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i <br /> PUBLIC HEALTH SERVICES yoP �o <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., MTH. , Health Officer •.• . P. . <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 209/468-3420 FILE COP Y <br /> FLOYD BARNES NOV 0 31999 <br /> 9744 FOUNTAIN VALLEY <br /> STOCKTON CA 95209 <br /> RE : Barnes Trucking SITE CODE : 2506 <br /> 1817 Fresno Ave . <br /> Stockton CA 95206 <br /> San Joaquin County Public Health Services , Environmental Health Division (PHS/EHD) <br /> has reviewed the Work Plan forAdditional Subsurface Investigation dated 09/30/99, and <br /> the Groundwater Monitoring Report Third Quarter 1999 dated 10/01 /99 , that were <br /> submitted by Clearwater Group, Inc. on behalf of the above referenced site and has the <br /> following comments. <br /> The work plan proposes to continue the investigation of the lateral extent of hydrocarbon <br /> contamination at this site , and to look for potential off-site sources, with a series of direct <br /> push geoprobe soil borings. Six of the borings are proposed to be located on S . Fresno <br /> Ave . , which runs along the east side (down-gradient) of the subject site . Two additional <br /> borings were described as being located one each on the north and west boundaries of <br /> the subject site, but the site map included in the work plan shows both borings located <br /> on the northern property line. These two borings were suggested to look for potential <br /> off-site sources . Soil and grab groundwater samples will be collected from each boring <br /> for analysis of TPHg and BTEX by EPA Methods8015 (modified) and 8020, and for <br /> MTBE by EPA Method 8260. The work plan also proposes to replace Monitoring Well <br /> #5 (MW-5) by overdrilling it and reinstalling a new well casing in the same boring. <br /> Analytical results of groundwater samples collected from MW-5 before it was damaged , <br /> and more recently from MW-6, indicate that the lateral extent of the dissolved <br /> hydrocarbon plume has not been defined in the down-gradient direction . PHS/EHD <br /> approves the portion of the work plan directed at addressing this concern , the geoprobe <br /> borings proposed to be located on S. Fresno Ave. , but requests that the borings extend <br /> deeper than 20-feet below surface grade (bsg). The work plan stated that the extent of <br /> sorbed-phase contamination surrounding the former UST complex was adequately <br /> delineated by the analytical sample results from the January 1999 installation of MW-4, <br /> MW-5 and MW-6. However, these borings extended to only 19-feet bsg , and <br /> documented soil contamination near the former tank pit exists at 21 -feet bsg in SB-5 , at <br /> 26-feet bsg in SBA at 26-feet bsg in SB-6 and at 31 -feet bsg in SB-2. Soil <br /> contamination was detected in the 19-feet bsg soil samples collected from both MW-6 <br /> and MW-5 . Shallow soil and groundwater samples collected along Fresno Ave. may <br /> indicate whether or not there is an off-site source of contamination , but to be useful in <br /> completing the evaluation of the lateral extent of the documented on-site soil <br /> contamination , the proposed borings should extend to at least 36-feet bsg. <br /> A Division of San <br /> J oa1 uin CountyHealth Care Services <br /> I <br />