Museum, Park Conservancy Hire Firm That Gets Bank Collapse Wrong
Result: Costly Engineering, Bulldozing, Tree Cutting, Logs, Sheet Pile, Concrete Block and Damaged Buffalo Bayou
May 16, 2021
A decade ago a prominent engineering firm misdiagnosed bank failure on Buffalo Bayou for a controversial $12 million bank “restoration” project that was subsequently dropped. Now the same company has been rewarded with new bank repair contracts. And it appears to be making a similar error.
What could be the motive for repeating such basic mistakes? And why does it matter?
Inappropriate streambank projects can result in costly failure, of which there are too many examples littering Buffalo Bayou. Any alteration of the channel and banks can cause unforeseen problems, including environmental and property damage, increased flooding and erosion.
Watch this slideshow of some of the many failed erosion control projects on Buffalo Bayou:
Riprap, concrete bags, and concrete puzzle block all slid away.
There are two kinds of riverbank failure: banks that wash away with the horizontal flow of the stream and banks that collapse vertically from the top down. True, sometimes they do both.
But the slippery sand and clay banks of Buffalo Bayou primarily collapse vertically, usually when they get soaked from the top. They quiver and slump, sliding across the ancient hard red clay layer at the base of the bank. There’s not a whole lot to be done about that. However, common sense solutions include: stop doing what is causing the bank collapse.
But that doesn’t generate high-dollar contracts for engineering companies.
What does cost a lot of money? Cutting trees, bulldozing, scraping, grading, filling, pounding sheet pile, concrete, and logs into the bank, none of which will necessarily provide a long-term solution to bank slumping and can even make it worse.
The Background
Around 2010 a long-established engineering company was hired by the Harris County Flood Control District to develop a plan for a “natural channel design” project on Buffalo Bayou flowing between Memorial Park and the River Oaks Country Club in the center of Houston. The project, initiated by the Bayou Preservation Association (BPA) and supported by the Memorial Park Conservancy, was called the Memorial Park Demonstration Project. It would have stripped the trees and vegetation, scraped and graded the banks and channel and rerouted the stream for over a mile along one of the last publicly accessible forested stretches of the bayou in the city, a historic nature area. Though it would have destroyed the natural habitat and most aquatic life in the stream, the project was billed as “hastening recovery” of the river.
The engineering company was KBR (Kellogg Brown and Root), but at the end of 2015 KBR was purchased by Stantec. KBR’s manager for the demonstration project was Betty Leite, who also served on the advisory board of the nonprofit BPA at the time.
Now Stantec has been hired to develop plans for stabilizing the bank of the bayou below the historic Bayou Bend Collection and Gardens and in Memorial Park. The project manager is Betty Leite.
The Mistake
Developed in the mountains of Colorado in the 1990s, “natural channel design” is a controversial method of standardizing, categorizing and “repairing” streams in a diversity of geographic settings. (See here and here.) Criticized as unscientific and for being focused on symptoms rather than causes, among other things, it has spawned a highly-profitable “river restoration” industry based on stripping, grading, and altering streams to “stabilize” them, which ironically often means preventing them from seeking equilibrium, which rivers naturally do. (p. 7)
Controversy aside, the mistake made a decade ago by KBR in its “natural channel design” plan for Buffalo Bayou was to focus exclusively on what is called “shear stress,” which is the force of the lateral or horizontal flow of a stream. Bank erosion in the demonstration project area was entirely caused by shear stress, claimed KBR in documents submitted in April 2014 seeking a federal permit for the project.
Vertical instability (slumping) was “not an issue,” claimed KBR. (p. 39)
This was wrong, as Save Buffalo Bayou pointed out in 2017 to Harris County Commissioner Jack Cagle, whose Precinct 4 includes Buffalo Bayou flowing between the public park and the private club. The Memorial Park Demonstration Project was shelved by Flood Control soon after. The River Oaks Country Club, which was also participating in the project as the owner of the bank across the bayou from the public park, subsequently scraped and graded and armored three areas of the bank with sheet pile and concrete at a cost of tens of millions of dollars. The club had previously cut down the long-standing forest on the bank and expanded the golf course up to the edge, regularly mowing and watering, contributing to instability. No doubt some members of the club (and others) had enjoyed the rare privilege of walking in those lovely woods cut down for golfers.
