Laserfiche WebLink
1 <br /> N � <br /> 22 November 2006 <br /> AGE-NC Project No . 95-0167 <br /> IJ Page 11 of 15 <br /> 6. 1 .3 , MONITORING ACTIVITIES <br /> One of the potential problems associated with air sparging is lateral spreading of the contaminant <br /> plume. This can be caused by either mounding of ground water above injection points or lateral air <br /> flow away from sparging wells. To detect this problem, ground water elevations in monitoring wells <br /> and extraction wells (if appropriate) should be monitored on a monthly basis, at the minimum, to <br /> detect mounding and the presence of organic vapor. <br /> 6 . 1 .4. FEASIBILITY <br /> In-situ air sparging of dissolved hydrocarbons in ground water at the site may have high feasibility. <br /> lRemediation of ground water at the site would require only a moderate number of injection and <br /> -J extraction points and utilization of a small area for an underground injection/extraction piping <br /> network. Air injection and extraction rates must be balanced to prevent the forced migration of <br /> I contaminants. An IAS pilot test has not been performed at the site; however, data from soil samples <br /> - collected at the site indicate that soil in the saturated zone between 15 feet and 30 feet bsg consists <br /> of a moderate amount of sand and silty sand, which typically possess hydraulic conductivity values <br /> that are favorable for air sparging (Figure 3) . <br /> h One concern with IAS remediation is precipitation of iron and/or manganese, which can cause <br /> clogging of sparge points. <br /> j � 6. 1 . 5. DURATION <br /> J Air sparging in highly permeable aquifers generally results in rapid reduction of hydrocarbon <br /> concentrations in the saturated zone. Remediation times are generally comparable with soil vapor <br /> extraction times. At the site, we estimate a remediation period of 12 to 24 months for shorter-chain <br /> ( l hydrocarbons . <br /> IJ <br /> ( I 6. 1 .6. COST <br /> l J Installation of an in-situ air sparging system will require the installation of several sparging and <br /> extraction wells, piping system and equipment. Setup costs would likely range from $20,000.00 to <br /> 4- $40,000 .00 . Sparging equipment maintenance and monitoring would range from $5 ,000.00 to <br /> $ 10,000 .00 annually. <br /> If air sparging is chosen for ground water remediation, vapor extraction will be used for vadose zone <br /> J Advanced GeoEnviron ental, Inc. <br />