Harborview Wastewater Treatment Expansion
Expansion from 24 to 36 MGD with new secondary clarifiers, aeration basin, blower building and UV disinfection, constructed inside an operating plant adjacent to a residential neighborhood.
What made it hard.
The plant had to meet its permit every day of construction, including wet-weather flows that arrived without warning. The nearest homes were fewer than 300 feet from the new aeration basin, and odor complaints were already a sensitive issue for the authority.
The site had no available laydown area, so material delivery and crane positions had to be planned daily.
How we built it.
We sequenced every tie-in against the authority's hydraulic model and kept temporary treatment capacity in reserve. Covered channels and an upgraded odor-control system were installed early, before the first basin was brought online.
A full-time community liaison managed notices, site access and complaint response. Deliveries were scheduled outside school hours, and the noisiest work was moved to daytime windows agreed with the neighborhood association.
Where it landed.
The plant remained in permit compliance throughout construction, with zero odor complaints recorded over the final eighteen months. The expanded facility passed its 36 MGD performance test three weeks ahead of schedule.
On site.
The cost model was open from day one. We could see what every decision did to the GMP before we made it, which is rare in this market.
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