Research Quantifies Performance of TRM Reinforced Vegetation

Abstract

Public awareness plays a major roll in the implementation of federal, state, and local legislation requiring improved erosion and sediment control from construction and disturbed sites. These demands require engineers to continuously improve their ability to quantify soil loss for erosion control measures on specific projects. To assist the engineering community in this endeavor the rolled erosion control products (RECPs) industry continues to advance the availability of technology and improve d research methodology on turf reinforcement mattings (TRMs). Consequently, these advancements have improved the accuracy of available data further improving on design values of TRMs and reinforced vegetation to improve the accuracy in selecting effective erosion control measures for critical channel linings based on quantifiable data. Research was recently conducted at Colorado State University’s (CSU) Hydraulics Laboratory to further quantify the erosion control performance and vegetation reinforcement capabilities of four turf reinforcement mattings. The research was conducted using methods similar to those established in ASTM D 6460 Standard Test Method for Determination of Erosion Control Blanket (ECB) Performance in Protecting Earthen Channels from Sto rmwater-Induced Erosion and to simulate field conditions for channelized water flow. Numerous discharges and channel gradients were used to generate flows with known but various velocities and shear stresses. Two of the TRMs tested using this protocol were exposed to flows during all three developmental stages of a reinforced vegetated channel’s development. Prior to this research, reinforced turf was only considered for use in channels exposed to a maximum permissible shear stress of 384 Pascal (8 lbs/ft 2 ) or less based on design values published in the Federal Highway Administration’s Hydraulic Engineering Circular #15 (Chen and Cotton; 1988). The CSU research established new levels of erosion control and turf reinforcement for the TRM reinforced vegetatio n tested. The reinforced vegetation significantly reduced soil and vegetation loss at shear stresses that nearly doubled the maximum published values in the HEC15 for TRM reinforced vegetation. This testing, in conjunction with past research on the specifi c TRMs and reinforced vegetation has furthered the manufacture’s advancement of design software to assist engineers in the design, selection and use of TRMs and reinforced turf based on known and substantiated soil loss values for channel liner applications.