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SERVI SPUBLIC HkALTH <br /> SAN.JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D. M.P.H., Health Officer <br /> aL7p'R�\ <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 209/468-3420 <br />� MR ROBERT SIVELL <br /> CITY OF STOCKTON ECONOMIC DEVELOPMENT MGR <br /> 425 N ELDORADO STREET JAN -112000 <br /> STOCKTON CA 95242 <br /> RE: Gateway Project SITE-CODE: 0000701. <br /> 325 S. EI Dorado Street <br /> Stockton CA 95203 <br /> Dear Mr. Sivell, <br /> We are in receipt of your letter dated December 16, 1999. In the letter you brought up <br /> several issues concerning the discovery of two'underground storage tanks (USTs) at the <br /> above referenced site. Both tanks were subsequently removed under permit and <br /> inspection by San Joaquin County Public Health Services, Environmental Health <br /> Division (PHS/EHD). Soil samples for analysis,were collected from beneath each tank <br /> and from the related stockpiles. The first tank was removed on September 9, 1999 and <br /> analytical results were non-detect for all petroleum hydrocarbon constituents. The <br /> second tank was removed on October 8, 1999. Analytical results evidenced 78-parts <br /> per million (ppm) total petroleum hydrocarbons,as gasoline (TPHg) and 62-ppm TPH as <br /> diesel in the sbil sample collected from under the east end of this second tank. The <br /> f sample was collected at 9-feet below surface grade (bsg). The composite sample from <br /> the soil stockpiles had 21-ppm TPHd. <br /> In your letter you referenced a study sponsored by the State Water Resources Control: <br /> Board (SWRCB) which discusses the use of passive bioremediation at low-risk leaking <br /> UST sites. PHS/EHD is aware that the SWRCB considers sites for their risk potential <br /> and recommends closure for those sites that can be shown to pose low risk to human <br /> health and the environment. However, before a site can be properly evaluated for its . <br /> potential to pose this type of risk, the full extent of the contaminant impact present must <br /> be completely defined. <br /> It is acknowledged that different types of soil are-more or less prone to allow for <br /> contaminants. While generally considered to be an <br /> transport of specific types of cantam g y <br /> effective barrier to the spread of contaminants,.clay soils can contain enough silt or sand <br /> particles to allow petroleum hydrocarbons to pass through. To make a proper evaluation <br /> of the potential for contaminant transport in sol{ at this site to occur, a geologist must-log <br /> I site specific information on the soil composition in the area of the former tank pits. In <br /> addition, water tables in San Joaquin County are known to vary both locally and <br /> seasonally. A review of data from a listed contaminated site that is located <br /> E approximately three blocks north of your site indicates that the depth to water was 21- <br /> feet bsg when last measured (2199). The combination of an old release and fluctuating <br /> groundwater tables over time could create the potential for contamination in the soil to <br /> be released into the groundwater. <br /> f A Division of San Joaquin County'Health Care Services <br /> i <br /> ,M <br />