NASSCO Report – Proactive Approach to Trenchless Technology Damage Prevention
The nation’s underground infrastructure, which spans far and wide, has suffered from years of neglect, raising concerns of imminent failure due to the effects of time and natural deterioration. In response to this, Water District No. 1 of Johnson County, Kansas (WaterOne) is taking a proactive stance. They have embarked on a mission to identify water mains that have surpassed their expected lifespan or are in dire need of replacement, all in an effort to proactively prevent potential failures.
A distinctive challenge faced by WaterOne is that many of these water mains run through well-established residential neighborhoods. To address this, they often times utilize trenchless technologies, employing directional drilling techniques to install new PVC water mains into place.
With the underground utility corridors congested with a complex web of services, the significance of utility locates prior to construction activities cannot be overstated. This crucial step serves a dual purpose: It identifies potential alignment conflicts and, more importantly, acts as a safeguard against inadvertent damage to other vital utilities.
However, it’s essential to acknowledge that locating sanitary sewer laterals in advance of these activities presents a unique and intricate challenge. These sewer laterals are most often inadequately mapped or not readily locatable. In an effort to overcome this challenge, WaterOne has enlisted the expertise of TREKK Design Group. Their task is to precisely inspect and locate the sanitary sewer laterals, ensuring that they remain unharmed during the directional drilling process, and particularly to prevent disruption to any privately owned sewer service.
Properties within the project area are identified along the planned alignment, and sewer mains are overlaid to help identify the potential for interference. Those properties with service laterals considered to be a potential hazard are mapped and slated for locating. Crews employ main line closed-circuit television (CCTV) equipment, equipped with lateral launch capabilities and a sonde for precise surface locating. Alignment and elevation information is collected for each identified service lateral at four separate locations; the point of connection to the sewer main, middle of the street, back of curb, and the edge of the right-of-way. The combination of consistent location information and the utilization of advanced inspection equipment allows for the collection of invaluable data.
Before data delivery, all records are reviewed and verified to ensure accuracy and completeness. Sewer lateral alignments and elevations are scrutinized, and any potential interference is identified to help mitigate damage. Locations along each alignment are marked in the field and a photographic report is generated that includes survey data of each sewer lateral. The detailed information allows construction crews to confidently navigate the congested utility corridors.
Based on the data collected during this thorough process, the alignment and elevation of each service lateral are accurately mapped with survey-grade precision. The significance of this information cannot be overstated, as it equips construction crews with the knowledge necessary to make on-the-fly adjustments to the water main alignment and elevation. Most importantly, it serves as a mechanism, dramatically reducing the risk of damage to privately owned service laterals, and thus ensures the seamless continuation of WaterOne’s mission of “Setting the standard for utility excellence.”
WaterOne’s proactive approach to safeguarding its underground infrastructure is truly commendable, especially considering the challenges posed by aging water mains that run through the residential neighborhoods. Their commitment to using trenchless technologies and more specifically, directional drilling techniques, demonstrates a dedication to minimizing disruptions for local residents and protecting other utility services.
Ron Thomann is with TREKK Design Group LLC and a member of the NASSCO O&M Committee.
