The City of Houston has completed repairs on the Tree Lane Bridge over Ben’s Branch…at least for now. The City partially concreted a wing wall and placed riprap in the stream bed to help reduce erosion and scour. However, the root cause of the damage remains. Upstream development without adequate detention is funneling more and more water into Ben’s Branch. The higher volume will continue to contribute to scouring and erosion in major storms unless detention ponds upstream are built and fixed.
Water Under the Bridge
As I struggled to understand what I was looking at, an online search revealed this excellent 196-page, well-illustrated document. It’s titled “AN ILLUSTRATED GUIDE FOR MONITORING AND PROTECTING BRIDGE WATERWAYS AGAINST SCOUR.” Robert Ettema, Tatsuaki Nakato, and Marian Muste from the College of Engineering at the University of Iowa produced it for the Iowa Department of Transportation.
It begins with a maxim: “Person who overlooks water under bridge will find bridge under water.”
The document points out that bridge engineers often assume that a stream channel will maintain its course and dimensions. But most channels adjust their alignment and shape in response to floods and land-use changes in their watersheds. That has happened on Ben’s Branch in recent years.
“Channel changes sometimes have severe consequences for bridge waterways,” say the authors.
Scour and Progressive Degradation
A review of the entire paper reveals two types of destructive forces at work on the Tree Lane Bridge.
Long-term scour is one. It occurs over a time scale of several years, and usually includes progressive degradation and lateral bank erosion due to channel widening or meander migration.
Progressive degradation is another. It features the almost permanent lowering of the river bed at a bridge site owing to changes in the watershed [e.g., head-cut progression (head-cutting), or human activities (e.g., channel straightening or urbanization)].
The area around the Tree Lane bridge supports has been badly eroding for years. A 12-inch water line that was once buried 5 feet below the stream bed is now at the water surface. See below.
How the area downstream from the bridge looked in December before repairs started.
Scour and erosion under and around bridges are constant problems for engineers. This bridge is a great example. Any time a structure interrupts the flow of floodwater, it creates turbulence (vortices in the flow) that can lead to erosion.
During Harvey, scour destabilized the Union Pacific and US59 bridges across the West Fork. Both had to be replaced for safety.
The Tree Lane Bridge doesn’t appear to be to that point yet. But the heavier load placed on Ben’s Branch by new upstream developments, such as Woodridge Village,Woodridge Forest, and Brooklyn Trails, may be pushing this bridge beyond its design capacity.
Source: FEMA. Bridge constricts water flow (from top to bottom). The pressure of water stacking up behind the bridge forces the water to accelerate under the bridge, causing erosion and scour.See below.Major storms in the last four years have eroded a large area immediately downstream from the bridge.
Concrete and Rip Rap Should Help in Short Term
To address these problems, the City repaired part of a concrete wing wall. They also placed riprap (boulders) downstream from the bridge and below a stormwater drain.
Riprap breaks up the flow of water and slows it down. This reduces erosion and scour.
Partially concreted wall (left) and riprap at Tree Lane Bridge over Ben’s Branch, Kingwood, TX.Photo courtesy of COH Public Works.Tree Lane Bridge repairs, Kingwood, TX.Photo courtesy of COH Public Works.
…But Root Causes for Damage Remain
However, problems remain, both here and upstream.
That 12-inch water line could be taken out in the next flood by a tree flowing downstream. If the flood lasts for several days as it did during Harvey, the loss of water would be a major inconvenience to the residents of Bear Branch.
Until we can address the root causes of such damage, I fear that maintenance on this bridge will be a constant, long-term issue…despite the City’s best intentions.
Slabs of concrete still lean against water main.In extreme event, water could still get behind concrete repair and peel it away from bank.
