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Aerated Holding Tank (SW3454)
Background & Purpose: Western Wake Regional Water Reclamation Facility (WWRWRF) is an award-winning wastewater treatment facility that serves approximately 100,000 residents within the towns of Cary, Apex, and Morrisville. It is rated as an 18 million gallon per day (MGD) wastewater facility. The two end products of the treatment process are liquid, which is highly treated and clean water added back to the natural environment, and solids, which are dried and used by an outside vendor as an agricultural soil amendment.
WWRWRF operates continuously, but at variable flow rates. This variability creates operational challenges for treating solids effectively. An Aerated Holding Tank (AHT) placed in the open field downstream of the liquids treatment process will have numerous benefits. The storage will allow staff to mix solids from various treatment processes, optimize moisture content for drying and feed a consistent steady flow to the solids treatment process. The oxygen will continue the treatment process by stabilizing organic matter. Because there will be a constant supply of oxygen in the AHT, no offensive odors will be generated. Overall, the AHT will improve the operational flexibility of the facility and enable more efficient production of a higher quality solids product at a reduced cost.
Aerial image of Western Wake Regional Water Reclamation Facility
Project Plan: Like all WWRWRF projects, any costs associated with planning, design, construction, and operation will be allocated based on the ownership shares of the Western Wake Partners. Currently, the Partners are working with Brown and Caldwell, national wastewater experts with prior experience working at WWRWRF, to design the proposed AHT. Because the original design of the Western Wake facility had considered the addition of an AHT, a designated location already exists with minimal conflicts for construction. Project design is expected to be completed in 2026.
Aerated Holding Tank Site Plan
Construction: Construction could start as early as spring 2027. At that time, typical site preparations will begin with excavation for underground piping and foundations. Overall, the site disturbance will be less than an acre. The tank itself will be partially buried with about 20-ft above ground. The adjacent equipment building will extend about 8-ft higher and match the architectural aesthetic of other buildings around the facility. Overall, the height of the new building will be similar to the other structures at WWRWRF.
In order to minimize construction impacts on the community, the design team is planning to fabricate the tank walls offsite. This is expected to greatly reduce the construction traffic that would otherwise be required to deliver materials to the site. Construction is expected to last approximately 20 months.
Aerated Holding Tank 3D Model
Contact: Corrie Bondar, P.E.
(919) 460-4933