3-D camera technology is providing simple, remote access to manholes, while accelerating the valuable, if labor intensive, process of condition assessment.
Beneath every sewer manhole cover is a complex network of conduits filled with the infrastructure that makes life possible: water, utilities, sewer and sanitary sewer pipes. The manhole gives workers access to fix, repair or assess that infrastructure. But these assets are susceptible to the same effects of time and use as the utilities they provide access to. In fact, corrosion, inflow and infiltration (I/I), and other factors make significant contributions to asset failures.
Manhole rehabilitation: a valuable place to allocate resources
With the effects of traffic, corrosion, freeze-thaw cycles, soil movement and other normal wear and tear, manholes are subject to a lot of damage. Because of this, manhole defects can greatly impair the effectiveness of the entire collection system.
According to SEH Engineer Mike Ostendorf, manhole assessments are a great first step toward reducing manhole failure and I/I.
“Manholes can account for up to 30% of I/I, but only cost a fraction of what it costs to rehabilitate compared to laterals and mainlines. They can be a valuable place to allocate resources,” says Ostendorf.
A condition assessment is the first step. Enter 3-D scanning technology.
3-D manhole scanning: how it works
The team sends a fisheye camera, which is attached to a cable and pulley mechanism, down the manhole. As the camera ascends, it takes many images of the interior of the manhole in just a couple minutes. Those images are then stitched together by computer software, providing a highly accurate data set for you to make decisions and measurements.
Not only is the process accurate, it’s extremely fast.
“3-D scanning accelerates manhole condition assessments by 2-3X in terms of rate and 4-6x in terms of labor hours,” says Ostendorf.
In the past, determining the condition of a manhole involved sending staff down each one with a clipboard and a flashlight at a rate of 16-20 assessments per day. Today, with 3-D scanning technology, a team of one can assess 30-60 manholes in a day.
Interested in reducing I/I and learning more about manhole scanning or manhole condition assessments?
About the Expert
Mike Ostendorf, PE, is an SEH engineer dedicated to helping clients make the best use of their resources.