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GROUNDWA TER ASSESSMENT REPORT SOEL SAMPLING Prior to drilling, ESA contacted Underground Service Alert (USA)to clear the location for underground utilities and obtained necessary drilling pernuts from the SJCEHD Soil borings were installed by direct push technology, which provided sampling cores advanced in four-foot sections using an inert acetate liner set within the stainless steel core tube Acetate liners were not reused and the core tube was washed with detergent and rinsed after each use Select sections of the core were cut from the continuous core, sealed with end caps and Teflon and placed in cooled storage prior to transportation under chain-of-custody to McCampbell Analytical Laboratories, a state-certified laboratory in Pacheco, California Handling and exposures of the core to air was kept to a minimum to reduce potential for volatization of hydrocarbons and volatile organic compounds Soil borings for the groundwater monitoring wells were advanced to 30 feet bgs, and TP-20 was advanced to 38 feet below ground surface Soil samples were collected for observation and logging purposes approximately every five feet, at obvious changes in lithology as observed by the field geologist,and at the capillary fringe Groundwater was encountered in the monitoring wells and in soil boring TP-20 between 11 and 12 feet below mean sea level (17 feet and 19 feet bgs) Soil samples selected for laboratory analysis were determined based on observed lithology, distance from former tank pit, and depth to first encountered groundwater The field geologist did not detect petroleum odors or hydrocarbon sheen in the soil samples ESA observed the drilling and sampling activities and prepared soil logs using the Unified Soil Classification System(USCS), that, in some cases were based on previous logging because of consistent lithology, as shown in Appendix B GROUNDWATER SAMPLING TP-20 The groundwater sample from boring TP-20 was collected through a Hydro-punch in-situ groundwater sampling device Once the Hydro-punch probe was inserted to depth, groundwater was allowed to enter the borehole through its screened, temporary sampling point Groundwater was extracted using a slow-speed peristaltic pump with dedicated tubing Approximately four well-point volumes of water were purged prior to collecting the groundwater sample After purging, groundwater was transferred into appropriate pre-cleaned glassware supplied by the laboratory, labeled and placed in cool storage prior to transportation to McCampbell Analytical Upon completion of soil and groundwater sampling activities, boring TP-20 was grouted to the surface and capped with asphalt to match the surrounding surface MONITORING WELL CONSTRUCTION _Monitoring wells MW-1 through MW:4 were constructed using factory pre-pack wells installed _ -- within the 2 5-inch borings The wells were constructed of solid 0 75-inch diameter, schedule 40 PVC casing from 0 to 10 feet bgs, with 0 75-inch diameter schedule 40 PVC 0 010 well screen installed from 10 to 30 feet bgs The PVC is isolated with two collars that include a bottom cap and plug The pre-pack is constructed of 1 25-inch diameter schedule 40 PVC 0 010 well screen installed from 10 to 30 feet bgs containing number 2112 sand filter pack material The sanitary It Groundwater Assessment Report 12 ESA/200252 September 2003