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was not present during well construction. The augers were withdrawn during filter pack ' placement to allow the sand to fill the annular spaced between the auger and borehole wall. The volume required to fill the annulus was compared with the volume of filter pack material to ensure that no bridging or belling out of the borehole occurred. The ' top of the filter pack was periodically sounded using a decontaminated weighted tape measure, and installation was deemed complete when the sand extended approximately three feet above the top of the screen, as determined by sounding. ' Following filter pack sand placement, the filter pack was pre-developed by surging the inside of the well screen to remove voids and alleviate bridging. Additional sand was ' added when necessary to bring the filter pack up to design depth. An approximately 5-foot thick bentonite seal consisting of medium-sized chips was ' placed over the well filter pack. The thickness of the bentonite chip seal was determined by sounding the top of the seal with a weighted measuring tape. After reaching the minimum design thickness, the bentonite chip seal was hydrated by pouring potable ' water down the inside of the hollow stem augers. After the water was poured into the augers, the chip seal was allowed to hydrate for at least 30 minutes prior to placement of the upper neat cement grout. The remainder of the borehole annulus was sealed with an expansive neat cement grout ' consisting of Portland Type 1/II cement and powdered sodium bentonite mixture with a water-to-cement ratio that included no more than 8 gallons of water per sack of cement and 5 percent bentonite by weight. The grout was placed in the annulus using positive ' displacement tremie techniques. Well heads were finished with locking stovepipe-type monuments embedded in concrete pads and protected by concrete-filled traffic posts (bollards). Diagrams summarizing well construction materials and dimensions are included in Appendix B. A summary of well construction is provided on the following table. ' Table 6 ' Phase 11 - Permanent Well Construction Summary Well IDGround Surface Total Depth Screen Interval Filter Pack Bentonite Chip Elevation (msl) (ft) Interval Seal Interval ' MW-9A 295.74 105 76.3-96.3 72-96.3 67.2-72 MW-10A 278.95 86.3 66.3-86.3 62.2-86.3 57-62.2 MW-11A 263.63 51.1 31.1-51.1 27-51.1 22-27 ' 4.4.5 Well Development Well development, groundwater sampling, and aquifer recovery testing took place on March 28, 2012, under the supervision of a California State Certified Hydrogeologist. ' Gregg Drilling was contracted by San Joaquin County to develop the wells to the EMP Report—Phase IIGeo-Logic Page ■ 12 ' Corral Hollow Sanitary Landfill ASS O C I AT KS August 21,2012