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PUBLIC"' HEALTH SERN/rCES <br /> Huish tJftiicc; :` l <br /> P-08ox 2009 •(1601 East Hazelton Avenue) 0 Stockton. California 95201 <br /> (204)468.3400 <br /> �...., <br /> HARRISON PEDDIE ,. <br /> COLOR SPOT INC. <br /> P C) BOX 5011 FES 0 2 110 <br /> RICHMOND CA 94805 <br /> RE: 5400 EAST HART LAND SUE CODE: 2343 <br /> LORI CA <br /> San Joaquin.County Public Health Services. Environmental Health division(PHSIEHD) has Completed a <br /> comprehensive review of the activities concerning this site to date and has the following comments. <br /> I he over-excavadon of the former 4.000 gallon tank pit area appears to have removed the bulk of the <br /> contaminated soil from the shallow subsurface area. The sample results from the vapor survey, the soil <br /> borings and the monitorin swell.installation indicate that the soil contamination did not;migrate <br /> extensively in a lateral direction. However. the vertical extent of the coatanunation in the area directly <br /> below tate former tank has not been investigated and has not been ruled out.as a possible source of the <br /> domestic well contamination. <br /> In addition, PHS/F-HD was acct notified of the work at the site and was not present to verify the-proper <br /> retrieval, handling and storage of the soil samples. Also, only a limited amount of data has been generated <br /> from the sail borings as only two soil samples were analyzed from each of the borings completed. <br /> Therefore, due to the limited amount of data generated from the soil borings and to the uncertainty Of the <br /> reliability of that data, PHS/EHD cannot concur with the assumption in the reports that-this tank pit area. <br /> is not the source of the domestic well contamination. <br /> The monitoring well completed at this site as a "dry"well does not provide adequate groundwater data for <br /> this investigation. To effectively monitor the groundwater in the area of the former tank, a minimum of <br /> three monitoring wells will need to be installed. An adequate number of soil samples should be obtained <br /> during the installation of the three monitoring wells to supplement the data obtained froth any additional <br /> soil borings for a thorough investigation of the lateral and vertical extent of any remaining soil <br /> contamination. The wells should be completed sufficiently into first groundwater so that repeatable <br /> representative groundwater samples can be obtained and analyzed. The three wells are needed to <br /> establish and verify the groundwater flow direction(s)for this site and to document any influences the on- <br /> site wells may have on the groundwater flow patterns at this site.. <br /> "Rte information generated from the analysis of the groundwater samples from these wells, from the results <br /> of the soil sampling,and from the groundwater flow determinations may provide an indication;as to <br /> whether this tank pit area is indeed the source of the contamination being detected in the domestic wells. <br /> Therefore, a workplan to investigate the full lateral and vertical.extent of the sail contamination and to <br /> investigate the quality of the groundwater beneath the former tank pit area shall be submitted to <br /> PHSIEHD and the Central Valley Regional Water Quality Control Board (CVRWQCB) by March 201.. <br /> 1993. <br /> Yw- <br /> EXHIBIT A-1 <br /> A txvlAM&UO roUquLa Cowm Heli h C;nrt*-rm.,a <br /> S t*T ",7 C-,T--,T— <br />