AlexRenew advances $190m nutrient reduction project via progressive design-build

AlexRenew advances $190m nutrient reduction project via progressive design-buildThe Virginia utility expects to approve a contract in January 2026 to expand treatment capacity while adhering to strict Chesapeake Bay nutrient limits, marking its first use of the collaborative delivery model.

AlexRenew is finalizing negotiations for a progressive design-build contract for its Nutrient Reduction Project, with board approval anticipated in January 2026.

The project, estimated at $190 million, aims to expand capacity by 4 MGD while meeting fixed Chesapeake Bay nutrient load limits.

Scope includes upgrading tertiary settling tanks, converting existing filters for denitrification, and potentially constructing up to six new filters.

The utility selected progressive design-build to accelerate the schedule and allow for design advancement without a pre-existing 30% design.

Alexandria Renew Enterprises (AlexRenew) is in the final stages of negotiations to award a contract for its Nutrient Reduction Project, with the Board of Directors expected to approve the agreement in January 2026. The project, currently estimated at $190 million, is designed to expand the facility’s capacity while ensuring compliance with strict Chesapeake Bay nutrient regulations. The initiative is driven by a need to increase the Water Resource Recovery Facility’s capacity from 54 million gallons per day (MGD) to 58 MGD to accommodate growth in the City of Alexandria. Staff explained that while flows are increasing, the facility’s total nutrient load limits for the Chesapeake Bay remain fixed. To remain compliant, the plant must treat wastewater to lower nutrient concentrations as volume rises. The proposed scope includes upgrading tertiary settling tanks and converting existing filters to denitrification filters. The conceptual design currently allows for the construction of up to six new denitrification filters. However, staff noted that during the design phase, they intend to model process optimizations—such as densification and hydrocyclones—to potentially reduce the number of new filters required, thereby saving costs. AlexRenew has selected progressive design-build (PDB) for the project, a first for the utility. CEO Justin Carl told the Board that the method was chosen due to schedule criticality and the lack of an advanced existing design. Unlike a fixed-price approach which would require a 30% design to bid, the PDB model allows the utility to bring a contractor on board immediately to advance the design and identify efficiencies. "We did not advance the design to 30% in house... we felt it was more advantageous to enter into a progressive model," Carl said, noting that this allows the team to proceed with straightforward work, such as the tertiary settling tank upgrades, while modeling the complex biological nutrient removal processes. The estimated cost of $190 million covers owner support, design, and construction, representing a key component of AlexRenew’s broader PhaseForward capital program. With the project slated for completion around 2032, the team will move into Phase 1A for preliminary design and investigations following the anticipated contract award in January.