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I <br /> Langston 's Market <br /> 15615 Seventh Stree4 Lathrop, California <br /> I <br />' Quarterly Groundwater Sampling Report <br /> December, 1995 <br /> Narrative <br /> On December 18, 1995, WHF, Inc , in conjunction with E KM Groundwater Monitoring, <br /> tconducted field measurements, well pumping and groundwater sampling on four (4) <br /> groundwater monitoring wells located at this site (Figures 1 & 2) <br />' Groundwater elevations were taken from four (4) wells prior to pumping (Table i & <br /> Appendix B) Monitoring wells EW-1, also referred to as MW-1, MW-2 through MW-4 <br /> were evacuated by means of a steam-cleaned, stainless steel bladder type pump Dunng <br />' the three (3) volume pump down samples were collected to measure field pH, electrical <br /> conductivity and temperature (Table 3 & Appendix B) EW-1 (MW-1) did not recharge <br /> M after the first purge volume A sample was taken from EW-1 (MW-1) after the first purge <br /> volume but is invalid A minimum of three (3) well volumes were removed and the <br /> samples were collected with a steam-cleaned disposable bailer The samples were then <br /> labeled and placed in an ice chest cooled with Blue Ice® <br /> The samples and trip blank were then logged on a Chain of Custody (Appendix A) and <br /> transported to a State-certified laboratory, California Laboratory Services, Inc , in Rancho <br /> Cordova, California The analysis requested for the water samples was EPA method 602 <br /> for BTX&E and EPA method 5030/LUFT for gasoline The analytes and concentrations <br />' detected are listed in Table 2 of this report <br />' Groundwater Gradient <br /> The water level measurements from three (3) of the four (4) monitonng wells, MW-2, 3 <br /> and 4, were used to construct a groundwater gradient map and calculate the gradient <br /> (Figure 3) EW-1 was not used in the gradient calculation nor the construction of the <br />' groundwater gradient map EW-1 did not recover after the first purge and is therefore <br /> invalid This well is scheduled for re-development before the next quarter's sampling <br /> event The current gradient is 0 0002 ft/ft to the S 1°W direction Historical gradient <br />' maps are included in Appendix C <br />