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PRi06LE)w Assmsmwr Rsxwr <br /> 14800 West Frontage Road Manteca Caldornia <br /> 5.2.2.3 Air Sparging <br /> Air sparging is a variation of in-situ bioremediation A similar evaluation of subsurface <br /> characteristics and conditions as those to be assessed for in-situ bioremediation must be <br /> undertaken With air sparging, an appropriate naturally occurring micro-organism colony <br /> will have been demonstrated to exist in the subsurface throughout the area(s) of interest <br /> Other key elements of subsurface conditions such as lateral and vertical permeabilities, <br /> pH, and other factors will have also been determined to be suitable for in-situ <br /> bioremediation The technical approach to air sparging is to augment the natural <br /> I biodegradation process by increasing the supply of oxygen within the soil matrix and <br /> groundwater zone This is accomplished by injecting air, and sometimes nutrients, at <br /> strategic locations within the sod and groundwater plume <br /> IAs with other groundwater remediation alternatives, once technical feasibility has been <br /> demonstrated, a preliminary design of a potential system may be undertaken At that <br /> point, preliminary project costs and nontechnical considerations can be reviewed and the <br /> desirability of air sparging versus other remediation alternatives may be evaluated <br /> 5.2.3 Ex-Situ Groundwater Remediation Alternatives <br /> Ex-situ groundwater remediation alternatives include the design, installation, and operation <br /> of a suitable number of groundwater recovery well(s) located so as to enable the capture <br /> of the contaminant plume Following extraction, contaminated groundwater is treated by <br /> an appropriate water treatment-technology to achieve target cleanup levels, with treated <br /> water being discharged by either re-injection, discharge to sanitary sewer, storm sewers, <br /> and/or land surface This treatment alternative is also referred to as "pump-and-treat" and <br /> experience has demonstrated this technology alone is not an effective groundwater <br /> treatment alternative Therefore, groundwater extraction and treatment systems are <br /> usually installed for the purpose of hydraulic control, to halt migration of a contaminated <br /> plume, and are usually used in combination with in-situ technologies to effectively <br /> remediate contaminated groundwater <br /> I The selection of an ex-situ groundwater remediation alternative depends on adequate <br /> design of the extraction system (recovery wells) Depending on the site, a suitable water <br /> treatment system must be designed to be compatible with the flow rate delivered from the <br /> I extraction system as well as the contaminant type Before embarking on design of an <br /> extraction and treatment system, the feasibility of discharge of treated water to various <br /> receptors, National Pollutant Discharge Elimination System (NPDES) permits, etc , must <br /> be considered <br /> All of the aforementioned design parameters, cleanup objectives, and compatible in-situ <br /> treatment technologies must be evaluated to develop the most feasible, cost-effective <br /> cleanup system for a specific site <br /> 90-097A PAR 14 <br />