Stabilizing Streambanks
New products and techniques help keep banks steady in heavy-use areas.
By
Donna Gordon Blankinship
The people of DuPage County in the western suburbs of Chicago know Salt Creek as a lovely place to hike, bike, canoe, and bird watch. They visit the peaceful, tree-filled area to get away from their concrete- and asphalt-paved suburban lives. What they may not know is that the Salt Creek watershed is also an amazing example of water-quality renewal resulting from a multiyear, 10-mile project of streambank stabilization.
The Salt Creek renewal project began in 1998 as a citizen initiative to address water quality, streambank maintenance, habitat, flooding, land use, public education, and recreation. The Salt Creek watershed covers about 150 square miles and involves more than 30 municipalities where nearly 500,000 people live. Salt Creek starts in northwest Cook County, runs south and east through DuPage County, and empties into the Des Plaines River in central Cook County.
The dense population had put a lot of pressure on the creek, causing soil erosion, water pollution, flooding, habitat loss, and decreased species diversity. Local and state government agencies tapped into the federal Clean Water Act—Salt Creek was labeled a priority watershed—to help fund what became such a huge project the dollar amounts and time involved made putting a price on it difficult.
Five stages of the project were completed over five years in two villages—Wood Dale and Elk Grove—by one contractor, McGinty Brothers. Jim Safran, vice president of McGinty Brothers, says this has been a complex operation with a need for creativity and skill. He gives a special nod to his backhoe operator and superintendent on all five phases, Sixto Casas, who he says is a bit of an artist with the materials used on this job, especially placing the A-Jacks interlocking concrete blocks, which should be perfectly even and level for long-lasting success.
 |
| A-Jacks interlocking concrete blocks |
“It probably took us a couple of years to learn how to do it quickly and efficiently,” Safran comments. “There’s a trick to it. I know I couldn’t do it. I was out there supervising.”
He’s quick to add, however, that the product is worth the effort in the results it achieves and in the way the job looks when it’s finished. “It works very well. We’ve had very little failure with it,” Safran says of the miles of A-Jacks installed along Salt Creek.
Creativity and coordination both are very important on a job like this, notes Doug Buch, Great Lakes regional manager for Armortec Erosion Control Solutions, creator of A-Jacks. Another big challenge was access—the difficulty of working in a densely populated area while disturbing as little land and property as possible. And despite the immensity of the project and the diversity of agencies supporting it, money was still an issue. “You can design anything, but can you build it within economic reason?” Buch says that is always the question project planners must ask.
Access Issues
To conquer some of the access issues, the project managers chose A-Jacks. The interlocking concrete pieces are relatively small in comparison with other kinds of hard-armor solutions and can be moved with smaller machines that weigh only 3,000 to 4,000 pounds, as compared to big excavating equipment that can weigh up to 90,000 pounds. This enabled the workers to avoid crushing turf on a golf course, for example, and keep from ruining existing landscaping in residential areas.
The A-Jacks are connected together along the bank in a way that is flexible and permeable. They can be installed either randomly or in a uniform pattern. Space is left between the pieces to be filled in with habitat for fish below the water or with soil above the water that can be planted with grasses, shrubs, and trees.
 |
PHOTO: ARMORTEC |
| Oak Meadows Golf Course project stages from start to finish. |
 |
PHOTO: ARMORTEC |
 |
PHOTO: ARMORTEC |
 |
PHOTO: ARMORTEC |
 |
PHOTO: ARMORTEC |
 |
PHOTO: ARMORTEC |
Safran says he was pleased with how quickly and thoroughly the land around and over the A-Jacks revegetated. The blocks were installed in several different configurations on the job, depending on the severity of erosion. In some places, one row of blocks, partially under water, was enough. In other spots, the pieces were stacked in small pyramids with two blocks under water supporting another one on top. In a third scenario, three blocks under water supported two partially submerged and one on top. Safran says the coordination and skill needed to make such arrangements takes a bit of work, but once A-Jacks are installed they last a long time. “Salt Creek is a tricky creek. It really rises fast and comes down quickly,” he adds.
