the former gasoline UST where a 1998 UST closure assessment found a “hot spot” of elevated DRO. Soil borings HB04 and HB05 were advanced at the same location as the “hot spot” mid-way in the length of the west side of the former gasoline UST and mid-way in the length of the east side of the out-of-service regulated waste oil UST. No soil discoloration or fuel odor was noted in soil cuttings. The benzene result in the HB04 soil sample was slightly above its migration to ground water cleanup level (0.00295 mg/kg) with DRO non-detect. DRO concentration in soil reached 49.2 in HB05 but benzene was not detected. Monitoring well MP1 was installed in HB05 and all analytes in the ground water sample were either below instrument detection or below Table C cleanup levels.

Action Information

Action Date Action Description DEC Staff
4/8/2000 Leaking Underground Storage Tank Cleanup Initiated - Petroleum 4/7/08 Administrative update Evonne Reese
4/8/2000 Leaking Underground Storage Tank Release Confirmed - Petroleum LUST Site created in CSP for source area ID 77852 1500 gallon diesel and 500 gallon gasoline USTs removed. DRO detected at 16,000 ppm at one sample location. No soil excavated. * Not Assigned
4/8/2000 Site Added to Database * Not Assigned
10/2/2001 Update or Other Action Changed Project Manager from Colin Basye to Bill Janes Cynthia Pring-Ham
12/12/2001 Underground Storage Tank Site Characterization or Assessment Project tickler update: email to Dennis LyBarger at DOT rgd need for Release Investigation. Email stored in Outlook project folder. Bill Janes
2/8/2002 Update or Other Action Site tickler update - No action per now based on Carnahan's email this date (saved in Outlook site folder for Sitka Halibut Point Maintenance Station). Check back with DOT early in new fiscal year to see if any of the SE sites are higher on their budget prioritizaton list. Bill Janes
2/20/2002 Cleanup Level(s) Approved 18 AAC 75.350 determination and 10X Rule on groundwater and soil is agreed upon by the property manager Bruce Wanstall
2/20/2002 350 Determination Administrative update: a 350 determination has been established for this site. Kristin Brown
1/31/2003 Update or Other Action File reviewed for possible closure - unknown quantity of contaminated soil remains in place. A nearby heating oil UST and waste oil UST also appear to remain. Additional work needed. Bill Janes
5/11/2007 Exposure Tracking Model Ranking Initial site ranking; additional data requested from ADOT SE Regional Shop; sent by electronic mail. Bruce Wanstall
7/17/2007 Update or Other Action Site management transfer to Wanstall for State-lead cleanup plan development Bruce Wanstall
7/20/2007 Update or Other Action Request for propsal draft completed and and ledger code requested. Bruce Wanstall
7/25/2007 Update or Other Action Notice to proceed draft for soil and groundwater assessement project completed. Bruce Wanstall
10/9/2007 Update or Other Action Review and comment on the draft workplan. Approval for the final version of the soil and groundwater assessment workplan sent to the contractor. Bruce Wanstall
11/1/2007 Update or Other Action ArcGis software used to make correction to the latitude longitude coordinates entered by the state term contractor. NAD 83 datum used with accuracy estimated at less than fifty meters. Bruce Wanstall
2/1/2008 Report or Workplan Review - Other 2007 UST Assessment Report data meet the ADEC quality assurance criteria. Analytical results of the HB04 soil boring sample found benzene at concentrations at 0.00295 mg/kg, just above the method detection limit and slightly above Method Two soil cleanup level of 0.0002 mg/kg. Bruce Wanstall
2/4/2008 Report or Workplan Review - Other Regulated underground storage tank soil and ground water assessment for tank closure and development of a conceptual site model was completed at the facility. ADEC reviewed and approved ADOT&PF Airport Maintenance Shop Site Assessment Report Sitka, Alaska by SLR. The Report indicates that target analytes were detected in soil and ground water below applicable Method Two screening levels with the exception of benzene in soil from HB04 at 0.00295mg/L. Bruce Wanstall
10/21/2008 Conceptual Site Model Submitted SLR 2007 Report data determined that since ground water at the facility is shallow (4.1 feet below ground surface) and the underground storage tanks are in the zone of ground water influence, a direct release from the existing buried tanks could occur. Even though no contaminant concentrations exceeded cleanup levels, ground water is considered an impacted media with regards to the conceptual site model. Other completed exposure pathways include incidental soil ingestion or dermal contact and indoor or outdoor air. The level of risk is abated by the presence of an asphalt cap across the site. Bruce Wanstall
2/25/2009 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 77852 USTs. Bruce Wanstall
3/11/2009 Final Cleanup Report Reviewed The fall 2007 investigation re-assessed residual soil contamination next to the former gasoline UST where a 1998 UST closure assessment found a “hot spot” of elevated DRO. Soil borings HB04 and HB05 were advanced at the same location as the “hot spot” mid-way in the length of the west side of the former gasoline UST and mid-way in the length of the east side of the out-of-service regulated waste oil UST. No soil discoloration or fuel odor was noted in soil cuttings. The benzene result in the HB04 soil sample was slightly above its migration to ground water cleanup level (0.00295 mg/kg) with DRO non-detect. DRO concentration in soil reached 49.2 in HB05 but benzene was not detected. Monitoring well MP1 was installed in HB05 and all analytes in the ground water sample were either below instrument detection or below Table C cleanup levels. Since the pocket of contaminated material (historical) that did exceed human health risk levels for direct contact and ingestion is underground, beneath an asphalt cap, and has not migrated to groundwater then the migration to groundwater pathway is incomplete. The 2007 data indicate that any remaining soil contamination is de minimis in both concentration and volume. Bruce Wanstall
2/2/2012 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 77852 USTs. Bruce Wanstall
2/29/2012 Cleanup Complete Determination Issued Based on the information provided to date, the DEC has determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment. No further remedial action is required at this site. This determination is in accordance with 18 AAC 78.276(f) and does not preclude DEC from requiring additional assessment and/or cleanup action if future information indicates that this site may pose an unacceptable risk to human health or the environment. Bruce Wanstall
3/12/2012 Update or Other Action Project manager changed from Bruce Wanstall to IC Unit. Evonne Reese
6/21/2013 Institutional Control Compliance Review IC compliance review conducted. Reminder system set-up to follow-up with the responsible party in 2016. Kristin Brown
3/18/2016 Institutional Control Compliance Review IC compliance review conducted. IC reminder letter drafted and scheduled to send out next year as part of this site's five-year review. Kristin Brown
5/18/2017 Institutional Control Compliance Review IC compliance review conducted. ICs Verification letter issued. Reminder system set for future follow-ups to occur every three years. Kristin Brown

Contaminant Information

Name Level Description Media Comments
GRO < Method 2 Most Stringent Soil
DRO < Method 2 Most Stringent Soil
Benzene Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation Soil

Control Type

Type Details
Land Use Plan / Maps / Base Master Plan A deed restriction agreement for future development on properties at the Sitka Airport managed by the ADOT&PF Airport Property Lease Division establishes restriction against accessing groundwater by requiring coordination with the DEC prior to installing any wells. Water and sewer are supplied to the area by the City of Sitka Public Works Department.

Requirements

Description Details
Groundwater Use Restrictions Development of drinking water wells is prohibited.
Other The monitoring wells currently installed at the property that are not needed for area-wide monitoring must be decommissioned in accordance with ADEC guidance as soon as it is determined these wells are no longer needed.
Advance approval required to transport soil or groundwater off-site. Standard condition.
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.
Periodic Review Every three years.

Missing Location Data

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