2003-08-28_REVISION - M2000113 (2)

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.` E R O S I O N & S E D I M E N T C O N T R O L Amedcan Green C350, composite-turf reinforcement matting (GTRM), along [he side slopes. The gabion-reinforced riprap was specified as the means of erosion protection in the low flaw channel bed. Use of this type of pro- tection was deemed necessary in this portion of the channel due to an almost constant flaw of water and extreme flow-induced shear forces dudng the specified design event. The hydraulic forces In the channel would exceed the permissible values for veg- etation, reinforced vegetation and non-gabionized dprap, The channel was excavated and reconfigured and two channels were actually constructed. A pilot channel was dug in the base of the larger channel. The pilot channel carries the normal flow of water,while the larger -- channel carries the overflow during heavy rainstorms. When analyzing a GTIUvI for a protect, it is recommended that eng1- veers or designers review the manu- facturer's Index and performance test data on the unvegetated and fully veg- etated matting. Additionally if the mat- ting is a composite, the designer should also review data on !ts perma- nent structure (without the degradable component) to make sure that it will satisfy both short-term and long-term requirements. Conventional TRMs should also be reviewed for adequate index and performance properties. This review is necessary because:- there are some mattings on the marked-~ which aze labeled TRMs or C-TRMs, yet aze not supported by performance test data or do not meet the Federal Highway Administration's (FHWA) speUficatlon outlined in FP-96 for such. In mast instances these products permanent structure does not meet the 0.5 inch (12,7 mm) thickness requirement "The C-TRM we specified for use on the Wichita project Ss well supported by performance testing on the vegetative reinforcement properties November/December 2002 of its permanent three-dimensional structure alone, and the unvegetated performance. While the permanent structure also exceeds the FHWA's physical speclflcations for TRMs" states Jednoralski: "This matting 1s ?. truly a permanent TRM that is supple- mented with coconut fiber for Improved Immediate erosion protecton and vegetation growth enhancement." Unlike conventional TRMs which consist of .100% synthetic matedals ;(e,g:%polypropylene, .PVC, nylon), ~C-Tiu$s contairi both degradable organic and nondegradable synthetic components drawing on [he erosion control, vegetation estabiisfunant and reinforcement benefits of both erosion control blankets and turf reinforoe- ment mattings. The result is an ero- sion control system that outperforms conventional TRMs while Increasing the erosion resistance of vegetation to that of 24' rock dprap. A coconut fiber matrix is stitch-bonded between aheavy-duty Ianti and Water bottom net and a super heavy duty corrugated intermediate net, overlaid with a heavy-duty top net. This unique triple net canstrucdon forms prominent ridges across the matting to trap sediment and provide a perma- nent tluee-dimensional structure for stem and root reinforcement The mat provides long-lasting erosion wntrol and permanent vege[adon reinforce-. ment on .severe slopes with heavy run-off and channels with super-cdti- cal flow velocities. 'The matting nor only addressed . the long-term turf reinforcement, but also addressed the short-term erosion protecdon needs, meaning that if a heavy rain came the day after they put it down they could feel safe and not lose anything in the protect, even before vegetation," states John E. Warren of ASP Enterprises, Inc. to Kansas Ciry, MO. ASP was the suppli- er of the erosion control matedals and technology for the protect, °There is a big difference between The surlaee installation of the C-TRM provided immediate erosion control against channel now before vegetation estabiishmenl while also providing an effective match layer to enhance seed genninatfan and plant growth.