Posted by Bob Rehak on 3/31/2020
945 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/03/20200327-RJR_0444.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-03-31 18:07:122020-03-31 18:13:17City Completes Repairs on Tree Lane Bridge, But Concerns Remain
On March 24, Montgomery County Commissioners approved a resolution that allowed the County Attorney to sue a new Carriage Hills sand mine operating on the West Fork of the San Jacinto. The text of the lawsuit was vague as to actual violations. But on Monday, March 30, B.D. Griffin, the Montgomery County Attorney supplied more details about the complaint. He also discussed the status of the suit, what the mine is doing, and likely long-term outcomes.
Operator Violated Floodplain Permit
According to Griffin, counties in Texas have few tools to regulate land use. However, floodplain regulations are one of them. Montgomery County alleges that the Carriage Hills sand mine operator, Skilled International, was in violation of the floodplain permit issued to MBM Sand Company, the landowner.
Griffin says there were two main issues. First, MBM obtained the permit, but it was not transferrable to Skilled. Second, Skilled is operating in the floodway of the San Jacinto West Fork. The MBM permit allowed floodplain operations, but not floodway.
Therefore, according to Griffin, they operated where they should not have. Floodway operations are subject to more regulations and more stringent regulations than floodplain operations. “They were operating outside the boundaries of their permit,” said Griffin. “That’s why we sought the authority to file suit against them. They were in violation of their floodplain permit.”
Mine Closes Voluntarily Until It Gets Proper Permit
The County, however, did not actually have to file the suit against the Carriage Hills sand mine. “They have complied voluntarily and shut down the sand pit operations until they get their approvals to operate in the special flood hazard area,” said Griffin.
He further stated that, “If you fail to enforce your regulations, then you jeopardize the county’s participation in the national flood insurance program. That’s major. But we try to enforce the regulations anyway because it’s the right thing to do. We’re not after fines necessarily, but we do have that ability if necessary.”
“The operator also told us in writing that they will cease operations until they get the proper permits,” said Griffin. Three officials from Montgomery County checked and found that the mine has, in fact, ceased operations.
What Mine Must Do to Comply
“Basically, they need to show where they are operating. If it’s in the floodway, there are more regulation than if they are just in the flood plain. They need to show that they’re not increasing the base flood elevation and that there are no adverse impacts to adjoining properties. AND they have to have it all certified by engineers in order to get their permit.”
That means the engineer will need to conduct an H&H (Hydrologic and Hydraulic) study for the floodway portion of the mine’s permit. “They need that to show that they won’t raise the base flood elevation and that they won’t adversely impact adjoining properties.”
Truck Traffic Will Likely Return When Permits Obtained
While the threat of a County suit has eliminated all the truck traffic through Carriage Hills for now, in the long run, things may not change much. Griffin says, “You have to understand. Land use regulation by a county is fairly limited in Texas. We don’t have the powers of a municipality and we don’t have the powers of the State.”
Griffin continued, “So, we can only regulate land use with very limited means. One of those is floodplain regulations. The other is subdivision regulations. So, what we look to and require, is often not the same as what an adjoining landowner may want.”
“We want compliance with our permitting process and with the actual regulations themselves. The Carriage Hills sand mine can’t increase water on adjoining property and they can’t raise the base flood elevation. Those are the two big ones,” said Griffin.
Regarding the heavy truck traffic on residential roads, Griffin says,“It’s a public road. Unfortunately, we can’t do much. The state can issue overload permits and they have the right to run on our roads. We can’t do anything about it. There’s a limit as to what the county can do. And, you know, we are in a fast-growing county. As population density increases, we can get more of these problems. There’s not always a win-win solution. But if we take some actions like this, it makes people think about being good corporate neighbors.”
Up to 600 trucks per day were disturbing these quiet residential streets in Carriage Hills, a Conroe subdivision near the West Fork San Jacinto.
Threat of County Lawsuit Remains
Skilled International, the mine’s operator has not given a timetable for compliance yet. But Griffin says they have hired a consultant who is working directly with the County Engineers office. In the meantime, they have agreed to suspend operations until they get their proper permits.
