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hydraulic conductivity values of 0 017 to 0 134 feet per minute (24 5 to 482 feet per day) The estimated storatnvnty ranged from 0 0019 to 0.05 indicating that the A Zone aquifer is partially if not fully confined Slug tests performed by WEGE (May 1990) on monitor wells MW1 - MW10 showed hydraulic conductivities ranging from<1 to 79 feet per day, suzular in magnitude to the LFR calculations SITING DOWNGRADIENT OF TPHg PLUME FOR "LATERAL EXTENT" Chemical analysis of the groundwater samples obtained from the R603 wells indicated that MW12 (offsite downgradient well) was installed into the leading edge of the gasoline plume This well showed a gradual increase and then decreases in concentrations as the pre-vapor extraction plume migrated past it Using analyte high concentration peaks (Benzene and Toluene) found at MW-8 and assuming that the high concentration peaks found at MW-12 represented the downgradient travel velocity of those peaks the following velocities were estimated TPHg 28 feet/year, Benzene 30 feet/year, Toluene 21 feet/year, Ethylbenzene 115 feet/year and Xylenes 12 S feet/year, see Appendix B Degradation estimates based on these peaks indicated that at 130 to 190 feet downgradient of MW12 (still within the public right of way) the following concentrations would be expected. TPHg 378 ug/L and Benzene 35 ug/L No Ethylbenzene or Xylene degradaton comparison can be made because the MW8 peaks had not reached MW12 since the initial sampling on October 8, 1992. CPT-1 (SB8) was positioned at approximately 135 feet downgradient of MW12 within the City of Stockton public right of way(north side of Douglas Road), see Figure 3 PERMITS A City of Stockton encroachment permit and a San Joaquin County Health drilling permit were necessary to perform the CPT - sample borings, see Appendix C FIELD ACTIVITIES On April 26 and 27, 2001, Western Geo-Engineers supervised two Cone Penetrometer and three associated groundwater sampling borings using Gregg Drilling's 25 ton Cone Penetrometer Testing (CPT)ng The dead weight of the CPT ng is used to push the cone penetrometer using a hydraulic ram. Soii parameters such as cone bearing (Qt), sleeve friction ratio (Fs), friction ratio (Rf) and pore water pressure (U) were measured as the cone penetrometer was advanced These measurements are sent uphole through the cone rods to the support ng's on-board data acquisition system All data is processed in the field in real time, see CPT logs in Appendix D The CPT-1 log showed the top of this water zone at approximately 48 to 53 feet below ground surface (bgs). 3 R-603 May 2001