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• qennedy/Jenks Consultants <br /> Mr. Tim O'Brien <br /> California Regional Water Quality Control Board <br /> 25 August 2006 <br /> Page 4 <br /> Response: <br /> a. The physical parameters measured by the CPT include cone bearing pressure, sleeve <br /> friction, and pore water pressure, which are measured at 5-centimeter intervals. The <br /> sleeve friction divided by the cone bearing pressure is the friction ratio, which is plotted <br /> with cone bearing pressure and sleeve friction. The cone bearing pressure and friction <br /> ratio has been empirically related to provide an interpreted soil type. The interpreted soil <br /> type is also presented on the CPT logs <br /> b. The pore pressure can be used as an indicator of groundwater. In the case of erratic <br /> pore pressure readings (sometimes encountered when pushing CPT rods through dense <br /> layers), the depth to groundwater from monitoring wells and monitoring well construction <br /> details will be used to guide the depths at which groundwater samples are collected. The <br /> groundwater sample depth is expected to be approximately 80 feet below ground <br /> surface. <br /> c. Groundwater samples are collected using a HydropunchTM or equivalent method. In this <br /> method, a 5-foot length of PVC screen is fitted to a sacrificial cone. The PVC is inserted <br /> into a steel sampling rod and the sacrificial cone is fitted to the end of the steel rod. This <br /> becomes the lead rod, and is then pushed by the CPT rig to the desired depth. Upon <br /> reaching the desired depth, the rods are retracted by a specified amount (typically four to <br /> five feet), and the sample is collected using a stainless steel bailer once groundwater <br /> begins entering the PVC and steel rods. <br /> d. The CPT and HydropunchTm boreholes will be grouted with neat cement using tremmie <br /> pipe. Because samples from the first-encountered groundwater will be collected (in <br /> contrast to cases where multiple aquifers are penetrated) it is anticipated that the same <br /> borehole will be used for the CPT and the groundwater sampling. <br /> After collection of the groundwater sample, the steel rods will serve as tremmie pipe. <br /> Cement will be added into this string of steel rods as they are removed from the <br /> borehole. Cement will be added to the steel rods periodically to maintain a cement-filled <br /> borehole. <br /> e. Drilling permits will be acquired from San Joaquin County Environmental Health <br /> Department (SJCEHD) before conducting the CPT program. One permit is anticipated <br /> for each separately-owned parcel. A right-of-entry agreement is also necessary for each <br /> separately-owned parcel. <br /> A separate permit will be acquired from SJCEHD prior to installing any monitoring wells. <br /> g:Gs-groupladrrdngobk031030118.08_barrelten106cwspndVbstrspns_cm Wcmmts-01.doc <br />