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    1. Erosion Control
    2. Vegetation Management

    Engineering Meets Environmental at Fee Fee Creek

    Sept. 1, 2003
    There’s a certain irony in living by a creek. People choose to build or buy existing homes near these waterways because of the natural beauty they can provide. But the very nature of development can change the hydrography, hydrology, and morphology of a creek. What was once friend has become foe.It was that way with Fee Fee Creek, located in Maryland Heights, MO, a suburb of St. Louis. Fee Fee Creek is a tributary to the Creve Coeur Creek, which in turn flows into the Missouri River.

    The condition at Fee Fee Creek before the project was a severly eroded stream filled with debris.Homes had been built along Fee Fee Creek’s north bank in the 1960s and 1970s, before the city was incorporated in 1985. This development – as well as residential and commercial development farther upstream – increased the imperviousness of the watershed feeding Fee Fee Creek, which in turn increased the runoff and velocity of water flowing in the creek. Through the years, homeowners began dumping grass clippings and other debris down Fee Fee Creek’s banks, killing vegetation that had held soil in place.Fast-forward a couple of decades, and the once-attractive, meandering stream had changed dramatically. Because of the increase in stream flow, the creek began to undergo entrenchment, a process by which the stream bottom drops, which caused the banks to slide into the stream. Several hundred feet of embankment had a near-vertical face because of the erosion. A number of outfall pipes from an existing drainage system had been undermined and were in varying states of disrepair. Many trees with trunks as large as 3 ft. in diameter had fallen victim to Fee Fee Creek’s destructive forces and had plunged into the water.The entrenchment of Fee Fee Creek was so advanced that residents were losing their backyards; some fences were ready to tumble into the water. Left unchecked, the creek threatened to claim sheds and swimming pools. In 2001, the City of Maryland Heights stepped in to stabilize a 1,900-ft. section of Fee Fee Creek. The city hired Woolpert LLP, a national consulting firm that provides engineering and environmental planning and design, to study the creek’s problems and recommend a sustainable stream design solution. Woolpert assembled a team of surveyors, geotechnical engineers, hydraulic engineers, and environmental scientists to perform the project, which included the following:Topographic and boundary surveysHydrologic and hydraulic modelingBiostabilization designPlans and specifications preparationCost estimatingEasement plat preparationBid servicesTechnical support during constructionAt the center of Woolpert’s recommendations was the use of certain instream and on-bank design techniques, including the J-hook weir, Newbury riffle pool, wrapped earth, and root wads. These techniques have been used in other regions of the United States but were relatively new to the St. Louis region. They are part of a sustainable stream design movement that takes a natural and holistic approach to stream stabilization.Although the City of Maryland Heights is considered progressive when it comes to stormwater management, some city officials and local homeowners still were a little skeptical of the techniques that Woolpert was recommending. Convincing stakeholders that sustainable stream design is as effective as traditional stream improvement methods – not to mention healthier for water quality and wildlife – was part of the educational process that included public presentations describing the process and benefits.“We’re taking a different approach to creek stabilization,” says L.G. Loos, P.E., assistant director of public works for the City of Maryland Heights. “We’re looking at Fee Fee as an overall unit – as an entire ecosystem – instead of doing spot fixes. We’re learning what caused problems to form in the first place and remedying them with sustainable solutions.”The Beginning