Says Griffin, “We have the lawsuit prepared to be filed. As long as they cease operations, we won’t file a lawsuit. If we see them starting up the operations again and there’s no permit, we will file the suit.”
The complaint approved by Commissioners required remediation for any dirt Skilled International may have brought into the Carriage Hills sand mine. Griffin says, “If they ultimately do NOT get a permit, we will require them to remove anything they may have brought into the floodway.”
This could prove substantial. New draft FEMA floodplain maps show the floodway has expanded. The new floodway now takes in the vast majority of the area being mined.
Black oval shows approximate location of new Carriage Hills sand mine relative to the new draft FEMA flood plain maps. The vast majority of the mine is within the floodway represented by the red crosshatched area.
It is unclear whether the County Engineer and Attorney will apply the new floodplain map when considering the mine’s permit or use the old map.
Posted by Bob Rehak on 3/31/2020
945 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/03/Screen-Shot-2020-03-31-at-10.21.20-AM.jpg?fit=1200%2C823&ssl=18231200adminadmin2020-03-31 11:18:322020-03-31 11:18:45New Carriage Hills Sand Mine Halts Operations For Now
I have received a flood of emails lately from people complaining about the sudden explosion of crayfish in their yards this year. The worst cases seem to be in yards that flooded last year, either from nearby construction, which altered drainage, or from Tropical Storm Imelda.
The most common complaint: the mud chimneys make mowing yards nearly impossible. And, “You can twist an ankle without even trying,” says Gretchen Dunlap Smith, one of the affected homeowners. On an even more serious note, they can also undermine earthen dams. “What to do?” people ask.
Louis A. Helfrich, Extension Specialist; Jim Parkhurst, Extension Specialist; and Richard Neves, Extension Specialist; Department of Fisheries and Wildlife Sciences, at Virginia Tech published a study called “The Control of Burrowing Crayfish in Ponds.” They say that burrowing animals such as crayfish “construct their homes or ‘burrows’ by digging into soil banks along the shorelines of waterbodies. Tunnels dug below the water level provide channels through which water can escape. Tunnels dug above the water level can decrease structural support of the embankment and increase the risk of washout during flood conditions. These hazards are multiplied in waters where burrowing animals are abundant and where water levels fluctuate.”
Chemical Treatments Not Recommended
The breeding season peaks in early spring, say the authors. “Complete elimination is usually not possible … Control is successful when the balance between the predator (fish, birds, mammals) and the prey species (crayfish) is reached, and excessive burrowing damage is reduced to an acceptable level.”
The Virginia Tech study does not recommend chemical treatments because they: (1) threaten water quality, (2) kill beneficial plants and animals as well as pests, and (3) can be widely distributed by wind and water movements.
No chemicals are currently registered for crayfish control. Never apply toxic chemicals directly to waters or near shorelines where they can seep into waterways.”
An explosion of crayfish chimneys in a yard flooded last year next to the Perry Homes’ Woodridge Village construction site. This and photos below courtesy of Gretchen Dunlap Smith.Gretchen Dunlap Smith’s yard after smashing the crayfish chimneys.As soon as you smash them……the crayfish rebuild them. This is because they burrow. Tunnels can go down 2-3 feet with side chambers.
Another homeowner, Susanne Kite says, “Places in my yard have not completely dried up since Imelda. A lot changed after that flood. I don’t understand what was so different and caused so much to change.”
Crayfish Love Wetlands
Suzanne Simpson, a wildlife biologist with the Bayou Land Conservancy, may have an explanation. “Crayfish love wetlands. So much so that the presence of crayfish mounds is considered a secondary indicator of wetland habitat on wetland delineation sheets for the Corps of Engineers.”
“Crayfish feed on detritus and mostly make their mounds during the rainy season,” says Simpson. “I’m sure the floodwaters brought in some detritus with them, and flooding leaves traces that likely lead the crayfish to identify these yards as good habitat. They’re not too easy to get rid of, but it can be done.”
