Charlotte Water's Systematic and Comprehensive Sewer Maintenance and Rehabilitation Program Leads to a 75% Reduction in SSOs over the last 15 Years

Charlotte Water, located in Charlotte North Carolina, is the largest sewer utility in the Carolinas with approximately 4,500 miles of gravity sewer. Charlotte has been implementing a substantial and aggressive long-term sanitary sewer maintenance and rehabilitation program to reduce sewer system overflows (SSOs), correct historic maintenance problems, and reduce infiltration and inflow (I/I) into aging sewers. Charlotte Water was placed under an EPA Administrative Order in 2007 mandating the reduction of sanitary sewer overflows (SSOs). Charlotte developed a systematic and comprehensive sewer maintenance and rehabilitation program to address the Administrative Order. Due to the success of Charlotte's program, EPA lifted the Order in 2012, five years after it was issued. Maintenance and Rehabilitation Program Direction and Approach With the Administrative Order, Charlotte was faced with expanding their program and expediting the SSO reductions. Over the last 15 years, Charlotte Water has been rehabilitating their sewer system to address known maintenance issues and structural defects and to remove inflow and infiltration (I/I). Charlotte has developed a very specific, systematic maintenance and rehabilitation program and approach to renew and restore the sewer system. Charlotte's program approach has been focused on targeting known SSO areas and expediting the identification and prioritization of sewers to be rehabilitated and cutting out the lengthy review, analysis, evaluation, and reporting that is often done by municipalities that are implementing similar programs. Charlotte's sewer problems were obvious there was a list of known maintenance issues, there was a list of repeat backup areas and customer complaints, and there was detailed information on where sewer system overflows (SSO) were re-occurring that clearly showed high-density SSO problem areas. With all of these known and obvious problems, Charlotte had a very clear direction for their maintenance and rehabilitation program. Charlotte moved immediately to implementing a sewer rehabilitation program to repair the known and obvious problems while systematically implementing improved and targeted maintenance measures focused on fixing the problems, instead of proceeding along a 'traditional' approach of prolonged, expensive engineering evaluations, studies and reports. Program Components Charlotte has been systematically implementing their sewer maintenance and rehabilitation program over the last 15 years. The key components of their program include the following: 1.Implementation of a find-and-fix sewer rehabilitation approach to fast-track sewer rehabilitation construction every year. Charlotte's sewer rehabilitation budget is currently about $25.5 million. Charlotte performs three find-and-fix rehabilitation projects yearly totaling approximately $10 million per year to rehabilitate their 8' to 24' sewers. Separate large-diameter rehabilitation projects are also performed every year at a typical budget of $6 million per year. In addition, Charlotte's maintenance department manages a $1.5 million per year maintenance rehabilitation contract to repair issues identified by Charlotte's in-house crews. Charlotte follows the find-and-fix approach exclusively to rehabilitate their sewer system. The find-and-fix rehabilitation approach quickly and efficiently targets the sewer areas/basins with the highest density of SSOs. This targeted rehabilitation approach directly eliminates SSOs. 2.Implementation of a significant root control program, treating over one million feet of sewer every year. This root control program is believed to be one of the largest in the country. Roots have been a major reason for SSOs in Charlotte's sewer system. 3.Implementation of enhanced and increased sewer cleaning and television inspection efforts. The increased efforts included increased assistance from outside contractors as well as significantly increasing Charlotte Water's maintenance staff and equipment. Many of Charlotte's SSOs are caused by debris, roots, grease, and sags in the sewers, so the increased cleaning efforts directly eliminates SSOs. Charlotte Water also implemented a siphon cleaning contract to clean all of their existing 56 siphons every year, with the problematic siphons being cleaned twice per year. 4.Implementation of a targeted 'right-time' cleaning program to focus cleaning efforts on the sewers that actually need cleaned. The targeted cleaning approach efficiently utilizes the sewer cleaning crews' time and focuses the work where it needs to be done. 5.Implementation of a Smart Cover flow metering network to monitor sewer levels throughout the system. Smart Cover meters are level-only meters installed in manholes to measure wastewater flow levels. Charlotte currently has over 400 Smart Covers throughout their system and will be increasing their network to over 500 meters in 2024. When the Smart Cover meters transmit a high level alarm in the manhole, Charlotte Water crews mobilize to clean the sewers before an SSO occurs. 6.Implementation of a Multi-Sensor Inspection (MSI) program to evaluate Charlotte's largest sewers and most critical assets. A 5-year $5 million MSI inspection program will begin in 2024. Proven Success Charlotte has reduced SSOs by over 75% since 2007, an unprecedented reduction of SSOs in a relatively short period of time. Charlotte met the terms of their EPA Administrative Order by 2012 (within 5 years) due to the success of their find-and-fix sewer rehabilitation program and their enhanced operation and maintenance efforts. Charlotte has quickly and systematically fixed problems instead of studying problems. Charlotte has completed over $150 million of sewer rehabilitation construction work over the last 15 years following their find-and-fix approach. And on top of all of these significant successes, Charlotte has saved over $15 million in engineering and construction costs by following their find-and-fix approach. This presentation will review Charlotte Water's systematic and comprehensive sewer maintenance program and find-and-fix sewer rehabilitation approach/concept in detail. The presentation will detail how various maintenance programs were developed and are being implemented, how priorities are quickly developed without prolonged study and analysis, how the program is implemented including the find-and-fix construction projects, and the benefits of the approach. Documented successes, results, and the significant cost savings will be presented. And most importantly, the presentation will clearly detail how any utility can develop and follow a similar program and achieve similar results, including sharing years of lessons learned and tweaks made to the program to further achieve success.