    The entrenchment at Fee Fee Creek was so advanced that large trees had fallen over and backyards were losing footage.Several years ago, Fee Fee Creek was identified by the City of Maryland Heights’s stormwater management committee as highly eroded and therefore eligible for capital improvement. The $600,000 stabilization project would be paid for in part by a State of Missouri stormwater grant. The city hired Woolpert for its engineering and environmental expertise and knowledge of sustainable stream design solutions that had been implemented in such states as Ohio, Kentucky, and North Carolina.The first step, in 2001, was to walk Fee Fee Creek to take samples, evaluate existing conditions, and determine the root causes of the degradation. What was found was not only a highly entrenched stream but also evidence of manmade carelessness, including discarded car parts and tires, old washing machines, concrete rubble, and rotting yardwaste. A number of large-diameter trees had fallen into the creek, while others were about to. The next step was to conduct a topographic and boundary survey in which the locations of trees, homes, fences, streambanks, and property lines were identified. Woolpert further defined the stream’s existing characteristics by computer modeling Fee Fee Creek using the hydraulic software HEC-RAS. The results established baseline hydraulic conditions for use in determining the impact of the proposed construction. Next, Woolpert subcontracted with Seattle, WAbased Shannon & Wilson Inc. to conduct a geotechnical investigation, which involved analyzing existing soil conditions, including the types of soil, natural moisture content, and the soil’s inherent stability. Shannon & Wilson found that the types of soil at Fee Fee Creek – ML and CL (silty and sandy clays) – would be suitable for the stream stabilization improvements that Woolpert was recommending. The consultant also made recommendations regarding the maximum allowable bank slope and compaction requirements.Based on the field investigation, various surveys, computer modeling, and the geotechnical investigation, it was determined that a combination of natural on-bank and instream design solutions would be used to stabilize Fee Fee Creek. The creek was again modeled using HEC-RAS to verify that there would be no rise in the 100-year water surface elevation (as defined by the Federal Emergency Management Agency) as a result of the proposed stream improvements.Construction drawings and specifications were prepared to the same level of detail as traditional engineering projects and were sent out for bid. Larry Ortmann Contracting Inc. of Labadie, MO, was awarded the construction contract in December 2002, and actual construction began in early 2003.On-Bank Solutions
    A geotechnical engineer uses a pocket penatrometer to determine the strength of the soil.The streambanks and riparian zones were fortified using several techniques that worked in concert with each other.One technique was the riprap toe, a commonly used method that stabilizes the base of a bank. In the case of Fee Fee Creek, large riprap stones were installed along the lowest 3 ft. of eroded bank areas.In one area of the creek, a more radical approach – the rock buttress – was needed to shore up a 22-ft.-high bank that had no room to flatten the existing 1:1 failing bank slope. Stones ranging from 6 in. to 2 ft. in diameter (5-650 lb.) were placed on the face of the 1:1 slope. Once a depth of 5 ft. of rock had been achieved, soil was compacted on top. Coir fabric and willow live stakes then were installed.In the area of a particularly sharp bend, the riprap toe was supplemented with a technique known as a root wad, which consists of recycling large trees (18-24 in. in diameter) that have fallen over because of erosion. The tree trunk is cut 10-12 ft. above the root ball, and the end is sharpened in the shape of a pencil tip. Then the pointed end is embedded 8 ft. into the existing earth, leaving the root ball exposed along the bank and facing slightly upstream to absorb scour energy, thus reducing the impact of shear stress on the bend.A series of root wads is set in place with the root balls overlapping each other while large stone is placed around the exposed trunks. Depending on the species, the root balls can last up to 25 years while providing scour protection and aquatic habitat.
    Installing root wads at Fee Fee Creek“It’s like a natural ‘ armor’ that protects the bank at sharp turns,” explains Joseph Krypciak, P.E., a senior engineer with the City of Maryland Heights. “We felt it was an odd technique at first, but we believe it’s based on sound principles and will be effective at Fee Fee Creek.” A bank treatment known as wrapped earth was used to complement the root wads.The wrapped-earth technique consists of wrapping coir fabric – a woven coconut fiber mesh – around compacted earth lifts and placing willow branches between each lift. Wrapping the earth in this way enables rebuilding and revegetating banks at a somewhat steeper slope than simply compacting the earth. In areas of milder slopes, coir fabric was laid directly on top of the earth and live willow stakes were driven through the fabric and into the bank.The live branches and live stakes are installed during the dormant period of the growing season (late winter to early spring). The stakes and branches are about 48 in. long and have a diameter of 0.250.50 in. They consist of a mix of buttonbush, Streamco willow, Bankers willow, and red osier dogwood.In addition to willow plantings, native shrubs, grasses, and wildflowers – those with deep root structures that thrive in the shade – will be planted along Fee Fee’s banks. A variety of trees also will be planted along the banks to help shade the water, reduce the temperature, and promote aquatic habitat.“Revegetating the banks of Fee Fee Creek is the common ‘ theme’ or technique throughout the design,” Krypciak says. “We’re following an approach that is supported by the US Army Corps of Engineers – to use natural methods [that] not only stabilize the creek but also support aquatic life. Just a few years ago, we might have considered Fee Fee solely for its drainage function and lined this channel with concrete – and that’s what a lot of people are used to seeing. But residents are really pleased with these more natural techniques.”Instream Solutions