Drainage Improvement and Traps: Your Best Bet. Puppies? Not So Much
You best bet: terrascaping to improve drainage, say the experts. Failing that, “traps are humane and non toxic. You don’t have to worry about poisoning other animals or leaving persistent residue in your soil,” says the web site Gardening Know How.
“My littlest schnauzer had puppies Dec 30th,” said Gretchen Dunlap Smith. “The puppies are DIGGING them up at a rapid rate and EATING them! It is GROSS hearing them crunch!! Sounds like they are chewing gravel. So, no chance for étouffée…the dogs are having sushi.”
Posted by Bob Rehak on March 30, 2020 with help from Suzanne Simpson, Gretchen Dunlap Smith and Susanne Kite
944 Days after Harvey and 193 since Imelda
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/03/20200330-GDS-Crayrish-CU2.jpg?fit=1200%2C767&ssl=17671200adminadmin2020-03-30 19:05:152020-03-31 00:54:23Many Yards That Flooded Last Year See Crayfish Population Explosion
City Completes Repairs on Tree Lane Bridge, But Concerns Remain
The City of Houston has completed repairs on the Tree Lane Bridge over Ben’s Branch…at least for now. The City partially concreted a wing wall and placed riprap in the stream bed to help reduce erosion and scour. However, the root cause of the damage remains. Upstream development without adequate detention is funneling more and more water into Ben’s Branch. The higher volume will continue to contribute to scouring and erosion in major storms unless detention ponds upstream are built and fixed.
Water Under the Bridge
As I struggled to understand what I was looking at, an online search revealed this excellent 196-page, well-illustrated document. It’s titled “AN ILLUSTRATED GUIDE FOR MONITORING AND PROTECTING BRIDGE WATERWAYS AGAINST SCOUR.” Robert Ettema, Tatsuaki Nakato, and Marian Muste from the College of Engineering at the University of Iowa produced it for the Iowa Department of Transportation.
The document points out that bridge engineers often assume that a stream channel will maintain its course and dimensions. But most channels adjust their alignment and shape in response to floods and land-use changes in their watersheds. That has happened on Ben’s Branch in recent years.
Scour and Progressive Degradation
A review of the entire paper reveals two types of destructive forces at work on the Tree Lane Bridge.
Long-term scour is one. It occurs over a time scale of several years, and usually includes progressive degradation and lateral bank erosion due to channel widening or meander migration.
Progressive degradation is another. It features the almost permanent lowering of the river bed at a bridge site owing to changes in the watershed [e.g., head-cut progression (head-cutting), or human activities (e.g., channel straightening or urbanization)].
The area around the Tree Lane bridge supports has been badly eroding for years. A 12-inch water line that was once buried 5 feet below the stream bed is now at the water surface. See below.
Scour and erosion under and around bridges are constant problems for engineers. This bridge is a great example. Any time a structure interrupts the flow of floodwater, it creates turbulence (vortices in the flow) that can lead to erosion.
During Harvey, scour destabilized the Union Pacific and US59 bridges across the West Fork. Both had to be replaced for safety.
The Tree Lane Bridge doesn’t appear to be to that point yet. But the heavier load placed on Ben’s Branch by new upstream developments, such as Woodridge Village, Woodridge Forest, and Brooklyn Trails, may be pushing this bridge beyond its design capacity.
Concrete and Rip Rap Should Help in Short Term
To address these problems, the City repaired part of a concrete wing wall. They also placed riprap (boulders) downstream from the bridge and below a stormwater drain.
…But Root Causes for Damage Remain
However, problems remain, both here and upstream.
Until we can address the root causes of such damage, I fear that maintenance on this bridge will be a constant, long-term issue…despite the City’s best intentions.
Posted by Bob Rehak on 3/31/2020
945 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.
New Carriage Hills Sand Mine Halts Operations For Now
On March 24, Montgomery County Commissioners approved a resolution that allowed the County Attorney to sue a new Carriage Hills sand mine operating on the West Fork of the San Jacinto. The text of the lawsuit was vague as to actual violations. But on Monday, March 30, B.D. Griffin, the Montgomery County Attorney supplied more details about the complaint. He also discussed the status of the suit, what the mine is doing, and likely long-term outcomes.
