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. (Two-thirds of the average concentration is considered conservative <br /> Additionally, the estimated area of impact is based on the <br /> assumption that impacted soil was present at uniform concentration <br /> from the surface to 15 feet bgs and attenuated to non-detect from 15 <br /> feet bgs to the clay layer at 36 feet bgs) <br /> Mass TPH in Area 3 <br /> before remediation= [(V3) X (2,000 lbs/ton) X (199 ppm)]/lE6 <br /> =61 pounds <br /> Waste Oil UST pit(Dec 1991) (See attached figure) <br /> Volume of Area 4 (V4) = 15 yds3 =20 tons <br /> Average TPH <br /> concentration = Avg Concentration of Spoils Samples CWS-1 <br /> and CWS-2 <br /> = 1,970 ppm <br /> Mass TPH in Area 4 <br /> before remediation= [(V4) X(2,000 lbs/ton) X(1,970 ppm)]/1E6 <br /> = 79 pounds <br /> Total Original Mass of TPH= 1,213 pounds <br /> Substance Remediated excavation and disposal) <br /> UST pit (east end) <br /> Volume of Area 1 (VI) = (length) X(width) X(depth) <br /> = (9 feet) X (5 5 feet) X (20 feet) <br /> = 9,900 ft = 367 yds3 =477 tons <br /> Volume of Area 2 (V2) = 112 X(8 feet) X (27 feet) X (20 feet) <br /> =2,160 ft = 80 yds3 = 104 tons <br /> Average TPH <br /> concentration = Avg Concentration of Samples S-6 through <br /> S-9, SW-2, SW-3, and TP-1) <br /> = 729 ppm <br /> (The average concentration is considered conservative <br /> Additionally, the estimated area of excavation is based on the <br /> assumption that impacted soil was present at uniform concentration <br /> and was excavated to a total depth of 20 feet bgs by the over- <br /> excavation activities ) <br /> Mass TPH Removed <br /> . in Areas 1 and 2 = [(VI + V2) X (2,000 lbs/ton) X (729 ppm)]/l E6 <br /> = 847 pounds <br /> 9201036A/MASSBAL DOC June 4, 1997 <br />