    Constructing a Newbury riffleA total of six J-hook weirs, so called because the placement of rocks involved resembles a “J,” will be developed around bends in Fee Fee Creek. The technique was pioneered by Dave Rosgen, a geomorphologist and founder of Wildland Hydrology based in Pagosa Springs, CO. It has been used for about a decade throughout the US but still is gaining acceptance in the St. Louis region.The J-hook weir is a series of strategically placed rocks designed to redirect the flow of water to the center of the stream. The J-hook is embedded approximately 5 ft. into the bank and curves out into the water, gradually sloping downward. The rocks are placed without gaps between them closer to the bank (to slow the water and direct it toward the center of the stream) and with gaps between them nearer the center and end of the J-hook (where the swirl of water is more beneficial, creating deeper, oxygenated pools for aquatic life). Rocks should be square; their size depends on the size and velocity of the stream. At Fee Fee Creek, the size of rocks will vary from 2.5 to 3.5 ft. across, weighing from 1,000 to 4,000 lb.The Newbury riffle pool – also gaining popularity in the St. Louis region – was chosen as another way to slow the velocity of water and to improve water quality by aerating the water with riffles and providing deeper pools for aquatic life. A total of 11 Newbury riffle pools are being installed at Fee Fee Creek.Created by Robert Newbury of Newbury Hydraulics in British Columbia, Canada, the technique is based on the principle that riffles and pools can be created to mimic naturally occurring riffle-pool complexes. Similar to their naturally occurring counterparts, the manmade riffles at Fee Fee Creek are being strategically placed to create upstream pools through the bends.To create this system, the riffle crest first is built across the stream using large-diameter boulders. At Fee Fee Creek, stones from 2.5 to 3.5 ft. in diameter (1,000-4,000 lb.) will be used to create the crest, which spans the width of the stream and embeds into the bank. The goal is to set the crest stones at the proper elevation to create the desired pool elevation upstream of the crest. Next, support stones ranging from 1 to 2.5 ft. in diameter (75-1,000 lb.) will be set in place behind and in front of the crest. Each riffle will have a 4:1 sloped upstream face and a 20:1 sloped downstream face. Smaller stone is used to fill the remaining gaps.Special Considerations at Fee Fee Creek

    Installing willow stakes into the wrapped earth at Fee Fee Creek
    Educating Decision-Makers, the Public, and the Contractor. Because sustainable stream design in the St. Louis region is relatively new, Woolpert gave a presentation to the city’s public works department and stormwater management committee as the project began to ensure a level of comfort with the specific recommendations. The presentation described the techniques that were being proposed for Fee Fee Creek. Woolpert also held a prebid meeting that included a video and PowerPoint presentation so contractors would feel comfortable submitting bids for this unique type of stream stabilization. Once a contractor was selected, a workshop was held with the city’s inspectors and the contractor to discuss details of the techniques and construction methods. Maryland Heights also must continue the education process when the project is completed in order to convince residents to refrain from discarding grass clippings and debris onto the streambanks in the future.Obtaining Permits. Because of its urban setting, stabilizing Fee Fee Creek required permits from several agencies. Early on, the applicable agencies – the US Army Corps of Engineers, the Missouri Department of Natural Resources, and the Metropolitan St. Louis Sewer District – were engaged in the design process. A preapplication meeting was held where representatives of these agencies walked the site with the consultants and ideas for improvements were discussed. Input from the agencies was sought early in the project and was incorporated into the plans and applications so that there were no surprises during the permitting process. Gaining Access. One challenge at Fee Fee Creek was to obtain adequate access to the construction site. One side of the stream consists of homes perched high on a terrace; access via this side would have been impossible. The other side is flat and without homes but includes a railroad track corridor. In order for construction equipment to access the creek, permission was sought and granted from the railroad authority, which involved a series of meetings and negotiations. Once approval was obtained, special consideration had to be given to ensure safe access of personnel and construction equipment across the railroad tracks.
    A stretch of improved Fee Fee Creek that includes root wads, wrapped earth, and rock toeDealing With a Tight Time Frame. Time became an issue in several ways. First, the construction contract had to be awarded by the end of 2002 in order for Fee Fee Creek to still be eligible for state grant funding. Second, negotiations with the railroad authority slowed the start of construction. The slow start pushed back the time that the planting of vegetation was to occur – and this planting had to happen during the colder months, while plants were dormant, to ensure that they would take root properly. Although some plants were installed in winter and early spring 2003, other plants were not scheduled to be installed until later in the year. A number of shrubs and trees that are not as sensitive to planting times were installed but will need to be watered for up to a year on a regular basis to make sure they take root.Merging Engineering and Environmental Worlds. For years, engineers in the St. Louis region have recommended stream stabilization designs based solely on engineering and hydraulic principles as opposed to sustainable environmental techniques. The challenge at Fee Fee Creek was to merge traditional engineering techniques with environmental methods to design the best solutions for the situation. “The city believes in this approach. We’re looking beyond just stabilizing an eroded area and toward the overall health of the stream,” Loos says.The natural on-bank and instream techniques that were chosen to help stabilize Fee Fee Creek not only will address erosion but also will become an attractive and integral part of the stream’s ecosystem, designed to promote aquatic and wildlife habitat for years to come. By assembling a team of qualified engineering and environmental professionals, Woolpert was able to provide Maryland Heights a natural, effective, and long-term method to address the stream degradation problems at Fee Fee Creek.