SITE INFORMATION AND CORRESPONDENCE_FILE 1

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A ENVIRONMENTAL HEALTH D- EPARTMENT SAN JOAQUIN COUNTY unit Supervisors Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. Director 304 East Weber Avenue,Third Floor Mike Huggins,R.E.H.S.,R. , Al Olsen,PLE.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. Program Manager Telephone: (209)468-3420 Margaret Lagorio,R.E.H.S. i:ifi Laurie A.Cotulla,R.E.H.S. Fax: (209)464-0138 Robert McClellon,R.E.H.& Program Manager Mark Barcellos,R.E.H.S. KASHMIR SINGH & DALWINDER DHOOT 14AY 13 2003 15600 S HARLAN ROAD LATHROP CA 95330 RE: Joe's Place SITE CODE: 231585 15600 Harlan Road Lathrop, Ca San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has reviewed "Phase 11 Environmental Assessment of Soil and Groundwater" dated May 15, 2002, and Quarterly Groundwater Monitoring Reports dated August 19, 2002, September 30, 2002, January 21, 2003 and April 21, 2003, prepared by Avalon Environmental Consultants for the above referenced site. The lateral and vertical extent of the MTBE contamination in the soil and the groundwater has not been defined at this site. MTBE contamination has migrated off site in both the soil and groundwater. The soil sample from 20 feet below surface grade (bsg)from Monitoring Well OAX evidenced soil contamination. That sample and the sample from Geoprobe GP2 are the only 20 feet bsg soil samples analyzed and they both evidenced contamination. In addition, groundwater samples from MWOAX and MWO-2 continue to evidence MTBE. A site conceptual model (SCM) should be prepared for this site using existing data that shows the relationship between contaminants, retention/transport media, and receptors. The SCM is a written description supported by maps, geological cross-sections, tables, and diagrams that provide information about the site. The SCM should include the following: 1. Local and regional plan view maps showing location of sources, extent of contamination (i.e., an interpretive drawing - not merely a plot of laboratory results), direction and rate of groundwater flow, and locations of receptors. "Receptors" include, but are not limited to, all supply wells within 2000 feet of the source area; 2. Cross-sections showing subsurface geologic features, depth of groundwater, man-made conduits, monitoring well construction, and an interpretive drawing of the vertical extent of soil contamination;