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... t.i -ter-= ., _._......_ .... <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> s .oG unit Supervisors <br /> Donna K.Heran,R.E.H.S. Carl Borgman,R.E.H.S. <br /> 304 East Weber Avenue, Third- <br /> Director Mike Huggins,R.E.H.S.,R.D.I. <br /> LLQ:. Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> Pro Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> q : Laurie A.Cotulla,R.E.H.S.g g ram Manager <br /> Fax: (209).464 Robert McClellon,R.E.H.S. <br /> �tFOR -01.38 <br /> Program Manager` - `�` "" � -Mark Barcellos,R.E:H.S. <br /> JOHN JOHNSON MAR 0 S 2004 <br /> THE CUSTOMER COMPANY <br /> 4457 PARK ROAD <br /> BENICIA CA 94510-1124 <br /> RE: The Customer Company SITE CODE 1404 <br /> 15 East Grant Line Road RO: 0545 <br /> Tracy,California - <br /> San Joaquin County Environmental Health Department(EHD)has received and reviewed Site <br /> Conceptual Model(Report)dated February 2, 2004,prepared by ATC Associates Inc. (ATC)on <br /> your behalf. The Report is comprised of four parts: <br /> 1. Background information with significant findings noted from each phase of investigation; <br /> 2. A site conceptual.model (SCM) addressing hydrogeology, stratigraphy,hydrocarbon- <br /> impacted soil and groundwater, and potential exposure pathways; . <br /> 3. A general corrective action plan(CAP)that provides descriptions of remedial alternatives <br /> for soil and groundwater; and <br /> 4. Recommendations, which include a brief work plan to advance three cone penetrometer <br /> testing(CPT)borings to assess the vertical extent of impacted soil and groundwater and <br /> the lateral extent of shallow impacted groundwater toward the north. <br /> EHD comments on the Report as follows: <br /> The background information provides a useful discussion of the work to date,noting the <br /> significant findings of each phase of investigation,which lends understanding to the objectives of <br /> the subsequent investigation. <br /> The hydrogeology and stratigraphy portions of the SCM provide a general description of the <br /> geologic media and groundwater flow characteristics that govern the distribution and migration of <br /> the known contamination. The discussion of soil and groundwater contamination provides a <br /> preliminary model of the distribution of contaminants in the subsurface. Not included in this . <br /> phase of the SCM are: <br /> 1. Estimates of the masses of dissolved contaminants in groundwater and sorbed <br /> contaminates in soil; <br /> 2. An estimate of the seepage rate of groundwater,which provides an estimate of the <br /> maximum migration rate of contaminants; and <br /> 3. A geologic cross section parallel to the general groundwater flow direction; <br /> These items can be addressed after the next phase of work. The SCM, as presented,is adequate <br /> for EHD to evaluate and comment on the currently proposed scope of work. <br />