Shoreline and Streambank Protection

July 1, 2004
Finding a happy medium between beauty and function has always been a challenge in shoreline protection projects, but some new materials and methods have helped alleviate this difficulty in recent years.A Manicured CourseErosion control and shoreline stabilization at golf courses is an excellent example of this progress, because that’s where the need for beauty is equal to the necessity of solving the erosion problems. Scott Werner, superintendent of the Lincolnshire Fields Country Club in Champaign, IL, says he learned the hard way how important it is to consider the look of a project and not just the function. In 1997, Lincolnshire Fields, in cooperation with the local drainage district, worked to clean out and restore a creek running through the golf course. They decided to revegetate the slopes with native grasses to correct the erosion.
BeforeRiverwalls replaces broken concrete and riprap with steel at a 14-acre Lincolnshire Fields Country Club Lake
After“We really expected that to be very well received by our club members, and, frankly, it hasn’t been. Not all-but enough-of the members just didn’t like the look of the longer grass. Some of them call it weeds. Golf balls go in and they can’t find them,” Werner says.So the next time Lincolnshire Fields had a need for erosion control, it called in a golf course architect, William Spears & Associates of St. Charles, IL, to advise on ways to solve the problem in the most aesthetically pleasing way. The architect sent them to Riverwalls Ltd. in Barrington, IL, where CEO Darryl Burkett has developed a new method for installing steel retaining walls that does not mar the appearance or function of the surrounding golf course.Burkett has applied for a patent for his trailer-mounted crane, which uses a thousand-pound vibratory hammer to drive the steel walls into the ground without impacting the surrounding greens. He says his clients are surprised by how quickly the work is completed and how neat the results are. When Riverwalls is finished, all that’s needed is a quick pass with an aerator and some fertilizer for good measure. “After one or two cuttings, you can’t tell where we were,” he is fond of saying.Burkett’s team just finished this past spring another project at Lincolnshire Fields, which involves shoring up a pond on the 13th hole that also serves as stormwater storage. Ever since the creek bed project in 1997, the stormwater pond had experienced erosion, according to Werner. So the course hired Riverwalls to put a steel wall around the pond and, at the same time, to build a waterfall on the high end of the pond where the creek flows into it. The pond is less than an acre in size and required 600 linear feet of steel shore. The waterfall is built out of outcropped stone in three tiers.Werner says he’s excited about the way the project, which got underway in December 2003, combines beauty and function. Before winter arrived in earnest, Burkett’s team was able to install most of the shore wall and complete about 60% of the waterfall. When the weather broke in March, they got back to work and finished in April.In 1998, Riverwalls installed another steel wall on a 14-acre lake on a different part of the course, where the shore had been protected by broken concrete and riprap “that really was not very attractive,” according to Werner. “We looked at different methods of dealing with the erosion and the aesthetics, and the golf course architect steered us toward the steel.”Werner notes that steel is certainly not the least expensive way to approach shoreline protection, but for the long term, it can make up for the initial expense with longevity – which, at a golf course that has been in use since 1965, is important. “It is expensive; however, anything we’ve looked at as far as hardscape solutions has all been very costly. And out of all of those things, the steel is the most attractive. It also is a long-lived solution. All the people involved don’t really expect to deal with it again within their lifetimes,” Werner says.Club members like the look of finished grass right up to the edge of the steel barrier. Werner says he likes working with Burkett because he understands the unique pressures of golf course management-not only through his work, but also as a member of Rolling Green Country Club in Arlington Heights, IL. “He does most of his work on golf courses,” says Werner. “He’s a long-time golfer and member of a country club, and he understands the special requirements” to not wreck the course while working to repair it.Protecting Streambanks
Stacked concrete wall reinforcing the shoreline at a 90° turn in Napa Creek. Top and Above. The wall just after completion. Open spaces allow vegetation to grow.
