Technology:
Land Treatment
- Stockpiled soil was washed and screened into stockpiles by particle size.
- The small diameter soil was placed into windrows and tilled during summer months.
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Cleanup Authority:
Remedial Action under Alaska Department of Environmental Conservation UST Regulations
Regulatory Point of Contact:
Rielle Markey
Alaska Department
of Environmental Conservation
University Avenue
Fairbanks, AK 99709
(907) 451-2117 | USACE Contact:
Bernard T. Gagnon
USACE - Alaska District
P.O. Box 898
Anchorage, AK 99506-0898
(907) 753-5718 |
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Contaminants:
Semivolatile and volatile nonhalogenated hydrocarbons - gasoline, diesel fuel, and BTEX components. Maximum contaminant concentrations of 3,000 mg/kg gasoline range organics, 1,200 mg/kg diesel range organics, and 20.2 mg/kg BTEX. |
Waste Source:
Leaks from USTs and/or overfilling of USTs or ASTs |
Type/Quantity of Media Treated:
Soil
- 11,939 yd3 screened and washed
- 9,800 yd3 land treated |
Purpose/Significance of Application:
Application of land treatment to treat gasoline and diesel contaminated soil ex situ |
Regulatory Requirements/Cleanup Goals:
- The goal of this remedial objective was to meet the ADEC Level A standards for UST-contaminated soils (as cited at 18 AAC 78.315) so that the soil could be used as final cover material for Landfill 7. The Level A standards are: DRO - 100 mg/kg, GRO - 50 mg/kg, benzene - 0.1 mg/kg, total BTEX - 10 mg/kg, and RRO - 2,000 mg/kg. |
Results:
- The concentrations of hydrocarbons in the contaminated UST soil stockpiles was reduced to below the ADEC Level A standards in two summers (with the exception of two samples that still contained DRO above the cleanup standard). The soil was used in the capping of the landfill.
- The average concentrations of contaminants indicate that the mass of DRO in the contaminated soil was reduced from 4,641 kg to 719 kg (approximately 85 percent), and the mass of GRO in the contaminated soil was reduced from 175 kg to nondetectable levels (approximately 100 percent) during the land treatment.
- Initial estimates, based on oxygen uptake measurements taken during a treatabililty study, showed that the remediation of the soil would take approximately 60 days of summer temperatures. The actual remediation took more than twice that long (July 1995 through July 1997). |
Cost Factors:
- The total cost of this remedial action was $696,171, consisting of $405,883 Phase I, soil screening and washing (including site preparation and mobilization) and $290,288 for Phase II, land treatment of soil.
- A total of 11,939 yd3 of gasoline- and diesel-contaminated soil were processed in Phase I and 9,800 yd3 (approximately 82 percent of the total volume) were treated in Phase II. The unit cost breakdown is: $34/yd3 for Phase I, $29.62/yd3 for Phase II, and $58.29/yd3 for the total treatment. |
Description:
The UST soil stockpiles are located at the 1970s landfill or "Landfill 7," located in the southeast sector of the U.S. Army Ft. Greely military facility. Ft. Greely is located approximately five miles south of Delta Junction, Alaska. The contaminated soil stockpiles were generated from the excavation of contaminated soil during a facility upgrade and site restoration activities at the Black Rapids Ski Area during the Summers of 1992 and 1993 and from the excavation of contaminated areas near buildings 602 and 606 at Ft. Greely in August 1991.
In the Fall of 1994 and Summer of 1995, Phase I of the remedial action was conducted, involving the screening and washing of the contaminated soil stockpiles and the completion of a biotreatability study on samples of the contaminated soil. The biotreatability study determined that the contaminated soil could be effectively treated via land treatment. In the Summer of 1995, the contaminated soil stockpiles were separated into windrows, to which nutrients and water were added. The windrows were tilled on a regular schedule during the summers of 1995 and 1996. Samples of the contaminated soil were collected at the end of each summer. In June 1997, closure samples were collected, which showed that the levels of contaminants in the soil had been reduced to below ADEC Level A cleanup standards in all but two of the samples. The soil was then used in the capping of Landfill 7. |
