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R10/71-51-1G <br /> 7 3 3 1 Containment and Treatment <br /> Install hydraulic barriers control groundwater migration. Typical methods were discussed <br /> in Section 7 3 2 1 Upon containment, the contaminated groundwater is recovered and <br /> treated, then a long term groundwater monitoring is implemented The depth to <br /> groundwater precludes the use of this alternative <br /> i <br /> 7332 Pump and Treat <br /> Contaminated groundwater is pumped from one or more recovery wells and channelled <br /> to a collection point The contaminated groundwater is then treated biologically, by air <br /> stripping, by carbon absorption, by separation, by coalescing, by ultraviolet, or suitable <br /> methods The treated groundwater is then disposed of into POTW, natural water, or <br /> recharged/irrigated on site <br /> The objective for treating the extracted groundwater is to remove or reduce the <br /> concentration of organic compounds which is the case of Shop-10 are benzene and <br /> toluene Groundwater treatment methods after extraction are described briefly below <br /> o Biological treatment - removal of organic compounds is accomplished <br /> biologically by using a variety of microorganisms, principally bacteria The <br /> microorganisms are used to convert organic matters into various gasses <br /> and into cell tissue <br /> o Air Stripping - is a unit process in which water and air are brought into <br /> 1 contact with each other for the purpose of removing volatile substances <br /> from the waste stream In a packed tower, water flows downward by <br /> gravity and air is forced upward The packing provides renewed air-to-water <br /> t interface by continually disrupting the liquid flow This improves the mass <br /> transfer of the contaminant from the aqueous to the gaseous phase The <br /> packed tower system is characterized by a high liquid air interfacial area <br />' compared to the total volume of liquid in the tower Volatile aromatic <br /> hydrocarbons of concern at Shop-10 (i a benzene and toluene) can be <br /> effectively removed by air stripping because these compounds have <br />' relatively low boiling points and low solubility in water Therefore, these <br /> compounds would be expected to be removed by air stripping. A VOC <br /> removal efficiency of greater than 99% can be achieved for these <br />' compounds Removal efficiency is a function of the air/water ratio and the <br /> Henry's Law Constant for each compound <br /> 29 <br />