Below. A poured-in-place concrete wall along Napa Creek was falling
Another series of projects where both beauty and function were important occurred along two creeks on the central California coast near Santa Rosa. A series of streambank enhancements became necessary over the years as development upstream led to increased peak flood loads, according to Steven Shigematsu of Matterhorn California Inc.Near a new apartment complex on Napa Creek, Matterhorn was able to help the engineers improve the stability of the slope while completing with a 90° turn in an attractive way. At first, the engineers involved in the project had planned to install a cast-in-place concrete retaining wall because Juan Hildalgo, the project geotechnical engineer, felt the wall would be the best way to withstand the increasing water flows. Gil Pridmore, the grading contractor, suggested they contact Phil Zeidman of Matterhorn to see if he had a more environmentally favorable alternative.After spending time visiting similar creek bed projects using what the company calls “bioengineered streambank stabilization,” Hildalgo decided to go with Matterhorn’s segmental block retaining walls, which allow natural revegetation over time. Four years after this project was completed, about 40% of the block face is now covered in vegetation, despite the fact that several times a year the creek rises almost to the top of the wall.This shoreline project was completed as a protective measure before the apartments were built, not because of an emergency. “Through observation, [government officials] saw that the creek bank would be falling in more and more each year. They were afraid that when they built the apartments, erosion would eventually undermine the apartments,” Hildalgo says.The project was complex for several reasons, including the space restraints and the weather, but Hildalgo says he is pleased with how well it has held up to the high waters of the creek. Since then, he has used the segmental blocks for several of his projects because of the aesthetics and flexibility of the product, but he sticks with concrete walls for very steep slopes.
Matterhorn’s block now can be seen (or not seen, depending on the extent of the revegetation) all along Napa Creek. In fall 2003, at a different place along Napa Creek, Matterhorn was able to help the California Department of Fish and Game complete an emergency replacement of a failing poured-in-place concrete wall. The failed concrete retaining wall had allowed the bank to erode to the point that a concrete slab supporting the property owner’s in-ground pool had subsided about one foot at the top edge of the creek bank. Engineers believed two flood-stage storm flows would have taken out enough of the eroded streambank to collapse the concrete slab, the pool, and most of the owner’s backyard into Napa Creek. Installation of the new concrete block structure was made in time to avoid the winter flood season.Reinforcing Sandy ShoresBauman Park Lake, in Cherry Valley, IL, presented some tough shoreline erosion problems. The lake is a former sand quarry that was sold to the village of Cherry Valley. The Illinois Environmental Protection Agency (IEPA) hired Hanson Professional Services of Springfield, IL, to monitor quality of the lake and later contracted with the company to repair the shoreline in hopes of improving that quality.
At Bauman Park Lake, applying an articulated concrete mat to the sandy shore (above), the shoreline finished (below), and the river’s edge covered in grasses that render the erosion control installation virtually invisible (bottom)
“There were significant water quality concerns because of shoreline erosion,” explains Chris Cooper, project manager for Hanson. The shoreline was all sand, so it was difficult to get vegetation started. Once it was started, it had to hold out against the next biggest problem at the lake: aggressive anglers, who trampled most new vegetation before it got a good hold on the land.Hanson selected ArmorFlex for one section of the complicated shoreline job, in part because it can be backfilled with topsoil that can subsequently be planted and results in shoreline protection that is nearly invisible. ArmorFlex, from Armortec, is made up of individual concrete blocks that are cabled together and delivered to a job site “pre-laced” into site-specific engineered mats. “The beauty of it was how uniform it looks and how quickly it went in. The riprap looks nice too, but installation is much more complicated,” says Cooper.IEPA decided to try multiple approaches to solve both the shoreline erosion problem and the “fisherman problem.” Cooper does not recall why IEPA took a multifaceted approach to this erosion control problem, although he suspects they were interested in seeing the different alternatives side-by-side to compare them for future uses.First, steps and fishing piers were constructed in several places on the lake to encourage fishermen to keep off the sensitive shoreline while vegetation was establishing itself. Cooper says this corralling was somewhat successful in the areas where the piers were located but that it also created another, affiliated problem: the fishermen had a bad habit