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CALIFORNIA GEOPHYSICAL GROUP, INC. <br /> P O Box 578341, Modesto, CA 95357 Tel (209) 527-1247 <br /> June 30, 1995 Fax (209) 527-4810 <br /> Public Health Services <br /> San Joaquin County <br /> P.O. Box 388 �1 <br /> Stockton, Ca 95201 <br /> RE: Activity Report �' 1 � 1995 <br /> Darpetro Service Station <br /> 749 E. charter Way ORONMENTAL HEA171 H <br /> Stockton, Ca. "ERM IT/SERVICES <br />' Site # 1060 <br /> On June 19 , 1995, two hydropunch borings were attempted at the <br /> I Sun Gardens Property located at 721 E. Charter Way, Stockton, CA. <br /> The purpose of the hydropunch borings was to assess the <br /> abnormally high TPH readings found in well BM-9 , since its <br />' construction, September 1994, <br /> Table I lists the history of the water analyses taken at the site <br /> since Jan. 26, 1990 . Table II is the history of the water table <br />' measurements, Table III list the history of hydraulic gradients <br /> and Table IV lists the contamination found in the soil samples. <br /> The water samples were obtained by using a pre-cleaned bailer <br /> from wells BM-4,5 ,6 , 7,and 9. This was performed after the <br /> measured field parameters had stabilized during the purging. See <br /> protocols. Water samples were placed in appropriate glass <br /> containers with teflon-lined lids. <br /> The hydropunch borings were drilled using a Cone Penetration rig. <br />' The cone tip pressure and the friction ration were recorded in <br /> HP-1 to define the lithology. The results of these data <br /> confirmed the same lithology exists at the two hydropunch <br />' borings, as at the monitoring wells located at this site. <br /> I <br /> A hydropunch devise was placed 50 feet below the ground surface <br /> and opened. The devise was allowed to remain open for 1 . 5 hours <br />' at which time a water sample was obtained in well HP-1. In <br /> boring HP-2 no water was evident after 1. 5 hours. An attempt to <br /> close the hydropunch and push it to a deeper layer failed, <br />' therefore, no water was obtained from this well . <br /> Upon removing the hydropunch from boring HP-2 a small amount of <br />' soil was found in the punch. This soil was believed to have come <br /> from the depth where the punch was closed, between 45 and 50 feet <br /> below the surface (bgs) . A sample of this soil was taken and <br /> sent for analysis. The results showed the soil to have non- <br /> detectable amounts of gasoline and its components. The soil was <br /> 10 a dry stiff clay. <br /> Page 1 <br />