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One result of the model is the calculation of the current <br /> contaminate mass in the soil . This is shown on the following <br /> table in pounds . <br /> Polygon Gasoline Benzene Toluene Ethylbenzene Xylene <br /> VSB13 (4) 129 . 23 ib <0 . 1 lb <0 . 1 ib 1 . 1 lb 10 . 6 lb <br /> VSB14 (3) 349 . 6 lb <0 . 1 lb 0 . 2 lb 0 2 lb 7 1 lb <br /> VSB15 (1) 52 .4 lb <0 . 1 lb 0 .4 lb 0 3 lb 5 . 0 lb <br /> TOTAL 531 . 23 0 . 0 lb 0 6 lb 1 6 lb 22 . 7 lb <br /> The site was modeled for 100 years assuming no remediation and no <br /> degradation of the compounds, (see resulting print outs) . <br /> Without remediation or degradation, the soil contaminates will <br /> have the following impacts on ground water in 100 years . <br /> VSB13 15 lb <0 . 1 lb X0 . 1 lb 0 . 8 lb 8 . 8 lb <br /> VBS14 79 lb <0 1 lb 0 . 2 lb 0 . 2 lb 7 1 lb <br /> VSB15 16 lb <0 . 1 lb 0 4 lb 0 . 3 lb 5 . 0 lb <br /> The above impacts are the worse case for the above compounds as <br /> the VLEACH does not take into account the natural biodegradation <br /> that will occur over the 100 year period modeled The rate of <br /> this biodegradation would be governed by the rate of oxygen <br /> exchange between the soil and the air. There are two sources of <br /> oxygen avalible to support biodergradation, diffuse vapor <br /> transport between the soil and the air and the dissolved oxygen <br /> that enters the ground in rain water. The site was modeled with <br /> an average rain impact 1 1 feet per year. With an average <br /> concentration of 8 mg/l 02 , 1 1 feet per year of rainfall will <br /> produce an oxygen impact on one square foot of soil of 1 . 1 ft x 1 <br /> ft' x 28 . 32 1/ft3 x 8 mg/l x lg/1000mg = . 249 gm/ft2 = 0 . 00055 <br /> lb/foot <br /> This allows the following calculations, of the impacts of oxygen <br /> for the polygons : <br /> VSB13 , 110 ft2x 0 . 00055 lb/ft2 = 0 . 061 lb/year = 6 1 lb/100 years <br /> VSB14, 140 ft2x 0 . 00055 lb/ft2 = 0 . 077 lb/year = 7 7 lb/100 years <br /> VSB15, 120 ft2x 0 . 00055 lb/ft2 = 0 066 lb/year = 6 6 lb/100 years <br /> The other source of oxygen is by diffuse migration from the <br /> atmosphere . Using VLEACH to model the oxygen diffusion into the <br /> soil it was shown that an average of 255 . 5 gms/ft2 per 100 years <br /> (0 . 563 lb/ft2 ) of oxygen entered the soil . <br /> VSB13 , 110 ft2x 0 . 563 lb/ft2 = 61 . 9 lb/100 years <br /> VS814, 140 ft2x 0 563 lb/ft2 = 78 9 lb/100 years <br /> VS815, 120 ft2x 0 . 563 lb/ft2 = 67 6 lb/100 years <br />