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Additional Soil and Groundwater Investigation Report Canepa's Car Wash(Park Street) May 8,2002 Page 2 interface In a letter dated September 7, 2001, Mr Wong of the PHS/EHD requested a work plan to Idefine the lateral and vertical extent of the contamination in groundwater and the vertical extent of the contamination in soil be submitted to the PHS/EHD by October 20, 2001 Condor prepared the Work Plan Additional Soil and Groundwater Investigation, dated October 17, 2001, and received conditional ' approval from the PHS/EHD in a letter dated October 24, 2001 The approval condition was the elimination of a proposed direct push groundwater sample location near monitor well MW-1 The field work was generally performed in accordance with the work plan and the conditional approval as ' described above 3.0 FIELD AND ANALYTICAL METHODOLOGY iThis section includes a description of the site preparation, cone penetrometer boring procedures, direct push (hydropunch) groundwater sampling and soil sampling procedures, and the laboratory analytical testing methodology 3 I SITE PREPARATION Appropriate permits were obtained from the PHS/EHD and the City of Stockton prior to conducting the fieldwork The boring locations were marked with white paint, and the Underground Service Alert(USA) was notified approximately 72 hours in advance of the fieldwork to locate and identify underground ' utilities in the vicinity of the work area A utility locator was retained to scan for the presence of private buried utilities on site that were not marked by utility representatives in response to the USA request The PHS/EHD and City of Stockton were notified of the fieldwork schedule at least 48 hours in advance ' • 3 2 CONE PENETROMETER AND DIRECT PUSH PROCEDURES Prior to conducting investigation activities, an on site tailgate safety meeting was held with all drilling ' and Condor personnel in attendance A site-specific Health and Safety Plan was discussed with and presented to a]1 personnel for their signatures Gregg Drilling and Testing, Inc (Gregg) of Martinez, California, installed the CPT, soil and hydropunch borings CPT borings CPT] and CPT2 were hydraulically advanced from the ground surface to the bottom of the boring Measurements of the cone bearing pressure, sleeve friction, and dynamic pore water pressure were recorded at approximately two-inch intervals to provide a nearly continuous hydrogeologic log of the subsurface conditions Following completion of the CPT logging procedure, the CPT borings were abandoned by grouting from the bottom of the boring to the ground surface To collect the water samples, the hydropunch sampler was advanced to the desired sampling depth, the sampler push rod was pulled back, thereby exposing the sampler inlet screen to the formation material The groundwater samples were collected using a stainless steel bailer lowered through the hollow push rods into the sample screen The hydropunch borings were tremie grouted from the bottom of the boring to the ground surface upon completion of sampling tOne soil boring, SB-1, was advanced using direct push sampling technique The soil boring was sampled using a piston type soil sampler that was advanced to the desired sample depth, the piston pulled back, thereby opening the sampler, and the sampler advanced one foot to retrieve the sample After sample retrieval, the sampler was reinserted in the down-hole tubing and advanced to the next sample location The push rods and other down-hole equipment were decontaminated between sampling events by steam cleaning in order to prevent cross-contamination CONDOR