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FZae <br /> vast majority of the area will be paved. Although this will not prevent continued <br /> t to the water table upgradient of the Truck Stop, development will create <br /> and semi-impermeable surfaces such as buildings, asphalt and concrete parking and <br /> as. This will attenuate the continued downward migration of nitrate currently in the <br /> der the facility once it is built. <br /> Thirdly, on-site stormwater drainage managed by retention basins will provide a certain volume <br /> of recharge water that will contain no nitrate. This will theoretically provide a dilution effect to <br /> the water table nitrate concentration downgradient from the retention basin. This recharge <br /> dilution effect will also apply to the treated sewage effluent. <br /> Water sampled and tested by EHD from the on-site public water supply well shows very low <br /> concentrations of nitrate in the deeper aquifers. This may be attributed to upper clay strata, and <br /> possible influence from the San Joaquin River. Considering the nitrate concentration in the <br /> water table upgradient from this well that serves the entire facility, a higher nitrate concentration <br /> would have been expected. <br /> Filter bed upgradient and downgradient water table test results conducted for the Soil Suitability <br /> Study suggests that there may be denitrification occurring under the filter bed. This may be <br /> attributable to saturation within the soil profile under the filter beds creating anaerobic <br /> conditions, and thus promoting denitrification. <br /> The percolation rates obtained from this Study suggest an acceptable soil permeability at the <br /> traditional leachline depth of 42 inches. Additional soil testing will be required for the new <br /> Truck Stop facility, which may include hydraulic conductivity testing of the surface and <br /> subsurface soils. <br /> Based upon the septic tank capacity example presented, the current volume of septic tank <br /> capacity may be deficient. Consideration may be given to increasing the capacity or decreasing <br /> the pump-out intervals. A flow meter would accurately assess wastewater flow volumes. The <br /> filter bed requirement example indicates the existing filter bed is over seven times what is <br /> needed. <br /> 11 <br /> Chem Cmuu&V <br />