Tag Archive for: sand
Yes, They Really Are Moving Sand Out of the River
At a community meeting last night, someone asked whether the Army Corps was REALLY taking sand out of the river. They didn’t see any dump trucks and they were concerned that the project was just a big hoax, on the order of Roswell, aliens and UFOs.
You have no idea how often I hear comments like this! Where are they putting all the sand? How does it get there?
Yes, they really are moving sand out of the river. But it’s not with trucks. Two dredges are pumping it though 24-inch pipe and six booster pumps miles upstream. One dredge is south of the Kingwood Country Club. The other is just east of Kings Harbor.
The first dredge is pumping sand back to an abandoned sand pit south of Kingwood College on Sorters Road. The second dredge is pumping it back to a pit on Townsend Boulevard in Humble. Here’s what it looked like today at the Townsend Pit.
After the sediment drops out of suspension and settles to the bottom of the pit, sediment-free water returns to the river through this drain.
Posted by Bob Rehak on 3/12/2019
660 Days After Harvey
Why You Should Be Concerned About Sediment and Sand Mines
For readers new to the site, I’d like to explain why I frequently mention sand mines in posts.
Bright, White Trail of Sand from the Mines
Shortly after Harvey, I became alarmed by the huge buildups of sand and sediment along the banks of the San Jacinto and in the river itself. I rented a helicopter to see if I could determine where it came from. It didn’t take long. I found bright, white trails of sand and monstrous dunes leading from sand mines on the East and West Forks of the San Jacinto all the way downstream to Lake Houston. I posted four hundred and fifty photos that I took that day (9/14/17) in the gallery section of this web site. See for yourself.
TACA claims that all the sand came from somewhere else, a contention that I have always found self serving and hard to believe. Miners exposed approximately twenty square miles of sand surface to 131,000 cubic feet of water per second at the height of Harvey. As one of the world’s leading hydrologists told me, “The miner’s claims don’t appear plausible.”
Sand certainly came from other sources. But I believe my own eyes. Review the photos and Google Earth for yourself. You can see far more sand in the river and on the banks now than before. It had to come from somewhere.
Sand now reaches into the tree tops at the West Lake Houston Parkway Bridge and blocks water from flowing under it.
The problem comes in determining how much came from different sources: Spring Creek, Cypress Creek, West Fork, Peach Creek, Caney Creek, East Fork, channel scouring, channel widening, sand mines, sand stockpiles, urbanization, etc. The short answer: some came from all of the above. How much came from each source? I personally can’t say with certainty.
So why should you worry about sand mines then?
- Because sand and sediment DID come from the mines.
- Mines are the one source of sand that you can control with best management practices.
- Texas mines do not always follow best practices that reduce sedimentation and that are commonly accepted in other states and countries.
- Reducing sedimentation could reduce flooding and save taxpayers millions of dollars.
Restoring Channel Conveyance is Costly
The U.S. Army Corps of Engineers is currently trying to remove 1.8 million cubic yards of sediment from a 2-mile stretch of the West Fork. Their objective: restore channel conveyance to the river between River Grove Park and King’s Harbor. Cost: Approximately $70 million.
That project will NOT include the “mouth bar” between King’s Point and Atascocita Point. Estimated cost of that project: another $100 million…if it happens. And we have not yet even estimated the cost of dredging the remainder of the West Fork, the East Fork, and channels down through the FM1960 bridge.
HGAC has discovered alarming levels of bacteria in both forks of the San Jacinto and linked the levels to sedimentation.
The capacity of Lake Houston is rapidly decreasing at a time when the City of Houston plans to radically increase the number of people using its water.
River migration could soon capture a number of abandoned sand pits, increasing levels of sediment in the river.
It could be years before land for additional upstream detention is identified and purchased. Harris County and the SJRA are still awaiting funding from FEMA for the study that will help identify the best locations. FEMA has studied the study since April.
Stephen Costello, the City’s flood czar, told a meeting of residents at the Kingwood Community Center in October that additional flood gates for Lake Houston could take 5-10 years.
It’s Time for Progress, Not Promises
The next legislative session starts in less than two months. Two things we can focus on NOW: strengthening sand mine regulation and putting some teeth in the TCEQ. Let’s get the sand mines out of floodways. Let’s establish an erosion hazard zone like they have on the Brazos.
Other mitigation projects to reduce flood risk are far off. And if the mouth bar project is delayed, any additional sediment coming downstream will likely be deposited behind the bar in the heavily populated Humble/Kingwood/Atascocita corridor again.
The risk of a future flood could be catastrophic to the community. Dozens of people I have interviewed have told me that they are rebuilding now based on the Mayor’s assurances of additional dredging, upstream detention and flood gates. However, they say they will never rebuild again if flooded a second time.
It’s been 448 days since Hurricane Harvey. We need progress, not promises.
As always, these are my opinions on matters of public policy. They are protected by the First Amendment of the United States Constitution and the Anti-SLAPP statute of the great State of Texas.
Posted by Bob Rehak on November 19, 2018
448 days since Hurricane Harvey
Clock Starts Ticking on Army Corps Dredging Project
Officials from the U.S. Army Corps of Engineers (USACE) announced yesterday afternoon that representatives from Great Lakes Dredge & Dock Company, LLC of Oak Brook, IL, met with Corps’ contracting and project managers for a pre-construction conference. The meeting finalized project requirements for the $69,814,060 dredging and debris removal emergency operation and the clock has started ticking on the project.
