As the third of a three-part series on stream restoration, this article is intended to provide some insight gained from direct experience by owners, designers, and contractors, and for the readers’ consideration to improve success with their own projects. Having the knowledge of shared experience up front can help facilitate a successful stream restoration project.
The first article of this series dealt with stream restoration as a valuable watershed management practice. The second article discussed construction issues. This final article combines these perspectives and ties them together through a lessons-learned perspective.
Owners
Owners can range in type—from a small property owner to the federal government. Similarly, levels of project sophistication may vary as a function of budgets, staffing, experience, and skills. Stream restoration has a longer period of design, construction, and monitoring than conventional projects because it incorporates living materials as an integral part of the design. Once established, your project should endure for many years and require very little maintenance. Can the same be said of a gabion basket?
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| Low-pressure equipment allows for better site access and reduced compaction. |
One of the biggest problems with stream restoration projects is with logical physical termini, which is largely a function of the owner’s perspective of the problem and potential solution. Where do you begin and end the project? This decision can be driven by property lines, municipal jurisdictions, the physical limits of the problem, the infrastructure being protected, funding sources, or funding limitations. The key to success is to establish logical end points. Go beyond the limits of the problem or begin at a culvert or a bridge. Select locations where there is horizontal and vertical control, where the forces of the stream are no longer unstable, or where you can successfully design a robust solution to end on (like a riffle).
One problem is that too many owners try to attack the project as a point or localized segment fix, and the project unravels from either the upstream or downstream project boundaries. If you are aware of this problem up front, you may be able to select these boundaries yourself. It is also not unusual to have the designer come back with recommendations for a new terminus. You cannot fix all the problems in a stream, but you can take the steps to improve the success of your project by recognizing the problem, understanding the potential solutions, and starting and stopping in the right place, and you must have the resources to do it right.
Understand the nature of your problem and how it affects your alternatives. Streams that are straightened and/or incised want to return to a natural dimension (cross section), meander pattern, and vertical profile, while developed or actively developing watersheds experience an increase in water runoff, which impacts the channel cross section, which, in turn, changes the meander pattern. If you do not understand your problem, hire someone who can. The basic concept of natural channel design is that you construct the channel properties required to accommodate the current and future processes. This includes maintaining bed load movement, restoring pools and riffles to the stream, reducing stresses on the banks, providing a floodplain, reducing flooding, and improving water quality. Failure to understand the source of the problem can result in overarmoring the channel bed and banks or default to gray solutions (concrete and sheet pile), which ultimately create a maintenance problem in perpetuity, and lead to the loss of opportunity to solve a problem and benefit the stream and adjacent land uses.
Property owners along a stream need to be on board with the design, the construction, and the maintenance of a project. The owner can delegate this task to the designer, but that implies that time and money is allotted. Property owners must be informed and educated to the impacts and the benefits in an honest and open manner. The loss of property, fences, trees, or the use of the back yard for the summer is no easy sell, not to mention the noise and dust.
Hopefully the property owners can see past the short-term inconveniences and buy into the long-term benefits of the project, such as increased aesthetics, reduced flooding, increased wildlife, and improved property value. Failure to get signed easements goes back to that logical termini discussion and potential failure from within the project limits. If the presentation of the project idea goes right and common expectations are established, then there is often an element of excitement, and the “jump on the bandwagon” mentality takes hold. Further, the long-term success of the project is dependent on those property owners taking ownership and initiating certain steps to maintain and protect the measures that install. The goal is to prevent yard waste disposal, mowing to the creek edge, and tree removal—all classic property owner issues.
Designers
Not all designers are created equal. Stream restoration design is a multidisciplinary science: a mix of engineering, hydrology, biology, botany, geology, policy/permitting, and a host of other very specific skills. Given those disciplines, it is a further refinement to arrive at the science and art of stream restoration. When you see a core team of individuals trained and experienced in stream restoration, their designs (plans, details, specifications, and vendor lists) reflect the time and effort it took to arrive to that point. Admittedly, the stream restoration market is attractive because it is an emerging and expanding arena. The biggest problem is those firms that get into the market without the necessary staff or skills. The failure to properly execute a design is bad for the industry, the science, and the resource, and it reinforces the opinions of the naysayers who seek solace in traditional concrete solutions.
If you are an owner, seek out firms with the specialized staff, expertise, and experience to work in this field. If you are proficient in your field, push the limits, study your results, and publish what you learn. If you have decided to get into the field, recognize the commitment that you need to make up front to hire and train staff, purchase the software, develop the details and specifications, and go through the learning curves. It is also important to note that stream restoration is an evolving field. Methodologies and computational equations used just five years ago for things like bed load movement or placing Bendway weirs on the outside of a bend have changed substantially.
