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' Groundwaterlavestigation,Monitor Well Destruction and Installation,and Interim Remediation Pump Test Report Boyett Petroleum,419 S.Main St.,Manteca,CA 3anuary 30,2004 Pulte 4 3.3 CPT PROCEDURES 1 A Condor geologist was on site to supervise the work. Prior to commencement of fieldwork, a tailgate safety meeting was held and a site-specific Health and Safety Plan was discussed with, and presented, to all field personnel for their signatures. ' Four CPT boring pairs (CPT-3 through CPT-6) were advanced between October 20 and 23, 2003, using an integrated electronic system in accordance with ASTM standards (D 5778-95). The borings were ' advanced to evaluate the vertical extent of groundwater contamination in the vicinity of the USTs and in the predominant down-gradient direction of the plume. Borings CPT-3, CPT-4, and CPT-6 were each advanced to a depth of approximately 125 feet bgs; boring CPT-5 encountered refusal and was terminated at a depth of approximately 66 feet bgs. The boring locations are shown in Figure 3, Appendix A. ' At each boring pair location, the first boring of each group was used to investigate the litholo of the site g gY at that location. The first borings for CPT-3, CPT-4, and CPT-5 were completed on October 20, 2003; the ' first boring for CPT-6 was completed on October 21, 2003. Pilot holes were hand-augured to five feet bgs for each boring. The borings were hydraulically advanced downward into the subsurface using an electric piezocone tip. Measurements of code resistance, sleeve friction, and dynamic pore water pressure were ' measured at approximately five-centimeter (cm) depth intervals to provide a nearly continuous geologic log of the subsurface. Pore pressure dissipations were recorded at five-second intervals when appropriate during pauses in the advancement of the borings. The four geologic logs were compared and correlated to ' identify potential horizons that are laterally extensive and relatively conductive of groundwater (clean sand) and/or potential horizons that may act as relative groundwater barriers (clay and silt). A copy of the presentation of Cone Penetration Test Data is provided in Appendix E. ' The piezocone and associated push rods were steam cleaned prior to each boring. Upon completion of the CPT logging, each boring was grouted from the bottom to the surface with neat cement introduced to the bottom of the boring through the push rods. 3.3.1 Discrete Depth Groundwater Sampling 1 One direct push boring was advanced within two feet of each CPT borehole to collect discrete groundwater grab samples from horizons identified in the CPT boring logs. The second boring at each pair location and five direct push borings were completed between October 20 and 23, 2003. Pilot holes were hand-augured to five feet bgs for each boring. The direct push borings, corresponding to CPT-3, ' CPT-4, CPT-5, and CPT-6, were hydraulically advanced using a two-inch diameter conical bit to depths of approximately 121 feet, 122 feet, 61 feet, and 119 feet bgs, respectively. Five shallow direct push borings, HP-1 through HP-5, were advanced to investigate the lateral extent of petroleum hydrocarbon ' contamination in shallow groundwater cross- and down-gradient of the site. The shallow borings were hydraulically advanced to a maximum depth of approximately 28 feet bgs and groundwater samples were collected using a push-type groundwater sampler. ' Groundwater was first encountered in borings at depths ranging from 22 to 28 feet bgs. Discrete depth groundwater sample intervals were selected based on the results of the CPT boring logs. In each direct ' push boring, an attempt was made to collect a discrete groundwater sample from above a relatively continuous clay stratum underlying the site from approximately 22 to 26 feet bgs, as indicated by the CPT boring logs. Attempts to collect groundwater samples from CPT-3 at a depth of 22 feet, CPT-6 at a depth of 21 feet, and HP-1 at a depth of 22 feet were unsuccessful as the horinus were. annarpritly rin, 1µ..7p discrete depth groundwater grab samples were collected from boring CPT4, and four discrete depth groundwater grab samples were collected from each of borings CPT-3, CPT-5, and CPT-6. One discrete depth groundwater grab sample was collected from HP-1; two discrete depth groundwater grab samples ' �� CONDOR