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r i <br /> F <br /> 1 <br /> A period of recharge began in December, 1992 and reached a peak <br /> { in March, 1993 . During this period, ground water elevations rose <br /> approximately 2 .5 feet throughout the site. Ground water <br /> elevations have dropped approximately 1. 5 feet since the last <br /> depth-to-water measurements on March 31, 1993 . The current r <br /> ground water elevation gradient across the site is fairly flat <br /> with an average slope of 0 . 001 (0 . 001 feet per linear foot) <br /> downward from MW3 toward MW7 and an overall flow direction to the <br /> south southwest . A local ground water 'high' is observed at MWS, <br /> this may be due to irrigation of the planter area approximately <br /> 10 feet west of the well; the rest of the monitor wells at this i <br /> site are in the paved lot of the station and shopping center <br /> excluding MWS and MW6 which are positioned in undeveloped areas <br /> of native soil . <br /> SITE INVESTIGATION <br /> i <br /> Ground water sampling was conducted on April 13, 1994 in <br /> compliance with the quarterly monitoring requirements for this <br /> site. The various ground water parameters were determined by: 1) <br /> recording depth to water (by use of a resistivity meter) at each <br /> monitor well ; 2) purging and containment of ground water from the <br /> wells; 3) collecting water samples from the wells; 4) submitting <br /> these water Tsamples to a State Certified Analytical testing <br /> laboratory via established "chain of custody" procedures. <br /> The water samples were analyzed for Total Fuel Hydrocarbons (TFH) <br /> as gasoline and volatile Aromatic Hydrocarbons (BTEX) using EPA <br /> Methods 5030 and 602, respectively. Laboratory detection limits <br /> are as follows : TFH is 0 . 02 mg/L and BTEX is 0 .5 µg/L. <br /> Methods and Procedures <br /> The ground water was sampled in eight monitoring wells (MWI thru <br /> MW8) by a Western Geo-Engineers (WEGE) geologist working directly <br /> under the supervision of California Registered Geologist #3037. <br /> Prior to sampling each well, the WEGE geotechnician measured the <br /> depth to ground water using a resistance probe . A ground water <br /> contour surface was later plotted from these depth-to-water <br /> measurements; ground water flow directions at the site were then <br /> inferred from the contour gradients . This information is <br /> presented in Figure 4C. <br /> i <br /> I <br /> ` , 3 <br />