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Southland/Stockton 14 <br /> March 1991 <br /> Drilling and Soil Sample Collection and Analysis The boreholes for the wells will be drilled <br />' with 7 5-inch outer-diameter, truck-mounted, hollow-stem auger equipment The boreholes will be <br /> continuously cored to depth of about 65-feet (approximately 15-feet below the water table) The <br />' continuous cores from the two off-site borings and one on-site boring will be observed to confirm the <br /> site lithology which appears to be very heterogeneous Soil samples will be collected during drilling of <br />' the on site boring by driving a brass tube into the continuous core at 5-foot intervals and where changes <br /> in iithology occur The samples from the on site boring will be capped, taped, labeled and placed on ice <br /> for delivery to a State of California-certified laboratory under standard chain-of-custody procedures <br />' Samples will be collected in the field and screened with a photo-ionization detector (PID) The results of <br /> the PID readings will be used, In addition to visual field observations, to select the samples for laboratory <br />' analysis A maximum of three samples will be collected from the on site well for analysis using EPA <br /> Method 5030/8020/8015 and EPA Method 6010 No laboratory analysis is planned for the soils <br />' collected from the off-site borings However, if field observations show that concentrations of <br /> hydrocarbons might be present in the sod profile, then samples will be submitted for analyses <br /> 1 • Well Construction_. The wells will be constructed with 2-inch diameter polyvinyl chloride (PVC} <br /> well screen and casing The well screen will be 0 020-inch slot size, extending from the bottom of the , <br />' borehole to about 35-feet from the surface Blank casing will then extend from 35-feet to the surface <br /> A sand pack will be placed in the annulus to extend about 2-feet above the top of the screen section <br />' Approximately 24eet of bentonite will overlie the sand pack, and the well will be completed with cement <br /> grout to the surface The wellheads will include locking caps for security under street-rated boxes for <br />' protection <br /> Well Development and W Ilhead Surveying_ The three wells will be developed after <br /> construction is complete to improve their efficiency and ensure that they yield representative aquifer <br /> water Development will be done using a surge and bad technique wherein water is alternately pushed <br />' and pulled through the sand pack This process will remove fine sod particles smeared on the borehole <br /> wall during drilling and will clean out the sand pack <br /> The wellheads will be surveyed for elevation control after they have been developed The well <br /> elevation data will then be used in determining the water elevation within the wells <br /> CA GROUNDWATER <br /> TECHNOLOGY, INC <br />