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Kennedy/Jenks Consultants Mr. Timothy O'Brien California Regional Water Quality Control Board 10 March 2005 Page 4 specified amount (typically four to five feet), and the sample is collected out of the PVC once groundwater begins entering. If another sample is desired from the boring, the PVC is removed and discarded and the steel rods are removed and decontaminated. Clean steel rods and a new sacrificial cone are then inserted into the borehole and pushed to the next deeper zone, and the sample collection process is repeated. The sacrificial cone from the upper sample interval is pushed aside by the rods advancing to the deeper sample. Item 7 — Physical Parameters The physical parameters measured by the CPT include cone bearing pressure, sleeve friction, and pore water pressure, which are measured at 5-centimeter intervals. The sleeve friction divided by the cone bearing pressure is the friction ratio, which is plotted with cone bearing pressure and sleeve friction. The cone bearing pressure and friction ratio has been empirically related to give an interpreted soil type. The interpreted soil type is also presented on the CPT logs. Item 8 — Perched Groundwater Zone Review of historical investigations at the site indicated that groundwater was encountered at a depth of 9 feet below ground surface in one boring in a geotechnical investigation conducted by Merrill & Seeley, Inc. in 1980 (See Reference list in Work Plan), and it is believed to represent a perched groundwater condition. We will pay close attention to this detail during our investigation because of this one finding and in order to be comprehensive. In particular during our CPT/HydropunchTA/ investigation, the presence of groundwater can be indicated by negative pore pressure at a specific depth range. The pore pressure alone, however, does not by itself indicate that a sample can be successfully collected from a given interval, because the saturated interval may be relatively impermeable clay or silt. The pore pressure and other indicators will be monitored during each CPT. Attempts to collect samples at shallower depths or potentially perched water zones will be made if a zone of negative pore pressure is encountered above the expected depth of groundwater, and if the other parameters indicate that the formation is sufficiently permeable to collect a sample. Item 9 — Grouting The CPT boreholes and the HydropunchTm boreholes will be grouted with neat cement using tremmie pipe. Upon completion of the CPT, the CPT rods will be removed and steel HydropunchTm rods will be inserted into the borehole to serve as tremmie pipe. Cement will be added into this string of steel rods as they are removed from the borehole. Upon collection of'a HydropunchTm water sample, the PVC pipe will be filled with cement. The PVC and steel rods will be removed, with cement added to the rods periodically to maintain a cement-filled borehole. g:Vs-graup�aCminyo0lU31WU1 t7.00Jrtandan106carspnalgwpvq_addeMunl.da