Erosion and Sediment Control
Product Case Study
Level of Presentation: All: Suitable for a broad audience
CRAFS® is the "Corrugated Retention and Filtration System(s) for Sedimentation Control" (Patent No.: US 9,677,243) that provides rapid filtered seepage for control outlets in a sediment control system.
The corrugated system eliminates the direct impact of sediment runoff against the structure. And its three dimensional stability resists the stress from runoff as it is divided and distributed into a multiple of adjacent "retention wedges" within the CRAFS® system.
The vertical support posts at the upstream and downstream vertexes of this corrugated structure work in tandem with the system's "filter fabric" to provide lateral load support and stability as runoff enters and is retained by the structure. This same structural stability is sturdy enough to resist the impact of debris transported within the runoff.
The filter fabric component of the "retention wedges" provides significantly greater surface area of geotextile adjacent to the retained runoff than a conventional silt fence with its linear alignment of "silt fence fabric". More surface area of "filter fabric" results in much faster filtered seepage through the corrugated system. And each new runoff event provides a "filter cake cleansing" from the filter fabric's surface that rejuvenate the system's rapid rate of filtered seepage.
The "corrugated retention and filtration system" can eliminate long term ponding and many of the "slow to no seepage" and structural problems encountered with conventional silt fences. CRAFS® is not intended to replace the silt fence that surrounds most construction sites. Instead, it's a solution for problem areas like control outlets for silt fences, where the retained runoff can't seep through fast enough, and "stone outlets" don't provide adequate sediment filtration or reduced runoff velocity as it exits downstream.
The presentation provides a brief introduction to CRAFS®, including 1) how the system works, 2) test results that validate system capabilities, and 3) several project summaries that show "on-the-job" system performance.
Target Audience: Academic,Consultant,Contractor,Engineer,Government Agency,Mining Industry,Utility Company
Product Development Engineer
R.G. (Bob) Carroll, Jr., P.E. earned an M.S. in Civil Engineering (1974) after completing a research program on "The use of filter fabric to replace graded aggregate filters in subsurface drains". He was a Tech Service Engineer in the Mirafi Program at Celanese Fibers Marketing Co for 6 years, then became New Products Development Manager at Mirafi Inc. There he created several new geosynthetic products including MiraDrain (prefabricated drainage composite), MiraMat (erosion control and revegetation mat), and MiraGrid 5T (the first textile type geogrid to compete with the punched and drawn geogrids that had been introduced to the industry). In 1985 Bob went with The Tensar Corp where he helped create and promote the technology along with the Tensar BX Geogrid for reinforcement of granular base in flexible pavements. While there he also helped created a line of drainage composites for subsurface drainage and the industries first turf reinforcement mat, Tensar TRM. During his career in geosynthetics he helped organize the first ASTM committee on Construction Fabrics (D13.61) and later became a Chairman of various ASTM D35 Committees. He was also a founding member and Vice President of the North American Geosynthetics Society (NAGS) . Since retirement he continues to stay involved with geosynthetic product development and industry activities.
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