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tj <br /> Ms. Lon Duncan <br /> June 12,2007 , <br /> CONESTO3A-ROVERS <br /> &ASSOCIATES <br /> Mass Flux(g/day)=Avg Concentration(µglL)x.Specifc Discharge(ftlday)x Area(sgft)x Conv(2.83x1Q"5 g-IJµg-cuft) <br /> Where;Specific Discharge=Hydraulic Conductivity(fUday)x Groundwater Gradient(fVft) <br /> The average MTBE concentration was taken,as the average MTBE concentration (285 ug/L) for the <br /> center isoconcentration`-contour interval determined in the preceding:section. The specifc discharge <br /> (0.00078 feetiday) was calculated using a hydraulic conductivity of 0:13 feet/day (Todd, 1980)which is <br /> consistent with silts and clays identified at-this site, and the groundwatengradient (0.006.feet/foot)based <br /> groundwater elevations measured during the first quarter 2007 monitoring event. The (vertical) area of <br /> interest was taken as 140 feet across the front-of the MTBE plume and the'15 foot groundwater thickness; <br /> which equates to 2,100 square feet. <br /> Based on these inputs, the mass flux of MTBE is estimated as follows: <br /> Mass Flux=285gg1L x 0.00078 ft/day.x.2,100 sqft x 2.83x10-5 g-L/gg-cuft=0.0132 glday <br /> The mass flux estimated in-the first equation was used to estimate the concentration of MTBE in water.at' <br /> the control point (virtual'supply well). after:blending with groundwater containing MTBE using the <br /> following equation: - <br /> Concentration in supply well(ug/L)=Mass Flux(g/day)x Conv(184 ug-gal-day/g-L-min)/Supply Well Pumping Rate(gpm) - <br /> Various supply well'pumping rates were inputted into this,equation to show -the change in MTBE <br /> concentration in the supply well. The results are as follow: <br /> 1. Concentration in Supply Well 0.0132 g/day x 184 ug-gal-day/g-L-minx.5 gpm=0.49 uglL <br /> 2. Concentration in Supply Well 0.0132 g/day x 184-ug-gal-day/g-L-min x 10 gpm=0.24 ug/L <br /> 3. Concentration in Supply Well=0.0132 g/day x 184 ug-gal-daylg-L-min x 25 gpm=010 uglL <br /> 4.- Concentration in Supply Well=0.0132 g/day x.184 ug-gal-daylg-L-min x 50 gpm=0.05 ug/L <br /> 5. Concentration in Supply Well=0.0132'g/dayx 184 ug-gal-day/g-L-minx 75 gpm=0.03 ug/L <br /> 6. Concentration in Supply Well 0.0132 g/day x 184 ug-gal:daylg-L-mini x 100 gpm=0.02 ug/L <br /> N <br /> 1667 5 <br /> Worldwide Engineering, Environmental,Construction,and 13 Services <br /> - v - 1 <br />