Acoustic assessment technology helps sewer cleaning contractor quickly determine whether mainlines need further inspection.
When trying to determine if sewer lines need cleaning, municipalities face a Catch-22. On one hand, it doesn’t make sense financially to hire a contractor to inspect a line if it’s not actually blocked. On the other hand, it’s hard to assess how badly a line is blocked without a camera inspection.
But there’s a solution to this conundrum: the SL-RAT, an acoustic pipeline assessment tool developed by InfoSense. SL-RAT stands for Sewer Line-Rapid Assessment Tool — an apt name for a device that can assess sewer line blockages (or lack thereof) in as little as three to five minutes, or 10 to 20 times faster than a typical camera inspection.
That speedy evaluation significantly reduces the cost of an assessment compared to a conventional camera inspection — especially if the televised inspection reveals a free-flowing sewer line that didn’t need an inspection in the first place. The technology also eliminates confined-space entry, precleaning and contact with waste flow.
“The SL-RAT provides a rapid assessment of pipe flow,” explains Bruce Jameson, regional manager for Ace Pipe Cleaning (part of the Carylon Corp.), a sewer inspection, cleaning and rehabilitation company headquartered in Kansas City, Missouri. “Think of it as a pre-screening tool you can use before doing a conventional sewer cleaning and CCTV inspection. It can help prioritize the need to do expensive camera inspections.”
The SL-RAT is designed to assess 6- to 12-inch-diameter pipes, but only in manhole-to-manhole increments. The technology centers on a simple concept: As sound travels through a pipeline, obstructions — such as tree roots, grease buildup, joint offsets, bad lateral connections or sediment and other debris — block and dissipate sound, just like they impede water flow. In effect, the SL-RAT measures how quickly sound energy dissipates in the air space between sewage flow and the pipe wall, giving the operator a clear idea about the conditions inside the pipe.
The SL-RAT essentially consists of two paired devices — an 18-pound transmitter and an 11-pound receiver — that are deployed atop adjacent manholes. The transmitter sends a series of tones down one manhole and into the pipe, while the receiver uses sophisticated algorithms to create a blockage assessment, based on what it “hears.” The system ranks pipelines on a scale from zero to 10; the higher the score, the lower the level of blockage.
Established in 1954, Ace Pipe started using the SL-RAT about five years ago and now owns seven units. While Jameson cautions that an acoustic inspection cannot provide an exact measurement of the amount of debris blocking a mainline or determine what’s causing it, it can quickly give the operator a general idea about whether the pipe is open or closed. If the acoustic inspection results in a score of five or below, a camera inspection is required, he says.
The SL-RAT also increases productivity because a two-man crew can inspect more linear feet per day compared to a conventional cleaning and inspection crew. If properly trained, a two-man crew can assess up to 10,000 linear feet per day. “This technology is especially suited for small municipalities, which usually just don’t have the money to spend on camera inspections,” Jameson says. “We can assess an entire small town in four or five days and tell them where to focus their resources, so it’s a very effective tool for them.”
Powered by one lithium-ion battery in each unit, the SL-RAT can also be used in remote manhole locations that aren’t easily accessed by camera and vacuum trucks, he adds.
Jameson points out another benefit from acoustic inspections: To do the work, a crew must remove manhole covers, which also allows them to visually inspect the manhole itself. Municipal workers typically don’t regularly open up manholes to look for signs of surcharging, tree roots or buildup of grease, sediment and other debris. “So it’s a huge benefit to the (sewer) owners because we’re opening every manhole and doing reconnaissance they otherwise wouldn’t do. And you can find out a lot just by opening a manhole cover.”
Because the SL-RAT offers such a cost-effective mainline assessment — less than $1 per linear foot — the technology helps Ace Pipe get a foot in the door that “otherwise might not open,” Jameson says. “And I’d say that opening the manholes alone is worth the cost of an (acoustic) inspection.”
Management at Ace Pipe first heard about the SL-RAT when another Carylon company, Bio-Nomic Services, beta-tested the product. Then Ace Pipe used an SL-RAT to successfully assess sewer lines in a Tennessee city and decided to invest in the technology. “In the beginning, I was a little skeptical,” Jameson says. “It sounded a little bit futuristic. But we’ve proven that the technology is accurate by comparing the scores to an actual camera inspection. We’ve also developed a template that breaks down what we can expect from various scores. It’s become a product that we truly believe in.”
If customers have reservations about the technology, Ace Pipe does product demonstrations. Sometimes the company also agrees to do a smaller pilot assessment program to give potential customers more confidence in the product. In other instances, municipalities only sign on for regular assessments of sewer line “hot spots,” where surcharges and overflows often occur. “Not every city understands the value,” Jameson notes. “But it’s widely accepted technology across the country and has a very good reputation.”
The technology also helps position Ace Pipe as a progressive company in the eyes of customers. “If you have an SL-RAT, you have another valuable tool in your toolbox, which helps people view you as more professional,” Jameson says. “When companies invest in technology like this, I think customers perceive that they also invest in other technologies from which they’re likely to benefit. It goes to the nature of our company’s interest in investing in technology other than just the basics.”