AN ECONOMICAL SOLUTION FOR FLOOD PROTECTION AND CHANNEL EROSION CONTROL

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1 AN ECONOMICAL SOLUTION FOR FLOOD PROTECTION AND CHANNEL EROSION CONTROL Amir Shahkolahi 1, Alec Tadman 2, Jason Crase 3 1 Applications Engineer, Global Synthetics, QLD, Australia, amir@globalsynthetics.com.au 2 Associate Engineer, Aurecon, QLD, Australia 3 Regional manager, Global Synthetics, QLD, Australia Abstract In February 2014, Moreton Bay Regional Council was seeking an economical, environmentally compatible yet technical solution to provide improved flood immunity to Gympie road Strathpine at the Coulthards Creek crossing. Coulthards Creek flows west to east under the north coast railway line. The solution involved modifying the Coulthards creek channel to include a low flow invert including control of the erosion adjacent to the concrete invert. A culvert upgrade including the reconstruction of an existing bikeway required protection of the new embankment from erosion during periods of overtopping. At the same time, the appearance of the treatment was important for this project and Council was looking for a vegetated surface in the treated areas. This needed a combination of erosion control and turf reinforcing. To achieve a suitable solution, the Consultant investigated various solutions and finally, Landlok Turf Reinforcement Mat (Landlok TRM) was selected as the most technically compatible, yet economical solution. Take home message: Turf Reinforcement Mats (TRMs) are economical permanent solutions for controlling erosion on slopes and in waterways and are an economical replacement for traditional hard concrete and rock rip-rap methods. Introduction Across parts of the Australian landscape, rates of soil erosion now far exceed rates of soil formation, frequently by a factor of some several hundred, and sometimes up to several thousand (Bui et al. 2011). This process represents a major threat to the sustainability of Australia s land resources and the ecosystem services they support (Hairsine et al. 2009). Much of this land is in Qld and northern Australia (Ryan 2013). Apart from soil particles being dislodged from channels and slopes due to erosion, there is also the possibility for attached pollutants such as fertilisers, pesticides and petroleum products to be transferred along with the sediment. The potential for erosion due to erosion forces such as flood must be considered and controlled by appropriate methods to establish permanent erosion control solutions. In this paper, various erosion control methods are investigated and the Propex Landlok Turf Reinforcement Mat (TRM) is discussed in further detail. This system was considered for application due to its extensive testing and performance history. Erosion Control Methods/Systems The traditional way to control erosion in highly erosive areas has been the use of hard-armour erosion control techniques such as concrete blocks, rock rip-rap, rock mattresses and reinforced paving systems. Although these permanent methods can withstand great hydraulic forces, they are costly and they do not provide the pollutant removal capabilities of vegetative systems.

2 These systems need special equipment to install and can present a hazard to people due to the weight of the components (EPA 1999, GMA 2009). Furthermore hard surfaces can pose safety hazards where there is a risk for accidental falls during operation and maintenance. Most recently, Rolled Erosion Control Products (RECPs) have been widely used as a high-tech cost effective erosion control system for both temporary and permanent application in channels and slopes [Lancaster and Austin 2003; Lancaster and Myrowich 2006). RECPs are described in detail in the following sessions. Classification of Erosion Control Methods/Systems Two basic types of lining classes are rigid linings such as concrete, and flexible linings such as rock rip raps, rock mattresses, and all RECPs (Kilgore and Cotton 2005; Witheridge 2010). Rigid linings are nonerodible, permanent and long life, but they are susceptible to failure from foundation instability and unreliable hydraulic pressure release. Construction of rigid linings requires specialised equipment and costly materials. As a result, the cost of rigid channel linings is typically higher than an equivalent flexible channel lining (Kilgore and Cotton 2005). The most recent classification for Rolled Erosion Control Products (RECPs) is (Koerner and Koerner 2012): degradable rolled erosion control products, nondegradable rolled erosion control products, and high-performance non-degradable rolled erosion control products. Rolled Erosion Control Products (RECPs) In the late 1960 s, a group of products known as RECPs were developed due to the limitation of conventional mulching techniques. This category consists of prefabricated products manufactured from wood excelsior, straw, jute, coir, polyolefins, PVC and nylon (Lancaster and Austin 2003). Rolled Erosion Control Products (RECPs) include a variety of temporary or permanently installed manufactured products designed to control erosion and enhance vegetation establishment and survivability, particularly on slopes and in channels. These products are often used on disturbed areas on steep slopes, in areas with highly erosive soils, or as part of waterway stabilisation (ECTC 2004, UDFCD 2011). The most common RECPs classification by the Erosion Control Technology Council (ECTC) is (Lancaster and Austin 2003): Temporary RECPs (degradable) and Permanent RECPs (non-degradable). Temporary Rolled Erosion Control Products (Temporary RECPs) For applications where natural vegetation alone will provide sufficient permanent erosion protection, a temporary degradable rolled erosion control product is used to effectively control erosion and assist in the establishment of vegetation under the site conditions. Some of temporary RECPs are mulch control nets, erosion control blankets and open weave textiles (Lancaster and Austin 2003, ECTC 2004). Temporary erosion control blankets and mats decompose over time, leaving vegetation unprotected and unreinforced. This type of blanket should only be used to establish vegetation under mild hydraulic conditions (EPA 1999). Permanent Rolled Erosion Control Products (Permanent RECPs) For applications where natural vegetation alone will not sustain expected flow conditions and/or provide sufficient long-term erosion protection, a permanent nondegradable rolled erosion control product with the necessary performance properties is used to effectively control erosion and reinforce vegetation under the expected longterm site conditions (Lancaster and Austin 2003, ECTC 2004). Turf Reinforcement Mats (TRMs) are permanent RECPs.