The concrete structures come in diameters of 24, 48, 72, 96, and 120 inches. When combined with bioengineering techniques and given a few seasons for surrounding vegetation to get established, the A-Jacks can become completely invisible. The smaller pieces weigh around 40 pounds so they can be put in place by human beings, but the larger ones weigh more than a ton and require a backhoe and sling for assembly.
The Salt Creek project also made use of wood and plastic lunkers about 6 feet long, 12 inches tall, and 2 feet deep to sink under the edge of the stream to provide places for fish to spawn and improve the habitat. “Lunkers are pretty pricey,” Buch points out. “You don’t want to do a whole stream in lunkers.” So the project managers combined several solutions—from lunkers to A-Jacks—alternating along the streambed.
This project demanded extensive negotiation skills on the part of the agencies involved. Much of the streambank had become more or less private property as homeowners ran their grasses right up to the edge of the stream. These turf grasses were part of the problem because of their short root base. When the streambank was built up with A-Jacks and filled in with thicker prairie grasses, the homeowners—and the managers of the Oak Meadows Golf Course—had to give something up in order to see the streambank stabilized.
Looking Ahead
At the other end of the erosion control timeline from Salt Creek is a project in Arlington, TX, that is just the beginning of what will likely turn into a multiyear, multimillion-dollar endeavor.
Johnson Creek runs through the length of Arlington, and when spring rains fall the water runs fast and flood danger is high. A series of projects is just beginning to address the flow and flood problems, as well as to look ahead at pedestrian access and beautification of the area. Arlington is about to become the center of a major urban renewal project. The Dallas Cowboys are getting ready to build a new stadium in this community halfway between Dallas and Fort Worth, and the city wants to take care of the flooding while building new public access areas like walking paths along the creek. A historical trail featuring pioneer cabins, an old one-room schoolhouse, and a barn are already attracting some tourist attention along the creek.
Jeff Tanner, area field superintendent for Ark Contracting Services, says his company recently finished a project installing gabions along one section of the creek to improve the shoreline and also slow down erosion after the city installed some new sewer lines. Johnson Creek runs mostly through residential areas, so much of the creek-side property is privately owned, offering challenges similar to those at Salt Creek. But erosion problems on Johnson Creek may be poised to get worse, not better, as construction work begins on the new stadium and new highways are needed to alleviate traffic problems in the area. Tanner says increased stormwater runoff from construction sites and new roads is bound to be bad for the creek.
He notes that the US Army Corps of Engineers is making efforts to improve some sections of the creek that are especially in need of help. Last June the corps completed the first phase of a $27 million project, which includes buying homes in the floodplain, building recreational areas, and making environmental improvements along the creek. The project includes the digging out and widening to 90 feet at the bottom for up to a mile of Johnson Creek to help water flow right before it enters the Trinity River system. Gabions were used for bank stabilization. The corps is scheduled to continue making bank improvements over the next few years.
Tanner says that unless the whole creek system is addressed, erosion problems will continue and could just move over the areas that are not addressed by the individual projects. Citizens recently defeated a ballot proposal to spend more than $25 million on improvements to the creek. Tanner felt that was shortsighted of the residents of this rapidly growing community, who had just approved spending millions of dollars to help build a new football stadium and its surrounding infrastructure.
“Johnson Creek is about the worst creek in Arlington,” Tanner says. Water comes and goes through the creek during rainy periods in a dramatic fashion. Flooding is inevitable in some sections of the creek, and with flooding comes erosion in many cases.
Tanner commends the City of Arlington for trying to plan ahead for the impact of rapid residential growth and the new football stadium. “They’re trying to save everybody a bunch of headaches,” he says. So when new sewer pipe needed to be laid across the creek, the city’s contractor decided to have Ark Contracting put in some gabions to slow down erosion in that part of Johnson Creek.
