Coffee Creek Water Resource Recovery Facility Expansion

In response to increasingly stringent nutrient regulations and the need to accommodate population growth, the City of Edmond undertook a $171-million expansion of the Coffee Creek Water Resource Recovery Facility (WRRF). The facility needed to increase capacity to treat an average flow of 12 mgd, with peak flows up to 36 mgd, and to meet upcoming nitrate and phosphorus effluent limits. Additionally, the aging infrastructure required significant upgrades to improve energy efficiency, system reliability, and long-term operational sustainability.

Carollo provided comprehensive study, design, and construction phase services for the expansion, which included a full reconfiguration of the WRRF’s electrical system, improvements to the influent pump station, new solids handling facilities, and a major retrofit of the biological treatment process. One of the project’s central innovations was the conversion of the aeration system from mechanical rotors to energy-efficient fine bubble disc diffusers. Carollo also designed a new blower building capable of housing five high-speed turbo centrifugal blowers, offering a flexible and high-efficiency solution for low-pressure aeration applications.

To meet nutrient removal goals, Carollo recommended and designed a Modified Johannesburg biological nutrient removal process with an external selector and dedicated return activated sludge denitrification, anaerobic, and anoxic trains. This approach provides operational flexibility, simplifies future plant expansions, and enables the facility to consistently meet effluent standards while reducing aeration energy demand.

Other major improvements included a new lift station, headworks facility with fine screening, secondary clarifiers, UV disinfection, post-aeration, and effluent metering. Solids handling upgrades incorporated membrane thickening, staged aerobic digestion, and belt filter press dewatering to produce Class B biosolids. The facility was designed with sustainability in mind, incorporating a green roof, geothermal heating and cooling, and recycled water use in all buildings.

Carollo’s approach not only provides long-term regulatory compliance and operational resilience but also positions Edmond’s WRRF as a regional model for sustainable, energy-efficient wastewater treatment and resource recovery.