Laserfiche WebLink
water table, and may not be effective in the clayey soils found at both <br /> saes The low permeability of the clayey soil makes the extraction <br /> process difficult and time-consuming To make the process effective, <br /> more wells would be required, increasing the cost of the alternative <br /> Even with the additional wells, treatment in clayey soils may not be <br />' sufficient For these reasons, vapor extraction was eliminated as an <br /> alternative for the site <br /> Bioremediation <br /> Bioremediation is a treatment alternative that can be used for <br /> remediating soil affected by hydrocarbons The affected soils would be <br /> excavated and treated at the site After treatment is complete, the clean <br />' soil could be backfilled into the excavation <br /> Several soil bioremediation methods are available, including <br /> landfarming and treatment cells In landfarming, the soil is spread out <br /> over the ground to a depth of 12 inches, moistened, and periodically <br /> tilled with conventional agricultural equipment to provide aeration <br /> The addition of water and oxygen stimulates the natural microbes and <br /> increases the rate of natural biodegradation (which is generally on- <br /> going at any site having petroleum hydrocarbons in soil) Microbial <br /> activity can be further stimulated by 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 landfarrning <br /> Because treatment cells are fully enclosed, commercial (non-native) <br /> microbes can be used to accelerate the biodegradation process <br /> Treatment cells are expensive to construct and offer no significant <br /> benefits for compounds, such as petroleum hydrocarbons, that are <br /> simple to biodegrade Therefore, treatment cells were eliminated from <br /> further consideration <br /> Chemical Neutralization <br /> Chemical neutralization involves treating the soils to neutralize the <br /> compounds present Neutralization is only used for soils affected by <br /> 4-5 <br />