Every effort toward erosion control helps, Tanner observes, even though he would like to see a bigger, more comprehensive plan completed for the creek. He has seen gabions make a big difference in projects like this, because products like the Terra Aqua Gabions that were used on this job are a much better solution for fast-flowing creeks than building a cement wall. He likes the way the gabions continue to fit the shoreline even when some dirt flows away. Molding to the situation is something a cement wall cannot do, he points out.
Tanner expects the work on Johnson Creek is just getting started, despite the lack of citizen enthusiasm for spending money on erosion control. The City of Arlington is doing its part with extensive public education about keeping the city’s creeks healthy. The city’s Web site offers a series of lively pages explaining why creek health is important and what citizens can do to make a difference in what is literally their own backyard.
Carrying Materials on Your Back
Beauty and erosion control are even more closely related when people move a little farther out of the city and start walking in our nation’s parks, forests, and recreational areas. Portability of construction materials becomes a crucial element when erosion control work is done in very remote locations, such as along a mountain creek where the only way to get to the site is on foot.
 |
PHOTO: STORMSLIDE |
| Lightweight and stackable StormSlide can be easily transported up a trail and quickly installed by one person. |
 |
PHOTO: STORMSLIDE |
 |
PHOTO: STORMSLIDE |
 |
PHOTO: STORMSLIDE |
Cam Lockwood, enterprise team leader for the US Forest Service’s Trails Unlimited enterprise, has more than 25 years of experience trying to do the impossible in remote locations. Lockwood says that for years he’s been trying to convince the people who build erosion control and stormwater solutions to create materials that can be easily carried up the trail to where they are needed. He was specifically looking for a lightweight, portable, stackable overside drain that could be used on trails. Because these devices were originally designed to be used on road projects, they are usually too big and heavy to be carried up a trail. And unfortunately for Trails Unlimited and the Forest Service, the trail business is a pretty small market compared to road construction.
Lockwood, who works and lives and Monrovia, CA, but is part of a nationwide team, was surprised and pleased when Jason Call of a new company called StormSlide seemed open to his ideas of creating some new lightweight products that would work for smaller, less accessible projects like trail work. The new product, called StormSlide, is an overside drain made of UV-protected polyethylene. It is lightweight and stackable and can be carried easily up the trail. Made from recycled materials and recyclable itself, it is designed to withstand heavy use from horses, hikers, and bikers, as well as the weather. Installed along trails near existing streams or lakes, the drain can send up to 0.75 cubic foot of water per second off of a trail and into the nearby waterway.
During a recent test project in Pleasanton, CA, the overside drains were installed on a hillside that later took a lot of abuse during California’s historic rainy season last year. When many other hillsides and streambanks lost integrity in the heavy rains, the demonstration site held its own. When StormSlide and Trails Unlimited asked for the materials to be returned after the testing period, Pleasanton asked if it could keep them instead. Lockwood says the project also helped the Forest Service see that it wanted to test StormSlide more extensively, and he ordered 100 packages of the materials to use around the country in demonstration projects.
Bringing Beauty Back Into the City
Questa Engineering of Point Richmond and Santa Barbara, CA, takes some of the same ideas of maintaining and enhancing natural beauty while doing erosion control work and brings them back to the cities. Questa’s streambank stabilization work seeks to minimize hard-armor solutions and maximize long-term natural solutions, says Syd Temple, principal civil engineer for Questa.
The company’s Coyote Creek project on a stream that flows from south to north into the San Francisco Bay is a good example of restoration work using this natural approach. Questa was hired to recontour 600 feet of severely eroded creek bank and to relocate a park access road and trail that had been destroyed by heavy rain. The project was funded by the Federal Emergency Management Agency, with a construction budget of $500,000. It involved coordination with the California Office of Emergency Services.
