Evaluation of Lateral Rehabilitation for Flow Reduction in Wheaton, IL - A Statistical Approach

The City of Wheaton, Illinois has had a proactive approach to rehabilitation of the public side of the sanitary sewer collection system, performing yearly sewer and manhole rehabilitation since the late 1980’s. In spite of this the City still experiences frequent basement backups and sanitary sewer overflows in less than one year recurrence rain events. Two pilot areas were identified with each slated to receive a different approach to private sector lateral rehabilitation. Using the City’s own meters, pre- and post-rehabilitation flow metering provided data to measure the effectiveness of the rehabilitation. A statistical approach utilizing the collected data and applying an ANCOVA was used to determine the effectiveness of the rehabilitation. This approach allowed the system response to be assessed for all storm events rather than the more common single storm evaluation, to provide an understanding of the significance of findings, and to quantify uncertainty in the results.