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Dalecarlia and McMillan Water Treatment Plants. Washington, DC.

These facilities owned and operated by the Washington Aqueduct Division of the US Army Corps of Engineers treat an average of 220 million gallons per day (MGD).

WRA prepared a study of chloramination process alternatives and provided the design of chloramination facilities for Total Trihalomethanes (TTHM) reduction at the Dalecarlia and McMillan Water Treatment Plant in Washington, DC. The project included aqua ammonia storage and feed facilities, upgrades of the gaseous chlorine feed and storage facilities, including chlorine gas leak scrubbers. Improvements were also made to the clearwell baffle wall system for maximizing chlorine contact time, polymer systems, bulk coagulant storage and feed facilities, and the addition of a pneumatic conveyance system for pebble lime. Other subsequent projects have included Dalecarlia Waste Stream Handling Improvements, Dalecarlia Pump Station Upgrades and McMillan Chemical Building Renovations for the construction of Maintenance Support Facilities.

Dalecarlia and McMillan Water Treatment Plants
Project Highlights

Biosolids and Residuals Handling

WRA provided preliminary design services, including pilot testing for residuals collection, dewatering and disposal. Subsequent design included facilities to minimize potential for waste streams being directed to the Potomac River and a dechlorination facility if a discharge was to occur.


WRA designed upgrades of all lighting systems within the Dalecarlia Pump Station to become more energy efficient. The upgrades included energy efficient fixtures as well as lighting control system upgrades to reduce lighting use in unoccupied areas.

Maintenance Facility Planning and Design

Renovations of the existing McMillan Chemical Building were designed to allow for maintenance support facilities. The design included emergency sleeping quarters, training rooms, lockers, and all related HVAC and electrical work.


The Dalecarlia Pump Station Renovation project included major roof repairs, including the replacement of large deteriorated ornamental cast stone cornice pieces around the entire building perimeter that had become a safety hazard due to falling pieces.