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,State of California Department of Health Services <br /> Memorandum Iq8J -P� <br /> ACM <br /> To <br /> Jeff Van Slooten, SMU, Region 1 pate : Z.1 - <br /> Subject: Review of <br /> Via Ed Leivas 3k _ McCormick and <br /> Senior Enginee ing Geologist Baxter Aquifer <br /> Testing Report <br /> From ; Toxic Substances Control Division <br /> 322-0508 <br /> On October 7 , 1988 the Technical Services Unit (TSU) received a <br /> request from the Site Mitigation Unit of Region 1 to review the <br /> Aquifer Testing Report for the McCormick and Baxter Creosoting <br /> Company of Stockton, California. The request was forwarded to the <br /> Geotechnical Assessment Unit of TSU on October 11, 1988 . This <br /> memo contains specific comments addressing aquifer test analysis <br /> methods used to characterize the hydrogeologic regime at the <br /> site. <br /> Section 3 <br /> Test Results: Drawdowns <br /> Figures 3-9 through 3-12 and Figure 3-14 depict anomalous <br /> increases in water levels occurring approximately 105 seconds <br /> after the initiation of pumping in wells DSW-4C and -4D. Such <br /> increases are commonly the result of either the cone of <br /> depression intercepting additional sources of water, or the <br /> malfunctioning of pressure transducers used in data recording. <br /> The occurrence of these water level increases and their probable <br /> causes must be discussed in the report in order to provide an <br /> adequate characterization of the shallow aquifer at the site. <br /> Appendix A <br /> A total of 18 wells were initially planned to be monitored <br /> throughout the aquifer tests. However, contrary to the <br /> information presented on Table 2-1 in Chapter 2 , the second <br /> paragraph on page A-1 notes that wells DSW-2A, -2B, -2C, -2D, <br /> and -2E 't . . . were not monitored with data loggers during [the <br /> aquifer tests] due to a malfunction in one of the data loggers. " . <br /> References to the total number of operational observation wells <br /> in either the text or appendices should therefore be adjusted to <br /> reflect the change from 18 to 13 wells. <br /> Appendix B <br /> Confined, Isotropic Analysis <br /> Most aquifer test analysis methods use water level data from <br /> observation wells located some distance from the pumping well <br /> because these data are typically unaffected by pump-induced <br /> turbulence and/or irregularly fluctuating pumping rates. The <br />