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Morita Brothers Service Station 4 August 21, 1992 <br />intervals, and between borings to reduce the possibility of cross -contamination The <br />drilling augers will be steam cleaned between borings, also to reduce the possibility <br />of cross -contamination Drill cuttings, and soil sample spoils will be contained in <br />D O T approved 55 gallon drums awaiting confirmation from laboratory analysis as to <br />whether the contents are hazardous Disposal of any contaminated soil is the <br />responsibility of the facility operator <br />A field engineer or geologist will be on-site to log the borings in accordance with the <br />Unified Soil Classification System, monitor soils during drilling for contamination, <br />collect soil samples, and construct wells <br />Groundwat r Monitoring Well Completion <br />Three groundwater monitoring wells will be installed to determine the presence of <br />groundwater contamination resulting from a release from the former underground <br />. tanks The wells will be constructed in accordance with the State of California <br />Department of Water Resources Water Well Standards, Bulletins 74-51 and 74-90, as <br />well as County of San Joaquin regulations The borings will be drilled to a depth of 15 <br />feet into the water table, unless a substantial confining layer or dense bedrock is <br />encountered The maximum drill depth is estimated to be 75 feet below surface grade <br />The wells will be cased with 20 feet of 2 -inch slotted PVC casing and appropriate <br />filter pack sand, installed from the bottom of the boring to 5 feet above the slotted <br />interval Blank PVC casing packed Volclay grout 11 extend from the surface <br />downward to the three foot bentonite seal p ac ove the filter pack A locking, <br />water -tight well cover will be set in concrete to protect and secure the well head <br />Well Development- and <br />Groundwater Sam lin <br />of <br />cross -contamination Prior to <br />Following completion <br />of the groundwater monitoring <br />wells, the wells will <br />be <br />developed by surging <br />and bailing to remove drilling <br />residues and produce <br />low <br />turbidity ground water <br />All development, purging, and <br />sampling equipment will <br />be <br />washed TSP (tri -sodium phosphate) detergent, rinsed <br />with clean tap water <br />and <br />deionized water, then <br />allowed to air dry before the well <br />is purged and sampled, <br />to <br />reduce the <br />possibility <br />of <br />cross -contamination Prior to <br />sampling, the groundwater <br />10 monitoring <br />wells will <br />be <br />purged with a pre -cleaned bailer <br />to remove stagnant water <br />BB -8301.3 <br />9208-E046 WP <br />