of creating litter in the areas where they congregated.The second solution was to use coir logs made of coconut fibers as “nurse logs” to establish vegetation along some parts of the shoreline. Native plants such as bulrushes were transplanted into these areas. The areas were cordoned off so the fishermen could not walk over the seedlings, but, unfortunately, Canada geese are unaffected by signs and barriers. Cooper says the geese have eaten a lot of the new plantings, so this part of the project hasn’t been as successful as the partners hoped.The third part of the project involved installation of either riprap or ArmorFlex. They both look attractive and encourage revegetation, but neither is very good at discouraging fishermen from walking over the new plantings, according to Cooper.The hard-armor alternative of Amortec was used in the steepest areas of the shore and then filled in with topsoil and slope mix. It has been very successful, as has the riprap, according to Cooper. Amortec is a little easier to maintain, he adds.Larger-than-usual rocks, averaging two feet in diameter, were used for the riprap, to give the area more aesthetic appeal, but Cooper says these large rocks also contributed to the difficulty of the installation.Both erosion and water quality have improved at the lake since the project was completed two years ago. Cooper says shoreline erosion has probably been mitigated for 80% of the lake, and turbidity has decreased, while the amount of dissolved oxygen in the water has increased. “There’s been significant improvement,” Cooper says. “We ran out of money, so we might have beaten the fishermen.” The community and IEPA would not consider making the lake off-limits to fishermen until the problems could be resolved; otherwise there could have been a 100% success rate, Cooper believes. “There are areas that could be improved further, if there was more money to spend,” he says.Oceanfront Applications
Shoring up a small stormwater storage pond at the Lincolnshire Fields 13th hole before, during, and after, from top
When Virginia Marine Structures of Virginia Beach won the contracts for two projects with the US government-one at the Norfolk Naval Base and the other at the Assateague Island Bridge Project contracted by the National Parks Service-the first thing it did was file a “value engineered concept proposal” to use a new product that Northstar Vinyl had developed for large-scale shoreline protection projects. Chris Coleman, CEO of Virginia Marine, says his company has been working closely with Northstar as a sort of guinea pig to demonstrate this new sheet piling that he says fills in the gap between vinyl durability and steel durability, between 8 feet and 20 feet.“We used to have to use steel because it was the only product available [for projects that needed more durability than conventional vinyl could provide]. It almost put a lot of projects out of reach,” Coleman says. “It’s a great concept, and as far as the line of work I’m in, it’s a perfect match.” Northstar claims that its new Endurance composite seawalls are 10 times stronger than vinyl. The patent-pending carbon-enhanced polyurethane resin uses a special fiber-reinforcing matrix.Coleman’s company works with all three products now: vinyl, composite seawalls, and steel. The potential cost savings, combined with a guarantee from Northstar of long-term durability-a 50-year warranty on this product-is what convinced the government to agree to the proposal. Contractors who successfully sell the government on such proposals get to split the cost savings, 55/45: The contractor saves 55%, and the government saves 45%. Between the two projects, the government saved a total of about $500,000 over the use of steel. Coleman says this is partly because steel is now at its highest price in about 50 years.The Norfolk Naval Base project was completed first, repairing a 50-year-old docking area for oceangoing vessels. The steel bulkhead in the docking area was deteriorating. Brian Horton, president of Northstar, says his in-house engineers worked with the Navy for about four months to redesign the project to work with the composite sheets.Although the sheet piling itself isn’t much less expensive than steel, the installation is faster and some components can be eliminated. For example, for this $4 million project along 3,900 feet of shoreline, Virginia Marine was able to eliminate the entire well system and the tie-back system. The project took half the time it would have if steel had been installed instead.The 1,100-foot $1.7 million shoreline project at the Assateague Island Bridge was scheduled to take a year but was finished in five months. Just the savings in labor has a significant impact on the final cost, according to Coleman.He says federal officials were “thrilled to death” by the project results. “The federal Department of Transportation is writing an engineering report on this project. They are very pleased.”The Navy site was hit by two big storms last summer in the middle of installation-a nor’easter and a hurricane-and the sheets held. If the project had not been underway, the storms could have caused more serious damage to the old structure, Horton believes.