SITE INFORMATION AND CORRESPONDENCE_FILE 1

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N PUBLIC HEALTH SERVICES yopQ� lN SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION Karen Furst, M.D . , M.P.H. , Health Officer 304 East Weber Avenue, Third Floor • Stockton, CA 95202 209/468-3420 NOV 2 2 1999 FLOYD BARNES comoy 9744 FOUNTAIN VALLEY STOCKTON CA 95209 RE : Barnes Trucking SITE CODE : 2506 1817 Fresno Ave . Stockton CA 95206 San Joaquin County Public Health Services , Environmental Health Division (PHS/EHD) has reviewed the Work Plan Addendum for Additional Subsurface Investigation dated November 9 , 1999 that was submitted by Clearwater Group, Inc. on behalf of the above referenced site and has the following comments. The addendum was submitted as a modification to the previously submitted Work Plan for Additional Subsurface Investigation dated September 30, 1999, which had been conditionally approved by PHS/EHD in correspondence dated November 3 , 1999. Further modifications were discussed in a phone conversation between PHS/EHD and Clearwater on November 15, 1999 . The addendum proposes the advancement of six soil borings, three of which will be converted to monitoring wells (MW) . One of the wells will replace the damaged MW-5 , the other two will be placed down-gradient, across Fresno Ave . to the east and south- east. These wells are intended to provide lateral definition of the groundwater contamm`ant plume in the down-gradientziirectionAlrborings-will-be-advanced-by- — hollow stem auger drilling technique to a depth of 36-feet below surface grade (bsg) to look for lateral contaminant plume definition in soil . The monitoring wells will be built consistent with the existing on-site wells , to total depth of 25-feet bsg . In the phone conversation on November 15, 1999 it was discussed that the work plan addendum still did not address vertical definition of the groundwater contaminant plume. PHS/EHD suggested the use of cone penetrometer testing (CPT) to provide depth discrete groundwater samples. Clearwater suggested using a geoprobe direct push- sampling device. It was agreed that the investigation would incorporate use of a geoprobe for the exploratory boreholes, and that one additional boring to depth would be advanced in the source area. In the event that the geoprobe cannot provide the needed information , an alternative method will be used at another date. The suggested three wells will be drilled with hollow stem augers. The first well boring , MW-5 , will be drilled to 36-feet bsg . If soil contamination is not apparent at this depth in this boring , as based on sensory perception and screening for organic vapors with a photo-ionizing organic vapor meter, one or possibly both of the down-gradient well borings will be advanced to 25-feet bsg only . Borings advanced below 25-feet bsg will be backfilled by injection with bentonite clay slurry prior to setting a well casing . A Division of San Joaquin County Health Care Services