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Geologccal Tecluucs Inc Page 3 Soil and Groundwatei Investigation Woik Plan Cardoza(Main St) Project No 662 2 January 17, 2003 ' GTI has selected Gregg Drilling & Testing Inc (Gregg) of Martinez, California (C57##656407) to perforin the CPT boreholes Gregg has 20 — 25 ton trucks that can ' achieve the target depths of 80 feet below grade surface (bgs) In addition, Gregg has sampling devices that can be used to collect depth disci ete soil and groundwater samples from the boreholes Data on CPT technology provided by Gregg is included in Appendix B 1 Soil boring permits will be secured as necessary and the local regulatory agency will be notified 48 hours prior to commencing work The subsurface will be cleared of underground utilities by notifying Underground Service Alert ' The CPT testing will begin with a single deep boring CPT-4 to the depth of 80 feet bgs in the vicinity of existing deep well MW-104 The purpose of this boring is to determine the lithology lower than the tenninal depth of the MW-104 boring (55 feet bgs) After this ' borehole is completed, the rig will be moved several feet and a new hole will be advanced for the purpose of obtaining discrete water and soil samples In their November 18, 2002 letter the SJC/EHD stated that the vertical extent of the plume is undefined in the location of MW-104 The second CPT borehole in this location will be advanced to 80 feet so a groundwater sample can be obtained from over twenty feet below the screened interval of MW-104 (screened 48-53') The reminder of the CPT activities will continue as CPT-4 The first borehole will be installed to determme subsurface lithology, and the second to obtain soil and groundwater samples The need for two holes in each location is designed to alleviate the necessity of repeated removal and re-insertion of the rods, and changing the cone/sainpler fixtures during sampling The locations of the boreholes are similar to those as originally proposed by GTI in our October 8, 2001 work plan CPT locations are designated as "CPT- X" in Figure 2 CPT locations CPT-1, CPT-2 and CPT-3 will be located in proximity to existing wells MW-1 through MW-3 CPT-5 will be placed to the west of the dispenser island to provide up gradient data CPT locations CPT-6, CPT-7 and CPT-8 will be located in the predominant down gradient directions as shown in Figure 3 — Groundwater Gradient Rose ' Diagram 3.1.1 Soil Sampling iSoil sample depths will be targeted to complete a site conceptual model illustrating the lateral and vertical extent of the soil plume at the site Gregg will utilize a piston type soil ' sampler to obtain samples at depths to be determined in the field The sampler is attached to the end of the drill rods and then advanced to the targeted depth When the targeted depth is achieved, the rods are retracted 12 — 18 inches to allow the cone to slide upward into the hollow core of the sampler The rods are then advanced downward to allow soil to fill the now empty core A description and schematic of the process is included in Appendix B 3.12 Soil Sample Laboratory Analyses ' Petroleum Hydrocarbon Analysis Up to 4 soil samples per borehole will be submitted to Sherwood Labs (State Certified Laboratory #1400) for analysis for