Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 2
2 Applicability throughout the nation. These level designations provide guidance to the user for selecting each technique. For exam- A variety of concerns regarding the applicability of these ple, Level I techniques may be selected for use in situations techniques have been expressed by highway engineers. It is where a higher level of confidence is desired, whereas Level imperative that project designers consult with specialists III techniques may be used in trials or situations where exper- knowledgeable of local conditions to enhance the success of imentation is more acceptable. their project. As an example, the correct selection of a species This report found that major opportunities exist for study- of willow or cottonwood adapted to the local region is critical ing particular components of installation and the impacts to the success of many of these techniques. Climate zone will individual techniques have on project success. The need also dictate the growing and dormant periods of those species. exists for more performance data, such as allowable veloci- It is also extremely important for designers to understand the ties for some techniques and the amount of vegetative cover specific ecological issues surrounding a particular water body required to reach project objectives. As a result of the exten- and to design structures with those concerns in mind. For sive literature review performed and expert input and testi- example, a threatened or endangered species of fish in a par- monials, research opportunities are identified in the detailed ticular area may have specific requirements, which would be descriptions of each technique on the accompanying CD. identified by local agency representatives. The CD provides the information and guidelines needed to It should be noted that the knowledge gleaned from the case design and install structures and practices that will stabilize studies included in the CD is applicable to projects all across streams and rivers while providing the improved habitat and the nation, since the projects were installed in a variety of sit- ecological health needed for a better environment. This uations across a broad range of stream and river types. report documents the procedures used for gathering the infor- These guidelines are not meant to replace or disregard the mation needed to establish these guidelines. abundance of available engineering data, equations, or design protocol. It is critical that factors such as scour depth, PROJECT TASKS tractive force, and design high water be determined for each particular project and be incorporated into project design. The project commenced on May 1, 2001. This Final Report describes the work carried out from the inception of the project through November 30, 2004. The various tasks Sustainability of Environmentally Sensitive outlined in the Work Plan included the following: Techniques Task 1--Literature Review and Agency Survey Concerns are widespread throughout the industry regard- Task 2--Formulation of Work Plan ing the longevity and strength provided by environmentally Task 3--Interim Report sensitive techniques. Extensive research was performed to Task 4--Execution of Approved Work Plan obtain reliable information regarding hydraulic loading lim- Task 5--Preparation of Supporting Tools its for each technique discussed. It was found that many of Task 6--Final Report the techniques will be just as strong as, if not stronger than, "hard engineering" counterparts. One source (Escarameia, These tasks are enumerated and described in greater detail 1998) classifies bioengineering alone as light, meaning soft in Chapter 2. The results of the literature review and evalua- practices are known to withstand mean cross-sectional veloc- tion are described in Chapter 3. The literature review ities no greater than 1 m/s (3.3 ft/s). However, many bio- includes an evaluation of multiple information sources: engineering techniques and most biotechnical practices have books, conference proceedings, agency technical reports, been documented to withstand much higher local velocities. agency guidance manuals and handbooks, and websites. Structures such as riprap are usually enhanced rather than The research team discussed the appropriate term for the weakened by combining a "hard" technique with "soft" com- entire suite of channel- and streambank-protection measures ponents. The CD provides tables regarding velocities at some length and decided that technique was more appro- sustained by each specific technique and the sources of the priate than measure or countermeasure. It was recognized information. It was found that many of the techniques can that some treatments may be applied outside the highway withstand velocities up to 3.5 m/s (12 ft/s). right-of-way to mitigate and enhance stream morphology or corridor and habitat values. It was observed that some bank- protection procedures do not entail construction of some- Data Availability and Research Opportunities thing, but instead may actually require deconstruction, for example, slope flattening and regrading--a fundamental Data availability was found to vary considerably amongst approach for stabilizing slopes, including streambanks. the techniques. Each technique was assigned to one of three In light of these considerations, the word technique is used levels based on the amount and quality of available data and below to refer to all types of environmentally sensitive the number of successful case studies and examples found channel- and bank-protection measures.
OCR for page 2
3 The project research team developed a survey form (ques- In addition to the techniques discussed, the research tionnaire) that was sent to state DOTs and some representa- uncovered many subjects of direct relevance and applicabil- tive regulatory agencies asking about experiences relevant to ity to the entire spectrum of environmentally sensitive this project. Responses to the survey are summarized in channel- and bank-protection work. These special topics-- Chapter 4. The survey revealed information about the most ranging from management of conveyance and combining common problems or concerns with environmental tech- techniques to protecting and improving aquatic habitat and niques for channel-erosion control, the most common tech- the role of geotextiles and natural fabrics--are also listed in niques employed, and qualitative and quantitative data for a Chapter 5. The accompanying CD includes the discussion of variety of techniques. each of these special topics. Selected environmentally sensitive channel- and bank- The accompanying CD also includes other important protection measures (techniques) are described in Chapter 5. information, such as case studies and a photo gallery. The The project research team identified and narrowed down the case studies give detailed descriptions of past projects that list of candidate techniques to 44. These techniques are included environmentally sensitive techniques, the results of grouped into four major categories, namely, (1) River Train- the projects, and observations regarding project perfor- ing Techniques, (2) Bank Armor and Protection, (3) Riparian mance. The photo gallery includes photos from case studies, Buffer and River Corridor Treatments, and (4) Slope Stabi- examples, and more in an easy-to-access format for the user. lization. The work plan called for preparation of guidelines A rule-based technique selection system for use by DOTs for each technique. The research team initially focused efforts or consulting engineers is described in Chapter 6. The system on the preparation of brief summaries (fact sheets) for each contains a set of rules relating the strengths and weaknesses technique, which would provide short descriptions of each (hydraulic, geotechnical, and environmental) of each tech- method in addition to preliminary data. It was decided, how- nique to relevant site characteristics. This system, entitled ever, that these fact sheets were redundant to longer guide- Greenbank, is not intended for designing bank protection but lines, and work was terminated on them. A brief description rather to assist the user in selecting a reasonable technique or and schematic drawing of each technique can be found in countermeasure. Greenbank provides the user with a short list Appendix A. Chapter 5 lists all the subjects discussed in rela- of appropriate techniques for closer consideration and pro- tion to each of the techniques on the enclosed CD. These sub- vides references and justifications for these outputs. Appendix jects include the technique's category and propose, detailed B, Greenbank Decision Support Tool User's Guide, discusses design guidelines and specifications, and so forth. the information provided by the software in more detail.