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BOUWER AND RICE SLUG TEST During; this monitoring round, a water recovery probe (pressure transducer) was used to obtain information for Bouwer and Rice Slug Test calculations. Before purging the wells for sampling and after obtaining the depth to ground water measurements, a sensitive (to 0.01') transducer was lowered into each well to at least 4.5' below the top of the ground water surface. A sterile bailer Was then lowered into the well and allowed to completely fill with water. The transducer was raised one foot to calibrate the one foot reduction in head and then allowed to drop back to its previous position. A miliaamp reading was obtained before the bailer was rapidly removed and the drop in milliamps recorded (total drawdown). With every milliamp recharge the time was noted until total or near total recovery had been achieved. The natural log of the time recharge ,points was: plotted and-.values .for ;. hydraulic conductivity "K" were then calculateds- (4ea:.Table.2 and'. Ap 6ndix Ay. "Once the "K" values were computed, they were used to classify the formation type and to assign an effective porosity to each well (by assuming effective porosity is similar to specific yield, as found on page 8, and by using the table on page 12 of "Hydraulic Conductivity of Selected Rocks" in Basic Ground Water Hydrology, United States Geological Survey Water Supply Paper 2220, 1983). For all the monitor wells, with the exception of MW-2, effective porosity calculated to be approximately 22% (silty-fine clean sand); the effective porosity for MW-2 . calculated to be i approximately 2% due to its low K value (silty clay-silt). Using i _ the gradient information as displayed in Figure 4G, a velocity was ' then calculated for all of the wells and contoured on Figure 5. E Alsn based: on the slug test, data, stagnation points.,.veV ca'culated fa tnosi3tor,wesll HSI-1 at"a'hump"rete of"250 allons NE'r, day 7rand for monitor well HW-3 at,a 'pump;rate'af 900 .galldns :' per t :Kdayn(see Figure .6-.and,Table 3), 4.0 CONCLUSIONS 1. Based upon the results of our subsurfaces investigations, significant ground water contamination exists in monitor wells MW-1, MW-2, MW-3, MW-4, MW-6, MW-8, MW-9, and MW- s 10. 1 2. The ground water flow direction is to the east northeast and nortF; this variation is most likely due the difference in hydraulic conductivities and velocities of the wells and local pumping activities. 3. All measurable gasoline product has been recovered from monitor wells MW-1 and MW-3. - 4. No soil contamination exists inmonitor wells MW-1 thru MW-8 from the surface down to 65 feet below the surface. 20