Design issues are often the same and were covered in the first two articles. These problems include the identification and design for utilities, design for overland flow onto the project, planning for vegetation, planning for water conveyance, and permitting. Utilities never seem to be located where they are sited and require field adjustments. Overland flow is an unpredictable element and concentrates where least expected. Swales can be used to capture this flow and convey it through the project at designed locations or can be tied into stormwater best management practices such as bioretention swales. Bank treatments can often be driven by the ability to divert flow in the stream away from construction or the ability to access the project from the top of the bank.
In these days of austere government budgets, permitting is a top priority. Stream restoration requires careful coordination with all of the permits that are needed including floodplain permits, Section 404 permits from the US Army Corps of Engineers, Section 401 Water Quality Certifications from the state, Notices of Intent to construct in the stream, and numerous approvals from local municipalities and utilities.
Don’t forget about endangered species, archaeological clearance, contamination due diligence, and all of those other little issues that can bust a project budget. The agencies that handle these issues are understaffed and overcommitted. Start early—a year is not an unusual time frame for final approval. Methods to streamline the process include a knowledge of the permits required, data or field studies that will be required, early coordination at the beginning of the project, and pre-application meetings.
A good set of plans combines engineering, art, science, and common sense. Many designers default to putting everything in the specifications, which is good, but has anyone ever seen an excavator operator or a construction surveyor with a set of specifications? Not often, but a set of plans is always present, and the more information it contains, the more likely a good outcome. Things that improve plans are good, clear details; plenty of plan notes; vendor lists, pre-approved material lists; and a good standard set of drawings.
One way to improve the quality of construction is by presenting a slide show that actually shows the complete installation of all of the elements of a stream restoration, from instream measures to bank treatments to vegetation installation. And the alternative? Higher bids (with less variance) from contractors who are unsure of the methods or measures, delays due to materials, improper installation, requests for modifications, and more, when plans are not clear or contractors are uncertain.
Contractors
It takes a special set of skills, special equipment, and experience to construct stream restoration project.
Having the right equipment is critical. Low-pressure tracked equipment is best to prevent sinking into the stream bottom and compacting the banks. Smaller equipment tends be better, because it is lighter and more maneuverable and can work in tight places such as between trees. Excavators need hydraulic thumbs for vegetation removal, tree placement, and rock placement. Placing materials in a stream tends to be like a jigsaw puzzle, and the ability to turn logs and rocks every which way is critical to meeting the design and grade details. Without a hydraulic thumb, operators often get substandard results and take much longer to do the work. Getting the right hydraulic thumb is important, because the hydraulic cylinders on aftermarket thumbs can often be bent by the force of the bucket. (Note to contractors—that is a $5,000 tip!)
A good operator on the excavator will make or break the project. It takes a very precise touch to properly contour banks that are designed on a changing radius or to install an odd-shaped rock at a precise elevation. Bigger buckets do not save time by moving more material, as the loss in precision is too great. Have multiple buckets on site and size them to the task at hand. It takes time to learn how to properly feather the controls and work the thumb-control mechanism, to position materials, and to excavate on shifting slopes and radii. Some operators simply don’t have the touch or the patience to do this work, and trying to force an operator to do it can be detrimental to the project in terms of cost and safety.
Another common error in construction is the movement of equipment in the stream. The laws are fairly clear that construction needs to happen in streams where flow is diverted, bypassed, or in some manner separated from the work. The equipment and methods tend to be very specific to the amount of flow, the duration of construction, and several other physical parameters.
Once dewatering has occurred, there is still water in a stream, especially in the bed material. Equipment can completely disappear in a dewatered stream depending on the material in the stream bottom. This is not an issue in Colorado cobble streams, but in a silt-and-sand dominated channel in the Midwest, you had better plan on lots of really big swamp mats and fewer passes! More often the case, the stream bottom will hold up to construction equipment for a few trips and then go liquid, much to the dismay of the operator. It is best to stage and construct from the top of the bank and plan numerous access points when material is needed in the stream. Keep the traffic to a minimum. It’s better for permits also.
Summary
Stream restoration is quite different from other projects from a planning, design, construction, and ownership perspective. Water is very unforgiving, and if a mistake is made, it tends to show up after the first big storm event for the entire world to see. Fortunately, there are good guides and references to go by, but nothing takes the place of experience. In short, there is much to be done to restore water quality in our streams, and stream restoration will be an integral part of that process. So it’s absolutely essential not only that stormwater professionals should have a strong understanding of stream restoration elements, but also that owners, designers, and contractors buy in to the short- and long-term benefits.