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UPDATE 30 11-11-94 <br /> NOVEMBER 7, 1994 MODELING RESULTS - IMPACT TO GROUND WATER AT <br /> SB14 <br /> YEAR TPHg in DISSOLVED 02 TPHg mass/area <br /> ground water delivered to water <br /> mg/L mg/L grams/sq ft <br /> background 8 0 0 0 <br /> 10 <1 ug/L 7 37 1 . 31 <br /> 20 <1 ug/L 6 52 3 71 <br /> 30 <1 ug/L 5 30 6 22 <br /> 40 <1 ug/L 3 92 8 10 <br /> 50 <1 ug/L 3 71 9 10 <br /> 60 <1 ug/L 3 45 9 39 <br /> 70 <1 ug/L 3 75 9 21 <br /> 80 ¢1 ug/L 4 14 8 74 <br /> 90 <1 ug/L 4 63 8 13 <br /> 100 <1 ug/L 4 73 7 45 <br /> A sample of the influent vapor stream obtained on November 7, <br /> 1994 , was submitted to AEN for analysis and showed that Benzene, <br /> Toluene and Ethylbenzene are below detection limits of 0 5 ug/L <br /> and Xylenes are at 6 ug/L Total purgeable hydrocarbons as <br /> gasoline are at 400 ug/L <br /> SITE SPECIFIC LITHOLOGIC BARRIERS AND EVALUATION FOR POTENTIAL <br /> ATTENUATION EFFECTS <br /> Hydrocarbons can travel through the soil in a number of ways <br /> each of which is affected by different soil properties <br /> Hydrocarbons move in basically one of three phases <br /> 1 Liquid <br /> 2 Dissolved <br /> 3 Vapor <br /> 1 Liquid, Free Product <br /> The liquid or free product phase is dominated by 2 forces, <br /> gravity and surface tension, ei capillary tension Which <br /> of these is dominant depends on two factors soil pore size <br /> and degree of saturation Surface tension is dominant until <br /> the weight of the product exceeds the capillary tension at <br /> which point gravity becomes dominant In fine grained soils <br /> (similar in viewing a sponge) the small pore size makes <br /> capillary tension much greater than in coarse grained soils <br /> (similar to viewing a glass far full of marbles) , therefore <br /> capillary tension is dominant in finer grained sods and <br /> gravity is dominant an coarse grained soils . So in fine <br /> grained soils, as those found beneath Former Regal 604 , a <br /> liquid will have a tendency to move both laterally and <br /> verbally through the soil until soil saturation occurs <br /> within that soil unit (clay, silt, fine silty sand, etc ) <br /> Once saturation occurs the weight of the fluid exceeds the <br /> capillary tension When this occurs the product will begin <br /> to flow into the underlying layer (unit) Facies changes <br /> page7 <br />