ARCHIVED REPORTS XR0009905 - Laserfiche WebLink

Home Browse Search

Results of Groundwater Pumping Tests - 152 East 1 lth Street, Tracy Page 8 The test equipment was setup in the manner previously described, with the suction line, pump body and the section of discharge hose up-stream of the shut-off valve filled with water pumped from buckets The undisturbed depths to static water in the well to be pumped, NAV 6, and in NAV 3, the observation well, were measured using the conductivity-type water level probe Pumping from Well NAV 6 was started at 11 OOAM by rapidly opening the discharge shut-off valve shortly after the pump had been brought to full power The drawdown in Well NAV 6 was first measured 0 5 min after the start of the test, again 1 00 nun from the start and then at 1 00 min intervals up to 10 nun after the start of pumping Thereafter, these measurements were made at the times shown in Table 4, that records the data gathered during the test A first drawdown measurement was made in the observation well 15 00 min after the test started and more were made later at the times recorded in Table 4 During the progress of the test, the flow-meter reading was carefully observed and, as necessary, the flow-regulating valve and the pump air-supply were adjusted slightly to sustain a constant rate of discharge of 9 5 GPM, which was confirmed by checking the flow-meter reading against the mean time required to repeatedly fill a container of known volume with the discharged groundwater After a total pumping period of 160 min , a field plot of drawdown in the pumping well versus the logarithm of the pumping time showed that function to have maintained a straight-line form since a measurement of drawdown had been made 10 00 minutes after the test was started That being the case, and observing that the air temperature was steadily falling and there was a significant risk that conditions would develop that would cause the pump to freeze, pumping from Well NAV 6 was stopped by rapidly closing the discharge-line, shut-off valve Measurements of residual drawdown were then made while the wells recovered and until the water levels returned to close to their original elevations These measurements are also recorded in Table 4 Pumping Test on January 18th. 1994 Although the pumping test conducted on December 28th 1993 had been successful, it was decided that, if a suitable break in the weather appeared to be forthcoming, a second pumping test would be run using the Hermit SE2000 data logger and pressure transducer array to measure drawdown and recovery in the pumped and observation wells This second phase of testing was principally intended to be confirmatory and, through use of the data logger and pressure transducer array, to check that sufficient early time data had been obtained from the test conducted on December 28th , to preclude inadvertent miscalculation of geohydraulic parameters and to confirm that the small values of drawdown that had been observed in the observation well were reproducible An apparently reliable weather forecast was obtained for January 18th 1994 and personnel and equipment were mobilized into the field However, upon arrival, it was