Temple explains that the work done on Coyote Creek in 2002 involved a combination of approaches, from biodegradable coconut fiber blankets to a 5-foot rock wall and extensive replanting of the streambank. Today the area has completely revegetated, and the erosion control methods are holding nicely. The newly planted trees are now 20 feet tall, and a casual visitor cannot even tell that area was completely rebuilt in 2002.
“After three years, you couldn’t even tell that there was any kind of hard [armor] in the channel now. You’d have to crawl down through the banks to find it,” Temple says.
Temple says this project—and many others his company has completed like it—involve sensitive ecology and require special attention to state and federal rules. For example, Coyote Creek is home to the California red-legged frog and steelhead trout. The company specializes in meeting these environmental needs but also maintains a philosophical approach favoring natural over hard-armor solutions. “We try to fit each project into the geomorphic and hydraulic context of the river,” Temple says, explaining that Questa uses a combination of computer modeling and ecological expertise to achieve this goal.
“People want to have access to these creeks. They want to walk down to a natural environment,” he says. “We never place even rock without planting when we place it.”
Another Questa project to address streambank failure was completed a few years earlier in the city of San Luis Obispo. Widespread bank failure problems occurred along the San Luis Obispo and Stenner creeks following floods in 1995 and 1998. Questa was hired to design biotechnical bank stabilization demonstration projects at eight sites. The designs used a wide variety of solutions, including live crib walls, geosynthetically stabilized fill slopes with planted riprap, rock flow deflectors, willow-staked fiber rolls and fiber rock rolls, and end-wrapped planted geogrids. The projects also included aquatic habitat mitigation including root wads, rock vortex weirs, and lunker fish habitat structures.
Advertisement
The presence of so many “micro climates” in the state of California makes Questa Engineering’s work much more challenging or interesting, depending on your perspective. “Sometimes that’s one of the biggest challenges of a project—just getting the vegetation and irrigation systems going,” Temple comments.
He notes that this environmentally centered approach to erosion control is not more expensive than focusing on hard armor, and in some cases it can be less expensive. And he believes biotech approaches can be as effective as hard armor because they help the land repair and stabilize itself, saving money in the long run.
November-December 2005
Stabilizing Streambanks
New products and techniques help keep banks steady in heavy-use areas.
By
Donna Gordon Blankinship
The people of DuPage County in the western suburbs of Chicago know Salt Creek as a lovely place to hike, bike, canoe, and bird watch. They visit the peaceful, tree-filled area to get away from their concrete- and asphalt-paved suburban lives. What they may not know is that the Salt Creek watershed is also an amazing example of water-quality renewal resulting from a multiyear, 10-mile project of streambank stabilization.The Salt Creek renewal project began in 1998 as a citizen initiative to address water quality, streambank maintenance, habitat, flooding, land use, public education, and recreation. The Salt Creek watershed covers about 150 square miles and involves more than 30 municipalities where nearly 500,000 people live. Salt Creek starts in northwest Cook County, runs south and east through DuPage County, and empties into the Des Plaines River in central Cook County.
The dense population had put a lot of pressure on the creek, causing soil erosion, water pollution, flooding, habitat loss, and decreased species diversity. Local and state government agencies tapped into the federal Clean Water Act—Salt Creek was labeled a priority watershed—to help fund what became such a huge project the dollar amounts and time involved made putting a price on it difficult.
Five stages of the project were completed over five years in two villages—Wood Dale and Elk Grove—by one contractor, McGinty Brothers. Jim Safran, vice president of McGinty Brothers, says this has been a complex operation with a need for creativity and skill. He gives a special nod to his backhoe operator and superintendent on all five phases, Sixto Casas, who he says is a bit of an artist with the materials used on this job, especially placing the A-Jacks interlocking concrete blocks, which should be perfectly even and level for long-lasting success.
|
| A-Jacks interlocking concrete blocks |
“It probably took us a couple of years to learn how to do it quickly and efficiently,” Safran comments. “There’s a trick to it. I know I couldn’t do it. I was out there supervising.”
