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i <br /> i <br /> Table 2-2 <br /> Del Monte Disco Site <br /> AS/SVE Monitoring Results <br /> Respiration Test <br /> (Dissolved Oxygen Concentration(m ) <br /> f Time NP-1-80 NP-1-90 <br /> 3/12/95 12:20 4.7 3.6 <br /> 3112/95 14:30 4.2 3.3 <br /> 3112195 16:20 4.2 3.3 <br /> 3/12/95 17:45 3.8 3.1 <br /> 3/13/95 8:00 3.8 3.0 <br /> 3/13/95 10:00 3.8 3.1 <br /> 3/13195 12:00 3.6 2.9 <br /> 3/13195 14:00 3.5 2.7 <br /> 3/13/95 16:00 3.6 2.8 <br /> Test Procedure: AS and SVE blowers were turned off, and a <br /> dissolved oxygen probe was inserted into the groundwater. <br /> These results indicate that initial oxygen concentration is higher at the 80-foot depth than at <br /> 90 feet, and that oxygen declines at a steeper rate'at the shallower depth. The sparging well <br /> i screen interval is at 90 feet, and the expected migration path for sparged air is an upward are , <br /> to the groundwater surface, as shown in Figure 2-1. NP-1 is 10 feet from AS/SVE-1 and 17 <br /> feet from AS/SVE-2. <br /> iI In Figure 2-3, equations are presented for best fit lines found by lineregression. Based on <br /> the assumption that 3 pounds of dissolved oxygen are requir9d per pound of gasoline 2 <br /> biodegraded, for an oxygen up-take rate of 0.7077 mg/L/day, 0.236 mg/L of gasoline is <br /> . consumed per day. Further, by assuming a total volume of groundwater in the air sparging <br /> treatment zone of 2,100 cubic feet, the mass gasoline removal is approximately 12 pounds <br /> per year. If the 2,100 cubic feet of groundwater in the treatment zone is assumed to have a <br /> TPH(g) concentration of 39 mg/L, the total mass of dissolved gasoline in the 2,100 cubic feet <br /> of groundwater is 5 pounds. Therefore, approximately two contaminant mass exchanges are <br /> expected per year ,of gasoline:. from nonaqueous phase liquid (NAPL) into solution with <br /> subsequent biodegradation. <br /> Analytical results for NP-1 groundwater samples are presented in Table 2-3. NP-1-70' was <br /> not sampled on 12/29/94 because no groundwater was present; by 3/12/95,.groundwater had <br /> risen enough to take a sample. For NP-1-80', we can compare groundwater before and after <br /> operation of the AS/SVE system. All analytes, with the exception of benzene, show a decline <br /> in concentration apparently attributable to 490 hours of AS/SVE system operation. The first <br /> I <br /> order TPH(g) removal. rate "W' value calculated from NP-1-80' data is -0.017/day. The <br /> I <br /> SF010030981.doc 2-7 <br />