North Liberty Town Council retained DLZ to initially provide a preliminary engineering report (PER) for process and capacity upgrades to the Town’s Wastewater Treatment Plant (WWTP). The PER provided analysis on alternatives for adding grit removal at the plant headworks, adding phosphorus removal via chemical additions, various hydraulic improvements throughout the plant, upgrading the plant’s scum pumping, and final clarifier equipment, as well as switching from chlorine to UV disinfection. The PER was completed and accepted by the Town Council and the State Revolving Fund (SRF).
After the successful completion and acceptance of the PER, the Town Council requested that DLZ prepare a proposal to perform final construction plans. The final design of the project included:
- Upgrades to the control building and headworks
- Additions of flow split structures to improve plant hydraulics
- Upgrades to the final clarifiers and scum pumping equipment
- Replacement of the chlorine disinfection with UV disinfection
- A new storage building
- Upgrades to a remote lift station that provided flow from a residential development.
During the WWTP upgrades design, DLZ assisted in successfully negotiating new terms and conditions for the Town’s NPDES permit. When the Town renewed its NPDES permit, IDEM requested additional testing on various pollutants that had never been requested in the past. DLZ was vital in negotiating the final terms of the NPDES permit to be much more favorable for the Town. The Town has been very pleased with DLZ’s performance on the WWTP. DLZ has been awarded additional design work for the Town’s Water Treatment Plant, Water Tower, and various transportation projects.