ARCHIVED REPORTS XR0000575 - Laserfiche WebLink

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ATTACHMENT D OVERVIEW OF DPE PILOT TEST PROCEDURES DPE uses a high vacuum to extract both groundwater and soil vapor from a common extraction well. This technology is effective in situations with low permeability soil and relatively shallow groundwater. This technique utilizes a 2-inch diameter groundwater extraction pipe placed within a 4-inch diameter groundwater monitoring well. A vacuum is applied to the inner pipe and groundwater is extracted, thereby depressing the water table and exposing a greater portion of well screen for soil vapor extraction. Additionally, the depressed water table allows soil vapor to flow through previously saturated soil and also creates a hydraulic gradient to control or reduce downgradient migration of dissolved hydrocarbons. During each test, the subject well will be connected to a high vacuum liquid ring pump. Extracted groundwater and soil vapor will be separated above ground. The extracted soil vapor will be routed to a catalytic/thermal oxidizer for hydrocarbon abatement. The extracted groundwater will be routed to the holding tanks for profiling and disposal after the test. During the test, the following parameters will be monitored: • Vacuum pressure; • Vapor extraction flowratc; • Groundwater extraction flowrate; • Groundwater elevations; • Contaminant concentration in extracted groundwater stream; and, • Contaminant concentration in extracted vapor stream. System parameters will be monitored and vapor stream samples will be collected periodically during the test. The pilot test will involve the following procedures: • Depth-to-water(DTW) in observation wells will be measured prior to initiating the pilot test and every two hours, thereafter. The DTW measurements will be measured to the nearest 0.01 foot using an electronic water level indicator.