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19 July 2000 <br /> • AGE-NC Project No 96-0232 <br /> Page 10 of 29 <br /> Rocky's Restaurant domestic drinking water well (RDW-1), to characterize lithology, ground water <br /> gradient, potential contaminant migration pathways and to assess the horizontal extent of <br /> MTBE-impacted ground water west of the former UST system The location of multi-level well <br /> MW-11 is illustrated In Figure 2 A generalized design of multi-level monitoring well MW-11 is <br /> presented In Figure 20 <br /> Based on laboratory results of soil and ground water samples and field data collected from on- and <br /> off-site, multi-level monitoring well MW-11 was designed utilizing four separate screen intervals, <br /> 40-50 feet bsg (Second Zone), 65-75 feet bsg (Rocky's Upper Zone), 95-105 feet bsg (Secondary <br /> Aquifer Zone), and 130-150 feet bsg (Primary Aquifer Zone) <br /> 5 1 FIELD PROCEDURES <br /> All field procedures were overseen by an AGE representative under the supervision of a California <br /> Registered Geologist Procedures for the monitoring well Installation are described below <br /> 5 2 GROUND WATER MONITORING WELL COMPLETION <br /> • The pilot soil borings were advanced utilizing a truck-mounted, hollow-stem drill ng and 8-inch <br /> diameter hollow-stem augers Cuttings generated during drilling activities were placed on plastic <br /> sheeting and covered R nsate was containerized in properly labeled DOT-approved 55-gallon drums, <br /> and stored on-site In an area lacking public access <br /> The pilot borings were completed as a multi-level ground water monitoring wells utilizing 1 7-Inch <br /> outer diameter pre-made Precision multi-chamber polyethylene tubing equipped with stainless steel <br /> screen wrapping the depth-specific sampling ports <br /> After the advancement of the pilot borings, the pre-made multi-level chamber tubing (well casings) <br /> were Installed In the borings, generally to a total depth of approximately 150 feet bsg The screen <br /> Interval extended from approximately 150 feet bsg to 130 feet bsg A filter pack material consisting <br /> of pre-washed #2112 Lonestar sand was added through the augers over the screen Interval to <br /> approximately two feet above the screened Interval <br /> After Installation of the filter pack, a bentonite seal consisting of 114-Inch pell plug-coded bentonite <br /> pellets was placed above the filter pack to minimize the potential for hydraulic Influence from the <br /> other water bearing zones encountered In the monitoring well The bentonite seal was formed by <br /> pouring bentonite pellets Into the annulus and allowing them to settle on the filter pack The <br /> bentonite pellets were allowed to hydrate for a minimum of one-half hour prior to the Installation <br /> Advanced GcoEm ironmental,Inc <br />