Industrial Landfill
Williamsburg, Virginia
Roux Associates, Inc. was retained to complete a CW treatability investigation and design of a full-scale 60,000 gallons per day (gpd) treatment system in Virginia for the remediation of heavy metals in uncontrolled leachate and stormwater discharges from a manufacturing facility's inactive industrial waste landfill.
The objective of the project was to mitigate 1,700 mg/L acidity, remove reduced iron and remove zinc from the landfill leachate. The CW design involved the implementation of a series of passive sequential treatment cells including:
Anoxic Limestone Drains - mitigate acidity - Aerobic CW Cells - oxidize iron
- Anaerobic Sulfide Reducing Cells - precipitate zinc as the sulfide
- Aerobic CW Cells - polish and aerate the effluent
The design consisted of a 16-acre staged CW treatment sequence retrofitted into an existing on-site impoundment, and includes a 400-foot earthen dike, flow control and a storm-water bypass. Collection and treatment is passively operated while treated effluent is discharged to a publicly owned treatment works via a pump station and force main, also designed by Roux Associates.
Full time construction oversight was performed by a Roux Associates engineer for four months while the system was installed. Activities performed included the evaluation of bids, contracting, shop drawing review, full-time inspection of the installation, surveying, review and approval of field change orders, field design changes, preparation of as-built drawings, and review and approval of invoices.
The fully-operational CW system, which cost approximately $1.1 million to construct, has eliminated the need for the $10 million Resource Conservation and Recovery Act (RCRA) cap that was originally proposed for the site to control leachate and stormwater discharges from the landfill. Data indicate the CW system has reduced heavy metals concentrations to the State Pollution Discharge Elimination System (SPDES) requirement of less than 2 mg/L zinc. These results enabled the client to deactivate its on-site wastewater treatment facility only three months after the startup of the CW system.