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U-Haul#709-50 Preliminary Site Conceptual Model Blaes Environmental December 15,2006 4 2 TOP OF CASING WELL SURVEY KjeIdsen, Sinnock & Neudeck, Inc, a California licensed land surveyor, surveyed each new well to the same datum as the existing monitor wells by measuring the wellhead elevation on the north side of each well casing In addition, the longitude and latitude of each new well was identified to sub-meter accuracy in accordance with Geotracker requirements A copy of the well survey is included as Appendix K 4 3 WELL DEVELOPMENT ACTIVITIES Upon installation of the casing and filter pack at each well, the drilling contractor developed the wells by surging Using the drill ng, a decontaminated surge tool was Iowered and raised multiple times across the screened interval of the well to surge the well Surging the filter pack of the well ensured that the filter pack settled properly The sediment, pulled into the well during surgin,g was removed using a 1 5-inch ProActive "Mini-Monsoon" 12-volt, battery-operated groundwater pump Pumping continued until the water contained little or no sediment Purged groundwater from the four newly installed monitor wells was contained in four 55-gallon steel drums The drums were properly labeled and stored on-site behind the U-Haul building pending proper waste profiling and disposal • 4 4 GROUNDWATER MONITORING AND SAMPLING Blaes Environmental conducted quarterly groundwater sampling events at the site in March 2006, June, 2006 and September, 2006 The most recent groundwater sampling event from September 2006 is presented in the following sections, and the referenced tables include static water level measurements and laboratory analytical results from the groundwater monitoring program since 1991 to the present At the request of SJCEHD, groundwater monitoring is coordinated with GZA, the consultant for the Former Harry's Auto Mart site located southeast of the U-Haul facility The groundwater sampling program consists of five tasks including I) groundwater monitoring, 2) purging approximately three casing volumes of water prior to sample collection, 3) groundwater sample collection, 4) analyzing the groundwater samples at an analytical laboratory, and 5)preparing a quarterly report detailing the findings A description of each activity is presented as follows 4 4 1 Groundwater Measurements On September 18, 2006, Blaes Environmental measured the depth to groundwater in the 33 groundwater monitoring wells associated with the U-Haul site Groundwater levels in the well casings were measured from a surveyed point on the top of the monitoring well casing to the groundwater surface All water Page 12