Private sewer laterals are a major source of infiltration in many communities. Inspecting those pipes can be a chore, because in many cases cleanouts and other access points are hard to find, or don’t exist outside the homes or businesses.
The Lateral Evaluation Television System (LETS) from Aries Industries Inc. provides one way to solve that problem. It enables inspection crews to locate lateral openings inside the public sewer main, then look up the laterals for up to 150 feet. The process is usually much quicker and more cost-effective than trying to inspect laterals from the privately owned side.
The LETS enables inspection of all laterals on a pipe segment from manhole to manhole with just one mainline setup. The device combines a spotter camera mounted on a powered crawler with a push camera, also carried on the crawler, that does the actual lateral inspection.
National Power Rodding (NPR), a company of Carylon Corporation based in Chicago, Ill., operates some 10 inspection vans outfitted with the LETS technology. NPR provided one of its vans for a demonstration outside its Chicago headquarters.
Leading the demonstration, held on July 23, was Richard Schantz, P.E., product manager with Aries Industries. At the controls of the camera system was TV operator Rafael Concepción. NPR president Harold Kosova observed.
Walk-around
The LETS is a truck-based system. National Power Rodding uses box trucks equipped to enable either LETS inspections or conventional mainline inspections. At the rear of the truck are powered reels containing pushrod for the lateral camera, multi-conductor cable for LETS inspections, and single-conductor cable for mainline surveys.
The truck used for the demonstration carried 80 feet of push cable, backed by lighter-duty cable to enable traverse up the main.
At the front of the truck is a rear-facing operator station that includes all necessary camera and crawler controls, along with a monitor for viewing inspection detail and a laptop computer for entering observations. The LETS controller uses simple toggle switches to control the movements of the lateral camera.
One switch is used to tilt the lateral camera chute up/down and rotate it left/right. Another controls the extension of the lateral camera pushrod (extend or retract). Another regulates the speed of chute rotation and of insertion and retraction.
The LETS crawler itself is a tracked vehicle. It carries the self-leveling lateral camera and, mounted behind that, a spotter camera that helps the operator see laterals entering the mainline and direct the lateral camera into them. For this demonstration, the crawler was configured for a 12-inch main.
The pushrod for the lateral camera runs along the underside of the crawler through a set of powered rollers that the operator activates to send the camera out from the mainline and into the lateral. One roller senses the pushrod footage. The lateral camera head rests in a chute at the front of the crawler. The operator can use the controls to tilt this chute upward or rotate it right or left to enable access to the laterals.
The front end of the pushrod has a flexible neck to accommodate launching into elbows on laterals. The camera head includes a beacon (sonde) that emits a 512-Hz signal so that the camera can be located from above ground.
Once the camera is deployed, the operator observes progress on the computer monitor, which displays a full-screen image. The operator can choose four views:
• Spotter camera image only.
• Lateral camera image only.
• Picture-in-picture with the lateral camera image in full screen and the spotter camera image inset.
• Picture-in-picture with the spotter camera image in full screen and the lateral camera image inset.
