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r <br /> 1444 MARIPOSA <br /> WKA No. 2938.04 <br /> April 6, 1999 <br /> Page 2 <br /> truck-mounted drill rig equipped with hollow-stem augers. All drilling <br /> equipment will be steam cleaned between borings to reduce the potential <br /> of cross-contamination; rinse water generated during steam cleaning will be pumped <br /> into labeled 55-gallon drums and stored on site. All soil cuttings generated during <br /> drilling will be placed on and covered with plastic <br /> • obtaining soil samples at maximum intervals of five feet and/or at significant <br /> stratigraphic changes beginning at 5 feet below grade and continuing to the total depth <br /> of the borings. Soil samples will be obtained with a modified California sampler <br /> containing clean two-inch diameter, six-inch long brass tubes. A continuous core will <br /> be collected from the deep soil boring beginning at a depth of 80 feet below site grade. <br /> All sample tubes will be sealed with Teflon sheets and plastic caps, and preserved on <br /> ice. Soils encountered during drilling will be logged in the field using the Unified Soils <br /> Classification System. Each sample will also be field screened using an <br /> photoionization detector(PID)to assist in selecting soil samples for laboratory <br /> analysis, if warranted <br /> • converting three of the soil borings into groundwater monitoring wells. The wells will <br /> be constructed using a two-inch diameter, flush jointed, Schedule 40 PVC casing; a <br /> 0.02-inch slotted casing material will be used for the screened interval of 50 to 85 feet <br /> bsg). Number 3 sand will be placed in the well annulus as a filter pack. The filter pack <br /> will extend from the bottom of the screened interval to approximately two feet above <br /> the top of the screened interval. A minimum two-foot thick bentonite seal will be <br /> placed in the well annulus above the filter pack. A grout seal consisting of Portland <br /> Cement and bentonite slurry will be placed into the well annulus above the bentonite <br /> seal. The wells will be completed with locking well caps and a flush-mounted, traffic- <br /> rated well covers <br /> • surveying the location of the new wells and the top of casing elevation along with the <br /> existing wells to the nearest 0.01 foot with respect to mean sea level (MSL) <br /> • submitting a minimum of three soil samples per boring under chain-of-custody to a <br /> California-certified laboratory for analysis of Total Petroleum Hydrocarbons(TPIT) as <br /> `0% <br /> WALLACE-KUHL <br /> Recycled paper &ASSOCIATES INC. <br /> l <br />