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Client Name
City of Lenox
Client Type
Project Type
Services Provided
  • As-builts
  • Construction Administration
  • Construction Observation
  • Construction Staking
  • Funding Assistance
  • Permitting
  • Site Design
  • Topographic Survey & Subsurface Utility Engineering
  • Treatment Facility Design
  • Treatment Process Design
  • Wastewater System Analysis & Planning

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  • NPDES permit compliance
  • Reducing ammonia-nitrogen and E.coli with an aerated wastewater lagoon system
  • Upgrades to lagoon aeration
  • Addition of a Submerged Attached Growth Reactor (SAGR)
  • UV disinfection

Achieving NPDES Treatment Requirements

This project was developed to meet a NPDES compliance schedule issued to the City of Lenox for reduced ammonia-nitrogen and new E.coli effluent limits. Improvements to the existing aerated lagoon system considered through facility planning included mechanical plant upgrades, but reuse of the existing lagoons with added ammonia removal and disinfection equipment proved to be the most cost-effective solution. Upgrades to lagoon aeration will provide more reliable and energy efficient lagoon treatment, while the addition of a Submerged Attached Growth Reactor (SAGR) will provide the denitrification necessary for Lenox to meet stringent ammonia-nitrogen limits. UV disinfection of the final effluent will provide the seasonal treatment of E.coli that is required.

Snyder & Associates prepared the DNR required facility plan to address inflow and infiltration (I&I) issues, effluent limits, excessive influent loading values, and proposed alternatives to improve the treatment process. During the planning and design phase, new technologies were reviewed, including piloting a previously unpermitted treatment process that was ultimately not accepted by the Iowa DNR.

smoke coming out of manhole

Smoke testing for I/I issues

The ultimate design selection was a function of affordability, ease of maintenance, and treatment performance needs.

We provided a variety of wastewater planning and design services for this project. We’re also overseeing construction of the new wastewater plant, which was completed in the spring of 2019.  In addition, we’re also currently working with the city on a State Revolving Fund (SRF) sponsored project for water quality improvements within the city’s watershed that will be funded using a portion of the SRF loan interest.