Methodology for assessment of contamination of the unsaturated zone by leaking underground storage tanks
Three methods of measuring contamination of the partially saturated zone by leaking underground fuel tanks were investigated. Two of the methods relied upon obtaining a soil core from the field. These differed in the method of extraction: (1) by nitrogen purge of the entire core, followed by adsorption-solvent extraction and gas chromatographic (GC) analysis, and (2) by sonication of a small sub-sample from the core, followed by solvent extraction and GC analysis. The third method focused on saturation zone. This required use of a driveable ground probe (DGP) and activated carbon trap, followed by solvent extraction and GC analysis. The soil core procedures required construction of a sampling tube that proved successful in the system upon return to the laboratory. Recoveries approaching 100% were achieved in the nitrogen purge procedure by: heating the soil core to 100 C; trapping water exiting the soil core prior to the adsorption step; and using activated carbon instead of Tenax as the adsorbent. Vapor phase measurements provided a convenient way to map the extent of contamination from a leaking underground gasoline storage tank at the Camp Lejeune site. Concentrations of target compounds ranged from 10,000 micrograms/L (ug/L) to < 10 ug/L of vapor phase. The highest concentrations were found above the non-aqueous-phase liquid (NAPL). However, the method was able to show that contamination exists well beyond the NAPL, although the concentrations drop off precipitously. 36 refs., 29 figs., 11 tabs.
- OSTI ID:
- 6843542
- Resource Relation:
- Related Information: Water Resources Research Institute of the University of North Carolina Report No. 242
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
GASOLINE
MEASURING METHODS
GROUND WATER
CONTAMINATION
ADSORPTION
DRILL CORES
ECOLOGICAL CONCENTRATION
GAS CHROMATOGRAPHY
LEACHATES
LEAKS
MONITORING
NORTH CAROLINA
SOILS
SOLVENT EXTRACTION
TANKS
UNDERGROUND STORAGE
WATER POLLUTION
CHROMATOGRAPHY
CONTAINERS
DISPERSIONS
EXTRACTION
FEDERAL REGION IV
FUELS
HYDROGEN COMPOUNDS
LIQUID FUELS
MIXTURES
NORTH AMERICA
OXYGEN COMPOUNDS
PETROLEUM PRODUCTS
POLLUTION
SEPARATION PROCESSES
SOLUTIONS
SORPTION
STORAGE
USA
WATER
020900* - Petroleum- Environmental Aspects
540320 - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)