Laserfiche WebLink
ENVIRONMENTAL HEALTH DEPARTMENT <br /> POU'N , <br /> SAN JOAQUIN COUNTY Unit Supervisors <br /> Donna K.Heran,R.E.H.S. Third Floor Carl Borgman,R.E.H.S. <br /> N ( Director 304 East Weber Avenue, Mike Huggins,R.E.H.S.,R.D.I. <br /> L " ` Al Olsen,R.E.H.S. Stockton, California 95202-2708 <br /> Douglas W.Wilson,R.E.H.S. <br /> �.. Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> q4../F6Ra Laurie A.Cotulla,R.E.H.S. <br /> Fax: (209) 464-0138 Robert McClellon,R.E.H.S. <br /> Program Manager Mark Barcellos,R.E.H.S. <br /> ROBERT ALDENHUYSEN JUL U 8 20003 <br /> RMC PACIFIC MATERIALS <br /> PO BOX 5252 <br /> PLEASANTON CA 94566 <br /> RE: RMC Lone Star Kerlinger Aggr. Plant Site Code: 1737 <br /> 30350 S TRACY BLVD <br /> TRACY, CA 95376 <br /> San Joaquin County Environmental Health Department (EHD) has received Site Assessment <br /> Report dated April 4, 2003 (the report) prepared by RMC Pacific Materials (RMC). Five soil <br /> borings BH-1 to BH-5 were advanced using a double-walled air hammer to approximately <br /> 140 feet below surface grade (bsg) at the above-referenced site in August 2002. Grab <br /> groundwater samples and soil samples were collected for analyses. The highest <br /> concentrations of diesel reported in the analytical results of the soil samples were 1,400 <br /> milligrams per kilogram (mg/kg) from BH1-4 sample taken at 20 feet bsg, 340 mg/kg of <br /> diesel from BH4-1 sample taken at 4 feet bsg, and 270 mg/kg of diesel from BH3-1 sample <br /> taken at 8 feet bsg. Moderate levels of diesels were reported in BH2 soil samples at irregular <br /> depths: 16 mg/kg at 20 feet bsg,46 mg/kg at 39 feet, and 82 mg/kg at 124 feet bsg. <br /> Analytical results of grab groundwater sample BHI-W at 125 feet bsg was 720 micrograms <br /> per liter (µg/1), BH2-W at 124 feet bsg was 120 µg/l,BH3-W at 135 feet bsg was 120 µg/1, <br /> BH4-W at 123 feet bsg was 72 µg/1, and BH5-W at 115 feet bsg was 590 µg/l of diesel. <br /> Results of both grab water and soil samples were reported as inconsistent with a diesel <br /> pattern. <br /> Three of the five borings were converted to 4-inch monitoring wells BH-1 (MW-4), BH-2 <br /> (MW-5), and BH-5 (MW-6). The wells were developed in January 2003, and three <br /> groundwater samples were collected in February 2003. Analytical results of groundwater <br /> samples were all not detected above detection limit of 50 µg/l of diesel. RMC hypothesized <br /> that the initial grab groundwater samples were cross-contaminated within the inner drill pipe. <br /> RMC proposed installing dedicated pumps in each of the three wells. RN1C also proposed <br /> over-excavating the contaminated soil in the upper portion of MW-4, but recommended <br /> carrying out this remediation during the final active period of the plant's life due to <br /> obstruction of the rock-processing plant. <br /> EHD agrees that the initial grab water samples might have been cross-contaminated, but it is <br /> premature to conclude that the groundwater has not been impacted. At least 4 consecutive <br /> quarters of sampling and non-detect results are required before EHD would agree that no <br />