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130 All samples were transported under chain of custody to Castle Analytical Laboratory of Atwater, California for analysis by EPA method 8020 and 8260 for BTEX, TPHg, oxygenates and fuel additives including 1,2-DCA and EDB. All water sample analysis and groundwater elevations are summarized in the attached tabular recap sheets in Exhibit C. Copies of the original 135 laboratory data sheets from this sampling event are also attached and are in Exhibit F. 3. FINDINGS All monitoring wells were sounded in order to provide gradients. The groundwater elevations were calculated from known casing elevations and measured depth to water. The elevations are 140 summarized in the analytical recap tables in Exhibit C. A hydraulic gradient and direction of bearing for the first, second and third sand layer was computed. The gradients and bearings are represented graphically on the TPHg Contour map in Exhibit A. The first water is 29.5' to 40' below ground surface (bgs) and used monitoring wells 145 MW-1R, MW-2R and MW-3R to determine a gradient of 0.0035f1/ft with a bearing of N 51° E. The second water is 40' to 80' bgs and used monitoring wells MW-3, MW-10 and MW-11 to determine a gradient of 0.00 1 8ft/ft with a bearing of N 28' E. The third water is 80' to 100' bgs and used monitoring well MW-5, MW-6 and MW-8D to determine a gradient of 0.00 1 5ftIft with a bearing of N 83'E. 150 4.*MASS REMAINING With all wells being sampled the mass remaining was updated. The estimated mass remaining for the 3/23/12 sampling is 779Kg of gasoline. The mass remaining is estimated using the limited number of point source wells, proration of aged CPT data and conservative procedures of 155 projecting the limit of the plume. The mass remaining calculations are presented in Exhibit B. 5. TRENDS 160 Graphic representations of the current concentration trends are in Exhibit D. Since the pump and treat system had a dynamic influence on the concentrations, the trend lines are broke up into pre- pumping and post pumping data sets in order to plot the static attenuation behavior of the groundwater. Monitoring wells screened below the influence of EW-1 were plotted with a complete job to date data set. Excel was used to plot the linear equation of the data set with the 165 equation shown on the plot. The equation has the typical algebraic format of- y=mx+b were: m is the positive or negative slope of the line x is the day used to find concentration y 170 b is the y-axis intercept(initial statistical basis value) 4 of 82