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Langston 's Market ' 15615 Seventh Street, Lathrop, California ' Quarterly Groundwater Sampling Report March, 1996 1 Narrative 4n March 21, 1996 WHF Inc , in conjunction with ERM Groundwater Monitoring, conducted field measurements, well pumping and groundwater sampling on four (4) groundwater monitoring wells located at this site (Figures 1 & 2) Groundwater elevations were taken from four (4) wells prior to pumping (Table I & ' Appendix B) Monitoring wells EW-1 (also referred to as MW-1), MW-2 through NW-4 were evacuated by means of a steam-cleaned, stainless steel bladder type pump During the three (3) volume pump down samples were collected to measure field pH, electrical conductivity and temperature (Table 3 & Appendix B) A minimum of three (3) well volumes were removed and the samples were collected with a steam-cleaned disposable bailer The samples were then labeled and placed in an ice chest cooled with Blue Ice® The samples and trip blank were then togged on a Chain of Custody (Appendix A) and transported to a State-certified laboratory, California Laboratory Services, Inc , in Rancho Cordova, California The analysis requested for the water samples was EPA method 602 for BTX&E (Benzene, Toluene, Xylene, and Ethylbenzene) and EPA method 5030/LUFT for Gasoline The analytes and concentrations detected are listed in Table 2 of this report Groundwater Gradient The water level measurements from monitoring wells EW-1, MW-2 through MW-4 were used to construct a groundwater gradient map and calculate the gradient (Figure 3) The current gradient varies from 0 0007 to 0 0011 ft/ft at S2°W to S45°W Static water levels have risen an average oft 06 feet across the site EW-1 has a water elevation comparable Ito measurements taken during the 9130/95 sampling event Water levels, associated with this well (EW-1), have now stablilized since the excavation was backfilled Historical gradient maps are included in Appendix C