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USA 65 - QTR RPT 12/94 north, northeast from MW3 to MW2 , see Figure 4D Unlike the previous ground water gauging period (Figure 4C) the hydraulic gradient across the site is less stable, indicating that this may reflect a condition of flux between the inflow and outflow of water to the local aquifer and is represented by a variation or differences of hydraulic conductivities from well to well, this is expressed at the site by a 'high water ridge' from MW5 and MW3 and a ' ground water low' from MW3 to MW2 SITE INVESTIGATION Ground water sampling was conducted on December 28, 1994 in compliance with the quarterly monitoring requirements for this site The various ground water parameters were determined by 1) recording depth to water (by use of a resistivity meter) at each monitor well , 2) purging and containment of ground water from the wells, 3) collecting water samples from the wells, 4 ) submitting these water samples to a State Certified Analytical testing laboratory via established "chain of custody" procedures The water samples were analyzed for Total Fuel Hydrocarbons (TFH) as gasoline and Volatile Aromatic Hydrocarbons (BTEX) using EPA Methods 5030 and 602 , respectively Laboratory detection limits are as follows TFH is 0 02 mg/L and BTEX is 0 5 �tg/L Methods and Procedures The ground water was sampled in eight monitoring wells (MW1 , MW2 , MW3 , MW4 , MW5, MW6 , MW7 and MW8) by a Western Geo-Engineers (WEGE) geotechnician working directly under the supervision of California Registered Geologist ##3037 Prior to sampling each well , the WEGE geotechnician measured the depth to ground water using a resistance probe A ground water contour surface was later plotted from these depth-to-water measurements, ground water flow directions at the site were then inferred from the contour gradients This information is presented in Figure 4D Each well was purged before collecting water samples Purging was completed only after water temperature, pH, and conductivity had stabilized Purged water was contained in a labeled, secured 55 gallon drum on site The wells were allowed to recover after purging A water sample was then collected with a fresh bailer Each sample was divided among three 40-m1 VOA vials The vials are supplied pre-cleaned to exact EPA protocols and contain the appropriate preservative The sample vials were labeled as to station, well, time, and sampler, and documented on the chain-of-custody sheet, they were then placed into an ice chest with a travel blank and cooled to 40C with ice The samples were delivered to a California State 3 i