3 Alternate RECP Classification The Erosion Control Technology Council (ECTC) characterise Rolled Erosion Control Products (RECPs) based on their structure and application as follows (Lancaster and Austin 2003, ECTC 2004, Kilgore and Cotton 2005, UDFCD 2011): (a) Mulch Control Netting (MCN). A Two-Dimensional woven natural fibre or extruded geosynthetic mesh used as a temporary degradable rolled erosion control product to anchor loose fibre mulches. Because MCNs are not glued or stitched to the mulch, these nettings do not provide the same degree of structural integrity offered by prefabricated Erosion Control Blankets. Figure 1 shows some typical MCNs. Figure 1. Typical Mulch-control nettings (MCNs) (b) Open Weave Textile (OWT). A 2-D temporary degradable rolled erosion control product composed of processed natural or polymer yarns woven into a matrix, used to provide erosion control and facilitate vegetation establishment. OWTs are often employed where higher strength is required, such as on steepened slopes or channels as shown in Figure 2 (Kilgore and Cotton 2005). Figure 2. Open Weave Textiles (OWTs) for slopes (left) and channels (right) (c) Erosion control blanket (ECB). A temporary degradable rolled erosion control product composed of processed natural or polymer fibres mechanically, structurally or chemically bound together to form a continuous 2-D matrix to provide erosion control and facilitate vegetation establishment. ECBs are stiffer, thicker and OWTs. The most widely used ECBs are made from straw, wood excelsior, jute, coconut or polypropylene (Lancaster and Austin 2003). Typical ECBs are shown in figure 3 (Witheridge 2010). Biodegredable Blanket Biodegredable mesh (Jut mesh) Temperory Reinforced Blanket Figure 3. Open Weave Textiles (OWTs) Applications of ECBs include gradual to steep slopes, low to moderate flow channels and low-impact shore linings. Since these degradable materials are designed to provide temporary erosion protection, they generally are limited to areas where natural, unreinforced vegetation alone will provide long-term soil stabilisation (Lancaster and Austin 2003). (d) Turf Reinforcement Mat (TRM). A rolled erosion control product composed of non-degradable UV stabilised synthetic fibres, filaments, nets, wire mesh and/or other elements, processed into a permanent high strength three-dimensional matrix of sufficient thickness. They are typically used in high flow ditches and channels, steep slopes, stream banks, and shorelines, where erosive forces may exceed the limits of natural, unreinforced vegetation or in areas where limited vegetation establishment is anticipated. TRMs with higher shear resistance are called High Performance TRM (HPTRMs) and are being used for more critical conditions. TRMs will be described in details in the next session. Figure 4 shows two of the most common TRMs/HPTRMs. Figure 4. Landlok 450 TRM (left) and Pyramat HPTRM (right)

