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, and 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 clear-out 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,” says Dimiter Dimitrov, company manager. “So we opted for a compact, portable water jet solution.” 

A compact, powerful solution

epresenting the Russian company Zevs Technologies Ltd., Double D chose the powerful, compact, and maneuverable J-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 hp Honda engine with electric start provides an 8 gpm flow rate at 3,000 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 the J-3080,” Dimitrov says. “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. And Vibra-Pulse technology helped ensure thorough removal of the built-up sediment and debris.” 

Dimitrov also appreciated the J-3080’s positive lock braking system and heavy-duty frame with four 13-inch pneumatic tires. 

“Our J-3080 often sat in precarious locations on the job site at Dospat,” Dimitrov says. “And its stability, tough construction, and reliable wheel brakes really kept the machine solidly positioned.” 

Standard J-3080 safety features include a thermal relief valve to protect the pump from heat damage – as well as a backflow check valve and inlet filter. It comes complete with toolbox, 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: 5 hours, 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 J-3080 had hit maximum reach. Total work time: 5 hours, 30 minutes.
• Phase 3 — Double D then repositioned the J-3080 to clean 164 feet from the pipeline’s upper end. Total work time: 1 hour, 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. And 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,” Dimitrov says. “We could not have achieved those positive results without our J-3080.” 

For more information on the J-3080 or other jetting equipment, contact General Pipe Cleaners at 800/245-6200.