Tag Archive for: dredge

Crenshaw, Brady, Cruz and Cornyn Ask FEMA to Dredge More of West Fork Mouth Bar

On October 24, 2019, Congressman Dan Crenshaw, along with Texas Senators John Cornyn and Ted Cruz and Representative Kevin Brady (TX-08), sent a letter to Acting FEMA Administrator Peter Gaynor. The letter requested FEMA’s swift approval of the City of Houston’s new plan to dredge more of the San Jacinto river mouth bar.

Letter in Response to New Request Filed by City

The letter came in response to the most recent request from the City for FEMA aid on or about October 11, 2019.

While FEMA has already completed its initial 500,000 cubic-yard debris-removal mission, sediment brought by Hurricane Harvey still exists in the San Jacinto river mouth-bar. To protect Houston, Kingwood, and Humble residents from future flooding, it is imperative that the remaining debris is removed, said Congressman Dan Crenshaw.

“The City of Houston recently filed a Project Worksheet (PW) for debris removal as Category A work under the Public Assistance program,” the group of legislators wrote. “We urge you to use any and all necessary FEMA resources to expeditiously review and approve the city’s PW. Delay will only increase costs and prevent FEMA from fully leveraging presently available dredging assets.”

To see the complete letter, click here.

Great Lakes Packing Up

Great Lakes Dredge and Dock has finished its Army Corps assignment at the mouth bar. I photographed workers continuing to dismantle the company’s dredge this afternoon.

Packing it in. Great Lakes Dismantles its dredge after a little more than a year on the West Fork. Photo taken 10/26/2019.
The command post opposite Marina Drive in Forest Cove was a behind of activity this afternoon.
Note the sections of dredge pipe stacked up in the background. It is no longer connected to the dredge.
Crew and survey boats, cranes and other heavy equipment still remain to support a future dredging effort…but not for long.

The last line of the letter (“leveraging presently available dredging assets”) refers to assets other than the dredge itself. Such assets include the command post opposite Forest Cove, a second launch point in Atascocita, pipe, cranes, and other assets that could soon be removed. See photos above.

TDEM to Forward Request to FEMA

As of yesterday, according to Houston City Council Member Dave Martin, TDEM still had not forwarded the request to FEMA. However, this reportedly falls within TDEM’s normal processing time for such requests. I wouldn’t read too much into it yet. But let’s hope they hustle up. Those crews at the command site were working late into Saturday night. I’m guessing that represents overtime.

You can clearly see from the pictures above how much equipment it takes to support a dredging operation. And remember, each 40-section of dredge pipe weighs 4,000 pounds and there are about 10 miles of it! This request should not be taken lightly.

Posted by Bob Rehak on 10/26/2019

788 Days since Hurricane Harvey

Dredge Finally Reaches Mouth Bar

The Army Corps of Engineers announced last week that it had received a mission assignment from FEMA to dredge 500,000 cubic yards in the area of the mouth bar of the San Jacinto West Fork. This week, the dredge operated by Great Lakes was sighted within 200 yards of the bar. (See videos below.)

Dredging Could Start Next Week

Officials close to the project say actual dredging could start as early as next week. Dredgers only need more 24″ pipe to pump the sediment 10 miles back upstream to placement area #2, an old sand pit near Kingwood College. However, the City and Corps are still debating the volume deposited by Harvey. The Corps has not yet divulged where it plans to start dredging, what its objectives are for this phase of the project, or what the contributions of other partners will be.

More Meetings Needed to Finalize Volume

All parties will meet in the coming days to finalize the volume and a plan. The City of Houston and Army Corps are still 900,000 cubic yards apart in their estimates of the amount of sediment deposited by Harvey. The City hopes to get the Corps to increase its estimate of 500,000 cubic yards. However, that hasn’t happened so far. Meanwhile everyone wants to reduce flood risk by removing as much sediment as possible before the peak of hurricane season.

New Drone Video of Mouth Bar by Jim Zura of Zura Productions

New drone footage of the West Fork mouth bar shows just how much the mouth bar has grown since Harvey. I took the still shot immediately below from a helicopter two weeks after Harvey. To see what it looks like today, scroll down. Kingwood-based Jim Zura of Zura Productions shot two new drone videos this morning. They show what the mouth bar looks like 22 months later. As you watch the videos shot from different elevations, consider the immensity of the bar compared to the dredge at the tail end of each video.

