Laserfiche WebLink
1 <br /> } <br /> HYDROLOGY 1 <br /> The ground water had maintained an elevation of between 5 and 6 <br /> feet below sea level from January 20, 1989 to April 18, 1989 <br /> during a period of ground water elevation measurements following <br /> the installation of MW4 , MW5, MW6 and MW7 from January to March, <br /> 1989 . From April 18, 1991 through September 13 , 1991, ground <br />}; water elevation at the site decreased to approximately 13 ' to 141 <br /> below sea level . This may be attributed to both sampling time <br /> (summer vs . winter) as well as an effect of the continuing <br />{ drought period. Since the last sampling round in December . of <br /> f 1992, there has been an over all increase of approximately 2%1 in <br /> R <br /> the ground water level at this site (see Table 1) . <br /> Ground water was encountered at approximately 55` BGS and fi <br />€ stabilized at 50, BGS in MW8 . This. shallow ground water suggests <br /> E a partially confined condition and showed 5' of potentiometric <br /> rise during the drilling of MW8 (Appendix C, Limited Drilling <br /> Report-Borehole Log) . The present ground water flow direction, <br /> Figure 4E, is south to southeast with local variations to the <br /> southwest near MW1 and MW8 . The hydraulic gradient is fairly flat <br /> across the site from MW2 to MW7 at a slops of 0 . 0024 . <br /> SITE INVESTIGATION <br /> Ground water sampling was conducted on March 31, 1993 to comply <br /> with quarterly monitoring of this site. Various parameters of <br /> the ground water beneath the site were determined by: 1) <br />} recording depth to water (by use. of a resistivity meter) for the <br /> monitor wells; 2) purging. and containment of ground water from <br /> the wells; 3) collecting water samples from the wells; . 4) <br /> i submitting these water samples to a State Certified Analytical <br /> a testing laboratory via established "chain of custody" procedures. <br /> The water was analyzed for Total Fuel Hydrocarbons (TFH) as <br /> gasoline and Volatile Aromatic Hydrocarbons (BTEX) using EPA <br /> Methods 5030 and 602, respectively. Laboratory detection limits <br /> j are as follows : TFH is 0 . 05 mg/L and BTEX . is 0 . 3 gg/L with <br /> xylenes being 0 . 9 µg/L. <br /> Methods and Procedures <br /> The ground water was sampled in eight monitoring wells by a <br /> Western Geo-Engineers (WEGE) geologist, `working directly under <br />` the supervision. of California Registered Geologist #3037 . Using <br /> a resistance probe, WEGE personnel measured the depth to ground <br /> water prior to sampling each well . Each well was purged before <br /> collecting water samples . MW1, MW2 , MW3 , MW4, MWS, MW6 , MW7 and <br /> MW8 were sampled after purging the wells of enough water that <br /> I temperature, pH and conductivity stabilized. This data is <br /> :k <br />�f <br />�j <br />