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Extended Plume Definition,-7500 W 11th St.,Tracy,CA. Page 6 the local and regional groundwater flow regime, could be anticipated to have migrated to the east of the western side of Chrisman Road and north across West Eleventh Street. (See Figure 2 for cited locations.) In late July 1999, SJCEHD reviewed SJC's site characterization work plan and, with minor modifications, it was apparently approved by that agency (San Joaquin County Environmental Health Division 1999a). However, when application was made to the California Underground Storage Tank Cleanup Fund (USTCF) for funding of the proposed work, the installation of the proposed exploratory borings and groundwater-quality monitoring wells that had been planned for the east side of Chrisman Road and north and northeast across the intersection of that road with West Eleventh Street was denied by that agency (California Underground Storage Tank Cleanup Fund 2000), which denial was based on the recommendations made to the USTCF by the SJCEHD(Fua 2000). Consequently, the initial phase of site characterization work, which was completed in May 2000,was restricted to the installation of seven groundwater-quality monitoring wells,MW-1 through MW-7, at the locations shown on Figure 2. The casings of those wells have screened intervals that extend from approximately one foot above the high groundwater table elevation down to the bottom of the casings. All seven wells are 22 ft. in depth, which depth was ' carefully selected by the California-licensed engineer in responsible charge of the site characterization program so as not to penetrate through clay aquitards that are present beneath the shallow surface aquifer and that protect uncontaminated water in aquifers at greater depth. The presence of those aquifers and aquitards had been identified from the evaluation of the logs of the 14 small-diameter exploratory borings that were drilled on the site to depths up to 28 ft. as the first phase of the initial site characterization program, which had been designed to take advantage of the well-established observational method of geotechnical investigation. That method permits the engineer to adapt later stages of investigation to conditions revealed as the work progresses(Peck 1969). The clay aquitards at depth were identified based on the logs of, and the results of analyses of samples from, the exploratory borings that had penetrated beneath the bottom of the shallow aquifer that is present over the whole area of the Navarra Site. Those deeper exploratory borings were immediately sealed with Type 11 Portland Cement grout when it was found that they had penetrated into deeper aquifers that were unaffected by components of fuel hydrocarbons (The San Joaquin Company 2001g). 3.2 Initial Quarterly Groundwater-quality Monitoring Program Following completion of the restricted first phase site characterization work described in Section 3.1, which included an initial round of groundwater-quality monitoring using Monitoring Wells MW-1 through MW-7 in May 2000, SJC anticipated that SJCEHD would, based on the results of the initial site characterization program, call for a timely extension of the array of groundwater-quality monitoring wells to include wells both to the north of West } Eleventh Street along Chrisman Road and at locations to the east of that road. However, although direction to initiate a quarterly program of groundwater-quality monitoring in Monitoring Wells MW-1 - MW-7 was received in September 2000 (San Joaquin County SJC