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S� Results of Groundwater Pumping Tests - 152 East 11th Street, Tracy Page 7 Test Schedule Due to the previously described seasonal weather conditions, which cannot be reliably forecast with the necessary level of detail and certainty for the test to be run without risk of pump failure, it was decided that it would be prudent to schedule the groundwater pumping test in two phases An initial pumping test was planned during which depths to water in the pumping well and observation well would be measured using the conductivity-type water-level probe This probe is operated manually and has a resolution of 0 01 ft , which is adequate for the test conditions that had been determined from the pumping trial, but has the disadvantage that repeated measurements of the depth to water can not be made with the rapidity needed to obtain the successive measurements of drawdown data at intervals of seconds and fractions of seconds that are desirable during the first 5 to 10 min after pumping has started However, depending upon the hydraulic characteristics of the well and the geologic formation, such early data are not normally used when the test data are reduced for the purpose of calculating hydrogeological parameters They serve only to provide indicators of the time following start of the test when the data are suitable for use in making calculations of transmissivity and its derivative parameters Data suitable for the latter purpose is usually only obtained at times at least 10 min following the start of pumping Also, electronic data loggers and pressure transducers are expensive and would rapidly generate unjustifiably high project costs if they were brought into the field when a test had to be abandoned due to inclement weather conditions By planning an initial test that would not utilize the high cost pressure transducer array, it would be possible to cost-effectively 1 ) confirm the equipment selection made following the pumping trial, 2 ) obtain information on the total pumping duration that was necessary and, 3 ) in all likelihood, obtain all data necessary to compute of the desired geohydraulic parameters If it a second phase of testing, with an electronic data logger and pressure transducers, was shown to be essential, or could be performed within the constraints imposed by the seasonal weather conditions and the test schedule requested by SJCPHS, a test using that type of instrumentation was also proposed Based on the considerations outlined above, a careful watch was kept on weather conditions and pumping tests were performed in well NAV 6 on December 28th 1993 and on January 21st 1994 During the tests on December 28th drawdown was measured using a manually operated conductivity-type, water-level probe On January 21 st a data logger and pressure transducer array was used Pumping Test on December 28th. 1993 After being cold and somewhat foggy in the early hours, the weather on December 28th became mild with relatively low atmospheric moisture