Data-Driven Approach Justifies Better Outcomes

The City of Ottawa has fourteen CSSAs (Combined Sewer System Areas) totaling approximately 800 acres, 26 miles of combined sewer, more than 600 manholes and a variety of unique pipe shapes and materials discharging to either the Fox or Illinois Rivers. A portion of the Illinois River was designated a sensitive area. Crawford, Murphy & Tilly (CMT)’s challenge on this project was to find a cost-effective way of reducing annual CSO events to USEPA-defined limits. Our optimization of alternatives was made possible by recommending monitoring and modeling of both the collection system and receiving water quality. Public outreach and an affordability analysis ensured that citizens could provide feedback and would be informed on the economic impact of the project.

CMT’s emphasis on detailed investigation, modeling and creative engineering solutions provided the city with the most cost-effective program that complied with regulatory policy. The $15 million plan was defensible, and when combined with the affordability analysis, resulted in an extended schedule for compliance, easing the overall burden to the community and its residents.

This project demonstrates that while small communities have the option to undertake less comprehensive monitoring and modeling, the detailed investigation performed for Ottawa, along with the modeling, lead to a more appropriate and cost-effective control approach.  The quality data and system information formed the basis to develop a defensible plan that allows the City to invest funds back into the collection system.

This project demonstrates that while small communities have the option to undertake less comprehensive monitoring and modeling, the detailed investigation performed for Ottawa, along with the modeling, lead to a more appropriate and cost-effective control approach.  The quality data and system information formed the basis to develop a defensible plan that allows the city to invest funds back into the collection system.