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Ms Margaret Lagroio August 11,2004 Subsurface Assessment Report Project No 2033-15600-01 16 Joe's Truck Plaza, 15600 South Harlan Road,Lathrop,CA Page 4 were performed in accordance with American Society of Testing and Materials (ASTM) Method D3441 Locations of bonngs CPT-1 through CPT-8 are included on Figure 2 Upon reaching total depth, each CPT borehole was backfilled with neat cement to surface grade Fourteen pore pressure dissipation tests (PPDT's) were conducted at depths between approximately 22 5 and 91 5 feet bgs in borings CPT-1, CPT-2, and CPT-4 through CPT-8 PPDT's are performed by halting the CPT cone at the depth of interest, then measuring the pore water pressure (u2) through an orifice behind the tip of the cone Pore pressure measurements are collected by the CPT computer system until the values asymptotically approach a stabilized value (un,,,,,, in pounds per square inch [psi]) The time it takes for the pore pressure to dissipate 100% is referred to as tioo If the PPDT is allowed to proceed to tido, the depth of the water table (phreatic surface) can be calculated converting the stabilized pore water pressure to depth units (u,,,. times 2 31 feet per psi), then subtracting this result from the cone depth The CPT test data report in Appendix B includes the results of the PPDT's and additional information on the PPDT technique HydropunchTM Groundwater Sampling Grab groundwater samples were collected from a separate boring, directly adjacent to the CPT boring, using the HydropunchTM technique The initial 5 to 10 feet of each sample boring was hand-cleared to avoid damage to subsurface utilities The HydropunchTM sampling tool was advanced to the desired depth using hollow rods The CPT operator then retracted the drive rods, exposing a 4-foot long PVC screen A diagram illustrating the HydropunchTM sampler utilized by Gregg In Situ, Inc is included in Appendix B Grab groundwater samples were collected in a stainless steel bailer lowered through the drive rods Following retrieval of the bailer, the groundwater sample was decanted into appropriately preserved sample containers supplied by the analytical laboratory Each sample was appropriately labeled, identified on a chain-of-custody form, and then placed in an ice-chilled cooler Groundwater sampling intervals (successful and unsuccessful) are noted on the CPT logs in Appendix B, and on the borehole sampling logs in Appendix C Direct-Push Soil Sampling Soil samples were collected from the same boring as the groundwater samples Soil samples were collected by driving a 1 7-inch diameter piston sampler, equipped with two pre-cleaned 1 25-inch diameter by 6-inch long brass sleeves, into undisturbed soil Additional sleeves of soil collected at each sampling interval were field screened for the presence of volatile organic compounds (VOCs) using a photoionization detector (PID) The soil samples were also classified in the field using the Unified Soil Classification System P Voe's Truck Plaza\Reports\CPT report 08-2004 doc I