Site Report: NPS Denali Nat'l Park Toklat Maintenance Facility USTs 1 & 2
| Site Name: | NPS Denali Nat'l Park Toklat Maintenance Facility USTs 1 & 2 |
|---|---|
| Address: | Mile 54 Denali Park Road, Denali Park, AK 99755 |
| File Number: | 220.26.004 |
| Hazard ID: | 24051 |
| Status: | Cleanup Complete |
| Staff: | No Longer Assigned, 9074655229 dec.icunit@alaska.gov |
| Latitude: | 63.520128 |
| Longitude: | -150.046255 |
| Horizontal Datum: | NAD83 |
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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
The National Park Service Toklat Maintenance Facility is located at Mile 54 Denali Park Road in an area used for seasonal employee housing. The sources of contamination were two regulated 4000-gallon underground storage tanks (USTs). UST #1 contained gasoline and UST #2 contained diesel. Both USTs supplied fuel to a dispenser island via underground piping. In July 2000, the USTs were closed and a site assessment was conducted. At that time, both tanks, two dispensers, and the piping were removed. Approximately 137 tons of contaminated soil were excavated and transported for thermal treatment. Contaminated soil within the UST area was excavated down to the depth 9 feet below ground surface (bgs) where the groundwater table was found. Groundwater was found at 3 feet bgs in the piping and dispenser areas. Confirmation soil samples were collected and concentrations of benzene, gasoline range organics, and diesel range organics exceeding their respective soil cleanup levels were left in place due to the presence of groundwater and the presence of a storage building on the western side of the UST excavation area. Additional soil and groundwater characterization were conducted from 2001 through 2004. The site was closed in 2005.
Action Information
| Action Date | Action | Description | DEC Staff |
|---|---|---|---|
| 7/30/2000 | Leaking Underground Storage Tank Release Confirmed - Petroleum | LUST Site created in CSP for source area ID 78093 As per report, a release lead to the excavation of approximately 70-cubic yards, which were removed and thermally treated. (JBC) | John Carnahan |
| 7/30/2000 | Site Added to Database | Former Staff | |
| 2/26/2001 | Underground Storage Tank Site Characterization or Assessment | Conducted at time of closure. | John Carnahan |
| 2/26/2001 | Leaking Underground Storage Tank Cleanup Initiated - Petroleum | See below | John Carnahan |
| 2/26/2001 | Update or Other Action | The soil was removed as much as possible, and GRO/DRO levels were below Level A. However, benzene is still elevated above 0.02 mg/kg, and there is a dark black layer at the GW interface (which can be as high as 3 feet below grade) and is thought to be anerobically degraded diesel. They will investigate summer 2001. | John Carnahan |
| 4/10/2001 | Update or Other Action | Met with Joe Duremburger today to discuss the Toklat site. Discussed the site and the pending work to be completed this summer. Joe offered additional release investigation, specifically horizontal delineation. I proposed some additional and inexpensive groundwater monitoring as well. The only likely exposure pathways include: (1) dermal contact since the GW table is shallow (as high as 3-feet below grade); and (2) ecological receptor since the Toklat river is only 300 feet away. If they can complete some monitoring points and delineate the extent of a thin dark organic-rich layer that may be representative of he diesel contamination, they will have gone a long way to resolving the extent of the problem at hand. It is unlikely that extensive excavation will be required, although they do have the resources to do this work at this site, including equipment and a crusher or sorter. | John Carnahan |
| 11/26/2001 | Document, Report, or Work plan Review - other | Release Investigation report received | Jeff Conn |
| 5/14/2002 | Document, Report, or Work plan Review - other | Groundwater Monitoring Plan approved | Jeff Conn |
| 6/5/2002 | Release Investigation | Work Plan for Phase II investigation approved | Jeff Conn |
| 8/21/2002 | Update or Other Action | RECKEY has automatically been generated. | Cynthia Pring-Ham |
| 1/28/2004 | Update or Other Action | Transferred DEC staff lead from John Carnahan | Cynthia Pring-Ham |
| 11/14/2008 | Cleanup Complete Determination Issued | On March 3, 2005, ADEC issued a No Further Remedial Action Planned determination for the NPS Toklat site. This site is located at Mile 54 Denali Park Road in an area for seasonal employee housing. The sources of contamination were two regulated 4,000-gallon USTs. In 2000, the USTs were closed and both tanks, two dispensers, and the piping were removed. Approximately 137 tons of contaminated soil were excavated and transported to OIT for thermal remediation. Contaminated soil within the UST area was excavated down to a depth of 9 feet bgs where the groundwater was encountered. Six soil borings were installed in the source area and the highest soil sample indicated benzene at 0.2 mg/kg, ethylbenzene at 21.4 mg/kg, GRO at 1,070 mg/kg and DRO at 6,720 mg/kg. In 2002, three monitoring wells were installed to depths of 7 - 8.5' bgs. A total of 9 wells were installed at the site and were monitored semi-annually. MW-6 was placed in the area of highest remaining contamination and historically has showed groundwater contamination above Table C levels (highest level in 2001 at 0.05 mg/L). Sample results for all wells were below the respective cleanup levels for the last three monitoring events. Groundwater at the site is used for drinking water, however the installation of a drinking water well downgradient of the site is unlikely as water is already provided by a 75-80 foot deep well located 500 feet upgradient to the south. The NFRAP requires prior notification to the department for disposal, movement, and relocation of the contaminated soil off-site. Also, the NPS has agreed to place a notice on its GIS land management tracking database. | Deborah Williams |
| 6/27/2014 | Document, Report, or Work plan Review - other | Approved letter work plan to decommission monitoring wells MW-1 to MW-9 | Melody Debenham |
| 9/2/2014 | Document, Report, or Work plan Review - other | Approved letter report documenting decommissioning MW-1, MW-2, MW-3, MW-4, MW-5, and MW-7. Monitoring wells MW-6, MW-8, and MW-9 could not be located for decommissioning. | Melody Debenham |
| 9/30/2014 | Potentially Responsible Party/State Interest Letter | Potentially responsible party letter sent to the National Park Service. | Melody Debenham |
Contaminant Information
| Name | Level Description | Media | Comments |
|---|---|---|---|
| DRO | Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation | Soil | |
| Benzene | Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation | Soil | |
| Ethylbenzene | Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation | Soil | |
| GRO | Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation | Soil |
Control Type
| Type | Details |
|---|---|
| No ICs Required |
Requirements
| Description | Details |
|---|---|
| Advance approval required to transport soil or groundwater off-site. |
| Hazard ID | Site Name | File Number |
|---|---|---|
| 27132 | NPS Denali Nat'l Park Toklat Generator Bldg | 220.38.043 |