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i <br />+ PUBLIC HEALTH SERVICES f I L 04 Py <br /> P <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D ., M.P.H., Health Officer <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 tiFoa � <br /> 209/468-3420 <br /> DAVID ATWATER OCT 16 2000 <br /> VAN DE POL ENTERPRISES <br /> P O BOX 1107 <br /> STOCKTON CA 95201 <br /> Re: Van De Pol Enterprises Site Code: 1086 <br /> 3147 S. El Dorado St. <br /> Stockton CA 95206 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has reviewed the <br /> Quarterly Report (report) dated October 2, 2000 prepared by Advanced GeoEnvironmental (AGE) for the <br /> above referenced site. Groundwater samples collected at the site evidence increasing contaminant <br /> concentrations. Further investigation to determine the lateral and vertical extent of groundwater <br /> contamination at this site is necessary. <br /> The depth to groundwater was measured at 25.88 to 26.22 feet below surface grade (bsg) on June 15, 2000. <br /> Monitoring wells at this site have screened intervals from 50 to 30 feet bsg. Groundwater has risen above <br /> the screened intervals of monitoring wells at the site and analytical results for water samples collected from <br /> the wells may not be representative of actual groundwater conditions. Appropriately screened monitoring <br /> wells to evaluate the shallower groundwater must be installed at the site. The lateral extent of groundwater <br /> contamination must also be determined. It may also be necessary to install additional monitoring wells <br /> with deeper screened intervals to determine the vertical extent of groundwater contamination. <br /> This report and the May 31 , 2000 AGE quarterly monitoring report indicate the direction of groundwater <br /> flow to be northwest. The direction indicated in the February 2, 2000 AGE quarterly monitoring report was <br /> east. An adjacent contaminated property north of this site (Cal Tank Lines, 3105 S. El Dorado) reported a <br /> southeast groundwater flow in quarterly monitoring reports dated September 5 and May 15, 2000 prepared <br /> by Environeering, Inc. The groundwater flow direction identified in the Environeering reports is opposite <br /> the gradient direction as stated in the AGE reports. The AGE reports correctly state that, ". . . due to the low <br /> gradient at the site, slight variations in groundwater measurements or changes of recharge/discharge of the <br /> local groundwater could greatly modify the inferred groundwater flow direction." Therefore, groundwater <br /> data must be collected very carefully at this site. PHS/EHD directs you to continue to evaluate the <br /> groundwater gradient and direction of flow at this site while ensuring that accurate and precise data are <br /> collected. <br /> Additionally, PHS/EHD recommends that you contact the property owner and consultant for the Cal Tank <br /> Lines site, review the site files, and share knowledge regarding subsurface site characteristics. A <br /> comparison of investigative data for both sites would be economical and beneficial for a better evaluation <br /> of the extent of groundwater contamination and migration potential. Upon request, PHS/EHD would be <br /> pleased to facilitate a meeting for an informational exchange between responsible parties and consulting <br /> fans from both sites. <br /> In a letter dated August 10, 1999 PHS/EHD directed you to conduct a well survey for this site. A well <br /> survey report has not been received by PHS/EHD for this site. A complete well survey of domestic, <br /> municipal, agricultural, industrial and any other wells must be conducted within a 2,000 foot radius of this <br /> A Division of San Joaquin County Health Care Services <br />