Cleaning Up Contaminants in the Nation’s Capital
In 2003, AdEdge Technologies began working with EarthTech, the engineering firm responsible for specifying and selecting the various water treatment systems serving the National World War II Monument in Washington, DC.
Storm water and groundwater control and treatment are essential aspects of this project because the monument is located on the National Mall, adjacent to the reflecting pool and Washington Monument.
AdEdge was subsequently contracted by general contractor Walsh Construction to provide the integrated groundwater treatment system for the project. Treatment was needed for the shallow groundwater collected by the subsurface drainage system inside a bentonite slurry cutoff wall surrounding the 11-acre site.
Primary contaminants for treatment included iron, manganese and arsenic. Water must be extracted and treated to meet discharge limits permitted by the National Pollutant Discharge Elimination System prior to final conveyance to the Potomac River. The systems are located 20 ft below the memorial in a secured concrete vault containing other conveyance piping, pumps and support systems.
The system was placed into operation in early June 2004 and will be operated by the National Park Service.
The treatment systems consist of two parallel skid-mounted systems rated for 30 gal per minute (gpm), each capable of removing the contaminants of concern. Each treatment train includes an AdEdge AD26 iron removal system and an arsenic package unit (APU) to attain the stringent discharge limits. The water is pumped from the groundwater feed pumps and enters the dual-vessel AD26 system following inline hypochlorite (chlorine) injection.
Hypochlorite solution is fed inline through a computer-controlled metering and feed system that is capable of real-time chlorine residual measurement and control. Iron and manganese are oxidized and filtered/adsorbed with the proprietary AD26 catalytic media-based system. Treated water flows through the respective APU adsorption system, which contains the Bayoxide E/AD33 media. As a granular ferric oxide media, it is specifically engineered for arsenic removal.
The skid-mounted systems are equipped with automatic controls, backwashing features, switches and sample ports for complete-functioning packaged units. Instrumentation is provided on a control panel to measure critical operating parameters. Total gallon throughput and flow rate for each unit is measured continuously with a dedicated flow-totalizing meter. The adsorption system does not generate liquid or hazardous waste and requires no chemicals or regeneration. Media, when spent, will be discarded as non-hazardous solid waste.