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.•. r w <br /> i <br /> Between sampling events, equipment was cleaned using a three-bucket wash system. In this <br /> system, the brass liners and samplers are senibbed in a bucket of tap water and detergent,rinsed <br /> in a second bucket of tap water and given a final rinse in a bucket of distilled water. <br /> 5.2 Monitoring Well lnstalladan <br /> All borings were advanced to approximately 15 feet below static groundwater and converted to <br /> monitoring wells by the installation of 2-inch diameter, flush threaded, schedule 40 PVC screen <br /> (0.010 slot) and casing. The wells were filter packed using pre-washed silica sand with an <br /> approximate .5-foot thick hydrated bentonite seal placed above the filter pack. An annular seal <br /> of neat cement was placed above the bentonite seal. All well's viere completed at grade in water- <br /> tight, street-rated, well protectors and fitted with locking caps for security purposes. All <br /> procedures and protocol for groundwater monitor,;�g well construction, conformed to standards <br /> set by the California Department of Water Resources (CDWR) and the California Regional <br /> I Water Quality Control Board (CRWQCB): <br /> i <br /> Subsequent to well installation, the monitoring wells were developed using swab and pump , <br /> methods. Development water was comained in DOT 17H drums and stored on-site pending <br /> I laboratory analyses. <br /> The top,north side of the well casing was surveyed relative to a common datum for determining <br /> groundwater gradient information. Surveying was performed under the direct supervision of a <br /> California Registered Civil Engineer. Groundwater contours were constructed using a kriging <br /> P1gram. <br /> Groundwater monitoring data[r•able 1) collected during April 1991, indicate groundwatra flow <br /> Is toward the northeast at approximately .07 ft/ft or 370 feet per mile(Figure G). The estimated <br /> groundwater velocity at the site is 1.88 x 104 feet per day using a porosity of .50 and a <br /> F <br /> hydraulic conductivity of 104 gallons per day per squLre foot. These values of porosity and <br /> ([f <br /> KN lei"Fwan <br /> • R001091.wP a <br /> s <br /> tr <br /> ;i <br />