Soil Vapor Extraction at the North Fire Training Area (NFTA), Luke AFB, Arizona

Site Name:

Luke Air Force Base



Period of

October 1991 to December 1992


Full-scale cleanup


- Dan McCaffery
Envirocon, Inc.
- James Ramm
Rust Environment

Soil Vapor Extraction - 1 extraction well for each of 2 fire pits - Wells constructed with 35-foot screens to depths up to 57 feet - Thermal oxidizer used for destruction of organics in extracted vapors

Cleanup Authority:
State: Arizona

SIC Code:
9711 (National Security)
Point of Contact:
Jerome Stolinksi
U.S. Army Corps of Engineers
Omaha District

Total Petroleum Hydrocarbons (TPH) Benzene, Toluene, Ethylbenzene, Xylenes (BTEX), and Methyl ethyl ketone (MEK) - Initial soil contamination in two fire training pits - Benzene - 0.2 to 16 mg/kg; Toluene - 10 to 183 mg/kg; Ethylbenzene - 21 to 84 mg/kg; Xylenes - 69 to 336 mg/kg; and Total Recoverable Petroleum Hydrocarbons (TRPH) - 151 to 1,380 mg/kg

Waste Source:
Fire Training Area

Type/Quantity of Media Treated:
Soil - Permeable silty sands, very permeable, clean well graded to poorly graded sands, and permeable to low permeability inorganic silts - Moisture content 10% - Permeability of top soils ranged from 1 x 10[Sup -4] to 3 x 10[Sup-3] cm/sec - Porosity ranged from 36 to 46%

Purpose/Significance of Application:
Full-scale cleanup of two fire training pits using soil vapor extraction.

Regulatory Requirements/Cleanup Goals:
- Arizona Action Levels for soil - TPH - 100 mg/kg; and BTEX - 412 mg/kg - Applicable state air emissions standards

- Treated soil concentrations indicated TPH and BTEX were below the Arizona Action Levels - 12,000 lbs of contaminants were removed during 30 weeks of operation - Removal rate remained at 40 lbs/day after 30 weeks of operation - Soil gas concentration reductions achieved in 6 months for 8 constituents ranged from 72 to 96% (benzene)

Cost Factors:
Total cost - $507,185 - Capital costs - $297,017 (including site preparation, site work, startup, engineering, pipes, buildings, permitting, and regulatory) - Annual operating costs - $210,168 (including labor, laboratory charges, monitoring, fuel, electricity, maintenance, and disposal of residuals)

Routine fire training exercises were conducted at Luke Air Force Base in Arizona between 1963 and 1990, using petroleum, oil, and lubricant wastes, and JP-4 fuel. Fire training pits number 3 and 4 were used since 1973. During site investigations conducted between 1981 and 1989, soil at these two pits were determined to be contaminated with total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Cleanup goals were established for TPH and BTEX in soil based on Arizona Action Levels (AALs) - TPH at 100 mg/kg, and BTEX at 412 mg/kg.

A full-scale cleanup using Soil Vapor Extraction (SVE) of the soil in the two pits was conducted from October 1991 until December 1992. A thermal oxidizer was used for destruction of organic vapors extracted from the soil. The full-scale system, which used the thermal oxidizer, removed 12,000 pounds of contaminants in 30 weeks of operation. TPH and BTEX levels were below the AALs after five months of operation, with TPH and benzene reported as not detected in March 1992. Results of sampling in November 1992 showed ethylbenzene, toluene, and xylenes as not detected. System downtime was about 1% during this period. After a temporary shutdown period, an attempt to restart the system caused a malfunction in the thermal oxidizer and the destruction of the burner. As of December 1992, future activities at the site were pending.

The total cost of this treatment application was $507,185. It was noted that the site investigation underestimated the amount of contamination at the site. A pilot-scale study was conducted at Luke prior to implementing the full-scale system. The pilot-scale system used vapor-phase granular activated carbon to treat extracted soil gas. Due to unexpectedly high concentrations of volatile organic constituents, the carbon supply was exhausted after two days of operation and the study was aborted. In discussing remediation of sites contaminated with JP-4 jet fuel, the report includes a discussion of the relative benefits of using SVE and bioventing techniques.