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Each well was then purged of approximately 3 well casing <br /> volumes or until pH, specific conductivity, and temperature <br /> readings had stabilized prior to sample collection. Water <br /> samples were collected using a clean PVC bailer, decanted <br /> into clean containers, and transported in an iced cooler to a <br /> -- California state--certified laboratory for analysis following <br /> proper sample preservation procedures and chain of custody <br /> documentation. Eater development and sampling data are <br /> presented in Appendix E. <br /> 3.4 Ground Water Level Mnnj*or rng and 5uLvevina <br /> After well completion, the top of well casing elevations were <br /> surveyed on August 27, 1990 with respect to a City of Tracy <br /> temporary bench mark. This bench mark was located on top of <br /> the southernmost bolt of the street light pole base on the <br /> southwest corner of the intersection at Grant Line Road and <br /> Tracy Boulevard. The elevation of the temporary bench mark <br /> is 26.13 feet above mean sea level. <br /> Ground water level in each well was measured to the nearest <br /> 0,01 foot on August 27, 1990 from the top of the PVC casing <br /> using an electronic sounder. A ground water elevation <br /> contour map, based on interpretation of ground water level <br /> and survey data, is shown Figure 3. Survey data and water <br /> level measurements are presented in Table 1. <br /> 4.0 AQUIFER TESTING AND ANALYSIS <br /> -; The analysis of aquifer characteristics for the purpose of <br /> estimating the fate and transport characteristics of <br /> -• contaminants in ground water involves several steps. The <br /> first step involves the exploratory stage, using surface and <br /> subsurface geological and geophysical techniques to determine <br /> the water-bearing formaticn. The evaluation stage follows to <br /> determine hydrogeologic parameters and characteristics of -the <br /> aquifer necessary for the proper design and construction of <br /> recovery or extraction wells, and for the control of <br /> contaminant migration. The last step is the confirmation <br /> stage to optimize the design and operation of the wells for <br /> the management and remediation of ground water. <br /> 4.1 Lit erf►ture Review and Basis-of Analysis <br /> The hydraulic properties of aquifers and soil materials that <br /> define the rate of water movement into, through, and out of <br /> subsurface materials, and its effect on the piezometric <br /> surfaces or water tables, are hydraulic conductivity (K), <br /> transmissivity (T) , and storage coefficient (S) or specif'c <br /> - --- ------yield--for unconfined aquifer. <br /> 7 , <br />