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I Langston 's Market 15615 Seventh Stree4 Lathrop, California ' Quarterly Groundwater Sampling Report May, 1995 Narrative On May 30, 1995, WHF Environmental Consultants, Inc , in conjunction with E KM 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 1 & I Appendix B) Monitoring wells MW-1 through MW-4 were evacuated by means of a steam-cleaned, stainless steel bladder type pump During the three (3) volume pump down of each well, samples were collected to measure field pH, electrical conductivity and temperature (Table 3 & Appendix B) Once stability was achieved, a minimum of three (3) well volumes were removed and samples were collected with a steam-cleaned disposable bailer The samples were then labeled and placed in an ice chest with Blue Ice& The samples, bailer blanks and trip blank were then logged 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 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 the monitoring wells were used to construct a groundwater gradient map and calculate the gradient (Figure 3) The current gradient is 0 0021 ft/ft to the S450E direction Mstoncal gradient maps are included in Appendix C I Summary ofAnalydcal Findings Only two (2) groundwater monitoring wells had varying amounts of contamination as BTEX and Gasoline during this quarter (Table 2) MW-1 had detectable contamination of 14,000 �ug/l Benzene, 31,000 ,ug/l Toluene, 2,700 ,ug/1 E-Benzene, 18,000 ,ug/1 Xylene, and 74 mg/1