Client: City of Mattoon

The City of Mattoon operates a wastewater treatment plant (WWTP) that discharges treated water into Kickapoo Creek under an NPDES Permit. The plant has a design average flow rate of 5.3 MGD and a peak flow rate of 14.0 MGD, with dry weather flows averaging around 2.5 MGD. While the plant previously had a disinfection requirement, this requirement was suspended over 15 years ago. As a result, the chlorine contact tanks were demolished, and there is currently no available tank space for chlorine contact or UV lamp installation.

2019 Disinfection Study:

In 2019, Clark Dietz conducted a WWTP Disinfection Study to evaluate two disinfection options: UV disinfection and chemical disinfection using chlorine. The study concluded that a Trojan UV Signa or a similar open-channel UV treatment system was the most cost-effective option for the city. This system not only provided significant financial savings but also offered operational benefits. Based on this recommendation, the city chose to proceed with the UV Disinfection System Design to comply with the new draft NPDES permit, which includes a construction deadline within 18 months from the permit’s effective date.

This image appears to show an industrial or utility facility, related to water treatment or electrical distribution. The equipment includes control panels, electrical cabinets, and a transformer.

UV Disinfection System Design:

The design documents allowed for competition between two manufacturers: Trojan Technologies and Wedeco.
The upgrades included:

  • UV channel, equipment, and weir

  • Junction manholes

  • Electrical and communication upgrades

  • Engineered post-frame building: A post-frame building was constructed over the UV disinfection channel. This structure was a cost-effective solution that:

    • Protected electrical equipment and ballasts

    • Allowed for maintenance during inclement weather

    • Provided storage for the UV bulbs