Soil pile bioremediation is a simple and cost-effective method for remediating contaminated soils. This bioremediation technology uses vacuum to provide continuous aeration to contaminated soil that has been excavated and inoculated with nutrients and contaminant-specific bacterial cultures.
In this process, contaminated soil is generally placed on top of an impermeable plastic liner to control leachate and runoff. Vacuum is then pulled on the pile through a framework of perforated corrugated hose, while air is supplied to the pile through a separate network of inlet pipes. The blower exhaust exiting the pile is sent to vapor phase activated carbon to eliminate air emissions. The soil pile is covered with a black plastic liner to prevent odor and air emissions, evaporation, and loss of passive solar heat. During operation, nutrients, water, and additional bacteria are added as needed through a separate leach line inside the top cover.
Soil pile technology has been successfully used to remediate several non-RCRA petroleum contaminated sites. To take advantage of these field successes, WMNA and CWM decided to build a permanent facility that treats and recycles soil at WMNAs existing solid waste landfill in Cincinnati, OH. The net result is the ELDA Soil Center. To date, two soil piles, each with 15 000 cubic yard capacity, have been constructed at the ELDA landfill. The Soil Center is capable of recycling in excess of 250 000 tons per year of petroleum contaminated soils. This permanent facility uses a clay liner underneath the soil pile and perforated ABS pipe for air and vacuum lines. A biofilter was installed for controlling the VOCs prior to a 2-stage activated carbon system for air emissions control.
Soil treatment at the ELDA Soil Center provides several significant advantages. First, it enables contaminated soil that would normally be landfilled to be recycled as daily cover or as backfill offsite, thus saving landfill space and eliminating the liability associated with landfill disposal. Second, it effectively destroys organics through biodegradation resulting in nonregulated soil. Third, the ELDA Soil Center offers an off-site alternative to on-site remediation, particularly to space constrained sites that cannot perform on-site remediation. It also enables customers to take advantage of the low operating costs associated with a fixed site. The ELDA Soil Center is the first of its kind. Plans are underway to use the 128 WMNA solid waste landfill sites to develop a strategically located network of additional soil recycle centers throughout the United States. Soil treatment centers may also be developed for organic contaminated RCRA soils at CWM hazardous waste landfill sites in order to provide a cost-effective remedial option for these soils.