Mouth bar of the San Jacinto West Fork. Looking south toward FM1960 bridge and Lake Houston. Photo taken on 9/14/2017. Channel on either side is only 3-5 feet deep.
Here’s the first of two drone videos shot at different elevations by Jim Zura of Zura Productions. It shows what the mouth bar looks like on 6/18/2019. In the nearly 2 years since Harvey, much vegetation has started to grow on it. Notice also how much larger the two small islands behind the dune have grown compared to the still shot above.
Jim Zura’s second drone video is from a little higher. To see it, click here.

How Far Would 500,000 Cubic Yards Get Us?

Five hundred thousand cubic yards will not come close to restoring the full conveyance of the West Fork. How does 500,000 cubic yards compare with what NEEDS to be dredged?

Let’s start by looking at the channel that the Corps is dredging upriver and assume that they will extend that between the mouth bar and Atascocita Point. That strategy follows the relict channel. The relict channel is also the path with the least sediment at the moment. So that would make the most efficient use of funds.

Let’s also assume that the channel needs to be dredged an average of five yards (15 feet) deeper than its current depth along that path in order to match the profile below.

Endpoint of current dredge program shows channel 22.5′ deep by 400′ wide..

A “budget” of 500,000 cubic yards would allow you to dredge a channel 133 yards (400 feet) wide 5 yards deeper and 752 yards long. That equals 500,080 cubic yards. But 752 linear yards is only about one-fourth of the 3,000+ yards to the FM1960 bridge. And we haven’t even touched the mouth bar!

Extending the channel through the bridge is important because of the sediment built up behind it.

West Fork Map shows difference in sedimentation between 2010 and 2017. Note the white and violet areas near the FM1960 bridge. Red/orange/yellow/green areas represent decreases in sediment. Blue, violet and white represent increases.

Clearly, dredging the rest of the way to the bridge will require more money from the State, County and/or City. Thankfully for the Lake Houston Area, all of those entities have already allocated funds.

Details Yet to Work Out

However, the City, Harris County, and State of Texas have even more hurdles to clear beyond the volume debate.

They must find a suitable storage site that can accommodate all the sediment they hope to dredge. The storage site represents the biggest obstacle at the moment and a limiting factor.

The Corps would prefer a below ground site, i.e., an abandoned sand pit. That would reduce the risk of future floods carrying sediment back into the river. Also, it would NOT encroach on the flood plain.

Finally, the closer the site is to the dredging, the faster and cheaper the project. Long pipelines lead to more breakdowns. And each additional booster pump uses 1000 gallons of diesel per day.

Latest on Madden Property

The largest property evaluated so far is a 4000-acre site owned by Berry Madden of Humble. Madden’s property is close – half the distance of the sand mine on Sorters Road. It is also large enough to accommodate all the sediment people want to remove – including sediment from maintenance dredging down the road. Permitting one property instead of several would save lots of time (perhaps years).

But storage on Madden’s property would be above ground. Until someone builds on it, that introduces an element of risk that below-ground storage does not have. Madden has conducted an environmental survey of his property and is now conducting an archeological survey required for a storage permit. The Corps has not yet approved his property.

A source close to negotiations says the Corps is considering approving half of the Madden site for now while it performs additional evaluations of the rest of the site. That might be enough to accommodate immediate needs, reduce the cost of pumping sediment ten miles upstream, and provide storage room for future maintenance dredging.

80,000 CY More Sediment Deposited Since Last Survey

Meanwhile, time and sediment march on. Sources say the Corps recently found another 80,000 cubic yards of sediment deposited in the mouth bar area since the last survey after Harvey.

This supports the theory of two top local geologists, RD Kissling and Tim Garfield, who predicted that the mouth bar would form a dam that accelerated sedimentation. That theory also explains why the mouth bar must be removed, or at least why we must dredge a channel around it ASAP.

Posted by Bob Rehak on 6/18/2019 with drone footage courtesy of Jim Zura, Zura Productions

658 Days since Hurricane Harvey

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

356 Days since Hurricane Harvey