The FEMA-funded project covers about two miles of the West Fork of the San Jacinto River near the West Lake Houston Parkway and Lake Houston. FEMA guidelines limit the operation to restoring pre-Harvey conditions.
Beginning of First Phase
“This is the beginning of the first phase of a very challenging project,” said Al Meyer, a USACE Galveston District administrative contracting officer. “This project involves dredging and debris removal of 1.8 million cubic yards of sediment that has contributed to recent flooding in that area.”
The Focus for Next Week
He said the community should start to see activity within the next two-weeks. According to Corps Colonel Mark Williford, next week teams will be engaged in:
- Pre-dredge hazard surveys
- Before-cut surveys
- Disposal-area surveys
- Staging-area set up
Meyer, a professional engineer with more than 35 years’ experience with the Corps, says the conference allowed project team members to interact with Great Lakes representatives to ensure a complete understanding of contract requirements.
“The clock starts today; our contractors have 270 days to complete the project that will work to reduce, but not eliminate flooding, and return the area to pre-Harvey conditions.” said Meyers.
Less than 4 Months from Survey to Dredging
This will be one of the first projects initiated as a direct consequence of Hurricane Harvey.
Corps surveying began in April to determine sediment levels within the West Fork of the San Jacinto River after FEMA responded to a State of Texas request under the Stafford Disaster Relief and Emergency Act of 1988. Since then, the Corps has developed models based on their survey findings, evaluated several different dredging plans, finalized specifications, bid the project, vetted the bids, awarded the job and started mobilizing for it.
The USACE Galveston District was established in 1880 as the first engineer district in Texas to oversee river and harbor improvements. The district is directly responsible for maintaining more than 1,000 miles of channel, including 250 miles of deep draft and 750 miles of shallow draft as well as the Colorado River Locks and Brazos River Floodgates.
Posted 7/19/2018 by Bob Rehak
324 Days since Hurricane Harvey
Where did all the sand come from?
Our San Jacinto River is clogged with sand that impedes the flow of water and contributes to flooding. Where did all the sand come from? When? Under what conditions? Are there ways to reduce the volume of sand coming downstream? As the U.S. Army Corps of Engineers prepares to dredge the San Jacinto for the first time, we should ask ourselves these questions.
The river has eight tributaries that affect the Lake Houston Area: Spring Creek, Cypress Creek, Lake Creek and the West Fork on the west; and Peach Creek, Caney Creek, Luce Bayou and the East Fork on the east. All produce sand naturally.
They send sand downstream at different rates at different times, depending on the location of rainfall within the watershed, the volume of flow, the speed of flow, and management of the flood gates at Lake Conroe.
Other factors include the percentage of sand content in soil and the health of vegetation along stream banks. Vegetation retains and slows runoff, reducing erosion.
The map above helps us understand why so many sand miners chose to locate along the West Fork – lots of sand. The West Fork is also sparsely populated compared to Spring Creek as you can see in the satellite image below. It shows the sand mines around the Humble/Kingwood area highlighted in red. One is located on Caney Creek (right); the rest are on the West Fork (left).
While sand has been coming down the river and streams for thousands of years, rapid sedimentation in the West Fork between Humble and Kingwood didn’t become an issue until the growth of sand mining on the West Fork in the late 1980s.
Notice how most of the areas in red above are filled with natural vegetation in the 1985 image below.
Today, mines expose approximately 20 square miles of loose sand on the West Fork alone between I-45 and US59.
Dikes around the mines are supposed to keep sand from being discharged into the river. However, Harvey inundated the mines.
An analysis of satellite images before, during and after Harvey shows massive loss of sand from stockpiles within many of these mines.
During floods like Harvey when the SJRA releases water from Lake Conroe, dikes are overtopped and broken. I suspect that sand then comes down the West Fork in tremendous volumes that dwarf Spring Creek’s contribution.
To test this hypothesis, I looked at USGS flow data for both tributaries. I also reviewed all my aerial photos and Google Earth’s historical images.
Under normal conditions, Spring Creek flows at 80 cubic feet per second (cfs) and the West Fork of the San Jacinto at 150 cfs. These are not sufficient flow rates to suspend sediment the size of sand. (For an excellent discussion of sedimentation, see Fundamentals of Sediment Transport at Fondriest.com.)
However, during Harvey, Sring Creek flowed at 78,200 cfs; and the West Fork at 55,000 cfs. Then the San Jacinto River Authority opened the gates at Lake Conroe. That flipped the ratio dramatically. With the flood gates open, Spring Creek still flowed at 78,200 cfs, but the West Fork increased to 130,000 cfs. Flow rates that high can (and did) move houses off their foundations.
Four hundred and fifty aerial photos in the gallery of this web site show a bright, white trail of sand between sand mines and the sand clogging the East and West Forks around Humble and Kingwood. Flood waters swept that sand from a to b. The giant sand deposits at River Grove Park and elsewhere grew exponentially during recent floods.
This tells me that when discussing the origins of the sand, we need to primarily evaluate the river during floods. More water is moving faster under greater pressure. That’s when erosion and deposition happen quickly. That’s when the river overtops and ruptures dikes. And that’s when twenty additional square miles of exposed sand surface on the West Fork make their major contribution to our sediment and flooding problems.
We can’t control sand coming down rivers naturally. However, with better sand mining practices, we may be able to reduce mankind’s contribution to our flooding problem, not to mention the related cleanup costs borne by taxpayers.
In upcoming posts, I will discuss my research into sand mining best practices.
Posted May 22, 2018 by Bob Rehak
266 Days since Hurricane Harvey