AlexRenew: Where Soccer Meets Wastewater Treatment

A multi-purpose athletic field sits atop a nutrient management facility built as part of a major treatment plant upgrade in Alexandria, Virginia.
AlexRenew: Where Soccer Meets Wastewater Treatment
Boys play lacrosse on the multipurpose field.

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Expanding a wastewater treatment plant in a residential neighborhood and winning the enthusiastic support of its residents may seem difficult, but that is what Northern Virginia utility Alexandria Renew Enterprises (AlexRenew) did with its one-of-a-kind plant upgrade, completed in 2015.

Faced with tighter restrictions on discharge to the Potomac River, and with limited real estate available for expansion, AlexRenew (formerly Alexandria Sanitation Authority) chose to bury the new facility in an adjoining lot and cover it with an athletic field to provide residents with a new amenity: additional green space.

“Thanks to the scores of people throughout our community who helped us with this project, our water utility is now much more visible in Alexandria than ever before,” says Janelle Okorie, chief of engineering and technology.

Cutting nutrients

Driven by state regulations and an agreement among states in the region to lower the total maximum daily load (TMDL) of nitrogen and phosphorus discharged to the Chesapeake Bay watershed, AlexRenew added an 18-million-gallon nutrient management facility (NMF) on the former site of a 33-acre landfill 1/4 mile from a large apartment complex.

Constructed on a deep pile-supported, cast-in-place concrete base slab 30 feet below grade, nearly 1,800 precast concrete wall panels form four 4.5- million-gallon influent storage tanks that help balance incoming loads for optimum treatment at off-peak times in the main plant. Each 3-foot-thick panel weighs more than 22 tons.

Eight Flowserve pumps (four 40 hp and four 80 hp) transfer flow through two 30-inch headers across 625 feet between the main plant and the NMF. Flow is diverted and stored in the NMF when ammonia nitrogen loading is high. When loading is lower, it returned to the activated sludge process of the main plant (54 mgd design, 35 mgd average flow).

Operators can select between time-based, flow-based or nitrogen-based control using either a fixed setpoint or a SCADA-calculated moving average setpoint. Five carbon filters at the NMF provide odor control; having all the equipment buried eliminates noise. “The public has responded positively to our project and particularly to the decision to remediate an old landfill site,” says Okorie.

Also constructed on the AlexRenew campus is a concentrate pretreatment facility, the first designed and separately constructed full-scale sidestream deammonification system in North America, using Anammox microbes to control ammonia.

Making it vanish

Covering the NMF is the multipurpose Limerick Street Field, with artificial turf and a regulation-size soccer field. It is fenced and lighted, and fitted with seating and restrooms. The City of Alexandria Department of Recreation, Parks and Cultural Activities manages its use for soccer leagues and other activities.

Funding for the field was separate from the $92 million cost of the treatment plant upgrade. The field cost less than $1.5 million and did not affect AlexRenew’s rates, since the cost was offset through transfer of development rights and sale of property with AlexRenew’s development partner.

A new administration building with an underground parking garage capped off construction at the site. Called the Environmental Center, the multi-story LEED Platinum building includes interactive educational displays and meeting rooms available to local nonprofits. The garage roof is landscaped and serves as a grassy seating area overlooking the athletic field.

To celebrate completion of the seven-year project, a two-day field dedication event was held at the site. More than 700 attendees — including local officials, industry leaders and Alexandria citizens and their families — enjoyed speeches, live music, food and soccer field activities.

Okorie observes, “With our partners in the development process, we worked hard to listen so that we could make everyone’s vision of the project a reality.”



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