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San Joaquin Motor Pool Facility May 11, 1999 Site Assessment Report i 9.0 WELL INSTALLATION, DEVELOPMENT,AND SURVEY 9.1 Well Installation and Construction On March 18 and 19, 1999, monitoring wells MW-1 and MW-2 were installed using 10-inch (outside) diameter hollow stem augers The wells were constructed using blank and factory slotted (0 020-inch) 4-inch diameter Schedule 40 PVC casing The screened intervals for monitoring wells MW-1 and MW-2 were completed from approximately 20 to 60 feet bgs and 3 5 to 60 feet bgs, respectively The filter packs consisted of No 3 sand placed from the bottom of the screened interval to approximately 2 to 3 feet above the top of the screened intervals The wells were each surged approximately 15 minutes to fully settle the sand pack, then sealed using three (3) feet of hydrated, medium bentonite chips, and backfilled with type I-II cement to approximately one (1) foot bgs,followed by a traffic-rated well box cemented to surface grade A summary of well construction data is presented in Table 1 and boring logs/well completion details are presented in Appendix D ' 9.2 Well Development On April 14, 1999, well development was initiated using a Smeal development ng provided by WHD The wells (MW-1 and MW-2) were surged approximately 15 minutes A minimum of five (5)well volumes of water were removed from each well until the sediment was removed and baseline measurements for pH, temperature, electrical conductivity and turbidity were established Copies of the development records are presented in Appendix E 9.3 Survey jIn April 1999,the newly-installed wellheads were surveyed relative to a benchmark of known elevation above mean sea level (msl) (0 01-foot accuracy) Top of casing elevations are presented in Table 1 Surveying services were provided by Morrow Surveying, a State-licensed surveyor A copy of the survey information is presented in Appendix E 10 0 GROUNDWATER ELEVATION MONITORING AND SAMPLING 10.1 Groundwater Elevation Monitoring 1 On April 14, 1999, pnor to well purge, static groundwater levels in the wells were measured using a hydrocarbon/water interface meter No free-floating hydrocarbons (free product) were ' noted in any of the wells, although a slight sheen was noted on the tape after gauging well MW- 1 Groundwater was noted to be 42 51 and 42 78 feet below the top of the casing (toc) in MW-1 and MW-2, respectively The meter was decontaminated following each water level measurement Based on the data from the newly installed groundwater monitoring wells, static groundwater level averages -23 feet above msl An accurate groundwater gradient and direction of flow could not be calculated due to the limited number of wells at the SITE ' 6 