City of Clinton, Iowa

Q. What water quality practices do you use on your operation?
A. In 2009, the City of Clinton’s engineering consultant, HDR Engineering, Inc. (HDR), began designing a new 12-million gallon per day regional wastewater treatment plant with biological nutrient removal (BNR), known as the Clinton Regional Wastewater Reclamation Facility (RWRF). The Clinton RWRF incorporates facilities that proactively reduce ammonia and provide for biological nutrient removal.  At the design loadings and average daily flow of 8 MGD, the RWRF will remove approximately 500 tons/year of ammonia, 380 tons/year of total nitrogen, and 60 tons/year of total phosphorus. Biological nutrient removal is achieved at the heart of the plant - the aeration basins. At these locations, the RWRF incorporates anaerobic and anoxic zones with internal mixed liquor recycle, utilizing a three stage process, known in the industry as the “A20” process, to provide total phosphorus and total nitrogen removal. 

Q. Why did you voluntarily adopt these practices?
A. Although the stricter nutrient discharge limits are not expected to be regulated for another five to ten years, Clinton chose to incorporate an advanced level of treatment to proactively position themselves for anticipated future standards.  The Clinton RWRF is one of, if not the first, such plant in Iowa. It also provides for considerable future industrial development and growth.

Q. What, if any, assistance (financial as well as technical) did you receive to employ these practices?
A. Overall, it’s a $62 million capital investment.  Financial assistance included: $2.5 million I-Jobs grant; $860,000 STAG grant; State Revolving Loan – Iowa DNR and Iowa Finance Authority; Alliant Energy rebates totaling $145,708; 10,000 residential, 1,000 commercial and 15 industrial customers.

Q. What is your environmental philosophy as it relates to your operation? 
Missouri River and Gulf of Mexico water quality needs that drove the recently published Iowa Nutrient Reduction Strategy will require that approximately 100 other Iowa municipalities with flows greater than 1.0 million gallons per day to follow suit in achieving nutrient reduction. The city can be looked at for guidance and leadership and can replicate many aspects of the RWRF model, including: 

• the regional approach developed by the City; 

• the concept of incorporating anaerobic and anoxic zones with internal mixed liquor recycle to provide total phosphorus and total nitrogen removal; and

• the state-of-the-art turbo blower and rotary press technologies utilized.

While necessary to improve local, Mississippi River, and Gulf of Mexico water quality, resistance from many Iowa municipalities is anticipated. The costs are significant to already fiscally challenged cities. The City of Clinton’s foresight and willingness to lead the way can be cited in helping overcome the resistance that will likely be encountered. The model developed by the City will serve as a foundation for Iowa.