A water and sewer utility in the southeastern United States faced the prospect of spending $42 million to replace a 4,800-foot 28-inch steel force main that had been malfunctioning for three years.
Believing there must be a better way, the agency’s engineering consultants brought in AET Robotics & Inspection Services to diagnose the trouble. Using a special float rig with CCTV cameras and laser and sonar profiling, AET, based in Clemson, S.C., inspected the pipe from end to end as it ran 75 percent full of wastewater.
The investigation found the problem: a contractor using horizontal directional drilling (HDD) had bored clear through the pipe and installed a 6-inch sewer lateral that obstructed the flow. The utility ended up repairing a 14-foot section of the force main at a cost of $80,000 – which it ultimately recovered from the HDD contractor.
That’s the kind of value AET can deliver with its complete array of pipe inspection technologies. The company, based in Clemson, S.C., solves tough problems for water and wastewater utilities, municipalities, and diverse industrial customers.
With a core group of 12 employees who are experts in their fields, the company reaches out across North America and sometimes overseas. The AET team members oversee projects and contract locally for the equipment and labor they need.
Ideal background
Company founder Mike Mraovich came to the business with extensive experience and multiple certifications in environmental services and hazardous materials. He became an EPA Certified Hazardous Materials Instructor and later worked in positions of increasing authority with four environmental companies, including general manager of BVER Environmental Inc., which became one of the nation’s top companies in the field.
He started Top Gun Environmental in 1981, then merged it with two other companies to gain equipment and personnel and expand services. Those companies later split apart to go into different specialties. Mraovich started AET Robotics five years ago and serves as president and CEO.
AET still offers services such as hazardous materials management and transportation, waste minimization, industrial cleanup, site contamination investigation, and mold and bacteria testing. Mraovich added the inspection business because he saw a need for better ways to investigate pipe problems.
“At the time we entered the inspection business, all that was really available was CCTV,” Mraovich says. “Everybody needed more capability. On CCTV, you can look at a pipe and you’d swear it’s in pretty good shape. Then you look at the comparable laser image beside it, and you see that the pipe is more than 40 percent out of round in ovality. The naked eye is deceiving when you’re looking at a tubular image in distance. Even though our cameras are adjusted for barrel distortion, you still get that effect.”
Another challenge was inspecting large-diameter pipes without bypassing and without excavating. “One of the biggest problems we ran into was the high cost of pumping around large water lines and collectors,” Mraovich says. “That’s ridiculously expensive, and we’ve come up with ways to avoid that.”
Among the company’s favored tools is a float rig for inspecting large pipes while they are charged with wastewater or other fluids. The unit includes four high-definition digital video cameras, a laser profiler above the float, and a sonar profiler below.
“We have the software configured so that we get three images: a laser image above the waterline, a digital video image above the waterline, and a sonar image below the waterline,” Mraovich says. “From those images, we can tell how much debris is there, and detect any cracks, intrusions, deformities or other defects. We get all the information in one shot, and the pipe can be running at three-fourths full.”
