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I SAN JOAQUIN COUNTY SLUG TEST RESULTS AND ANALYSIS Slug tests were performed on three monitor wells MW-4, MW-6 nd MW-8 in the City of ' Stockton on October 30 and 31, 1991 to assess the hydraulic properties of the aquifer at the site Field Procedures for Slug Tests IAll equipment was decontaminated before conducting the slug test ' The static water level was initially measured with a Solinst water level indicator with water levels being recorded to the nearest 0 01 foot ' The total casing depth was determined with a weighted measuring tape I The water levels obtained during the slug test were measured with an Aquistar* Datalogger (DL- I/DL-IA) and pressure transducer The transducer probe was set in the well at approximately a foot above the total depth of the well as determined from the depth of the well, sensitivity of ' the transducer, height of the water column in the well, and length of the slug to be introduced in the well The probe cable was secured to the outside of the well casing and to the Aquistar datalogger (which sits on the well casing) The Aquistar* datalogger was directly connected to a laptop computer for easy viewing access during the slug test This was accomplished by a menu driven program (PGM3) executed through the laptop computer ' A measured and marked length of rope sufficient to lower the tip of the slug below the static water level was attached to the slug For the falling head test, the solid slug was lowered into the well so that the bottom of the slug was positioned approximately 2 feet above the initial static ' water level The data logger was then activated and the slug was quickly lowered to approximately 1 to 2 feet below the static water level in the well but above the transducer probe The test was continued until water levels returned to within 10 percent of their static water level ' The rising head test was performed immediately following the completion of a falling head test ' after the water levels were stabilized The data logger collection schedule was reset prior to commencing the rising head test The slug was quickly removed and measurements were collected until the water levels returned to 10 percent of the static water level ' All data generated by the pressure transducer and recorded by the data logger was saved in individual files in the laptop computer ' Data Ana! sis ' Since the static water levels in the wells were within the screened zones, the rising head test data was more applicable than the falling head test data This is due to the flow of water during a falling head test, not only through the screen but also through the vadose zone which increases the rate of fall of the water Ievel in the borehole and leads to an overestimation of hydraulic conductivity, K (Bouwer H , 1989) ' HTSISiC WP 0"1192