Tag Archive for: Army Corps

Take a Video Tour of the West Fork via Helicopter with the Army Corps

 U.S. Army Corps of Engineers’ (USACE) hydraulic engineers conducted an aerial tour of the West Fork of the San Jacinto River aboard an Army Blackhawk helicopter. USACE Galveston’s hydraulic engineer Michael Garske narrates the video tour, which is fascinating for its candidness.

Objectives

The tour’s objectives: to better understand the area’s dredging needs and to  scope out possible locations for storing the spoils.They identified numerous areas with excessive shoaling that contribute to area flooding and require dredging. Engineers estimate they will need to dredge from 1 to 3 million cubic yards.

Sand weighs about 100 pounds per cubic foot. So a cubic yard (27 cubic feet) would weigh almost a ton and a half. Three million cubic yards of sand would completely fill two and a half Astrodomes.

Results not yet final

So where would they put all this dredged material? Nothing is final yet. But it’s interesting to hear the engineers’ comments as they fly over random locations. See the video tour here.
According to reports from Harris County Flood Control, which is coordinating with USACE, the project is slated to start on June 8 and suppliers are being told they need to complete the project within a year.

Various Possible Scenarios Previously Examined

Here are some scenarios based on data from Brown & Root’s 2000 report on dredging, courtesy of David Seitzinger, a Kingwood engineer.  Seitzinger points out that Brown & Root also looked at dredging the West Fork. At the time, Brown & Root estimated that it would take 90 to 120 days to bid and mobilize the project. They estimated that one dredge could remove 5,000 cubic yards per day.

If that formula still holds true, a million cubic yards (the low end figure quoted by USACE) could be removed in 100 days using two dredges. If they need to remove 3 million cubic yards, two dredges would take 300 days.

Seitzinger looked at other options, too. Adding a third dredge cuts dredging time by a third – roughly two months to 200 days depending on volume removed.

Using 3 dredges could complete the project by mid-September – the peak of hurricane season – if they only need to remove 1 million cubic yards. That’s the best case scenario.

Worst case? Using two dredges to remove 3 million cubic yards would complete the project around the end of May in 2019.

Of course none of this considers weather stoppages for hurricanes and other flooding rains.  “Obviously the more dredges they can get in the river the better,” says Seitzinger.

The Army Corps plays a central role in many of the ongoing projects that affect Lake Houston. Please note the public-facing information sources that contain updates on their projects, including those in the Lake Houston area.

Online: www.swg.usace.army.mil
DVIDS: www.dvidshub.net/units/USACE-GD
Twitter: www.twitter.com/USACEgalveston
Facebook: www.facebook.com/GalvestonDistrict

 
Posted May 5, 2018
 
248 Days since Hurricane Harvey
 

Army Corps Finishes Sedimentation Survey Field Work on First Leg of West Fork

Below is the official press release from the U.S. Army Corps of Engineers about the field work for the sedimentation survey they completed on April 9.

“HOUSTON (April 10, 2018)

“The U.S. Army Corps of Engineers, Galveston District began surveying levels of sediment deposits last weekend within the West Fork of the San Jacinto River in response to a State of Texas and FEMA request.”

“To determine the level of shoaling and silt accumulation within the West Fork of the San Jacinto River, a New Orleans District Corps survey crew and vessel began collecting GPS and sonar data near Humble and Atascocita from Apr. 6-9 along a five-mile area between Hwy 69/59 and West Lake Houston Parkway

“Corps Surveyors operated a 20 foot Xpress Boat with survey grade GPS and a sonar transducer to determine sediment deposition,” said Alicia Rea, an emergency management response official with the Galveston District.

“FEMA responded to a request from the State of Texas and under Stafford Disaster Relief and Emergency Act of 1988, FEMA directed the Corps to begin the initial assessment of the conditions. Army Corps Hydrologists will utilize the survey data and use hydrologic modeling to determine the best course of action.

“County and City officials conducted a site visit to the locations on April 10, 2018” said Rea.

“We believe this is the most prudent action to take to better define the scope of work,” said Rea. “The USACE and FEMA are working diligently to expedite the process.”   (END OF PRESS RELEASE)

Results of Survey Available Soon

Sources tell me (Bob Rehak) that the results of the Army Corps survey may be available as early as next week. This is good news with hurricane season just six weeks away.

However, there is still a lot of work to do before dredging begins. Everyone must agree on specs for the job. Bidders must be identified. A location to store or dispose of the dredged material must be found. Bidders must have time to prepare their bids. An environmental survey must be conducted. They must allow time for a comment period. The bid must be awarded. Crews must be mobilized.

Some steps can happen in parallel but others must happen sequentially. Sources, who spoke on condition of anonymity, said it could take a month or two before dredging begins – more likely two than one.

We hope that while that work is underway, preliminary work can begin on subsequent legs of the river to further expedite completion of the entire job.

At Least Four Major Blockages on West Fork

Here are four photos from the West Fork that I took shortly after Harvey. They show some of the major blockages between 59 and the lake that we hope the Army Corps addresses. The first two were taken upstream of the West Lake Houston Parkway Bridge. The second two were taken downstream. Approximately 70% of the Kingwood homes that flooded were downstream from the bridge.

The new sandbar deposited by Hurricane Harvey now forces water coming out of the drainage ditch in the background on the left to make a 90 degree left hand turn before it can reach the river. This slows the velocity of runoff and backs up water into subdivisions, like the Barrington in the background. While the sandbar looks gentle from the air it is up to 15 feet high near the ditch.

South of the Kingwood Country Club’s Island Course, Hurricane Harvey deposited several feet of sand that is filling in the back channels and expanding the islands of the West Fork of the San Jacinto River, thus reducing its carrying capacity.

Looking north toward Kingwood’s Kings Harbor subdivision, a popular entertainment district that was destroyed by Hurricane Harvey. The West Lake Houston Parkway bridge is on the left. In the foreground, sand now reaches the tree tops and is virtually as high as the bridge itself. Water used to flow under the bridge and through the area in the foreground during floods. Now it is forced north.

A giant sand dune has formed near where the east and west forks of the San Jacinto join, inhibiting the flow of the river. Engineers say that sediment is not being carried out into Lake Houston (background) as expected. Areas beyond these dunes experienced far less flood damage from Harvey than the areas behind them. That’s the FM1960 Bridge in the background.

Here is link to an Army Corps Facebook post about the project that shows 20+ additional pictures of the survey crew at work on the west fork.

By Bob Rehak

Posted April 11, 2018, 225 days since Hurricane Harvey.