The Contradictions
Though KBR claimed in 2014 that vertical bank instability was “not an issue,” in fact the company had earlier noted that vertical instability was a significant issue on Buffalo Bayou. In a 1995 study for the flood control district, the company, then known as Brown and Root, found slumping, sloughing, and sliding of the bayou banks all the way from Beltway 8 to the Shepherd Bridge. (pp. 98-99)
That report also described the ancient bayou channel, lined with sandstone and hard clay, as remarkably stable, especially at the toe or bottom of the banks, but also sometimes higher up the slope. It noted that the hard red clay base of the banks provides stable support and resists erosion. (p. 75)
Interestingly, though broken sandstone rock along the banks is quite obvious to anyone looking down or paddling past Memorial Park, Harris County Flood Control claimed in a 2015 update to its federal permit application that there were “no existing rock outcroppings” in the areas to be “restored” (p. 4), despite having previously found sandstone rock outcrops “within the proposed project reach.” (pp. 124, 198)
These were just a few of the contradictory and bizarre claims made for the “natural channel design” demonstration project.
Focus on the Toe
And yet, like the elaborate bank engineering plans developed by KBR/Stantec in 2014, their new multi-million dollar projects on the bayou focus on the need to protect the “stable, erosion resistant” base of the banks by driving logs and sheet pile through the hard clay, dumping concrete riprap on top and covering it up with soil and stuff. (p. 95)
“Trying to avoid lateral shear at the toe of the slope is not a bad thing,” says research geologist Bill Heins, a board member of Save Buffalo Bayou. “But it will not stop bank slumping. It will cost a lot of money and ultimately add a lot of engineered material (including tree trunks) when it fails.”
Advisory board member Matt Kondolf agrees. A fluvial geomorphologist (author of a textbook on the subject) and director of RiverLab at the University of California, Berkeley, Kondolf emphasizes a “need to step back and look at what mechanism is causing bank collapse.” He also notes that the project involves a great deal of “cut and fill, very close to the bayou itself.”
Substantial sediment entering the bayou at low flow “can cause ecological damage,” Kondolf points out. “In California projects near rivers are required to monitor turbidity levels up and downstream, and the most common requirement is that the construction cannot increase turbidity levels more than 15% above the background level. I recommend that turbidity sensors be installed to monitor the effects of this project as well.”
The New Projects
Betty Leite, then manager for the Memorial Park Demonstration Project, is now the project manager for Stantec’s new bank repair projects. The company has been hired by both the Museum of Fine Arts, Houston, and the private conservancy running our public Memorial Park to come up with plans to “restore” the bayou banks to what they were prior to Harvey in 2017. The museum owns the Bayou Bend Collection and Gardens downstream from the park, upstream from Shepherd Bridge, and across the bayou from the sadly degraded Hogg Bird Sanctuary. Thanks to the Houston Parks Board, the small 15.5-acre bird sanctuary now features a wide concrete sidewalk on top of the bank leading to an excellent view of country club golfers on the once-forested opposite bank.
We asked Leite for comment on her team’s previous conclusion that vertical stability was not an issue on Buffalo Bayou along Memorial Park. So far she has not responded to our phone or email messages on that subject.
Never Done Here Before
The bank “restoration” plans for Bayou Bend include the removal of dozens of trees, excavating and bulldozing, pounding massive sheet pile walls deep into the bank, and most bizarrely of all, inserting some two dozen large logs (including the felled trees) into (or perhaps on top of) the ancient hard clay and sandstone at the bottom of the bank. The plans describe excavating “to sand bottom for toe wood.” (p. 98)
The big logs with roots towards the channel are to be buried perpendicular to the bank, similar to what had been proposed for the Memorial Park Demonstration Project.
We asked Leite whether this method of burying logs perpendicular to the bank had been tried on a similar stream anywhere in the region. She answered by email: “This technique was used along tributaries flowing into Lake Superior in Michigan.”