Operator Violated Floodplain Permit
According to Griffin, counties in Texas have few tools to regulate land use. However, floodplain regulations are one of them. Montgomery County alleges that the Carriage Hills sand mine operator, Skilled International, was in violation of the floodplain permit issued to MBM Sand Company, the landowner.
Griffin says there were two main issues. First, MBM obtained the permit, but it was not transferrable to Skilled. Second, Skilled is operating in the floodway of the San Jacinto West Fork. The MBM permit allowed floodplain operations, but not floodway.
Therefore, according to Griffin, they operated where they should not have. Floodway operations are subject to more regulations and more stringent regulations than floodplain operations. “They were operating outside the boundaries of their permit,” said Griffin. “That’s why we sought the authority to file suit against them. They were in violation of their floodplain permit.”
Mine Closes Voluntarily Until It Gets Proper Permit
The County, however, did not actually have to file the suit against the Carriage Hills sand mine. “They have complied voluntarily and shut down the sand pit operations until they get their approvals to operate in the special flood hazard area,” said Griffin.
He further stated that, “If you fail to enforce your regulations, then you jeopardize the county’s participation in the national flood insurance program. That’s major. But we try to enforce the regulations anyway because it’s the right thing to do. We’re not after fines necessarily, but we do have that ability if necessary.”
“The operator also told us in writing that they will cease operations until they get the proper permits,” said Griffin. Three officials from Montgomery County checked and found that the mine has, in fact, ceased operations.
What Mine Must Do to Comply
“Basically, they need to show where they are operating. If it’s in the floodway, there are more regulation than if they are just in the flood plain. They need to show that they’re not increasing the base flood elevation and that there are no adverse impacts to adjoining properties. AND they have to have it all certified by engineers in order to get their permit.”
That means the engineer will need to conduct an H&H (Hydrologic and Hydraulic) study for the floodway portion of the mine’s permit. “They need that to show that they won’t raise the base flood elevation and that they won’t adversely impact adjoining properties.”
Truck Traffic Will Likely Return When Permits Obtained
While the threat of a County suit has eliminated all the truck traffic through Carriage Hills for now, in the long run, things may not change much. Griffin says, “You have to understand. Land use regulation by a county is fairly limited in Texas. We don’t have the powers of a municipality and we don’t have the powers of the State.”
Griffin continued, “So, we can only regulate land use with very limited means. One of those is floodplain regulations. The other is subdivision regulations. So, what we look to and require, is often not the same as what an adjoining landowner may want.”
“We want compliance with our permitting process and with the actual regulations themselves. The Carriage Hills sand mine can’t increase water on adjoining property and they can’t raise the base flood elevation. Those are the two big ones,” said Griffin.
Regarding the heavy truck traffic on residential roads, Griffin says, “It’s a public road. Unfortunately, we can’t do much. The state can issue overload permits and they have the right to run on our roads. We can’t do anything about it. There’s a limit as to what the county can do. And, you know, we are in a fast-growing county. As population density increases, we can get more of these problems. There’s not always a win-win solution. But if we take some actions like this, it makes people think about being good corporate neighbors.”
Threat of County Lawsuit Remains
Skilled International, the mine’s operator has not given a timetable for compliance yet. But Griffin says they have hired a consultant who is working directly with the County Engineers office. In the meantime, they have agreed to suspend operations until they get their proper permits.
Says Griffin, “We have the lawsuit prepared to be filed. As long as they cease operations, we won’t file a lawsuit. If we see them starting up the operations again and there’s no permit, we will file the suit.”
The complaint approved by Commissioners required remediation for any dirt Skilled International may have brought into the Carriage Hills sand mine. Griffin says, “If they ultimately do NOT get a permit, we will require them to remove anything they may have brought into the floodway.”
