Most people don’t enjoy routine doctor visits. They record our weight and height (and we’re confronted with the disappointment that only one of them seems to be increasing). Nevertheless, at lunch an hour before, maybe you opted for a salad rather than a greasy cheeseburger. In an ideal world, maybe you went for a run earlier that morning. While some genuinely enjoy running in the morning, or eating kale, I certainly don’t.
So why do we subject ourselves to uncomfortable doctor visits, kale smoothies, and exercise we dread? Preventative care: the effort to take care of ourselves now when it is much easier and less expensive compared to dealing with catastrophic (and more expensive) issues later.
Not surprisingly, applying this same methodology to operating and maintaining sewer systems can prove beneficial. Like all infrastructure, sewer collection systems decay over time and eventually fail. Cracks and voids start to form in pipes, deposits build up and restrict flow, manholes experience deterioration…the list goes on.
Just like your body needs to be examined periodically to make sure it is in good health, a sewer system also needs to be routinely checked. Closed circuit televising (CCTV) of sewers is a fantastic way to gather information about the status of a sewer system. Roots growing into pipes, pipe material deterioration, calcium and grease deposits, offset pipe segment joints, cracks, fractures, pipe breaks, and pipe sags all can be found during cleaning and televising of sewers, when they wouldn’t likely be found otherwise.
Manhole inspections are another great way to routinely check a sewer system and are a relatively low- cost and simple option for sewer evaluation. Inflow and infiltration (I/I) sources from leaking joints, voids, and pipe penetrations all can be found during manhole inspections. Information about the sewer lines between each manhole can be gleaned from inspections, as well. For instance, a piece of pipe lying in a manhole suggests there may be a pipe break upstream.
Don’t Push it Off
Preventative medical care often keeps a small issue from becoming a big problem. The same theory applies to sewers. Cracks, voids, sags, bellies, breaks, etc. found during CCTV and manhole inspections may seem like minor issues now, but they will only worsen over time if not addressed. These defects can allow groundwater to infiltrate into a sewer system, increasing sanitary flows and wastewater treatment costs, which add up over time. I/I also can increase flows past a pipe’s design capacity, leading to sewer back-ups and overflow events. Additionally, pipe defects can allow sediment from outside the pipes to settle in the pipes. This transfer of sediment removes the supporting soil below roads and buildings and can lead to sinkholes and other structural issues.
To avoid these “emergency room” situations, sewer rehabilitation is recommended to pre-emptively fix defects found during inspections. Where possible, trenchless technologies are used to rehabilitate sewer lines, including internal point repairs and pressure grouting for small issues or pipe lining and coatings for full-segment repairs. These different options are chosen on a case-by-case basis, and provide varying levels of durability, structural support, and corrosion protection. When trenchless technologies are not viable solutions, pipes sometimes require excavation and replacement. Acting pre-emptively can help avoid reacting to a catastrophe.
Patients with family histories of heart disease, diabetes, etc. usually are mindful of their sugar and fat intake, and doctors may pay closer attention to any related symptoms. Sewer systems tend to have their own “medical histories.”
Sewer segments can have higher likelihoods of issues based on factors like pipe material, age, soil type, size, and customers. For instance, a concrete pipe is much more susceptible to surface corrosion than a PVC pipe, and older pipes are much more likely to have cracks, breaks, and failures than a newly installed pipe. Certain areas of a collection system that have historically experienced sediment and grease build-ups usually will continue these trends.
Evaluating the consequences of failure for any given section of a collection system is critically important. Relating back to human health, a pain in your chest raises much higher concern than an ache in your knee. Similarly, a failure for a sewer line that services a handful of houses pales in comparison to a failure in a sewer line that services half a city or one that lies under a major highway.
Areas of a collection system can be prioritized and targeted based on their likelihood of failure and their consequences of failure. This risk assessment is a powerful tool used to allocate where in the collection system to dedicate resources. Check out our Good, Better, Best Asset Management Plan checklist as an example of a risk assessment tool.
Initially, preventatively treating the issues in an entire collection system seems daunting, but like our own health, it can be easily managed with the right plan. First, find ways to do a “check-up” to identify major problems and gain a holistic understanding of a collection system. Next, address major issues that are found as soon as possible before they become “emergency room” situations. And finally, consider the system’s “medical history” to develop a strategic plan to maintain the health of the system. A preventative care plan, while sometimes seeming difficult or unnecessary in the short term, is much easier to handle - and often less expensive - than a trip to the emergency room.