4 Turf Reinforcement Mats (TRMs) and High Performance Turf Reinforcement Mats (HPTRMs) Vegetation offers an excellent form of erosion control and cover. Reinforcement is the only way vegetated channels and slopes can stand up to storm water once the channel hydraulic conditions exceed the maximum that can be withstood by the vegetation. Support of the vegetation to the point it will withstand more vigorous conditions can be achieved by Turf Reinforcement Mats (TRMs) and High Performance Turf Reinforcement Mats (HPTRMs). TRMs/HPTRMs consist of UV stabilised synthetics fibres and filaments processed into permanent, high-strength, 3-D matrices. TRMs are designed for permanent and critical hydraulic applications where design discharges exert velocities and shear stresses that exceed the limits of mature, natural vegetation. TRMs provide sufficient thickness, strength and void space to permit soil filling and/or retention and the development of vegetation within the matrix (Lancaster and Austin 2003). This synergism increases root systems lateral strength, reducing plant dislodgement under highvelocity, high-shear stress flows. TRMs with high tensile strengths which can provide a high design shear stress and velocity are called High Performance Turf Reinforcement Mats (HPTRMs). Advantages of TRMs/HPTRMs By protecting the soil from scouring forces and enhancing vegetative growth, TRMs/HPTRMs can raise the threshold of natural vegetation to withstand higher hydraulic forces on slopes, streambanks and channels which leads to reduction in soil loss (Thornton and Beasley 2013). In addition, the use of natural vegetation provides particulate contaminant removal through sedimentation and soil infiltration, and improves the aesthetics of a site (EPA 1999). TRMs/HPTRMs, unlike temporary erosion control products, are designed to stay in place permanently to protect seeds and soils and to improve germination (EPA 1999). Although most effective when used in fully vegetated areas, TRMs have also been used to prevent erosion in arid, semi-arid and high altitude regions with limited vegetative growth. Apart from that, TRMs reduce evaporation and insulates the soil, reduce soil moisture loss, moderate soil temperature, prevent crusting and sealing of the soil surface and increase infiltration (ECSWQM 2014). Reinforcing vegetation with TRMs/HPTRMs has become an acceptable, performance proven, cost effective and environmentally friendly alternative to concrete, rock riprap, rock mattresses and other forms of nonvegetative lining materials due to effectively reducing construction times, construction costs (about 75% reduction), material costs, equipment requirements and most importantly improving water quality and ground water recharge capabilities (GMA 2009, Lancaster and Austin 2003, EPA 1999). TRMs, with shear stresses up to 480 to 576 pa (similar to more than 80cm rock rip-rap), have proven their performance capabilities over the past 35 years in field and laboratory tests (Chirbas et al. 2005). HPTRMs such as Propex Pyramat HPTRM can stand even higher shears tresses up to 718 pa (Global Synthetics Propex Erosion Control). TRM/HPTRM Installation To perform properly, TRMs should be installed properly and remain in proper contact with the ground. Typical installations involve rolling out and fastening the TRM in intimate contact with the soil surface. Installation types can be soil-filled or non soilfilled (Chirbas et al. 2005). The manufacturer s installation manual should be the primary source for details specific to a product along with the designer s consideration of site specific requirements that may affect installation details such as soil types and ground movement.

5 TRMs/HPTRMs Design considerations Apart from the geotechnical analysis and considerations, a TRM/HPTRM design procedure includes Hydraulic design, vegetation type, product specification and installation considerations. Product specification is discussed in the following session. Hydraulic design is based on the shear stress and velocity. Shear stress predicts the performance or when erosion will occur and is the main parameter, superior to velocity, in predicting the failure. The magnitude of the shear stress generated by a flow, and so the hydraulic design depends on the discharge, depth of flow, flow duration, slope or energy gradient, surface geometry, channel geometry, hydraulic roughness of the liner, and underlying soil type (Kilgore and Cotton 2005). TRM/HTRM properties The properties of TRMs/HPTRMs consist of Index properties and Performance/Hydraulic properties. Index properties are physical, Mechanical and Endurance properties and include mass, thickness, fibres cross sectional shape, mat s structure, light penetration, tensile strength, elongation, resiliency, flexibility and UV resistance. Hydraulic properties include maximum permissible velocity, maximum permissible shear stress, roughness (manning s number) and seeding emergence (Kilgore and Cotton 2005, Global Synthetics Propex Erosion Control). Case Study: Coulthards Creek upgrade Moreton Bay Regional Council (MBRC) proposes to undertake works for the upgrade of Coulthards Creek between Leitchs Road and the North Coast railway line, which comprises a combination of concrete lined channel and open floodway. A culvert upgrade including the reconstruction of an existing bikeway required protection of the new embankment from erosion during periods of overtopping (Aurecon 2014). The Problem It was understood that there have been a number of significant flooding issues throughout the Coulthards Creek catchment system, which have affected commercial, industrial and residential development and public infrastructure within the area. The lowlying Coulthards Creek area is commonly sodden and difficult to maintain. To ensure the protection of people and property from the impacts of flooding to improve maintainability MBRC proposes to undertake works that include constructing a new wider concrete channel, earthworks to re-profile the drainage area, raising the existing bikeway, replacing the existing low-level culverts and providing scour protection (Aurecon 2014). The Final Solution The solution involved modifying the Coulthards creek channel to include a low flow invert including control of the erosion adjacent to the concrete invert. Council was looking for an economical, environmentally compatible yet technical solution. At the same time, they were looking for vegetated surface in the treated areas. Due to a recurring issue of scour adjacent to low flow channels in the area it was recommended that a combination of erosion control and turf reinforcing be used directly adjacent to limit the potential for this to occur. To achieve a suitable solution, the Consultant investigated various solutions and finally, Propex Landlok 450 Turf Reinforcement Mat (Landlok 450 TRM) was selected as the most technically compliant yet economical solution. To determine the performance of this system, several standard tests were reviewed. Figure 5 shows the final design cross section. Figure 5. Final designed cross section with Landlok 450 TRM