This could prove substantial. New draft FEMA floodplain maps show the floodway has expanded. The new floodway now takes in the vast majority of the area being mined.
It is unclear whether the County Engineer and Attorney will apply the new floodplain map when considering the mine’s permit or use the old map.
Posted by Bob Rehak on 3/31/2020
945 Days after Hurricane Harvey
Many Yards That Flooded Last Year See Crayfish Population Explosion
I have received a flood of emails lately from people complaining about the sudden explosion of crayfish in their yards this year. The worst cases seem to be in yards that flooded last year, either from nearby construction, which altered drainage, or from Tropical Storm Imelda.
The most common complaint: the mud chimneys make mowing yards nearly impossible. And, “You can twist an ankle without even trying,” says Gretchen Dunlap Smith, one of the affected homeowners. On an even more serious note, they can also undermine earthen dams. “What to do?” people ask.
Be Thankful You Don’t Live in Tasmania!
Crayfish, crawfish, crawdads, mudbugs, whatever you call them, they’re all essentially the same thing. More than 550 species exist worldwide. They range in size from less than an inch in Louisiana to more than 8 POUNDS in Tasmania. There are 390 species in North America, 338 in the United States. Texas alone has 40 species according to Texas Parks and Wildlife. Counties in the north Houston area even have their own unique breed.
Attracted to Water, Danger to Pond Dams
Louis A. Helfrich, Extension Specialist; Jim Parkhurst, Extension Specialist; and Richard Neves, Extension Specialist; Department of Fisheries and Wildlife Sciences, at Virginia Tech published a study called “The Control of Burrowing Crayfish in Ponds.” They say that burrowing animals such as crayfish “construct their homes or ‘burrows’ by digging into soil banks along the shorelines of waterbodies. Tunnels dug below the water level provide channels through which water can escape. Tunnels dug above the water level can decrease structural support of the embankment and increase the risk of washout during flood conditions. These hazards are multiplied in waters where burrowing animals are abundant and where water levels fluctuate.”
Chemical Treatments Not Recommended
The breeding season peaks in early spring, say the authors. “Complete elimination is usually not possible … Control is successful when the balance between the predator (fish, birds, mammals) and the prey species (crayfish) is reached, and excessive burrowing damage is reduced to an acceptable level.”
The Virginia Tech study does not recommend chemical treatments because they: (1) threaten water quality, (2) kill beneficial plants and animals as well as pests, and (3) can be widely distributed by wind and water movements.
Another homeowner, Susanne Kite says, “Places in my yard have not completely dried up since Imelda. A lot changed after that flood. I don’t understand what was so different and caused so much to change.”
Crayfish Love Wetlands
Suzanne Simpson, a wildlife biologist with the Bayou Land Conservancy, may have an explanation. “Crayfish love wetlands. So much so that the presence of crayfish mounds is considered a secondary indicator of wetland habitat on wetland delineation sheets for the Corps of Engineers.”
“Crayfish feed on detritus and mostly make their mounds during the rainy season,” says Simpson. “I’m sure the floodwaters brought in some detritus with them, and flooding leaves traces that likely lead the crayfish to identify these yards as good habitat. They’re not too easy to get rid of, but it can be done.”
Drainage Improvement and Traps: Your Best Bet. Puppies? Not So Much
You best bet: terrascaping to improve drainage, say the experts. Failing that, “traps are humane and non toxic. You don’t have to worry about poisoning other animals or leaving persistent residue in your soil,” says the web site Gardening Know How.
“My littlest schnauzer had puppies Dec 30th,” said Gretchen Dunlap Smith. “The puppies are DIGGING them up at a rapid rate and EATING them! It is GROSS hearing them crunch!! Sounds like they are chewing gravel. So, no chance for étouffée…the dogs are having sushi.”
Posted by Bob Rehak on March 30, 2020 with help from Suzanne Simpson, Gretchen Dunlap Smith and Susanne Kite
944 Days after Harvey and 193 since Imelda