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r <br /> ENVIRONMENTAL HF ALTH DEPARTMENT <br /> SAN JOAQ - IN COUNTY Unit Supervisors <br /> z Z Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. <br /> 304 East Weber venue,Third Floor <br /> N: •„ `< - Director 'Mike Huggins,R.E.H-S.,R.D.1. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> r._,.. ..:�a• 9) 468-3420 <br /> Program Manager Telephone: ( 0Margaret Lagorio,R.E.H.S. <br /> A�!j o6'R Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. <br /> Program Manager F (2� ) 464-0i 38 -Mark Barcellos,R.E.H.S. <br /> NOV 0 3 2004 <br /> ERNEST J POMBO JR <br /> 1755 W 11TH STREET <br /> TRACY CA 95376 <br /> RE: Pombo Ranch Property SITE CODE: 508110 <br /> 24100 Lammers Road <br /> Tracy CA 95376 <br /> San Joaquin County Environmental Health Depa ment (SJCIEHD) has reviewed <br /> "Subsurface Investigation & Second Quarter 200 Groundwater Monitoring.Report" <br /> (Report) dated August 17, 2004, submitted on yo ir behalf by M.J. Kloberdanz & <br /> Associates (MJK), and has the following commer ts. <br /> The Report documents the installation of three g undwater monitoring wells (MW-4, <br /> MW-5 and MW-105) and one soil boring (EB-4) on May 5, 2004, and a routine quarterly <br /> groundwater monitoring and sampling event conducted on May 14, 2004. Soil samples <br /> for laboratory analysis were collected during the drilling of the boreholes; reported soil <br /> analytical results were consistent with data from revious work at this site documenting a <br /> plume of petroleum hydrocarbon-impacted soil#at extends from the former underground <br /> storage tank pit area at least 50-60 feet down gr idient, at a depth of approximately 10 feet <br /> below surface grade (bsg). Groundwater analytical results demonstrated petroleum <br /> hydrocarbon impacts to all wells onsite except fo upgradient well MW-3. This was the <br /> first report of an impact to MW-1, and the seconc reported for MW-2. Well MW-105 was <br /> built to total depth 40 feet bsg, and was constructed with a discrete 5-foot screen interval. <br /> The Report states that the boring for this well was drilled "through at least 7 feet of <br /> relatively dry clay into a coarse sand and gravel ayer", but the boring log submitted with <br /> the Report does not support this statement. A second monitoring and sampling event that <br /> included the new wells was conducted on July 14, 2004. Analytical results showed a <br /> general increase in contaminant concentrations n the new shallow wells, and a decrease <br /> in the deeper well. Continued quarterly groundwater monitoring and sampling is required <br /> until directed otherwise by this agency. <br /> In correspondence dated January 18, 2001, SJ IEHD, in review of the "Corrective Action <br /> Plan"(CAP) dated March 31, 2000, submitted b MJK on your behalf, and in conference <br /> with the Regional Water Quality Control Board, Central Valley Region (CVRWQCB), <br /> recommended that the best alternative to protect future beneficial uses of the groundwater <br /> of the contaminated source material <br /> at this site was to proceed with excavation <br />