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Predicted Time to Cleanup of TPHg in Well MW-7, Shell-Branded Service Station, 620 Charter Way, Stockton, California <br /> Concentration Trend Prediction <br /> Calculate time to cleanup"given the first-order decay equation <br /> Days from Predicted <br /> y — be" => x=ln(y1b)/a Date First Sample Concentration(ugA) <br />` 4/26/1991 0 18 430 <br /> 4/25/1992 365 11056 <br /> Gwen 4/25/1993 730 6 632 <br /> Water Quality Oblecttva yg4/26/1991 <br /> uglL 4125/1994 1 095 3 979 <br /> Constant b 4125/1995 1 460 2 387 <br /> Constant a 4/24/1996 1825 1432 <br /> Date of first sample 4/24/1997 2 190 859 <br /> 4/24/1998 2 555 515 <br /> 4/24/1999 2 920 309 <br /> 4!2312000 3 285 185 <br /> 4/23/2001 3 650 111 <br /> Calculate 4/23/2002 4 015 67 <br /> Days from first sample x 4 221 Days 4/23/2003 4 380 40 <br /> Years from first sample 11 6 Years Calculated Half Life= ln(2)1a <br /> Estimated date of cleanup Nov 2002 495 Days <br /> 1 36 nears <br /> Predicted Concentrations <br /> 100 000 , <br /> gVE <br /> lit <br /> 10 000 »m , <br /> m 000 _ da' <br /> wr�.` <br /> 100 , <br /> .&�`i�a z y�.��ml� <br /> °E9 3 <br /> 10 <br /> C1 m c+f <br /> Qi M W (D Ql O O <br /> M m m m 4 0 <br /> N N <br /> Degrada0le Calculations As MW 7 TPHg Pred <br />