He’s quick to add, however, that the product is worth the effort in the results it achieves and in the way the job looks when it’s finished. “It works very well. We’ve had very little failure with it,” Safran says of the miles of A-Jacks installed along Salt Creek.
Creativity and coordination both are very important on a job like this, notes Doug Buch, Great Lakes regional manager for Armortec Erosion Control Solutions, creator of A-Jacks. Another big challenge was access—the difficulty of working in a densely populated area while disturbing as little land and property as possible. And despite the immensity of the project and the diversity of agencies supporting it, money was still an issue. “You can design anything, but can you build it within economic reason?” Buch says that is always the question project planners must ask.
Access Issues
To conquer some of the access issues, the project managers chose A-Jacks. The interlocking concrete pieces are relatively small in comparison with other kinds of hard-armor solutions and can be moved with smaller machines that weigh only 3,000 to 4,000 pounds, as compared to big excavating equipment that can weigh up to 90,000 pounds. This enabled the workers to avoid crushing turf on a golf course, for example, and keep from ruining existing landscaping in residential areas.
The A-Jacks are connected together along the bank in a way that is flexible and permeable. They can be installed either randomly or in a uniform pattern. Space is left between the pieces to be filled in with habitat for fish below the water or with soil above the water that can be planted with grasses, shrubs, and trees.
|
PHOTO: ARMORTEC |
| Oak Meadows Golf Course project stages from start to finish. |
|
PHOTO: ARMORTEC |
|
PHOTO: ARMORTEC |
|
PHOTO: ARMORTEC |
|
PHOTO: ARMORTEC |
|
PHOTO: ARMORTEC |
Safran says he was pleased with how quickly and thoroughly the land around and over the A-Jacks revegetated. The blocks were installed in several different configurations on the job, depending on the severity of erosion. In some places, one row of blocks, partially under water, was enough. In other spots, the pieces were stacked in small pyramids with two blocks under water supporting another one on top. In a third scenario, three blocks under water supported two partially submerged and one on top. Safran says the coordination and skill needed to make such arrangements takes a bit of work, but once A-Jacks are installed they last a long time. “Salt Creek is a tricky creek. It really rises fast and comes down quickly,” he adds.
The concrete structures come in diameters of 24, 48, 72, 96, and 120 inches. When combined with bioengineering techniques and given a few seasons for surrounding vegetation to get established, the A-Jacks can become completely invisible. The smaller pieces weigh around 40 pounds so they can be put in place by human beings, but the larger ones weigh more than a ton and require a backhoe and sling for assembly.
The Salt Creek project also made use of wood and plastic lunkers about 6 feet long, 12 inches tall, and 2 feet deep to sink under the edge of the stream to provide places for fish to spawn and improve the habitat. “Lunkers are pretty pricey,” Buch points out. “You don’t want to do a whole stream in lunkers.” So the project managers combined several solutions—from lunkers to A-Jacks—alternating along the streambed.
This project demanded extensive negotiation skills on the part of the agencies involved. Much of the streambank had become more or less private property as homeowners ran their grasses right up to the edge of the stream. These turf grasses were part of the problem because of their short root base. When the streambank was built up with A-Jacks and filled in with thicker prairie grasses, the homeowners—and the managers of the Oak Meadows Golf Course—had to give something up in order to see the streambank stabilized.
Looking Ahead
At the other end of the erosion control timeline from Salt Creek is a project in Arlington, TX, that is just the beginning of what will likely turn into a multiyear, multimillion-dollar endeavor.
Johnson Creek runs through the length of Arlington, and when spring rains fall the water runs fast and flood danger is high. A series of projects is just beginning to address the flow and flood problems, as well as to look ahead at pedestrian access and beautification of the area. Arlington is about to become the center of a major urban renewal project. The Dallas Cowboys are getting ready to build a new stadium in this community halfway between Dallas and Fort Worth, and the city wants to take care of the flooding while building new public access areas like walking paths along the creek. A historical trail featuring pioneer cabins, an old one-room schoolhouse, and a barn are already attracting some tourist attention along the creek.
