Successful I&I Reduction using Design-Build - Developing and Implementing the River Valley Highlands Design-Build Sewer Rehabilitation Project

River Valley Highlands has a developer-constructed sewer system that was dedicated over to City of Lancaster, Ohio less than 10 years ago, with aspects of the development still under construction. Numerous unexplained basement backups during heavy rains were causing basement backups 1-3 times per year. Following a focused root cause investigation, a turnkey sewer rehabilitation project using Progressive Design-Build to provide continuous highly collaborative interaction between the Owner, Engineer, Construction Manager, and Subcontractors was used to solve this problem. This paper will present the project from initiation through assessment of post-rehabilitation effectiveness. The project removed 61% of the RDII volume This paper will present how City of Lancaster developed the turnkey engineering and construction program to aggressively reduce I&I flows into their sewer system, relate the details of implementation, share the impact on flow reduction and benefit to extending sewer service life, and discuss engineering and construction management lessons learned. Significance This project was delivered as one of the few turnkey engineering and construction programs implemented for sewers systems with guaranteed maximum price, guaranteed schedule, and overflow elimination expectations. Results Construction was completed in November 2018. Control Basin Method pre- and post- rehabilitation flow monitoring in the basins rehabilitated yielded a 61% reduction in RDII volume. Given that most of the lateral length was unaddressed and that no inflow sources were removed by this project, this is consistent with expectations for this project. Warranty testing conducted 2 years after completion of rehabilitation showed that 99.8% of the joints were still completely airtight, that 97.6% of the lateral tap connections were still air-tight, and 100% of the pipes were structurally secure.