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February 4, 1994 <br /> Ms. Mary Meays Page 2 <br /> San Joaquin County Public Health Services <br /> Per the direction of the EHD letter to San Joaquin County Capital Projects dated February 17, <br /> 1993, analyses for TPH-D, EDB and Total Lead were conducted for a period of two calendar <br /> quarters (first and second quarter 1993). Since only very low or non-detectable concentrations <br /> of these compounds were detected during the first two quarters of sampling, these analytes were <br /> deleted from the analysis schedule for the remainder of the year. <br /> As you know, groundwater monitoring in the vicinity of the Human Services building has been <br /> ongoing since 1991, with continuous quarterly monitoring being conducted most recently <br /> throughout the 1993 calendar year. As shown in Table 3 of the attached report, only TPH-G <br /> is quantified in the vicinity of the building and then only in two apparently unconnected locations <br /> (MW-8 offsite to the northeast and MW-4 on the edge of the property to the southeast). As <br /> discussed in the report, the groundwater flow directions apparent at the site suggest that both <br /> locations are sidegradient to the former tank site. Therefore, the relationship of TPH-G at the <br /> two locations to the former tank site is tenuous at best. Given the lack of connection between <br /> the former tank location and the monitor wells showing TPH-G, continued quarterly monitoring <br /> will contribute little or no new information. At best, future monitoring of MW-4 and MW-8 <br /> may contribute general knowledge about groundwater conditions in downtown Stockton, but that <br /> should not be the responsibility of the Capital Projects Division. As discussed in the report, we <br /> are not in a position to suggest to what extent such data relates to a regional problem. On the <br /> other hand, your department, with its oversight of multiple independent project, is in such a <br /> Position. With this thought in mind, if TPH-G is a common problem in the area, there may be <br /> some value in continuing limited monitoring of MW-4 and MW-8 by others for the purposes of <br /> other offsite property projects or regional issues. <br /> Should you have any questions, please feel free to contact me in the Stockton office. <br /> Sincerely, <br /> ROY F. WESTON, INC. <br /> raj <br /> Paul V. Sundberg <br /> Sr. Project Director <br /> PVS/cmc <br /> Enclosure <br /> cc: Mr. Dick Callistro - SIC Capital Projects <br /> Ms. Elizabeth Thayer - California Regional Water Quality Control Board - Sacramento <br /> Sfi: SWEAYSMP <br />