6 This erosion control system can withstand high velocities in open channels and is more economical than other traditional methods such as concrete and using rocks or rock mattresses. The presence of this system ensures erosion protection even in time of drought or reduced vegetation and remains in place permanently to enhance the vegetation and root reinforcement of the established plant growth. creates a thick matrix of voids. That design allows X3 fibres to trap and house more soil and water required for rapid growth in steep slopes and moderate- to high-flow channels. Why Propex Landlok 450 TRM? Propex Landlok Turf Reinforcement Mats (TRMs) and Pyramat High Performance Turf Reinforcement Mats (HPTRMs) are advanced TRMs with X3 fibre technology and special pyramid 3-D shape which offer maximum performance. These materials are suitable for the widest range of erosion challenges, especially in Australian arid and semi -arid environments and when designers are faced with sandy soils, UV-exposed sites, utility cuts and areas with maintenance equipment and other large vehicles (Propex 2006). Figure 6 shows application of these materials in two projects. Figure 7. X3 technology in Landlok and Pyramat fibres Advantages of Propex Landlok TRMs and Pyramat HPTRMs Beside general TRM advantages, X3 fibre technology interlocking crimped fibres used in Propex Landlok and Pyramat TRMs/HPTRMs provide extra advantages compared to conventional TRMs with circular fibres (figure 9). Some of these advantages are (SI Geosolutions 2003): A 40% increase in seed germination and plant growth during the first 21 days. 60% greater tensile strength to ensure structural integrity during and after installation (Tested in accordance with ASTM D6818). Slope, Landlok TRM, Gladstone, QLD Channel, Pyramat HPTRM, Bulga, Coal Mine, NSW Figure 6. Applicationj of Landlok and Pyramat TRM/HPTRM on slopes and in channels X3 Fibre Technology This advanced fibre technology used in construction of Landlok TRM and Pyramat HPTRM is designed to capture more seed, soil and water for the fastest seedling emergence of all TRMs in the industry (figure 7). The secret is its shape and construction. X3 fibres are extruded through a unique process that gives them over 40% more surface area. Interlocking crimped fibres are then being constructed in a 3-D pattern that 10% better resiliency that provides a crushproof environment during the germination period, when seedlings are most vulnerable (Tested in accordance with ASTM D6524). Reduction in soil loss by 30% Improvement in vegetation growth by 50% over circular shaped fibres. Landlok TRM and Pyramat HTRMs capture sediments 4 times more efficiently than concrete and rip rap solution and are around 80% cheaper than concrete (Propex 2006). Propex TRMs and HPTRMs are resistance against UV and have been testes for up to 10,000 hours under exposed condition.

