Laserfiche WebLink
r HYDROLOGY <br /> Ground water elevations at the site ranged between 5 and 6 feet <br /> below sea level from January 20, 1989 to April 18, 1989 . From <br /> April 18, 1989 through September 13 , 1991, ground water <br /> elevations decreased an average of eight feet, to approximately <br /> 13 feet to 14 feet below sea level . This decrease may be <br /> attributed to both sampling time (summer vs . winter) as well as <br /> an effect of the continuing drought period. <br /> Ground water elevations decreased approximately % foot since the <br /> last depth-to-water measurements on March 30, 1995 . This <br /> discharge is effecting the current ground water elevation <br /> gradient across the site by a small decrease from the slope of <br /> 0 . 003 from MW1 to MW7 during the March 30, 1995 gauging to a <br /> slope of 0 . 002 ft/ft from MW1 to MW7 . The flow direction is to <br /> the south southeast from MW1 to MW5, to south southwest from MW5 <br /> to MW7, see Figure 4D. The hydraulic gradient across the site is <br /> relatively stable, indicating a condition where the inflow and <br /> outflow of water to the local aquifer have reached some kind of <br /> equilibrium. <br /> SITE INVESTIGATION <br /> Ground water sampling was conducted on June 29, 1995 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 samples 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 . 05 mg/L and BTEX is 0 . 5 µg/L and 2µg/L <br /> for xylenes . <br /> Methods and Procedures <br /> The ground water was sampled in eight monitoring wells (MW1, MW2, <br /> MW3 , MW4 , MW5, MW6, MW7 and MW8) by a Western Geo-Engineers <br /> (WEGE) geotechnician working directly under the supervision of <br /> California Registered Geologist #3037 . Prior to sampling each <br /> well, the WEGE geotechnician measured the depth to ground water <br /> using a resistance probe . A ground water contour surface was <br /> later plotted from these depth-to-water measurements; ground <br /> water flow directions at the site were then inferred from the <br /> contour gradients . This information is presented in Figure 4D. <br /> 3 USA 65 June 195 Qtr Rpt <br />