Wastewater Treatment Plant Expansion, Phases I & IIA, City of Washington, North Carolina
Phase I of this project increased the capacity at the Wastewater Treatment Plant to 3.65 MGD and included a 95' diameter clarifier, 2 additional tertiary filters, a 40' x 50' metal maintenance building, and a wastewater reuse system.? Phase IIA of this project included a parallel 2.1 MGD ditch with selector tanks, RAS Pump Station, and an associated power zone center.
The WWTP was expanded in phases based on grant funding available to the City of Washington.? The Phase IIA expansion was installed as a redundant treatment train to the existing oxidation ditch to meet permitted NPDES effluent requirements if the existing train required maintenance, and to reduce hydraulic restrictions through the plant. Although the new oxidation ditch and RAS pump station did not increase the overall capacity of the wastewater treatment plant, this phase of construction was an integral part of future phases of construction required for increasing treatment capacity. Future phases of construction will include a second preliminary treatment unit, a filter feed pump station, an additional disinfection structure to provide a complete second treatment train, and expansion of the effluent pump station and waste force main/diffuser in the Tar River.? Rivers services included a Preliminary Engineering Report, 201 Facilities Plan, Environmental Assessment, design, bidding, construction administration, Resident Project Representative and start-up.? Rivers was also the Engineer for the original WWTP completed in 1986.