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5 Third Street, Suite 400 <br /> providing environmental <br /> San Francisco, California <br /> fir=i consulting and <br /> w94103-3205 <br /> F= engineering services 415/495-7110 <br /> Fax: 495-7107 <br /> McCulley June 1, 1994 <br /> Frick & JUN 0 2 1994 <br /> Gilman, [Project No. 94-6119] <br /> ENVIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> Ms. Margaret Lagorio <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 445 North San Joaquin Street <br /> Stockton, California 95201 <br /> Subject: Results of Hydropunch° Groundwater Sampling <br /> Mission Ridge Shopping Center <br /> Manteca, California <br /> Dear Ms. Lagorio: <br /> Pursuant to our telephone conversation on May 23, 1994, attached please find copies of <br /> laboratory analytical reports for soil and groundwater samples analyzed during our groundwater <br /> quality reconnaissance at the Mission Ridge shopping center in Manteca, California (the Site). The <br /> Site is located at 1009 to 1205 South Main Street, Manteca, California. The work was performed in <br /> accordance with the work plan submitted to you, dated May 6, 1994. <br /> Hydropunch® groundwater sampling was performed at the Site on May 11, 1994. Six <br /> groundwater samples were obtained and analyzed using a fuel fingerprint scan (EPA Method 8260 <br /> modified) to detect gasoline- and diesel-range hydrocarbons though C12 (12 carbon atoms or less) and <br /> volatile organic compounds. One groundwater sample was additionally analyzed for total extractable <br /> petroleum hydrocarbons (TEPH) as diesel and motor oil (EPA Methods 3510/8015 modified). Copies <br /> of analytical reports and chain-of-custody records for these samples are attached. <br /> Based on the analytical results, petroleum hydrocarbons as gasoline or diesel were not present <br /> above laboratory detection limits in any of the samples analyzed. TEPH as motor oil was detected at <br /> 680 parts per billion (ppb) in sample B3, located near the central portion of the southern property line <br /> (see the attached Site Map, Figure 1). 2-butanone (methyl ethyl ketone or MEK) was detected in <br /> samples B1, B2, B5 and B6 at 35, 28, 200 and 14 ppb, respectively. <br /> To help verify that the data obtained during our groundwater reconnaissance at the Site are <br /> representative of Site conditions, we consulted with the drilling and laboratory subcontractors in an <br /> effort to rule out extraneous sources of MEK that could be responsible for the analytical results <br /> obtained for groundwater samples collected at the Site. The only probable source of extraneous MEK <br /> identified during our evaluation was the drilling subcontractor's use of a non-customary source of <br /> Hydropunch® screens. MFG obtained a screen sample from the drilling subcontractor, prepared a <br /> sample of distilled water used to rinse this screen sample, and analyzed this water sample for MEK <br /> (sample SR-1). Analysis of this rinsate blank detected 180 parts per billion (ppb) of MEK and 2.6 <br /> ppb of chloroform. Copies of the analytical report and chain-of-custody record for this sample are <br /> attached. The MEK detected in the groundwater samples from the Site, therefore, appears to have 6D <br /> Austin, TX • Boulder, CO • San Francisco, CA • Seattle, WA • Wallace, ID �P�° <br />