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CALIFORNIA GEOPHYSICAL GROUP, INC. <br /> O Box 578341, Modesto, CA 95357 Tel (209) 527-1247 <br /> Fax (209) 527-4810 <br /> WORK PLAN � <br /> FOR _ <br /> DARPETRO SERVICE STATION r.Y <br /> 749 E. CHARTER WAY <br /> STOCKTON, CALIFORNIA -� <br /> MARCH 15 , 1995 <br /> SITE HISTORY <br /> t� <br /> On November 14 , 1989 three underground tanks were removed from <br /> the site in accordance with the Tri--Regional regulations. <br /> Testing of the soil samples taken around the old tanks indicated <br /> the site had been contaminated with gasoline. <br /> The excavation site was backfilled with the original soil plus <br /> soil from a new excavation. The site was then remodeled and <br /> placed back in service. <br /> Drilling and sampling began on January 22 , and finished on <br /> January 26 , 1990 . A Site Assessment Report was submitted to San <br /> Joaquin County Health on February 9 , 1990. On October 1, 1990 we <br /> began quarterly sampling, by that time the water table had <br /> dropped below the bottom of the wells and has remained so to <br /> this time. <br /> In April 1992 , we drilled three additional wells at the site into <br /> the water table. The results of this work were reported in our <br /> Site Assessment of April 30, 1992 . <br /> In August 1993 , we drilled two additional wells in order to <br /> define the groundwater plume and to investigate the possibility <br /> of contaminated water entering our site from an up gradient <br /> source. The up gradient well BM-7 contained contaminated water <br /> at a level which was above the expected level. We believe this <br /> well was being contaminated from another source. The Public <br /> Health Service did not feel we proved this point. The down <br /> gradient well BM-8 was contaminated indicating the edge of the <br /> plume has not been reached yet. <br /> In September 1994 , three additional monitoring wells were drilled <br /> to further define the contamination plume. Wells BM-9, 10 and 11 <br /> were drilled. An site assessment of this work dated October 10, <br /> 1994 was submitted. <br /> SCOPE OF WORK <br /> A letter from San Joaquin County Public Health Services, dated <br /> March 1 , 1995 requested additional borings or wells to further <br /> define the groundwater plume suspected to be emanating off site <br /> Page 1 <br />