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PUBLIC EALTH SERVICESA <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer <br /> 304 E. Weber Ave., Third Floor • P. O. Box 388 • Stockton, CA 9 8 JFio �'�� <br /> 209/468-3420 a � <br /> JEFF GRANBERRY ,ULE JAN'l03190, ' <br /> SHELL OIL COMPANY <br /> PO BOX 4023 <br /> CONCORD CA 94524 <br /> RE: Hammer Lane Shell SITE CODE: 1660 <br /> 7910 Lower Sacramento Road <br /> Stockton CA 95210 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHSIEHD) has <br /> reviewed the "Third Quarter Ground Water Monitoring Report dated December 18, 1995 which <br /> was prepared by Fugro West. PHSIEHD has the following comments for your consideration. <br /> On January 10, 1989 an unauthorized release/contamination site report was filed indicating that <br /> on December 27, 1988 gasoline contamination was discovered. PHSIEHD requested' an <br /> F investigation based on the actual or potential effects of the contaminated soil on groundwater. <br /> Three monitoring wells were installed around the former tank pit and with few exceptions <br /> groundwater contamination has not been detected. PHSIEHD noted in correspondence dated- <br /> April 10, 1990, accompanied by Central Valley Regional Water Quality Control Board <br /> correspondence dated March 6, 1990, that additional soil investigation in the area of the pump <br /> island and beneath the former tank pit would be necessary. Subsequently PHSIEHD indicated <br /> in correspondence dated July 26, 1991 that further soil investigation would be necessary. A <br /> problem assessment report was submitted which indicated that no action altmative was <br /> appropriate for this site. PHSIEHD disagreed, in correspondence dated November 5, 1991, <br /> based on available information and leaching potential analysis. The vertical extent of the soil <br /> contamination has never been defined. <br /> PHSIEHD agreed in a meeting with Shell on November 22 1991 <br /> g g that MW2 would.be evaluated <br /> for the potential use as a vapor extraction well and that until such time as remediation equipment <br /> was available that monitoring would be acceptable. PHSIEHD requested an additional <br /> monitoring well in the area of the pump island, since the nearest down gradient monitoring well <br /> is approximately 100 feet away. PHSIEHD agreed to the reduction of sampling frequency of <br /> MW1 and MW3 to semi-annual and that residual soil contamination will require further <br /> information prior to the consideration of the site for closure. <br /> It seems difficult to justify these many years of groundwater monitoring in relation to the costs <br /> associated with the requested investigation to determine the extent of soil contamination. <br /> The regulations clearly put forth that Shell, as the responsible party of the unauthorized release, <br /> shall perform an assessment of the impacts that shall include the potential effects of residual <br />' contamination on groundwater. Until such time as the vertical extent of soil contamination has <br /> been determined it is impossible to evaluate any potential impact which may or may.not require <br /> any remediation. <br /> A Division of San JAMLIL1111'CUlillh' Htmith Care Services <br />