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results are shown on Figure 7 and historical groundwater analytical results are summarized in bottom of the borehole to approximately 5 feet bgs.Sand will be placed in the remaining annulus Table 3.Graphs comparing CDC concentrations over time are included as Appendix A. to the ground surface and completed to match the surrounding surface conditions. 5.0 PROPOSED MONITORING WELL DESTRUCTION AND INSTALLATION 5.5 Monitoring Well Installation The current monitoring well network will be destroyed and replaced with wells installed to 65 feet Monitoring wells will be installed using a hollow stem auger drilling rig. During drilling,soil cores bgs.The proposed monitoring well network modifications are summarized below and shown on will be collected using a split-spoon sampler every 5 feet and logged in accordance with the Figure 6: Unified Soil Classification System.The wells will be constructed or 2-inch diameter Schedule 40 polyvinyl chloride(PVC)casing with 20 feet of 0.010-inch factory-slotted screen from 45 to 65 feet • Well destructions:MW-1,MW-2,MW-3,MW-4,MW-5,MW-6R,MW-7,and MW-6 bgs.The annular space between the borehole walls and well screens will be backfilled with a silica sand filter pack to approximately 2 feet above the top of the well screen.A 2-foot bentonite • Well installations:MNA2R,MW-3R, MW-4R,MW-SR,and MW-6R transition seal will be installed above the filter pack and hydrated in place.A neat cement sanitary Well MW-1 will not be replaced because CDC concentrations are historically below water quality seal will be installed from the top of the bentonite seal to just below the ground surface. standards,the well is no longer included in the monitoring and sampling program,and the well is Wells MW-5R and MW-eR will be completed with a flush mount traffic-rated well box. The not needed to evaluate the groundwater flow direction.Additionally,wells MW-SR and MW-7 will remaining wells will be completed in an aboveground monument set in a concrete pad. The not be replaced because the proposed well MW-2R i Wit provide representative data at the same proposed monitoring well construction details are shown on Figure 9. location. 5.1 Permitting 5.6 Well Development In accordance with California Well Standards(Department of Water Resources Bulletin 74),the Well installation and destruction permits will be obtained from the San Joaquin County M wells will be developed a minimum of 46 hours after installation by a combination of bailing, Environmental Health Department (SJCEHD) prior to the start field work. Encroachment surging, and pumping. The total well depth, depth to groundwater, temperature, pH, specific permits will also be obtained from SJC for the replacement of wells W-5 and MW-8 along Welty conductivity, dissolved oxygen, and oxidation-reduction potential will be measured prior to the Road.Rubik will notify the SJCEHD and RWQCB at least 46 hours prior to the field work. start and periodically during development. Development will continue until a minimum of five 5.2 Health and Safety Plan casing volumes of water have been removed and water quality parameters have stabilized. A site-specific Health and Safety Plan(HASP)will be reviewed and signed by all field personnel, 5.7 Well Survey including subcontractors,pdorto work initiation.The HASP will identify potential health and safety The location, ground surface elevation, and top of casing elevation will be measured by a hazards for each phase of site work and include requirements and procedures for protection.The California-licensed Professional Land Surveyor in accordance with the requirements for the State HASP will be maintained onsite during the field activities. A traffic management plan for work Water Resources Control Board Geotracker database. performed along Welty Road will be developed and included in the SJC encroachment permit. 6.3 Utility Clearance 5.6 Decontamination and Waste Management Down-hole drilling equipment will be decontaminated prior to drilling each well using high- Underground Service Alert(USA)will notified a minimum of46 hours in advance of subsurface pressure cleaning equipment. The decontamination rinsate, well development water, and soil activities to identify underground utilities.l A private utility locator will also perform a geophysical cuttings generated during drilling will be placed into separate roll-off boxes or 55-galion drums survey tithe vicinity of each drilling location to identify potential utilities or other subsurface and labeled,dated,and staged on site prior to characterization and disposal at an appropriate off- obstructions. If factlity personnel, data from previous borings, and/or the utility clearance site facility. contractor are unable to verify a location is utility free, a hand auger will be advanced to approximately 5 feet bgs prior to drilling to manually clear the location. 5.9 Scheduling and Reporting 5.4 Monitoring Well Destruction Feld activities will be initiated after receiving the RWQCB's authorization to proceed and obtaining The well casing and annular seal will be destroyed by overdrilling to 2feet below the constructed well drilling and encroachment permits.A Monitoring Well Network Replacement Report will besubmitted approximately 8 weeks after completing the field activities.At a minimum,the report depth using a hollow stem auger drilling rig in accordance with SJCEHD requirements. The will contain: p resulting annular space will be sealed using neat cement delivered through a tremie pipe from the Monitoring We'll Neatwoik Replacement Work Phan Z 2.Ld. Nuaien ni; nal*Well ea r, a 3 ;266f� Monitodng Well NelveB Replacement Work Phan