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.

 

Operation

The demonstration took place on a side street outside NPR’s main garage, which is at 2500 W. Arthington St., Chicago. Concepción connected the multi-conductor cable and pushrod to the camera crawler and placed it next to a covered manhole. He then took his seat at the console and, with the camera on the street surface, demonstrated how the controls are used to tilt and rotate the lateral camera head and extend the pushrod.

 

Next he opened the manhole, deployed the camera, returned to the control console, and began to drive the crawler upstream into the 12-inch mainline. The NPR facility is an older area, of Chicago, where many homes and businesses have come and gone over time. That would explain the close spacing of laterals joining mainline, most of them abandoned and no longer flowing.

 

Watching the color image on his monitor, Concepción looked for lateral openings with reddish deposits around them, indicating recent wastewater flows. For the approaches to the lateral, he mostly used the picture-in-picture view with the lateral camera image as the inset. This helped him to “aim” the lateral camera into the opening.

 

As the main crawler camera traveled, an on-screen footage counter displayed the distance traveled from the manhole. The camera encountered four laterals, two on its right side and two on its left, within the first 54 feet. All four were either blocked, capped or badly broken, and none could be inspected with the lateral camera.

 

Concepción removed the crawler, reversed its direction, and resumed the demonstration traveling up-stream. At 5.6 feet from the point of redeployment, Concepción located a lateral on the left side of the main that appeared to be active. He drew the crawler up alongside and used the control panel toggle switches to rotate the lateral camera about 90 degrees.

 

Alternating between the two picture-in-picture views, he manipulated the controls to insert the lateral camera into the line, then switched to the full-screen lateral camera view, which displayed a footage counter for that camera. As the camera traversed the first few feet of the pipe, it encountered what appeared to be gelatinous solids filling the bottom of the opening.

 

“It’s hard to tell what that is,” noted Schantz. “It could be a solid slug, it could be fat or grease, or an amalgam of almost anything.” Concepción pushed past the first deposit, and the camera clearly showed two foam packing “peanuts” on the pipe floor. “This lateral is probably connected to a floor drain in a factory,” Schantz stated. “Otherwise, how would packing material get down there?”

 

By the time the footage counter read 7.0 feet, the pipe was half to two-thirds full of debris. Concepción tried to push through the blockage by extending and retracting the pushrod, then by pushing and pulling the rod with the tractor. When he was unable to break through, he retracted the lateral camera, switched back to the picture-in-picture view, and moved the crawler on down the line.

 

At the next lateral, a few feet farther down the line, Concepción inserted the push camera and found an apparently faulty installation in which a 6-inch lateral had been shoved into a section of 8-inch pipe coming off the main. This opening was plugged by a large mass of solids that the camera could not penetrate. At 23 feet, Concepción located a 6-inch lateral in which a mineral deposit prevented inspection.

 

At this point, a buildup of dirt in the mainline kept the crawler from proceeding any farther. Concepción therefore ended the demonstration by backing the crawler out of the mainline and retrieving it from the manhole.

 

Observer comments

Although the condition of the lateral on this segment of mainline did not enable the use of the LETS’ full 80-foot reach, the demonstration did clearly show the system’s functionality and its advantages as an inspection tool.

 

LETS appeared to provide a highly efficient means of inspecting sewer laterals from the main. At most of the openings, Concep-ción had little trouble inserting the lateral camera. Insertion was challenging only when laterals entered from acute angles, requiring the camera to be inserted at angles well beyond perpendicular to the main.

 

The control system appeared simple to use. The choice of four views gave Concepción considerable flexibility in visualizing the approaches to the lateral openings and in watching the process of lateral camera insertion. Once the lateral camera was in the line, the full-screen view from the lateral camera provided clear images that would enable an operator to make a good assessment of the pipe’s condition.

 

The lateral camera provides straight-ahead viewing only, yet with its high-intensity LED lighting still affords a reasonably good view of the pipe walls and their condition. Pan-and-tilt capability, recently made available, enables more detailed views of specific defects.

 

Manufacturer comments

“Lateral inspection is part of the mainline inspection business today,” says Schantz. “Laterals have become a very important aspect of trying to identify and pinpoint sources of infiltration and maintain the quality of the sewer system. This is a growing part of the industry, along with lateral cleaning, grouting, lining and other aspects of lateral inspection. Using this system, an experienced operator can inspect as many as 40 lateral connections in a day.”

 

“If you did not have this equipment, particularly in older residential and industrial areas, you would not find cleanouts in many locations. They may be buried. They may not be identified. You may not see anything above ground. Here we sit on a back street, and we can look at the buildings on either side and see no apparent cleanouts. Inspection from the main is really the only way in many older cities to determine where the lateral connections are, where they go, and what their condition is.

 

“We have a system that many contractors have selected because of the ease of operation. The way the front chute is configured, the fact it allows the camera to be rotated left and right, and the fact it can elevate the angle of the camera as it gets launched, all makes it easy to insert the camera into the lateral.

 

“Another attribute of this system is that once an operator pushes up a lateral, he can use the tractor to push the camera back and forth, should it get caught. You don’t have to rely on just the pusher motor and the pushrod. The tractor motor is a significantly more powerful motor. That gives the operator a fallback position to get over something in the line or, if the camera gets stuck coming back, pull harder to get the push cable out.”