Located just outside Raleigh, North Carolina, Cary challenges the standard of how to efficiently manage a wastewater collection system. Its municipal collection system spans nearly 1,000 miles with over 500 miles of easements, which require added effort to access. The collections system maintenance operation has further responsibility for over 28,000 manholes, 43 lift stations, and serves over 200,000 people in Cary and the neighboring Town of Morrisville. Cary has long excelled at both preventative and predictive maintenance.
THE CHALLENGE
Their current program splits their system into 17 basins — ranging from 200,000-300,000 ft. With three Aries CCTV vehicles, crews are out every day working basin-by-basin to inspect their system. Cary contracts out approximately 10 miles per year of chemical root control as well as contracting out the cleaning of pipes larger than 12 inches in diameter. Small diameter pipes are cleaned by one of four Vac-Cont trucks, and Cary also identifies certain hotspot lines which are cleaned on a frequent basis.
To efficiently handle the challenges of maintaining and managing these assets, Cary has relied heavily on its value of Evolution, meaning seizing opportunities to experiment, learn, and adapt to create a better future. In line with this value, Cary has embraced innovation and tested emerging technologies.
And their efforts have been rewarded. Cary recently won North Carolina One Water Association’s “Collection System of the Year” for the fourth year in a row. This award recognises Cary as a “municipality that protects the public health and the natural beauty of the environment through proactive practices of management, operations, and maintenance beyond what is required of its NCDEQ collection system permit,” according to the award criteria.
THE SOLUTION
Cary adopted a strong proactive maintenance strategy that leverages acoustic inspection as a force multiplier for their CCTV and cleaning crews. Cary started the SL-RAT program in 2017 and expandecl the program to its current form in 2019. Each day acoustic inspection crews go to one of the seventeen basins to take measurements. They record the scores into a custom GIS dashboard, and the data is downloaded to the InfoSense Sewer Line Data Organiser cloud application for archiving. Supervisors then use this information to allocate cleaning resources. For any pipe that scores under a four, a cleaning truck is dispatched as early as the following morning. After cleaning, an SL-RAT team reinspects each line to see if the score has improved above Cary’s threshold for maintenance. Pipes that continue to receive a low acoustic score – even after cleaning – require further investigation and may indicate issues with the cleaning process, pipe sags, or other anomalies, such as a missing manhole or collapsed pipe.
RESULTS
The results speak for themselves. In 2022 alone, Cary inspected over 4,000 pipes for a total of more than 670,000 ft. using just four people. In one basin, which encompasses 200,000 ft. of gravity sewer lines, they found only 13,000 ft. needed cleaning after inspection.
Overall, only around 5% of pipes measured with the SL-RAT needed to be cleaned in that specific basin. This has been particularly impactful for easements that require greater resources to properly access for CCTV and cleaning. The ability to tactically deploy cleaning and CCTV equipment more effectively has not only saved time and money but has also helped the environment by reducing truck emissions and flushing water usage. While every collection system in North Carolina must meet the same requirement for their NCDEQ permit, Cary has found a way to use technology to improve its efficiency and effectiveness. According to McDaniel, “Every day we are trying to stay one step ahead, and every day we are preventing a spill somewhere.”
– Paul Campbell, Collection System Operator, Town of CaryThe ability to tactically deploy cleaning and 60TV equipment more effectively has not only saved time and money but has also helped the environment by reducing truck emissions and flushing water usage.