Nobody in Charge
The Bayou Bend plans have been approved by the Corps of Engineers, the City of Houston, and the Harris County Flood Control District. Not that anybody really looked at the plans. The Galveston District office of the Corps, its regulatory branch short-staffed and short-funded, now routinely closes its eyes when receiving applications for construction permits under the Clean Water Act and then simply declares the permit granted at the expiration of the six-week time limit for the agency to respond.
In fact, the federal permit for the Bayou Bend project was issued in 2018 in conjunction with the Houston Parks Board’s ill-conceived bank “repair” project downstream. That project, which also stripped trees and vegetation, excavated, dumped dirt and concrete riprap, and drove sheet pile deep into the bank, is already having problems. The Bayou Bend plan submitted to the City of Houston, however, is entirely different from the plan approved by the Corps. No one from the Galveston district office responded to our questions about that.
However, Leite did answer our questions about it in an email. She said Stantec had been informed by the Corps that as long as “fill volumes” (the amount of material to be dumped onto the bank near the water’s edge) “stay within the fill limits stipulated in the permit we are compliant.”
The City of Houston Floodplain Management Office is responsible for issuing construction permits in floodplains and floodways. They send the construction plans to the flood control district for review, which consists of checking to see if the plans are stamped by a certified engineer hired by the applicant. That’s it. Stamped by the hired engineer. Anything goes. Nobody’s responsible when it falls down. Except the bayou, of course. It’s the bayou’s fault when it fails.
Other Places Do Better
Just for context, other cities, counties, and states actually take action to understand stream dynamics and protect their residents and waterways. Denton County in north Texas has adopted an admirable plan to protect greenbelts along its streams, complete with programs to educate property owners and developers about why this is important. The state of Vermont is aggressive about protecting the natural functions of its streams and prohibiting property owners from making changes that would impair that. Cass County in North Dakota, where there are similar streambank slumping problems, has setbacks and strict land use regulations to protect streams and property. Their guidelines point out that slumping is in fact a natural process due to the dynamic nature of a river and the weak clay soils of the Red River valley. They explain that this natural process can be aggravated by the activities of property owners.
It may seem surprising that erosion is a natural and necessary function of healthy streams. And that replanting and rebuilding of the bank is also part of nature’s work, even on urban streams.
The New Plans
The best that can be said about the novel, heavily engineered “slope repair” project planned for the bayou bank below the historic house and gardens of Bayou Bend is that it is smaller than originally described in 2018-2019. As initially planned, heavy equipment was to excavate and grade all the way around the wooded sandy point on the right bank of the bayou for some 735-1,350 linear feet. (The bend for which Bayou Bend is named.) The project is now some 534 linear feet of mostly steep bank just upstream and downstream of the pedestrian bridge that ends in the romantic if ecologically outdated “southern” gardens. The bridge provides access for visitors arriving from the public parking lot on Westscott.
Another positive is that plans also call for extensive planting of native, riparian plants on the slumping bank now planted with exotic and virtually useless monkey grass.
Note that there was once a popular swimming hole here known as the Rocky Bottom, along with a crossing known as the Old River Ford. (p. 57)
Long-term Slumping Problems, Implications for the Historic Banks in Memorial Park
The slumping of the high bank immediately upstream and downstream of the footbridge has long been a problem, as has the footbridge itself. Unfortunately the museum, like many property owners on the bayou, has tried to address this by, among other things, loading heavy concrete rubble or riprap onto the bank. This only adds weight to the bank, making it more prone to slumping.
Over the years we and others have tried to suggest more practical and ecological remedies and resources for a problem caused in part by poor management practices on the upper bank, including building a concrete parking lot and other structures on top of the bank, irrigating, removing native vegetation and landscaping the bank with useless and inappropriate exotic species.
Not that the bayou banks don’t naturally slump after floodwaters rise up and soak the floodplain, sometimes causing the upper layers to quiver and slip across the hard clay base. This naturally creates the more gently sloping bank engineers want to get paid to construct with heavy equipment. And then the banks naturally rebuild, replant, and restore themselves, with fallen trees lying on or in front of the banks collecting sediment from the stream, stabilizing and protecting the bank as they’ve been doing since the beginning of time. Unless or until all the trees have been cut down.
