Blockage of a critical 5-inch overflow pipe beneath a large, artificial lake at Dospat Dam, Bulgaria, posed extreme danger to dam wall integrity — risking catastrophic failure.
Over 50 years of hardened sediment and debris had accumulated. Drainage was reduced to a trickle. Construction of a new removal conduit proved unfeasible.
The remote setting also eliminated heavy cleaning equipment from consideration, and the 460-foot line descended over a 2.5-percent grade from 157 feet beneath the dam wall through four tight bends to its terminus, rendering clearout extremely difficult.
That’s when Double D Engineering Ltd., European specialists in industrial cleaning technologies and services, stepped in with an outside-the-box idea.
“Economics and facility condition forced us to work with the existing pipeline,” Dimiter Dimitrov, company manager, noted. “So, we opted for a compact, portable water jet solution.”
A Compact, Powerful Solution
Representing the Russian company Zevs Technologies Ltd, Double D chose the powerful, compact and maneuverable JM-3080 gas-powered water jet from General Pipe Cleaners.
Part of General’s popular Jet-Set™, the high-flow device is perfect for clearing larger, more difficult lines of grease, sediment, ice and other soft blockages. A 20-horsepower Honda engine with electric start provides an 8 gallon-per-minute flow rate at 3000 PSI, without risking pump damage if water supply can’t match pump demand. A 12-gallon frame-mounted buffer tank provides enhanced safety margins and extends operating time.
“We’ve specialized in industrial cleaning since 1998, and this was our first project with JM-3080,” Dimitrov added. “We were enormously pleased with its portability, power and performance.”
General’s gas- and electric-powered water jets also feature on-demand Vibra-Pulse® for greater nozzle thrust around tight bends and down long lines. Dimitrov especially liked that feature.
“The steel overflow line featured four turns over its length,” he noted. “And Vibra-Pulse® technology helped ensure thorough removal of the built-up sediment and debris.”
Dimitrov also appreciated the JM-3080’s positive lock braking system and heavy-duty frame with four 13-inch pneumatic tires.
“Our JM-3080 often sat in precarious locations on the job site at Dospat,” Dimitrov recalled. “And its stability, tough construction and reliable wheel brakes really kept the machine solidly positioned.”
Standard JM-3080 safety features include a thermal relief valve to protect the pump from heat damage, as well as a back-flow check valve and inlet filter. It comes complete with tool box, chemical injector and spray wand with trigger.
Fresh Approach Yields Results
Partially tapping lake water 130 feet away and using two hoses, three high-performance nozzles, and two standard nozzles, Double D cleared the blockage in three steps over roughly 12 hours and three days:
- Phase 1. About 295 feet were cleaned from the lower end of the pipe with all three high-performance nozzles. Total work time: five hours and 15 minutes.
- Phase 2. Another 75.5 feet from the lower end were subsequently cleaned with the three high-performance nozzles. By then, however, the JM-3080 had hit maximum reach. Total work time: five hours and 30 minutes.
- Phase 3. Double D then repositioned the JM-3080 to clean 164 feet from the pipeline’s upper end. Total work time: 1 hour and 24 minutes.
Conditions on the final project leg proved especially hazardous. Personnel had to descend to a gallery about 164 feet below lake water level. They risked catastrophic flooding from large chunks of loosened sediment blocking the clean downstream end, but by employing smaller jet nozzles and gradually removing the blockage from the center out, workers successfully completed the job.
Sediment and debris blockages plague thousands of dam, waterway and waste treatment pipelines. But not all are accessible to larger, trailer-mounted water jets, nor is larger wheeled equipment always economical to employ.
But Double D blended innovative removal techniques with a compact, powerful General water jet for a creative, yet effective, solution.
“Everything worked beautifully,” Dimiter Dimitrov concluded. “We could not have achieved those positive results without our JM-3080!”
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