Jeff Tanner, area field superintendent for Ark Contracting Services, says his company recently finished a project installing gabions along one section of the creek to improve the shoreline and also slow down erosion after the city installed some new sewer lines. Johnson Creek runs mostly through residential areas, so much of the creek-side property is privately owned, offering challenges similar to those at Salt Creek. But erosion problems on Johnson Creek may be poised to get worse, not better, as construction work begins on the new stadium and new highways are needed to alleviate traffic problems in the area. Tanner says increased stormwater runoff from construction sites and new roads is bound to be bad for the creek.
He notes that the US Army Corps of Engineers is making efforts to improve some sections of the creek that are especially in need of help. Last June the corps completed the first phase of a $27 million project, which includes buying homes in the floodplain, building recreational areas, and making environmental improvements along the creek. The project includes the digging out and widening to 90 feet at the bottom for up to a mile of Johnson Creek to help water flow right before it enters the Trinity River system. Gabions were used for bank stabilization. The corps is scheduled to continue making bank improvements over the next few years.
Tanner says that unless the whole creek system is addressed, erosion problems will continue and could just move over the areas that are not addressed by the individual projects. Citizens recently defeated a ballot proposal to spend more than $25 million on improvements to the creek. Tanner felt that was shortsighted of the residents of this rapidly growing community, who had just approved spending millions of dollars to help build a new football stadium and its surrounding infrastructure.
“Johnson Creek is about the worst creek in Arlington,” Tanner says. Water comes and goes through the creek during rainy periods in a dramatic fashion. Flooding is inevitable in some sections of the creek, and with flooding comes erosion in many cases.
Tanner commends the City of Arlington for trying to plan ahead for the impact of rapid residential growth and the new football stadium. “They’re trying to save everybody a bunch of headaches,” he says. So when new sewer pipe needed to be laid across the creek, the city’s contractor decided to have Ark Contracting put in some gabions to slow down erosion in that part of Johnson Creek.
Every effort toward erosion control helps, Tanner observes, even though he would like to see a bigger, more comprehensive plan completed for the creek. He has seen gabions make a big difference in projects like this, because products like the Terra Aqua Gabions that were used on this job are a much better solution for fast-flowing creeks than building a cement wall. He likes the way the gabions continue to fit the shoreline even when some dirt flows away. Molding to the situation is something a cement wall cannot do, he points out.
Tanner expects the work on Johnson Creek is just getting started, despite the lack of citizen enthusiasm for spending money on erosion control. The City of Arlington is doing its part with extensive public education about keeping the city’s creeks healthy. The city’s Web site offers a series of lively pages explaining why creek health is important and what citizens can do to make a difference in what is literally their own backyard.
Carrying Materials on Your Back
Beauty and erosion control are even more closely related when people move a little farther out of the city and start walking in our nation’s parks, forests, and recreational areas. Portability of construction materials becomes a crucial element when erosion control work is done in very remote locations, such as along a mountain creek where the only way to get to the site is on foot.
|
PHOTO: STORMSLIDE |
| Lightweight and stackable StormSlide can be easily transported up a trail and quickly installed by one person. |
|
PHOTO: STORMSLIDE |
|
PHOTO: STORMSLIDE |
|
PHOTO: STORMSLIDE |
Cam Lockwood, enterprise team leader for the US Forest Service’s Trails Unlimited enterprise, has more than 25 years of experience trying to do the impossible in remote locations. Lockwood says that for years he’s been trying to convince the people who build erosion control and stormwater solutions to create materials that can be easily carried up the trail to where they are needed. He was specifically looking for a lightweight, portable, stackable overside drain that could be used on trails. Because these devices were originally designed to be used on road projects, they are usually too big and heavy to be carried up a trail. And unfortunately for Trails Unlimited and the Forest Service, the trail business is a pretty small market compared to road construction.
