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i 'i 20 A feet. TOC elevation will be surveyed with a level sight instrument from the base elevation. Depth to water level will be measured n relation to the surveyed mark on the TOC. Measurement of Water Level and Product Thickness. Depth to water and product thickness will be measured with an electric interface probe sounder relative to the IIsurveyed elevation marked at the TOC. These data will be recorded to the nearest 0.01 foot Aquifer Testing. An aquifer test will be performed to determine aquifer parameters and the pumping rate necessary to capture the con aminated plume. The aquifer;,,test will be used to determine the following parameters. 3 • Yield of the aquifer • Transmissivity and hydraulic conductivity cf the aquifer • Storage coefficient of the aquifer • Drawdown at the extraction well • Drawdown at the monitoring wells • Additional sampling data on BTX concentrations The aquifer testing will entail slug testing of existing on-site monitoring well's and an extraction well pump test with a mobile groundwater treatment system. SlugTest--A slug test will be performed on the on-site monitoring wells to determine the hydraulic conductivity of the saturated slotted intervals. The changes in water level at regular, programmed time intervals will be measur as a known volume of water;)is added to or removed from the well. Extraction Well Pump Test--The pump test involves a step-drawdown pumping test followed by a constant discharge pumping test. groundwater treatment system will be required for treatment of the groundwater pumped during the pump test. Thegroundwater would be routed to two portable storage tanks co nected in series. Groundwater will be pumped continuously from the storage tanks through a granulated activated carbon (GAC) adsorption system. The storage tanks may allow th pump test to be performed at! a higher flow rate than the maximum flow rate allowed thr3ugh the GAC adsorption system. The option of disposing the treated effluent to the local sewer system is being pursued. A conceptual schematic of the extraction well and groundwater treatment system is shown on Figure 10_ The water generated during the step-dr wdown pumping test may be contained on site in portable Baker Tanks and later disposed of at an appropriate off-site facility. i Sten-Drawdown Pumping Tesc--A 6-hourstep-drawdown pumping test il will be performed to determine the optimum pumping rate for the constant discharge I pumping test. The test will consist of successive pumping periods under increasing';pumping rates. Pumping rates will be determined in ihe field and will be measured' from an in-line flow meter. Water levels will be mea tired periodically during the test with a water level probe. ii