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Extended Site Characterization Report: 7500 West Eleventh Street, Tracy, CA. Page 16 ifs k: latitude and longitude of a point on the earth's surface to within a } resolution of three meters. That resolution is clearly sufficient for such purposes and any other general mapping purpose related to geographical f or informational databases. However, solely to comply with the requirement of the recently-enacted California Assembly Bill 2886, it was necessary to resurvey their latitudes and longitudes to a resolution of less than one meter and in degrees recorded to seven places of decimal. This was achieved by mobilizing a surveying crew into the field equipped with GPS receivers and auxiliary equipment capable of that resolution. The elevational and latitudinal and longitudinal data for each well is recorded in Table 1. Unfortunately, the resolution obtainable even with the specialized GPS equipment used to obtain the latitude and longitude data presented in that table does not provide sufficient resolution for the purpose of measuring relative monitoring well locations, which is required to accurately compute groundwater gradients and flow directions. To provide measurements of sufficient accuracy, SJC employed standard i engineering surveying techniques to locate the wells and measured the distance between them using a surveyor's tape. F.. 5.5 Well Drilling and Soil Sampling Prior to the commencement of exploratory drilling and groundwater-quality monitoring well construction at the site, the necessary drilling permits were obtained from the SJCEHD. Encroachment permits for installation of groundwater-quality monitoring wells along both Chrisman Road and West Eleventh Street were obtained from the San Joaquin -� County Department of Public Works (SJCDPW). Bonds for the maintenance and eventual removal of those wells were also obtained to comply with the requirements of `+ that agency. During the period March 25-28, 2002, two small-diameter exploratory borings and eight monitoring well borings were advanced using an 8-in., open-stem auger drilling rig operated by Spectrum Exploration, Inc., a drilling contractor holding a C57 license issued by the California Contractors State License Board. Dr. Dai Watkins, P.E., a California- licensed geotechnical engineer, logged the borings. The well casings are 2-in, diameter PVC with 0.02-in., machine cut screen slots. These and other details of the well construction are shown on the well logs compiled in Appendix A, as are the logs of exploratory borings. While the borings for proposed Monitoring Wells MW-8 through MW-11, MW-3A, MW3B and MW-12A were being drilled, the drilling equipment was used to recover soil samples in clean, brass tubes from a depth of 5 ft. in each hole - and generally at 5-ft. intervals thereafter - to the bottom of the boring. However, responding to such factors as percentage core recovers and observed changes of lithology, the engineer directed SJC