Lockwood, who works and lives and Monrovia, CA, but is part of a nationwide team, was surprised and pleased when Jason Call of a new company called StormSlide seemed open to his ideas of creating some new lightweight products that would work for smaller, less accessible projects like trail work. The new product, called StormSlide, is an overside drain made of UV-protected polyethylene. It is lightweight and stackable and can be carried easily up the trail. Made from recycled materials and recyclable itself, it is designed to withstand heavy use from horses, hikers, and bikers, as well as the weather. Installed along trails near existing streams or lakes, the drain can send up to 0.75 cubic foot of water per second off of a trail and into the nearby waterway.
During a recent test project in Pleasanton, CA, the overside drains were installed on a hillside that later took a lot of abuse during California’s historic rainy season last year. When many other hillsides and streambanks lost integrity in the heavy rains, the demonstration site held its own. When StormSlide and Trails Unlimited asked for the materials to be returned after the testing period, Pleasanton asked if it could keep them instead. Lockwood says the project also helped the Forest Service see that it wanted to test StormSlide more extensively, and he ordered 100 packages of the materials to use around the country in demonstration projects.
Bringing Beauty Back Into the City
Questa Engineering of Point Richmond and Santa Barbara, CA, takes some of the same ideas of maintaining and enhancing natural beauty while doing erosion control work and brings them back to the cities. Questa’s streambank stabilization work seeks to minimize hard-armor solutions and maximize long-term natural solutions, says Syd Temple, principal civil engineer for Questa.
The company’s Coyote Creek project on a stream that flows from south to north into the San Francisco Bay is a good example of restoration work using this natural approach. Questa was hired to recontour 600 feet of severely eroded creek bank and to relocate a park access road and trail that had been destroyed by heavy rain. The project was funded by the Federal Emergency Management Agency, with a construction budget of $500,000. It involved coordination with the California Office of Emergency Services.
Temple explains that the work done on Coyote Creek in 2002 involved a combination of approaches, from biodegradable coconut fiber blankets to a 5-foot rock wall and extensive replanting of the streambank. Today the area has completely revegetated, and the erosion control methods are holding nicely. The newly planted trees are now 20 feet tall, and a casual visitor cannot even tell that area was completely rebuilt in 2002.
“After three years, you couldn’t even tell that there was any kind of hard [armor] in the channel now. You’d have to crawl down through the banks to find it,” Temple says.
Temple says this project—and many others his company has completed like it—involve sensitive ecology and require special attention to state and federal rules. For example, Coyote Creek is home to the California red-legged frog and steelhead trout. The company specializes in meeting these environmental needs but also maintains a philosophical approach favoring natural over hard-armor solutions. “We try to fit each project into the geomorphic and hydraulic context of the river,” Temple says, explaining that Questa uses a combination of computer modeling and ecological expertise to achieve this goal.
“People want to have access to these creeks. They want to walk down to a natural environment,” he says. “We never place even rock without planting when we place it.”
Another Questa project to address streambank failure was completed a few years earlier in the city of San Luis Obispo. Widespread bank failure problems occurred along the San Luis Obispo and Stenner creeks following floods in 1995 and 1998. Questa was hired to design biotechnical bank stabilization demonstration projects at eight sites. The designs used a wide variety of solutions, including live crib walls, geosynthetically stabilized fill slopes with planted riprap, rock flow deflectors, willow-staked fiber rolls and fiber rock rolls, and end-wrapped planted geogrids. The projects also included aquatic habitat mitigation including root wads, rock vortex weirs, and lunker fish habitat structures.
The presence of so many “micro climates” in the state of California makes Questa Engineering’s work much more challenging or interesting, depending on your perspective. “Sometimes that’s one of the biggest challenges of a project—just getting the vegetation and irrigation systems going,” Temple comments.
He notes that this environmentally centered approach to erosion control is not more expensive than focusing on hard armor, and in some cases it can be less expensive. And he believes biotech approaches can be as effective as hard armor because they help the land repair and stabilize itself, saving money in the long run.