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Table 1. Summary of Groundwater Monitoring Data: Water Elevations and Analyses <br /> ARCO Facility 2093, Tracy, California <br /> Top-of-casing Depth-to- Floating Water-level Change since Concentrations in L <br /> Well number elevation, water, product thickness elevation, last measurement, Total <br /> and date in feet(a) in feet in feet in feet b) in feet Benzene Toluene Eth lbenzene Xylenes TPH-G MTBE <br /> 4/18/96 9.22 -- 37.86 -0.37 <0.5 <0.5 <0.5 <0.5 <50 -- <br /> 7/18/96 9.53 -- 37.55 -0.31 <0.5 <0.5 <0.5 <0.5 <50 <5 <br /> 11/15/96 10.00 -- 37.08 -0.47 <0.5 <0.5 <0.5 <0.5 <50 <5 <br /> SM W-l 50.24 <br /> 1017194 12.86 -- 37.38 -- 250 110 <0.5 360 2200 -- <br /> 12/16/94 12.54 -- 37.70 0.32 740 210 330 600 5200 -- <br /> 2/28/95 12.40 -- 37.84 0.14 1000 330 450 790 8300 -- <br /> 4/26/95 12.71 -- 37.53 -0.31 470 110 270 480 5100 -- <br /> 7/27/95 13.00 -- 37.24 -0.29 410 42 360 630 7400 -- <br /> 10/26/95 (c) 13.03 -- -- -0.03 -- -- -- <br /> 10/27/95 -- -- -- 640 33 440 410 7600 -- <br /> 2/12/96 12.00 -- -- 1.03 390 <0.5 220 98 3800 -- <br /> 4/18/96 12.58 -- -- -0.58 60 <0.5 20 7.4 500 -- <br /> 7/18/96 12.85 -- -- -0.27 200 <5 130 56 3400 60 <br /> 11/15/96 13.40 -- -- -0.55 180 <2.5 62 21 2500 590 <br /> TEX-1 (c) <br /> 10/26/95 12.86 -- -- -- <5 <0.5 <0.5 <0.5 <350 -- <br /> 2/12/96 10.90 -- -- 1.96 <br /> 4/18/96 l 1.35 -- -- -0.45 <0.5 <0.5 <0.5 <0.5 <50 -- <br /> 7/18/96 11.52 -- -- 1.34 -- -- -- -- -- -- <br /> 11/15/96 12.30 -- -- -1.40 -- -- -- -- -- -- <br /> (a)All elevations corrected to an arbitrary datum based on a Notes: Dash indicates not measured or sampled. <br /> temporary on-site benchmark with an assigned elevation of 50 feet. TPH-G=Total Petroleum Hydrocarbons as Gasoline by EPA Method 8015, <br /> (b)Corrected water level elevation value(Wlc=Wlm+(b)(p)), where Wlc=water-level Modified. <br /> elevation corrected, Wlm=water-level elevation measured,b=hydrocarbon thickness(feet), BTEX Distinction by EPA Method 8020. <br /> p=specific gravity(0.7)of hydrocarbon. MTBE= Methyl Tertiary Butyl Ether by EPA Method 8020. <br /> (c)Top of well casing altered. Well casing has not been resurveyed. Water-level measured Wells ATR-1,ATR-3,ATR-6, ATR-9,ATR-10, and ATR-I 1 on a <br /> from the highest point of well casing. semi-annual sampling schedule. Sampled during thelst and 3rd quarters <br /> of each year. <br /> 33151TAQ LES12093NOV6.X LS <br />