MWH and Slayden Constructors worked with the City of Spokane to achieve major upgrades to their Riverside Park Water Reclamation Facility. The upgrade included a Next Level of Treatment (NLT) - a new membrane filtration system that significantly improved the quality of effluent released into the Spokane River. The primary reason for the NLT was to decrease 99% of the phosphorus from the effluent. The new filtration system also removed more significant amounts of heavy metals, PCBs, and other pollutants associated with the facility. The advanced membrane filtration technology provides pollution reduction benefits and is designed to treat an average wastewater flow of 50MGD. The NLT upgrade is part of a major initiative to improve the health of the Spokane River.
The project included 7 GMP’s to balance early construction with design evolution and procurement of long lead equipment. Phase 1 included upgrades to the existing facility such as: SCADA upgrades, a new primary clarifier, a new chemical storage facility, modifications to 4 aeration basins, and digester gas improvements.
Phase 2 consists of the installation of a 75MGD peak flow tertiary treatment facility that comprised of: a new diversion structure, a new drum screen structure for 18’ diameter drum screens, new flocculation basins, a new membrane pump wet well and a new membrane facility.
“This was the City’s fist alternative delivery project and we found that we received tremendous value during preconstruction. MWH/Slayden provided extensive value engineering and constructability ideas that resulted in $9.1M in accepted savings. Their experience in wastewater projects led to a good understanding of project details resulting in the project operating within the allocated budgets.”
This digital thread ensures that design engineers, construction teams, operations staff, and City leadership all work from the same validated foundation of information. In an environment as utility-dense as a 50-year-old wastewater treatment plant, this visibility is essential.
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In January, MWH officially launched its Women in Construction chapter—an exciting milestone for the company and a meaningful step forward for representation across our jobsites, offices, and leadership teams. The launch reflects a growing commitment to elevating the voices and experiences of women who contribute to every part of our work.
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MWH delivers a fully integrated Commissioning & Startup (C&SU) program that begins in preconstruction and carries through final acceptance and operator handover. Unlike traditional approaches where commissioning is treated as a late-stage activity, MWH embeds commissioning into every phase of project delivery, ensuring systems are designed, constructed, tested, and optimized as a cohesive whole.
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