Dredging Update: First Dredge Being Assembled, Miles of Pipe Being Welded
The U.S. Army Corps of Engineers’ Command Site for its San Jacinto West Fork Emergency Dredging Project is a beehive of construction activity. I spent two hours at the site this morning at the invitation of the Corps. Now I can see why the prep is taking as long as it is. I had no idea so much was involved. Last week, I posted pictures of dozens of trucks arriving with equipment and pipe. This week they are assembling the first dredge of two and welding miles of dredge pipe…even as more arrives every hour.
First of Two Dredges Nearing Completion
Because of their size, two dredges are being delivered to the site in pieces and assembled there. Great Lakes Dredge and Dock, the contractor, brought in a 300-ton crane last week to lift the biggest pieces to the water’s edge. At the moment, two smaller 70-ton cranes are completing the work – lifting pumps, motors, stabilizers and other equipment into place.
Two seventy-ton cranes lift the remaining pieces of the first dredge into place at the command post south of the river.
Worker installing safety rails.
Same dredge showing where the dredge pipe will hook in.
Massive fittings weigh thousands of pounds
More dredge pipe arrives as the first dredge nears completion.
One of the impellers that will force dredged material into the dredge pipe. These are bigger than the pallet they sit on and are made from solid steel. They are actually considered a disposable item in the dredging process because they wear out. They are the rotor located inside the case of a pump. it increases or decreases the pressure and flow rate of a fluid.
Miles of Dredge Pipe Being Welded and Weighted
As workers assemble the first dredge near the water’s edge, other workers weld miles of dredge pipe together from 40-foot sections in a separate staging area. Each section weighs about 4,000 pounds. And each string is 1,000 feet long – about a fifth of a mile. These longer sections will then be put together with booster pumps to pipe spoils directly from the river to placement areas.
Acres of 24-inch HDPE pipe have arrived at the job site and are being stored in a massive pipe farm. Walls of the pipe are one inch thick. Each 40-foot section weighs about 4000 pounds.
Already five larger 1000-foot sections have been assembled. That’s nearly a mile of dredge pipe.
Welding machine shaves off the end of each pipe so the joints will be clean and even.
Next the welding machine heats up the ends of each pipe to 450 degrees and fuses them into one continuous piece.
This is what a completed weld looks like. It’s as strong as the pipe itself.
Next the pipe will be weighted with these steel collars to make sure it remains submerged during dredging operations. This is important because one pump might stop temporarily during dredging while other pumps continue to pull water through. The now partially filled pipe could become buoyant and a hazard to navigation.
To attach the collars, first, two halves are chained together then sledge-hammered into place.
Then the halves are welded together to form a permanent bond. This process is repeated over and over hundreds of times until each 40-foot section has its own collar/weight. The black screen is a safety device to protect the eyes of people nearby who may not have welding goggles. The flame from welding can be as intense as looking directly into the sun.
Safety Warning
Do not attempt to visit this site. Stay away for your own safety. Huge construction equipment is moving about the site. Operators have limited visibility and they’re focused on balancing their loads, not looking out for unauthorized visitors.
Actual dredging should start in about ten days. When it does, it won’t be safe to be in a boat between the US59 and the West Lake Houston Park Bridges.
The pipe you see above will be submerged and marked with these buoys.
Safety buoys mean submerged dredge pipe is in the area. Stay away for your own safety. Do not attempt to boat, water ski, fish, or swim in the vicinity of dredging operations. Pipe can move swiftly and without warning.
Dredging operations will continue 24/7 until completion. There is no safe time of day or day of the week to be in this section of the river.
Pipe will extend from wherever the current dredging is to one of two placement areas. One is south of Kingwood College and the other is between the river and Townsend east of US59.
Posted on August 20, 2018 by Bob Rehak
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