SITE INFORMATION AND CORRESPONDENCE FILE 2

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ENVIRONMENTAL HEALTH DEPARTMENT SAN JOAQUIN COUNTY Unit Supervisors e2� Donna K. Heron, R.E.H.S. Bor Carl man, R.E.H.S. 304 East Weber Avenue, Third Floor Director g Mike Huggins, R.E.H.S ., R.D.I. 119r1 Al Olsen, R.E.H.S. Stockton, California 95202-2708 Douglas W. Wilson, R.E.H.S. • �q , _ _ P • Program Manager Telephone : (209) 468-3420 Margaret Lagorio, R.E.H.S. Laurie A. Corolla, R.E.H.S. Robert McClellon, R.E.H.S, Program Manager. Fax : (209) 464-013 $ Mark Barcellos, R.E.H.S. RODGER LISTON !JUN 2 8 2004 DARPETRO INC USA SERVICE STATION 3450 EL CAMINO CERES CA 95307 RE : DARPETRO, INC Site Code: 1060 749 E CHARTER WAY STOCKTON, CA 95202 San Joaquin County Environmental Health Department (EHD) has received and reviewed Quality Assurance/Quality Control Protocols 2004 (Protocols) , undated , but received by EHD on 21 June 2004 . The protocols were prepared by California Geophysical Group , Inc. (CGG) in response to EHD letters dated 12 May 2004 , 16 April 2004 and 27 April 2004 , directing preparation of a written ground water monitoring program. - In the letters cited above, EHD directed that the submitted monitoring program document include a discussion of the program objectives , a monitoring schedule for each well , a description of the methods to be utilized to obtain depth-to-water measurements , to purge and sample the wells, and the quality assurance/quality control measures to be taken to ensure collection of high confidence data. The program objectives given in Protocols are more the tactical objectives of each monitoring event rather than the strategic objectives of the program itself, but this is not a major problem at this time as CCG verbally proposed at a 24 May 2004 meeting with EHD to monitor all the wells each quarter for the immediate future. However, the program objectives will need to be identified to modify the monitoring program at a later time. In general, the methods utilized to obtain the depths-to-water (DTW) are adequate. The well caps will be removed to allow equilibration of hydrostatic pressure with atmospheric pressure before collecting the DTW measurements . The measurements will be obtained by lowering a calibrated sensor from the highest point on the well casings and recording the depth measurement. Total depth of each well will also . be measured . EHD strongly recommends that the high point on each well casing be permanently marked . The proposed purging procedure , which generally includes use of the WaTerra system , appears to be adequate . As the WaTerra system will also be utilized to collect the groundwater samples , an 8-foot length of %-inch tubing should be inserted 7 feet into the dedicated 5/8-inch pump tube collect the sample with a non-turbulent flow into the sample vials , according to Solinst/WaTerra literature. The literature further states that with the one foot of '/4-inch tubing protruding , "Develop a steady water flow and upon