A Matter of Debris

A hydroexcavator helps a contractor’s crew clear a sludgy deposit up to 4 feet deep from a 72-inch retention culvert

Interested in Municipal/Industrial?

Get Municipal/Industrial articles, news and videos right in your inbox! Sign up now.

Municipal/Industrial + Get Alerts

Floor drains and downspouts backing up at a company’s training center near St. Louis, Mo., caught the attention of a general contractor shooting grades for an extension of the building’s parking lot. The contractor called Mike Laughlin of Mid America Drain Service in Valley Park, Mo. Laughlin popped the lid on the parking lot manhole farthest from the building and saw water, which he and Kevin Bessler pumped out using a hydroexcavator from Vac-Con Inc.

“Nobody had any idea what piping was down there,” says Laughlin. It took two hours flushing at 80 gpm/3,000 psi to clean the completely blocked line entering the manhole. The pipe was an overflow.

What Laughlin and Bessler found at its other end was a 320-foot-long, 72-inch underground retention culvert belonging to the company. It discharged into the St. Louis Metropolitan Sewer District’s main trunk line, but grit and organic material 3 to 4 feet deep impeded the flow.

Work on the parking lot extension stopped while Laughlin’s crew struggled to get into the culvert to remove the sludgy, mostly solid material. They spent hours hunched over in darkness, lit only by the lights on their hard hats, using the hydroexcavator to remove the material. Despite muscle strain and fatigue, they completed the job ahead of schedule, saving the general contractor more than $7,000.

Mystery guest

The 13-foot-deep culvert was installed in the 1990s, then forgotten. It collected mud and grit washed off the parking lot and training center roof, keeping the material from reaching the wastewater treatment plant. “The parking lot design called for more storm drains, and they couldn’t be installed until we cleaned the debris in the culvert,” says Laughlin. He bid the job based on an estimate of 250 tons of material.

Laughlin’s men parked their vehicles on a road, then extended the hydroexcavator boom its full 20 feet before adding another 20 feet of 6-inch corrugated pipe to reach the upstream manhole. The truck, sold by Craig Suhre of E.J. Equipment in Centralia, Ill., and manufactured to custom specifications by Vac-Con, has a 12-cubic-yard debris tank and 1,100-gallon water system rated at 80 gpm/3,000 psi with variable flow. The Dresser Roots positive displacement blower delivers 6,000 cfm/18-inches Hg.

The culvert was accessible through three 30-inch manholes about 100 feet apart. “Cody Gamble, who did most of the vacuuming, is a big guy,” says Laughlin. “After putting on his confined-space entry gear, he barely fit down the manhole.”

Although air quality wasn’t a big concern in the storm drain, Laughlin still required the men to wear gas meters. “I’m not taking any chances with their lives,” he says. Another company provided the OSHA-certified spotter.

Changing places

After Gamble reached the floor of the manhole, Bessler lowered the 6-inch vacuum hose and handheld lance with standard nozzle attached to the 1/2-inch jetter hose, then operated the truck. Every 90 minutes to two hours, the men switched positions.

“We anticipated jetting the debris to loosen it, but the power distribution unit on the truck did such a great job sucking up the tough material that we made better headway working dry,” says Laughlin. “We hardly used any water.”

Each load was decanted and taken to the wastewater treatment plant in downtown St. Louis, a 90-minute round trip. In a 10-hour day, the men averaged two to three loads and cleaned 60 feet. “That was great progress for as full as the pipe was and the time needed to dispose of the loads,” says Laughlin. Although the men rested until the truck returned, the exertion from working stooped over for six days was hard on them.

“The Vac-Con enabled my guys to finish the job ahead of schedule and save the general contractor thousands of dollars on the bid,” says Laughlin. “The customer was so pleased that they referred us to a branch plant to flush a 70-foot-long line.”


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.