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' sufficient For these reasons, vapor extraction was eliminated as an <br /> alternative for the site <br /> Biommediation <br /> Bioremediation is a treatment alternative that can be used for <br /> remediating soil affected by hydrocarbons. The affected soils would <br />' be excavated and treated at the site. After treatment is complete, the <br /> clean soil could be backfilled into the excavation <br /> Several soil b-ioremediation methods are available, including <br />' landfarming and treatment cells. In landfarming, the soil is spread <br /> out over the ground to a depth of 12 inches, moistened, and <br /> periodically tilled with conventional agricultural equipment to <br /> provide aeration. The addition of water and oxygen stimulates the <br /> natural microbes and increases the rate of natural biodegradation <br /> (which is generally on-going at any site having petroleum <br />' hydrocarbons in soil) Microbial activity can be further stimulated by <br /> adding fertilizer <br />' Loss of volatile hydrocarbons through aeration occurs during <br /> landfarming activities, and it is therefore difficult to distinguish <br /> between treatment results achieved by biodegradation and those <br /> achieved through volatilization/aeration Therefore, the <br /> implementation of a bioremediation strategy only adds to the costs of <br /> the aeration alternative Thus, landfarming has no advantages over <br /> on-site aeration and was eliminated from consideration. <br />' The use of treatment cells allows for better control of soil moisture, <br /> temperature, and nutrient and oxygen content than does <br />' landfarming. Because treatment cells are fully enclosed, <br /> commercial (non-native) microbes can be used to accelerate the <br /> biodegradation process Treatment cells are expensive to construct <br />' and offer no significant benefits for compounds, such as petroleum <br /> hydrocarbons, that are simple to biodegrade. Therefore, treatment <br /> cells were eliminated from further consideration. <br /> Chemical Neuta&atign <br />' Chemical neutralization involves treating the soils to neutralize the <br /> compounds present Neutralization is only used for soils affected by <br /> acidic or alkaline conditions, rather than hydrocarbons This <br />' treatment is not effective for hydrocarbons Therefore, neutralization <br /> has been eliminated as a potential soil treatment alternative <br />' 7-5 <br />