Wastewater Treatment Plant Expansion Holds the Key to Iowa City’s Future Growth

After over two years of construction, the major expansion to Iowa City’s South Wastewater Treatment Plant has been completed.  The plant, located south of town, received multiple process and equipment upgrades and can now treat 24 million gallons per day, more than double its previous capacity.  The $50.2 million expansion is the city’s largest public works project ever. 

Completion of the project marks the culmination of a 40-year vision to move all wastewater treatment operations out of the city’s core.  The diversion of all wastewater treatment operations to the South Plant necessitated the expansion in its capacity.  The increased capacity is important for the future growth of Iowa City and for the first time in decades it provides the city with the possibility of significant population expansion.  Iowa City currently has a population of 71,000.

The expansion includes multiple process and equipment enhancements that improve efficiency, sustainability, and safety.  A new ultraviolet disinfection process replaced the chemical process that used chlorine gas and sulfur dioxide, eliminating the potential hazards to the staff and residents posed by the transportation and use of these highly dangerous chemicals.  A unique Bio-Augmentation Reactor (BAR) system decreases the amount of tank space necessary for treatment and reduces the high concentrations of ammonia produced by the treatment process.  

Energy costs are reduced through the use of high speed blowers, which more efficiently match process air requirements, as well as adjustments to the discharges of the influent pumps that reduce the overall pump lift required to move water into the treatment system. 

Stanley Consultants permitted and managed the construction of the original plant in 1999 as well as designing its 2003 expansion.