Unfortunately, the Harris County Flood Control District hasn’t helped by hauling away the fallen trees and other large woody debris that would have performed this function.
Enlightened erosion control methods seek to mimic this natural stabilizing and rebuilding, habitat-creating process by tying “mattresses” made of brush and tree trunks strategically positioned parallel or at a 45 degree angle to the bank, among other things. However, to some people that can look messy, too natural.
So-called Natural Channel Design or the “Rosgen method” would seem to be based on these natural strategies. Unfortunately, Rosgen’s “system” has created a nationwide profit stream for private engineering companies. Along with well-intentioned individuals convinced they are overnight fluvial geomorphologists, these companies—and public agencies—often leave behind a wake of damaged waterways.
The Harris County Flood Control District has been using “natural stable channel design” as an excuse to strip the banks and bulldoze the few remaining forested streams all over the county. See, for instance, Pillot Gully in northwest Harris County, until recently a wooded stream (see before and after), as well as Buffalo Bayou Park in downtown Houston.
The Fate of the Ancient High Banks in Memorial Park
Stantec’s plans for Bayou Bend, a mix of traditional and natural channel design, are no doubt a harbinger of what’s to come for the ancient high banks in the Old Archery Range of Memorial Park, a historic section of the park west of Loop 610 containing a public boat launch. The Memorial Park Conservancy, in conjunction with the Uptown Development Authority, have hired Stantec and Leite to develop plans there.
And what happens in the Old Archery Range under the auspices of the conservancy and the Uptown Development Authority will no doubt foretell the fate of the banks in the rest of the park, our magnificent living classroom on natural history and geology in the middle of the city.
The company’s “concept design” for grading the banks and rerouting the bayou to cut off meanders in this part of the park is to be finalized by next fall, according to a presentation given to Save Buffalo Bayou in February by George Athanasakes, vice president for river restoration at Stantec in Louisville, KY. The schedule includes meeting with property owners on the opposite bank who appear to benefit from the proposed plan to slice off of parts of the publicly-owned meanders.
Arranged by the conservancy’s then conservation manager, Carolyn White, formerly with Harris County Flood Control and a longtime proponent of the Rosgen’s “natural channel design,” Athanasakes lectured us on Rosgen’s methodology.
Though focused on “shear stresses,” he did describe bank slumping with an emphasis on “toe cutting,” showing an example of a naturally slumped grassy bank that looked remarkably like what the engineering company plans to do with heavy equipment for a large fee.
Athanasakes also explained in a later telephone interview that the high banks and much of the remaining forest, home to an abundance of rabbits, cardinals, herons, and many other creatures, were to be scraped and graded in order “to improve floodplain access” for the bayou.
However, it’s clear from field observations by our experts and nearby residents that the bayou is quite able to flow over and across the meanders, leaving behind a thick layer of rich sediment that even Stantec’s technicians would have noticed. The deep tracks of their vehicles have been evident everywhere.
How to Contact the Memorial Park Conservancy
How to Contact the Uptown Development Authority
How to Contact the Mayor’s Office
It’s worth repeating this beautiful quote from landscape architect Janet Wagner, who wrote the following about Buffalo Bayou to the National Trust for Historic Preservation on August 4, 2014:
The alignment of Buffalo Bayou, fronting along the Hogg Bird Sanctuary and upstream along Memorial Park, exhibits a historic land formation documented in 1840 Harris County Surveyor George H. Bringhurst. He traveled several days along the north side of Buffalo Bayou (now Memorial Park) beginning at Shepherd Drive to beyond Dutchman’s Crossing (near Woodway Bridge). Bringhurst’s survey mapping along the bayou ridge matches the current alignment of Buffalo Bayou meanders, giving rise that the present bayou bank pattern is well over 175 years old. The alluvial nature of the old Archery Range dates the Range alignment to 12,000 years. A canoe trip down Buffalo Bayou or visit to Memorial Park reveals a step back in time that is outstanding for stream preservation, education and reverence to historic vistas.
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