The U.S. Army Corps of Engineers has just released a video that shows dredging equipment at work. Shot from the river, it gives viewers a rare glimpse into a world few will ever see first hand.
Where All the Sand is Going
As equipment moves downriver, the Corps is piping sand back upstream to two placement areas. Sand from Dredge #1 currently operating near Kings Harbor is piping sand back to an old sand pit on Townsend south of the river and east of US59. The second dredge, currently operating south of the Kingwood Country Club is piping sand to another old pit on Sorters Road just south of Kingwood College.
Make Sure Your Kids and Grandkids See This
If you have a child or grandchild who likes to play with earth-moving equipment, make sure you show them this video. Then take them down to Kings Harbor to see it in person. It really is very impressive. Who knows? It might encourage them to take up a career in engineering!
Some Mind-Boggling Statistics
The equipment currently deployed on the West Fork of the San Jacinto is moving enough sand and sediment to fill the Astrodome. And it’s moving it six miles upstream! The Corps originally estimated the volume of sediment at 1.8 million cubic yards. The video now estimates the volume at 1.9 million cubic yards.
Sand moves through the pipeline at 11 feet/second. That means it takes about 45 minutes to get to its destination. That’s much faster than a truck could be loaded and make the round trip.
Here are some more mind-boggling statistics.
- If they were using average commercial dump trucks to haul all this sand, it would take 135,000 to 190,000 loads to haul. The average commercial dump truck holds 10-14 cubic yards.
- Each 40-foot section of pipe weighs 4,000 pounds. That’s as much as the average weight of a new vehicle was in 2010.
- These sections of pipe are welded into strings of pipe about a quarter of a mile long and FLOATED into place.
- Each section has a steel-collar to help keep it submerged once it’s in the river and filled with slurry.
- The strings are then welded together to form continuous pipelines more than 30,000 feet long that lead back to the placement areas. Those 30,000 feet of pipeline weigh about 3 million pounds when empty.
- There are two pipelines working simultaneously. Total weight: about 6 million pounds.All of this, including the dredges themselves, had to be trucked in and assembled on site.
Mouth Bar Status Still a Question
These statistics help explain why mobilization was such a huge part of the cost of this job – about 25% or $18 million. It also helps explain why everyone is so eager to resolve the mouth bar issue before this job is finished. If we could keep the equipment working, taxpayers could save the cost of a second mobilization.
Alas, still no news on that front. At last report, the City was still trying to determine how much sand was deposited DURING Harvey. FEMA refuses to pay to remove sand that was there BEFORE Harvey. They say that was deferred maintenance and the City’s responsibility.
I hope we resolve that quickly. $18 million might actually pay for all the sand that needs to be removed. Said another way, if that’s true, we might be able to get the sand removed at no additional cost! More to follow on that point.
Posted by Bob Rehak on 2/22/2019
542 Days after Hurricane Harvey