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T Undisturbed soil samples were collected at least every 5-feet as drilling progressed for lithologic and hydrogeologic description and for possible chemical analysis. Soil samples were collected continuously below 30-feet bgs. The samples were collected by driving a split-barrel sampler lined with 6-inch diameter brass tubes using repeated blows from a 140-1b hammer dropped 30-inches. Selective soil samples were immediately trimmed, sealed with Teflon tape and plastic end caps, labeled, and stored on ice for transport to Kiff Analytical, LLC of Davis, California under chain of custody. Soil from the remaining tubes was described by the site geologist using the Unified Soil Classification System (USCS) and was screened for volatile compounds using an organic vapor meter (OVM). The soil was screened by emptying soil from one of the sample tubes into a plastic bag. The bag was then sealed and placed in the sun f o r approximately 10 minutes. After the volatile compounds were allowed to volatilize, the OVM measured the vapor in the bag through a small hole punched in the bag. OVM readings are used as a screening tool only, since the procedures are not as rigorous as those used in the laboratory. The OVM readings are listed on the boring logs presented in Appendix D. Drilling equipment was cleaned with a TSP solution between sampling intervals to prevent potential cross-contamination. 5 .3 Monitoring Well Construction Monitoring well MW-6 as constructed in the boring with 2-inch diameter, 0.0 ch slott flush-threaded, Schedule 40 PVC well screen and blank casing. The well is screened between 39-feet bgs and 44-feet bgs to monitor the targeted water-bearing zone. The well casing was lowered through the augers and #2112 filter pack sand was placed in t h e annular space between the well casing and the borehole from the b o t t o m of the boring to 2-feet above the well screen. A 3-foot thick hydrated bentonite layer separates the sand from the ovcrl}irtg ccillent surface seal. The wellhead is secured with a locking wellplug beneath an at-rade traffic-rated well box. Well construction details are shown on the boring log in Appendix D. 5 .4 Monitoring Well D-Lyelopmen On August 20, 2001, ASE associate geologist Erik Paddleford developed monitoring well MW-6 using two episodes of surge-block agitation a n d submersible pump evacuation. Over ten well casing volumes of water were removed from the well during development, and evacuation 574 West Grant Line Road CAP — January 2002 -6-