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i <br /> HaMat Drilling Company of Rancho Cordova, California. The <br /> soil borings were logged using the Unified Soil <br /> Classification system. Copiers of the Boring Logs are <br /> included in Appendix E. <br /> Borings B-1, B-2, B-3, and B-a4 were drilled to a total <br /> depth of 25 feet below grade using a truck mounted drill <br /> rig with 10-inch-diameter hollow-stem augers. During <br /> drilling, soil samples were collected at 5-foot intervals <br /> using a modified California split-spoon sampler lined with <br /> clean stainless steel tubes. The sample tubes were sealed <br /> using Teflon tape, capped, and immediately placed into an <br /> iced cooler. The samples were then delivered to a <br /> California-certified laboratory for analysis following <br /> proper chain of custody documentation. <br /> 3. 1.2 Ground Water Monitoring Well Construction <br /> Soil Borings B-1, B-2, B-3, and B-4 were converted to <br /> Ground Water Monitoring Wells AW-1, AW-2, AW-3, and AY7-4. <br /> The four monitoring wells were each completed with <br /> 4-inch-diameter casing to a total depth of 25 feet below <br /> grade. The wells were constructed of flush-threaded, <br /> Schedule 40, PVC blank casing, and 0.020-inch, slotted PVC <br /> casing. Monitoring well installation and construction <br /> procedures are presented in Appendix D, while well <br /> construction details are included as part of the boring <br /> logs in Appendix E. <br /> Ground water was first encountered during drilling at an <br /> approximate depth of 10 feet below grade in Soil Borings <br /> 19-1 through B-4. Based on initial water depth encountered <br /> and results of previous investigations, the slotted screen <br /> was installed from 5 feet below grade extending to the <br /> total depth of the boring to account for water level <br /> fluctuations. The wells were then completed with blank <br /> casing from the top of the slotted casing to approximately <br /> 1 foot above grade and protected with watertight locking <br /> well caps and monument boxes. Surface seal materials <br /> consist of 1 foot of bentonite and 2 feet of cement. <br /> 3.1.3 Monitoring Well Development and Sampling <br /> Well development and sampling procedures.were conducted in <br /> accordance with RWQCB guidelines. The monitoring wells <br /> were developed on September 27, 1990, and sampled on <br /> . October 2, 1990. A diaphragm pump was used to purge 8. well <br /> volumes during development and 4 well volumes'.prior to <br /> sampling. Copies of the well development and water <br /> sampling survey forms are included in Appendix F. <br /> During purging of the wells,` pH, ;specific conductance, and <br /> f temperature measurements were recorded. After these ground <br /> water parameters stabilized, indicating that the water was <br /> 7 <br />