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1 3.0 PROCEDURES 3.1 Drilling and Sampling ' Fieldwork was performed on October 26, 1993 Three groundwater monitoring wells (MW-1 through MW-3) were drilled with a truck-mounted drill rig equipped with 8- inch-diameter hollow-stem augers (Figure 2) Great Sierra Exploration of Union ' City, California provided the drill rig and 2-man crew Soil samples were collected at 5-foot intervals, usually starting at a depth of 5 feet, using a 140-pound hammer to advance a split-tube sampler loaded with three brass sleeves The number of blows ' required to advance the sampler 18 inches was recorded on the boring log (see Appendix A) ' After removal from the sampler, the ends of the bottom tube were covered with sheets of aluminum foil, capped, and sealed with tape Samples were labelled and placed on ice until delivery to WEST Laboratories for analysis Soil in the middle ' and upper tubes was extruded into a plastic bag and screened for volatile organic vapors using a portable photo-ionization detector (PID model OVA-580A calibrated to isobutylene) Sample descriptions and PID readings were recorded on the boring ' log To avoid contamination of subsequent samples, the tubes and sampler were then triple-rinsed in a phosphate solution, the augers were steam-cleaned between borings 3.2 Well Completion ' The wells were completed as groundwater monitoring wells by the installation of 2- inch diameter PVC casing Perforated casing ( 010-inch slots) extends from total depth (46 feet) to '26 feet below surface grade (BSG) Blank casing extends to I ' I surface grade Appendix A shows the details of the well design E I, I 3.3 Well Surveying and Sampling' I I I ! � I The wells were surveyed and the depth to water was measured on November 1, 1993 The elevation of the top of the PVC casing was measured relative to a temporary benchmark (the fire hydrant on the northeast corner of Yosemite and Acacia) A Solinist water meter was used to measure water depth Elevation and depth data are ! shown in Table 1 Ii I ! I After the depth to groundwater was measured, a PVC bailer was used to purge each I well' l'of standing water Nine gallons of water were removed from each well I(miniinum of 3 to, 5 well volumes) to stabilize temperature,,pH and conductivity Parameters were measured at done-gallon intervals using a Hydac water analyzer ' ! (Table 2) , Purge water was stored in 55-gallon DOT drums on the site III I I 'I I f E 'I E E I I I I I I I I 1 I �MI it I E E I I I' V I I I di EI E I E'!E Ie E E I Ii El Etli'I E I IE I E�Ililu`I E t 11 .v9 IIS In f F�EI I EIE� EEI SII�E