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Project 113-26-04,05, Page 6 November 17,1995 construction were obtained from the same County agency (Appendix A Permits, �t Notifications) Excavation limit markings were made and Underground Service Alert was notified for underground utilities locating An encroachment permit from the City of Tracy was obtained for the borings B-15 to B-21 A State Water Well Drillers's Report was completed and attached in Appendix A. The project scope included the drilling and installation of four new groundwater monitoring wells and fourteen additional soil borings Soil sampling was performed during drilling Days after well installation, the wells were developed, then purged and sampled The well casing tops were surveyed for groundwater flow calculations Two of the well locations (MW-6, 7) were chosen as possible intercept points for contaminants migrating in the verified down gradient direction from the subject tank pit The other two wells (MW-5, 8) are located up gradient from the UST system and include one large diameter well for aquifer testing and groundwater extraction/treatment MW-6 and MW-8 were relocated from their originally proposed locations at the request of the regulators The twelve borings include two which were placed downgradient from the tank system (B-8, B-14), four upgradient and on site (B-10, 11, 12, 13), and six more at up- or cross gradient locations across Holly Dr and across or along E. Grant Line Rd B-15, 16, and B-17 were placed along Holly Drive to the west from the site B-18 was located across Holly Dr and across E Grant Line Rd in front of what is now Tracy Auto Stereo B-20 and 21 were advanced in the sidewalk of E Grant Line Rd just south of the property line and on the NE corner with Holly Drive, respectively Drilling and Soil Sampling The drilling, well installation, and soil sampling took place on July 20, September 1, and October 24, 1995 The well borings were drilled with a truck mounted hydraulic rotary drill using 4 25" I D. by 8" outside diameter (O D.) hollow stem augers After soil sampling the MW-8 boring was then widened to 12" diameter The rig was operated by V&W Drilling, a State Licensed Water Well Driller (C-57 #554979). No utilities or other structures were encountered during the monitoring well drilling Twelve of the fourteen soil borings were successfully advanced with a 4" O.D hand turned auger No utilities or underground structures were encountered during the hand augenng with the exception of a possible sewer line encountered but not damaged during the first attempt at B-8, and an obstruction at 7 feet depth in B-21 Native course gravels were encountered at B-9 which prevented augenng past 2 5 feet BGS. At B-19, fill gravel prevented advancement beyond 5 feet depth No sampling was performed at B-9 or B-19. Excavated soils were placed on plastic sheeting on site The hollow stem augers and down hole tools were high pressure hot-water washed before use and between borings Hand auger tools and sampling equipment were washed in a TSP solution and double rinsed with tap water Used waters were retained in labeled DOT 17H drums i Parker Environmental Services, 190 East 7th Street, Pittsburg, CA 94565-2317 Phone (510) 439-1024 Fax (510) 439-2566