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— BF, C�EARWArlER G R O U P I N C 5.2 Feasibility Testing Field Methods 5 2 1 A uifer Testing On December 19, 1995, Clearwater conducted a constant discharge pumping test on recovery well RW-1 A four-inch diameter, 1/2-horsepower, submersible electric pump (Grundfos Redi-Flo4 model 10E8) was placed in RW-1 at a depth of approximately 26 feet bgs The pumping rate was regulated using a diaphragm valve and measured with a flowmeter Water produced during the pumping test was stored on-site in a 21,000-gallon storage tank pending removal by a licensed hauler for disposal Prior to starting the test, static water levels and SPH thicknesses were measured in all monitoring wells Static water level elevations before the test are shown on Figure 8 Groundwater was extracted from RW-1 at a flowrate of 5 gallons per minute (gpm) for a period of 14 25 hours over the course of the pumping test At the end of the test, a water sample was collected from the discharge hose from RW-1 The water sample was analyzed for TPHg and BTEX by Trace Analysis Laboratory, Inc in order to determine what effect long term pumping had on dissolved hydrocarbon concentrations Water levels were measured throughout the test in all monitoring wells to obtain data necessary to quantify subsurface hydraulic characteristics and zone of capture 5 2 2 Dual-Phase Groundwater and Soil Vapor Extraction Testing After water levels had stabilized in the extraction test well (RW-1) on December 20, 1995, a vacuum blower (regenerative type, Rotron model E707) was attached to the well to perform a dual phase groundwater and soil vapor extraction test This was performed to evaluate the area of influence generated by the vapor extraction blowei under depressed water table conditions The dual phase test was conducted in steps of increasingly higher vacuums and groundwater extraction rates from RW-- 1 Air flow from RW-1 was regulated using a dilution valve at the inlet of the blower Each step lasted approximately 30 to 45 minutes and the entire dual phase test was completed in 2 5 hours During the dual phase test, vacuums, air flowrates, hydrocarbon concentrations, and percent lower explosive limit and oxygen were monitored at RW-1 Induced vacuums were measured at all monitoring wells (except MW-3) and vapor wells for radius of influence data Water levels in the extraction well were monitored during the test, and the pumping rates were increased with each step of increasing vacuum to keep approximately 11 to 12 feet of unsaturated screen exposed An air sample was collected at the end of the test for TPHg and BTEX analysis to evaluate the potential hydrocarbon removal rates of contaminants trapped in the vadose zone Vapor emissions from the test well were treated with granular activated carbon contained in a 55-gallon vessel D-107,PAR/RAP 8 February 21, 1996