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21 March 2006 <br /> AGE-NC Project No 97-0290 <br />' Page 9 of 15 <br />' extraction The SVE system composed of a regenerative vacuum blower and granular activated <br /> carbon adsorption vessels along with an IAS compressor In April 2001,the remediation system was <br /> removed from the site for construction of the current on-site buildings In July 2001, the SVE/IAS <br />' piping network was installed below surface grade and each well casing was lowered approximately <br /> 3 feet bsg In December 2001,the SVE/IAS systems was relocated to the structure's rooftop to allow <br /> for continual remediation, which restarted full-scale operation after a restart inspection in <br />' December 2001 <br /> On 16 September 2004,the carbon adsorption vessels were removed from the SVE system because <br />' the low contaminant detections in soil vapors since February 2004 did not require treatment as <br /> previously permitted <br />' The thermal oxidation and carbon-based SVE system operated for approximately 4 years, with a <br /> general reduction of influent contamination over the time period The hydrocarbon mass (TPH-g) <br /> removed during the operating period was calculated over multiple monitoring events The calculated <br />' mass of hydrocarbons removed was based on laboratory analysis of soil-vapor samples The mass <br /> of extracted hydrocarbons was calculated using average hydrocarbon concentrations of influent <br /> soil-vapor samples collected and the average air flow rates A calculated total of 19,512 6 lbs, or <br /> 3,122 gallons,of gasoline (TPH-g)were removed Soil vapor extraction and dissolved oxygen data <br /> are included in the tables in Appendix A <br /> I <br /> 63 AIR-SPARGE SYSTEM INSTALLATION/MONITORING <br />' A compressor-based EnviroSparge IAS system was installed at the site on 10 March 2000 The <br /> compressor was connected to the sparge wells using a 1-inch diameter PVC pipe network via surface <br />' piping The IAS system delivered 7 to 10 scfm at a pressure of 12 to 15 pounds per square inch(psi), <br /> adequate to volatilize the petroleum hydrocarbons in the ground water and transfer hydrocarbons <br /> from the dissolved ground water state into the soil vapor phase The EnvioSparge IAS system began <br />' full-scale operation in April 2000 <br /> The IAS system was monitored regularly during remediation periods A YSI-55 dissolved oxygen <br /> meter was used to measure the groundwater in observation wells near the remediation points During <br /> each monitoring event, the depth to ground water and percent dissolved oxygen were measured for <br /> each monitoring well General system maintenance and adjustments were performed at these events <br /> The sparging flow rate was adjusted to approximately 7 to 8 scfm and to a pressure of 12 psi <br /> (Appendix A) <br /> IOn 28 June 2005 the SVE/IAS system ceased operation <br /> Advanced GeoEnvironmental,Inc <br /> I <br />