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Ms. Mary L. Boyd <br />CVRWQCB <br />August 18, 2006 <br />Page 2 <br />Clayton Project No. 25003-003242.00 <br />1. Location of reinstalled wells <br />The preferred relocation sites for MW -9 and MW -10 would be off the waste footprint <br />Y" on the perimeter of the cap area just north of the property line between Cove <br />Contractors and Universal Recycling Services. However, the locations will be <br />determined based on the analytical results from two groundwater monitoring events. <br />2. Drilling Details. <br />Each boring will be continuously cored using the Sonic drilling method. Soil <br />sampling will not be conducted; however, the continuous coring will prove an <br />accurate and detailed record of the soil strata. A field geologist will record the <br />lithology of each soil boring using the united soil classification system in accordance <br />with Clayton SOP -12 (Appendix A). <br />3. Monitoring Well Design. <br />The borehole at each location will be approximately 10 inches in diameter. Both <br />wells will be constructed using 4 inch (in.) schedule 40 PVC with 20 ft of 0.001 in. <br />slotted PVC well casing. The sand pack, constructed using Monterey sand (#1/20), <br />will extend to one foot above the slotted screen. A three foot layer of bentonite <br />(medium chips) will be placed above the sand pack and will be topped with a layer of <br />cement/bentonite grout. A concrete seal will be place at the top of the well extending <br />to approximately five feet (ft) below ground surface (bgs). In addition, a threaded <br />PVC bottom cap and locking top cap will be used. <br />The monitoring wells will be installed to total depths of 40 ft (MW -9) and 60 ft <br />(MW -10) bgs. The details for the shallow and deep wells are illustrated in the well <br />diagrams provided in Appendix B. <br />4. Well Development. <br />After installation and development are completed, each well will stand for a period of <br />48 hours before sampling occurs. During sampling activities, each well will be <br />purged to remove standing water from the casing and filter pack in order to draw <br />representative water from the surrounding formation into the casing. During purging, <br />pH, temperature (Celsius), electrical conductivity (µmhos/cm), dissolved oxygen, <br />groundwater elevation (feet and hundredths mean sea level) and turbidity will be <br />S: ES Proj-.P03242 Groundwater G\4'_In%e tigation_Addendum_FINAL.doe <br />