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FILE COPY <br /> PUBLIC HEALTH SERVICIES ,o . <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION ;a <br /> Karen Furst, M.D., M.P.H., Health Officer ` - <br /> �a <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 aCf F'o <br /> 2091468-3420 <br /> ERNEST J POMBO LTR JAN 18 2001 <br /> P O BOX 805 <br /> TRACY CA 95378 <br /> RE: Pombo Ranch Property SITE CODE: 508110 <br /> 24100 Lammers Road <br /> Tracy CA 95378 <br /> On March 31, 2000, San Joaquin County Public H alth Services, Environmental Health <br /> Division (PHSIEHD) received the "Corrective Actic n Plan" (CAP) prepared by M.J. <br /> Kloberdanz and Associates (MJK) for the above rE ferenced site. Review of the CAP took <br /> considerable time and effort because of errors anc inconsistencies within it. PHSIEHD <br /> enlisted the assistance of Central Valley Regional Water Quality Control Board <br /> (CVRWQCB) in reviewing and commenting on the CAP. PHSIEHD and the CVRWQCB <br /> provide the following comments. <br /> The site is an operating ranch. Prior to 1993 two underground storage tanks (UST) were <br /> removed. The tanks were farm exempt, and thus were removed without permits, <br /> inspections or soil sampling. In September 1998 an environmental assessment of the <br /> former tank pit areas was conducted. Eight geop obe direct push soil borings were <br /> advanced on site for the collection of soil and grat, groundwater samples. Petroleum <br /> hydrocarbon contamination to soil and groundwater was detected, and further assessment <br /> of one of the former tank pit areas was required. our additional geoprobe borings were <br /> advanced in July 1999, followed by the installatior of three groundwater monitoring wells. <br /> Soil contamination appears limited to 10 feet belo surface grade (bsg) in the immediate <br /> area of the former tank pit. Groundwater contamination was detected in the grab samples <br /> to 38-feet bsg, with the highest concentrations at 5-feet bsg. The monitoring wells have <br /> been sampled one time, and the results were non-detect. <br /> CAP Review <br /> The CAP describes the site lithology as silty plastic clay that grades to fine-grained silty <br /> sand at 15 to 20-feet bsg. A thin, shallow sand unit is purportedly present within the silty <br /> clay, as well as a fine grained well sorted sand at the base of the borings, which dips <br /> westward. This description is inconsistent with the boring logs submitted with previous <br /> reports, and indeed seems to have no relation to he boring logs at all. Moreover, the <br /> boring logs submitted with previous reports are grossly inconsistent with the unified soil <br /> classification system (USCS), making them difficult, if not impossible, to read. For <br /> example, the boring logs use the letters "CM," "GS" and "MC" as group name symbols <br /> throughout the earlier reports, even though these letters are not used as symbols within <br /> the USCS. For some logs the meaning is simply impossible to infer. In the case of boring <br /> B-11, the 20-foot sample is given the symbol SC and the description states that it is a <br /> "well sorted, medium to fine grained well sorted sand, slightly plastic, angular quartz <br /> grains." The symbol "SC" in the USCS stands for"clayey sand." However, the group <br /> name assigned to the sample in the soil description is "Sandy Clay." It is impossible to <br /> speculate as to whether the sample is a sand ora clay. <br /> A Division of San Joaquin County Health Care Services <br />