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I! {. 4.5 Groundwater Well Development and Sampling Procedures The monitoring well was developed one day following installation (February 12, 2000) The monitoring well was developed by surging the screen with a 2- inch diameter surge block by hand methods, followed by pumping using a cleaned stainless steel Grondfos "Reads-Flow II" submersible pump All wells were purged until the pH, conductivity and temperature stabilized or until at least five to ten well volumes were evacuated The pumping rate during the purging of all wells was approximately 1 gallon per minute (gpm) A total volume of approximately 45 gallons were discharged from all the wells All purged groundwater was collected in 55-gallon Department of Transportation (DOT) approved steel drums, sealed and temporarily stored on-site pending disposition based on the laboratory results One round of groundwater samples were collected from all six on-site monitoring wells on February 24, 2000 Before initiating sampling activities, measurements of the depth to water and depth to bottom of the well casing were made to determine the well volume A minimum of three well volumes were purged from each well before collecting groundwater samples All wells were purged using a submersible pump The pH, temperature and specific conductivity of the groundwater were measured during the well purging phase The final measurements were compared with physical water quality data obtained during well development to ensure that aquifer water was inside the well casing before collecting samples a summary of the field measurements during well purging is / presented in Appendix V The water samples were collected with hand held PVC disposable bailers and were collected in 40 milliliter vials without headspace to avoid volatilization Sample containers were labeled and chilled on ice immediately after collection The groundwater samples were analyzed for petroleum hydrocarbon constituents (TPHd and TPHg) by EPA Modified Method 8015, BTEX by EPA method 8020, and 1,2-DCA , EDB, and Oxygenates by EPA Method 8260 Samples were analyzed by Kiff Analytical LLC In Davis, California, a Department of Health Services (DHS)-certified laboratory 5.0 PHASE 11 FIELD INVESTIGATION RESULTS 5.1 Soils Encountered Underneath the Subject Property ' The soils encountered in the borings consist of dense, medium dark-brown, silty sand in the upper five feet From ten and fifteen feet bgs the soils consisted of Avalon Environmental Consultants 4627-001-2 )oes Truck Plaza 15600 South Harlan Road March 20, 2000 6 Lathrop, California