Laserfiche WebLink
04 October 2000 <br /> . AGE-NC Project No 97-0290 <br /> IPage 7 of 9 <br /> 34 MASS OF RECOVERED HYDROCARBONS <br /> The hydrocarbon mass (TPH-g) removed during the operating period was calculated using the <br /> following equation M = C-Q•t <br /> where M = cumulative mass recovered (kg) <br />' C = soil-vapor concentration (kg/m3) <br /> Q = extraction flow rate (m3/hr) <br /> t = operational period, in hours <br />' The operational time was divided into three time periods Mass of hydrocarbons removed was based <br /> on analysis of soil-vapor samples The mass of extracted hydrocarbons was calculated for each time <br />' period using average hydrocarbon concentrations of influent soil-vapor samples collected and <br /> average air flow rates <br />' Approximately 717 4 gallons of hydrocarbons as gasoline were removed from the site between 05- <br /> 17-2000 and 07-06-2000 The volume/mass calculations are attached in Appendix D <br /> 35 IN-SITU AIR SPARGING <br />' Elevated concentrations of dissolved oxygen were detected in monitoring wells MW-1, MW-4 and <br /> MW-5, which were used as observation wells outside the IAS network on the site Dissolved oxygen <br />' concentrations in the remaining, down gradient wells showed smaller changes A small change in <br /> dissolved oxygen was observed in well MW-2 samples within the sparging well network The <br /> dissolved oxygen data for each well is summarized in Table 4 <br />' Sparging rates were measured at approximately 7 to 10 scfm during each monitoring event A <br /> pressure of approximately 12 to 15 psi was maintained for the air sparging flow rate <br /> 1 <br /> 4 0. SUMMARY AND CONCLUSIONS <br />' Based on the data collected during this phase of site remediation, AGE finds <br />' During previous assessment investigations the highest concentrations of petroleum <br /> hydrocarbons in soil were detected near the southeast portion of the site at depth intervals of <br /> 15 to 50 feet bsg Lower concentrations of hydrocarbons were detected in borings <br />' surrounding the southeast portion of the site (B4, MW4 and B6) at depths of 35 to 60 feet <br /> bsg, corresponding to the interval of historical ground water level fluctuations <br />' Advanced CeoEnvironmental,Inc <br />