SITE INFORMATION AND CORRESPONDENCE

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yields sediment-free samples. Ground-water samples will then be obtained for laboratory chemical analysis using a clean teflon bailer. Ground-water samples will be analyzed for TPH as gasoline using GC FID/5030 and BTEX using EPA 8020. Ground-water samples will be analyzed for TPH as gasoline and BTEX. Quarterly reports showing water level data, OVA readings in the TVMPs (discussed below), and water sample analysis results will be submitted to the EHD and the Regional Water Quality Control Board, Central Valley Region (Water Board). Ground-water monitoring will continue until site closure is obtained. Install Infiltration Probes and Inoculate Contaminated Soil and Water The infiltration probes will be drilled using a six inch hollow stem auger on 10 foot centers to just above the zone of soil contamination at the locations shown on the Site Plan, Plate 3. Each probe will be drilled, filled with approximately 200 gallons of microbial solution, and then sealed with cement bentonite grout in one continuous operation. To protect the subsurface from surface spill, no open probes will remain unattended during site work. The naturally selected hydrocarbon-degrading microbes that will be used are pseudomonas and bacillus bacteria that are non-mutagenic, non-pathogenic, and non-carcinogenic. They are microaerophilic bacteria, distinct from aerobic or anaerobic bacteria, in that they will respire in oxygen-rich or oxygen- poor environments. The organisms are shipped in dry form and are activated by mixing them in water with a blend of propriety nutrients. After a three hour activation time, the organisms have depleted the nutrients in the water to the extent that the water will meet drinking water standards. At this point, the microbial solution will be gravity fed to selected infiltration points. Infiltration probes will first be drilled on the periphery of the contaminated area, beginning with the downgradient side. Infiltration will proceed from the periphery toward the center of the area of contamination. The soil cuttings stockpile will be inoculated with the microbial solution using a hydrolance on three- foot centers to remediate gasoline constituents. Care will be taken not to saturate the soil and create a leachate. The microbial solution will also be mixed with the drummed water to remediate gasoline constituents. When OVA readings collected from the soil stockpile and drummed water reach acceptable levels, samples of the soil and water will be collected for laboratory analysis. Soil and water will be disposed to an appropriate facility based on laboratory analysis results. Monthly Monitoring of Vapors in TVMPs and Water Levels in the Wells Following inoculation of the subsurface, twice during the first two months and monthly thereafter, organic vapors in the TVMPs will be tested with an OVA to monitor the progress of remediation. Typically the progress of remediation is characterized by a bell-shaped curve of concentration versus time. Initially the microbes break down less volatile long chain hydrocarbons into more volatile short chain hydrocarbons, resulting in a rise in readings with time. After a while, the microbes biodegrade the short-chain hydrocarbons, resulting in a drop in OVA readings. When the OVA readings become December 15, 1994 Job No. 1278.02.01 - 4 -