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R NAI.R6MEOIATION PIAN 1399 East Yosemite Avenue Manteca California 1 ' The radius of influence induced by the vapor extraction plot test on well MWA B was ' measured at wells MW-2, MW-3, and MW-5 An average influence of -1 05 inches of water was measured at well MW-2, at a distance of approximately 31 feet from the well MW-1 B An average influence of -0 68 inches of water was measured at well MW-3, approximately 40 feet from the well MW-1 B An average influence of-0 73 inches of water was measured at well MW-5, approximately 42 feet from well MW-113 ' The measured airflow yield from well MW-1 B, together with the calculated radius of influence on the surrounding monitoring wells, indicate well MW-113 would be a viable candidate for in situ vapor extraction 4.0 AQUIFER ANALYSIS TEST ' Rising head tests (slug tests) were performed in monitoring wells MW-2, MW-3, and MW-5 on July 3, 1991, in order to estimate the hydraulic conductivity (K) of the water-bearing horizon in the immediate vicinity of the monitoring wells A pressure transducer was placed in the subject well at a depth varying between 7 to 9 feet below the standing water The transducer was connected to an "Aqua Star" data logger to record the changes in water level over time The slug tests consisted of dropping a 5-foot-long, 1-1/4-inch-diameter PVC pipe, capped at both ends and filled with clean sand, into MW-2 and MW-3 A 3-inch-diameter slug was use in MW-5 When it was determined by monitoring the output from the data logger that the groundwater elevation had stabilized in the subject well, the PVC pipe was removed resulting in an instantaneous lowering of the groundwater elevation in the well The recovery rate (rising head) of the well was then ' recorded by the data logger The software package "Agtesoly" (Geraghty and Miller Inc 1989) was used to analyze the data The program has curve drawing and matching capabilities The data is analyzed by plotting the time and change in groundwater elevation on the appropriate log or sem,- log paper, then matching the data with the appropriate published "type curves " The ' method of analysis depends on site-specific hydrogeologic conditions, both human-made and natural The method used to analyze the data at the subject site was the Bouwer and Rice slug test method for unconfined aquifers (Bouwer, et al 1976 ) The values for K ranged from 1 024 x 10-'to 5 0802 10'feet per minute (ft/min) The "Agtesolve" output is included in Appendix C ' The method used to analyze the potential pumping rate of the aquifer (Q) was the Dupuwt equation (Dupuit, J , 1863) The values for Q ranged from 0 05 to 6 04 gallons per minute ' (gpm) Data and assumptions made in analyzing the data are included in Appendix C 1 ' 90-09$F RPT