SITE INFORMATION AND CORRESPONDENCE

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piping, which causes the major portion of the contaminants in the ground water to be stripped into the vapor phase. Stripping efficiencies exceeding 95% are possible; however, stripping efficiency is dependent upon site-specific variables, including the vacuum intensity, the air/vapor/water ratios, contaminant concentrations and contaminant physical properties. The "pre-treated" or essentially air-stripped water is routed through a pump to a carbon vessel for final polishing treatment to reduce contaminant concentrations to less than what can be detected in an analytical laboratory (non- detect). The extracted contaminant vapor stream will be routed to the catalytic oxidizer possibly with an intermediate and smaller "knock out" pod to trap excess moisture mixed with the vapor. Key features of the proposed DPE remediation system DPE remediation system piping, which will be installed underground in a 1'/2-foot wide by a 1'/2-foot deep trench; the proposed trenching lay-out is depicted in Figure 10; a cross sectional view of the trench is depicted in Figure 11 . A privacy chain-link, gated enclosure will be installed midway along the eastern site boundary to contain the DPE system. The system fencing enclosure is illustrated in Figure 10. A 25-horsepower, oil-ring vacuum blower and catalytic oxidizer will be utilized for simultaneous extraction of ground water and/or soil-vapor from various on-site wells and destruction of extracted hydrocarbons. A set of three granular activated carbon (GAC) vessels are to be utilized to treat the effluent wastewater to non-detectable concentrations for fuel additives prior to discharge into the City of Stockton sewer system. The extraction and treatment process From each well-head the extracted vapor and water will be transferred through the 1-inch diameter PVC piping to the liquid holding vessel (water-vapor separating chamber) and the source of the high vacuum at the oil-ring vacuum pump. From the separating chamber, the ground water will be processed (via 1- hp process pump and sediment filter) directly through three 2,000-pound media vessels containing liquid phase activated carbon; simultaneously soil-vapor may be processed through a secondary water knock-out pod, then processed through a catalytic oxidizer for soil-vapor treatment. The treated ground water will be discharged under a City of Stockton permit into the sanitary sewer system; the processed vapor will be destroyed by catalytic oxidation and the byproducts exhausted into the atmosphere under San Joaquin County Air Pollution Control District permit. A diagram of a typical DPE system is illustrated in Figure 12.