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1 PHASE VII SUBSURFACE INVESTIGATION San Joaquin County Montgomery Ward Auto Service Center Public Health Services Department 5400 Pacific Avenue, Stockton, CA Site Code 2163 samples were logged on chain-of-custody record forms (see Appendix B) Only those samples at or immediately above the water table, i e , the samples collected at 40, 45 and 50 feet bgs were delivered to the laboratory for analytical testing An HNU Model DL-101 Photoiomzer (PID), calibrated against an isobutene gas standard, was ' used on the soil contained in the second tube from the bottom of the shoe, at each sampling Interval within the boring, to determine if volatile hydrocarbon vapors were emanating directly from the soil Each sample was placed in an air tight "Ziploc" plastic bag The samples were ' allowed to sit in the sun and then the head space in the bags was analyzed using the PID The results of this field testing were recorded on the boring log (see Appendix C) 3.3 MONITORING WELL CONSTRUCTION ' Immediately after drilling, boring MW-7 was converted to ground water monitoring well MW- 7 Prior to drilling, a permit to drill and install the ground water monitoring well was obtained from the County (see Appendix A) The well was constructed of four-inch inside diameter flush threaded Schedule 40 PVC well casing All well casing materials were steam cleaned prior to installation The ground water monitoring well was designed with a slotted section (0 02-inch x 1 5-inch slots) which extends approximately 15 feet below the water table and 10 feet above The annular space between the borehole wall and well casing was backfilled with grade #3 Monterey sand to about two feet above the slotted section A two- to three-foot thick layer of hydrated bentonite chips was placed on top of the sand pack, and the remaining annular space grouted using a cement/bentonite mixture A flush mounted traffic grate was placed on the well Appendix D contains the specific well construction details for well MW-7 3.4 WELL DEVELOPMENT AND SAMPLING Well MW-7 was developed and sampled in March 1996 as part of the First Quarter 1996 ground water monitoring activities associated with the Montgomery Ward site The results of testing a ground water sample from well MW-7 will be included in the quarterly report to be prepared for this sampling event 3.5 EQUIPMENT CLEANING PROTOCOL The augers were steam-cleaned prior to drilling well MW-7 The sampler and hydropunch (equipment) were disassembled and decontaminated prior to each sampling using the following procedure - All excess soil was scraped off the sampler and hydropunch parts, - 'Tho- carmnlo-r nnrrll hvrirnrnwni-h %xrPPre cxraozh�P,ri in a crdTitinn of Alrnnn A,-tiand tan v .au...N ... ).. p. .b., Y water, and - The sampler and hydropunch were rinsed with tap water Project No 1232 - 6 - ENVIRONMENTAL AUDIT, INC