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Does the idea of designing and specifying erosion control products everseem too daunting? Do you worry about where to start and how to make sure you are creating accurate and effective designs?
Designing for erosion control does not have to be stressful. Many resources can help.
Handbooks from the U.S. Departmentof Agriculture (USDA) and Federal Highway Administration (FHWA) provide guidance in analyzing accurate channel and slope designs. These methodologies use a calculated soil loss value versus a tolerable soil loss value. But while very detailed and offering excellent design results, these publications can be difficult to wade through.
Software programs can simplify these methodologies into a user-friendly format. One such program features design modulesfor slope and channel applications as well as a module for basic vegetation selection.
To start designing you have to understand the project site parameters: for a channel application, the channel dimensions and grade, discharge rates, and soiltype; for a slope, project location, slope length and grade, and soil type. For both applications, it is also pertinent to know if the site is suitable for growing vegetation, and more specifically the type and density of vegetation for the matured site. Once you know the site conditions, you can determine the applicability of a temporary or permanent erosion control product. If unreinforced vegetation can permanently stabilize the site, a temporary erosion control blanket will be suitable.Temporary degradable products offer erosion protection until the vegetation establishes. Temporary products are rated on performance and longevity.
If unreinforced vegetation cannot adequately stabilize the site, a permanent turfre inforcement mat (TRM) may be necessary. A TRM can offer immediate erosion protection and reinforce permanent vegetation. TRMs are usually rated on permissibles hear stress or on how well the product will with stand high velocities. If a TRM will be needed, it is crucial to analyze both the unvegetated and fully vegetated scenarios to ensure adequate design from day one until complete vegetation.
Erosion control software design programs allow you to input the site parameters, while they calculate the stability of a site based on a safety factor. The safety factor is a ratio of the performance of a specified erosion control product to the calculated soil loss potential. The software helps identify the most economical product for erosion protection on the site. Besides analyzing different rolled erosion control products, these programs may also analyze varying vegetation types, rock, and concrete.
As erosion and sediment control regulations become more stringent, software programs can simplify the design process and offer accurate product selection withoutthe extra hassle.
Jill Pack is manager of technicalservices for North American Green, Evansville,Ind.