Water Pollution Control Facility Improvements

Water Pollution Control Facility Improvements


WHKS evaluated the City of Waverly’s existing wastewater treatment system with respect to nutrient reduction capabilities and the useful life of the existing equipment. After review of the report, the City decided to proceed with recommended improvements to eliminate the existing fixed film process – trickling filters and rotating biological contactors – and convert the Waverly Water Pollution Control Facility to a suspended growth process using activated sludge.

WHKS was in close coordination with the Iowa DNR during the Facility Plan approval process, including preparation of an antidegradation alternative analysis. After the Facility Plan was approved by the Iowa DNR, WHKS assisted the City in evaluating sources of potential funding assistance for construction of the improvements.

The improvements include oxidation ditches with mechanical mixing and aeration and built-in anaerobic and anoxic zones to provide enhanced biological nutrient removal, specifically phosphorus and nitrogen removal.

The upgrades to the facility included:

  • New oxidation ditch and sludge fermenter structures
  • Main lift station improvements
  • Clarifier modifications and equipment replacement
  • Headworks and pumping station modifications
  • Equipment replacement
  • Control system consolidation and upgrades
  • Additional biosolids storage tank and mixing system

After implementation of the improvements, the plant is expected to meet the required total nitrogen and total phosphorus removals required in the Iowa DNR nutrient strategy. The project is currently under construction.


  • Wastewater treatment system evaluation
  • Wastewater plant design
  • Permitting assistance
  • Funding assistance
  • Iowa DNR coordination