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outlined a program for temporary and permanent well construction, sampling, analysis, <br /> and data evaluation. This plan was approved by the RWQCB in late August 2011. <br /> Two phases of EMP field work were conducted to develop an understanding of VOC <br /> distribution in the upper aquifer. Phase I EMP field work was conducted in October <br /> through December 2011 and Phase II EMP field work was conducted in February <br /> through March 2012. Drilling was conducted by Gregg Drilling (California Contractor's <br /> License No. C57-485165) under contract to San Joaquin County, and under field <br /> supervision of a State of California Registered Professional Geologist with GLA <br /> 4.1 WELL PERMITS <br /> Drilling and well construction permits were obtained through the San Joaquin County <br /> Environmental Health Department. Copies of the permits are included in Appendix A. <br /> Caltrans granted an encroachment permit to drill and install the wells in their right of <br /> way. Easement to these locations has been granted by Caltrans allowing the County <br /> access for monitoring. <br /> 4.2 DRILLING, SOIL SAMPLING, AND LOGGING METHODS <br /> Prior to beginning drilling operations and between each location, all drill rig and <br /> sampling equipment was decontaminated using high-pressure wash and steam-cleaning <br /> equipment. Boreholes were drilled using an 8-inch diameter hollow stem auger. In the <br /> unsaturated zone, samples were collected at five-foot intervals using a California- <br /> modified split-spoon sampler. Logging of boreholes recorded the following elements: <br /> ■ Borehole designation and location. <br /> ■ Times and dates that drilling/excavation began and ended. <br /> ■ Type of exploratory equipment being utilized, including manufacturer, make, and <br /> model for special modifications. <br /> ■ Name of geologist responsible for log description. <br /> ■ Description of soils according to the Unified Soil Classification System and <br /> description of bedrock materials according to accepted geologic nomenclature. <br /> ■ Systematic descriptions of lithologic and micro-structural changes in strata or soil <br /> horizons, including thickness of units as well as the depth and elevation of <br /> lithologic changes. <br /> ■ Presence of and depth to groundwater. <br /> ■ Sampling interval(s). <br /> ■ Drilling advancement in feet-per-hour (average) and/or feet-per-minute, noting <br /> periods of difficult or very easy drilling. <br /> ■ Any subsurface structures or unusual features encountered. <br /> ■ Descriptions of mineral seams and fracture fillings. <br /> ■ Depth and thickness of weathering. <br /> EMP Report—Phase II Geo-Logic Page ■ 6 <br /> Corral Hollow Sanitary Landfill ASSOCIATES <br /> August 21,2012 <br />