Wastewater Treatment Improvements

The City of Sioux Center needed to update the previous wastewater treatment facility to meet the effluent ammonia and disinfection limits in their new Department of Natural Resources (DNR) permit and to meet Iowa’s Nutrient Reduction Strategy. During the planning stages, a comprehensive approach was taken to evaluate the facility and its environmental impacts. The City and Bolton & Menk worked together with businesses and industries to study the needs of the future and design this plant to meet those needs. Numerous treatment options were explored and evaluated, and the extended aeration activated sludge process with biological nutrient removal was selected because this process provides consistent high-quality effluent and operational flexibility.

Bolton & Menk provided the City of Sioux Center with a detailed wastewater facility plan detailing the options available to the City. The work included
alternatives for consideration, cost of services study (rate information), meeting with community industries to engage all stakeholders in the solutions,
and assistance with State Revolving Fund (SRF) financing. Included with the planning was the Iowa Nutrient Reduction Strategy Report along with an antidegradation alternatives analysis. This comprehensive effort allowed the City to proceed confidently with their wastewater treatment facility expansion of approximately $26.5 million to replace aging infrastructure, meet nutrient reduction and disinfection goals, and provide the community with a facility to last years into the future, thereby protecting the environment and allowing the community to continue to grow and thrive. The facility began operations in November 2019 and was fully operational by the summer of 2020.

The engineering cost opinion on this facility was within five percent of construction costs. The City staff and council were engaged throughout the process and the report/planning phase involved numerous public presentations (including handouts and graphical displays), stakeholder meetings, publications, newspaper articles, and television interviews to help educate the community on the improvements.

The project included two traveling perforated plate fine screens with a separate washer and compactor. Grit removal was provided with a new vortex grit removal system including a grit cyclone and classifier. The pretreatment screen and grit are rated for 7.0 mgd flow.