The City of St. Charles owns and operates two wastewater treatment facilities, the Main WWTF and the West Side Water Reclamation Facility (WRF). The West Side WRF has a design capacity of 0.70 million gallons per day (MGD) and serves areas of the community located west of Randall Road. The West Side Service Area has continued to develop in general conformance with the Comprehensive Plan.

The City requested Trotter and Associates, Inc. to update the Facility Plan to reflect as-built conditions and incorporate more detailed development information and address regulatory changes. The West Side Service Area served 6,275 PE in 2013 and the West Side WRF treated 0.49 MGD of wastewater. Taking into consideration ongoing development, governmental capacity commitments, and potential annexations, the population equivalent of the service area is expected to increase by 6,111 PE. This equates to a build-out projection of 12,386PE at an average daily flow (ADDF) of 1,110,000 gal/day or 1.11 MGD.

A detailed review of the collection system and its capacity was completed. The collection system was divided into four major drainage basins. The sewers were reviewed for long term capacity requirements and recommendations for maintenance and depreciation budgets were prepared. TAI performed a detailed analysis of each lift station. Maintenance and capital improvement budgets were prepared as part of the analysis.

The West Side Water Reclamation Facility currently has a capacity of 0.70 million gallons per day (MGD). TAI performed a detailed analysis of the existing facilities operational performance and condition. TAI also reviewed the plant’s capacity in comparison with existing, approved and future flows. Proposed expansion plans for the facility included analysis of alternative technologies to meet future regulatory requirements including total nitrogen and phosphorus.

TAI prepared cost analysis for incorporation into the City’s user and connection fees to address ongoing operational and capital improvements requirements for the infrastructure.

Technical Challenges & Solutions

Phosphorus Removal – Incorporation of control scheme to meet BNR with minimal structural modifications


Scott Trotter, P.E. / Jerry Ruth, P.E.