7 The tensile strength of these Propex systems is up to 58.4kN/m which is even greater than the tensile strength of the wire mesh used in a rock mattress for example. These materials have high resiliency, high light penetration and can be used on steep slopes and in channels with velocities and shear stresses up to 7.6 m/s and 718 pa respectively (Global Synthetics Propex Erosion Control). Apart from that, the high melting point of Propex HTRMs makes them resistance to possible bushfires and forest fires. These advantages will improve the performance, reduce the risk, reduce the cost and lead to less maintenance. Furthermore, the solution will be a natural vegetative solution. Standard Tests on Propex Landlok TRM and Pyramat HPTRM All index and performance properties of this system have been tested according to ASTM test methods. These tests include: 1. Hydraulic performance Large-scale testing has been performed by Utah State, Colorado State and Texas Transportation Institute in which a test plot is placed in a large flume and subjected to channelized flows. The test was performed un-vegetated and vegetated for various flow durations (figure 8). According to test results, the maximum design shears stress and velocity for vegetated Propex Landlok TRMs are 576 pa and 6.1 m/s respectively. For vegetated Propex Pyramat HPTRMs, the maximum design shear stress and velocity will be 718 pa and 7.6 m/s which are even greater than rock armour (Global Synthetics Propex Erosion Control). Figure 8. Full scale flume test 2. Vegetation Development Two main parameters that affect vegetation are Seedling Emergence and Light Penetration. Seeding emergence measures the number of seeds germinated, the plant height and the plant mass during the first 21 days of germination while under the protection of a TRM. According to test results, seeding emergence of Propex TRMs is up to 409%. This effectively means that more that more than 4 times more vegetation will establish in conjunction with Propex TRMs/HPTRMs when compared to unprotected soil and seed (SI Geosolutions 2003). Light penetration may be used to control the quality of many TRMs (ASTM D6567). The light penetration of Propex TRMs/HPTRMs has been tested in accordance to ASTM D6567. Test results show that the light penetration through Propex TRMs is up to 50% which is about 15 times more than the minimum requirement for vegetation (Global Synthetics Propex Erosion Control). Figure 9 Shows a Propex Landlok TRM project before and after vegetation. Figure 9. A Propex Landlok TRM project before (left) and after (right) vegetation 3. Durability (UV resistance) The long-term durability of a TRM largely depends on its UV resistance. Although installed TRMs are typically covered with a combination of soil and vegetation, one must assume that full exposure to constant sunlight is the critical design condition (Propex 2007). All components of Propex TRMs are stabilised against UV degradation by a special additive blended with the resin during processing. As a result, they have demonstrated UV resistance even when exposed to direct sunlight for extended periods of time. Test results show that

8 exposed un-vegetated Propex TRMs and HPTRMs retain over 85-90% of their tensile strength over that period of time. This property is tested in accordance with ASTM D4355 for up to 10,000 hours of exposure to an artificial xenon light source. Of course in reality, vegetation will occur after few months and the TRM will not be exposed for a long time and the UV resistance will be even more (Propex 2007, Global Synthetics Propex Erosion Control). 4. Long-Term Performance 4.1. Resiliency Resiliency may be indicative of a TRM's ability to retain its original configuration after exposure to the stresses which may be exerted during manufacture, shipping, and installation (ASTM D6524). The resiliency of Propex TRMs and HPTRMs is extremely high (around 80%) according to ASTM D6524 (Global Synthetics Propex Erosion Control). This test method covers the resiliency or recovery of turf reinforcement mats after they have been subjected to a specific load cycle. This test ensures the performance of the TRM after possible trafficking such as mowing Tensile strength The tensile strength of a TRM is mobilised when subjected to high flows in channels, gravitational forces on steep slopes and wheel loading from construction, operational (as with roadside shoulders) or maintenance (such as mowing) traffic. A high-strength, low-strain TRM minimises seed and root damage under load. As a matter of fact, the US EPA and the Federal Highway Administration (FHWA) recommend that a high performance TRM with a tensile strength of 44 kn/m or greater should be used whenever field conditions with high loading and high survivability requirements exist (SI Solutions 2003). This property is tested in accordance with ASTM D6818. For Pyramat HPTRMs, the tensile strength is up to 58.4 kn/m. As test results show, Landlok TRM and Pyramat HPTRM can perform very well for a long term even after possible trafficking such as mowing (figure 10), due to their high resiliency and tensile strength. Figure 10. High performance of Propex TRMs and HPTRMs under trafficking (mowing) Design considerations The EC Design software was used for the design. This software is based on HEC-15 design procedure for open channels (Kilgore and Cotton 2005), modified for Landlok and Pyramat. The main channel input data were the channel cross section, channel longitudinal slope and flow velocity. The TRM design parameters and specification used in the design are shown in table 1. According to the TRM design parameters and the design safety factor, Landlok 450 was suitable for the project. Table 1. Landlok 450 TRM design parameters With this method and by using Landlok 450, the Moreton Bay Regional Council achieved cost savings and an economical long term solution.

9 Conclusion Reinforcing vegetation with TRMs/HPTRMs has become an acceptable, performance proven, cost effective and environmentally friendly alternative to rock riprap, rock mattresses and other forms of non-vegetative lining materials. By protecting the soil from scouring forces and enhancing vegetative growth, TRMs/HPTRMs can raise the threshold of natural vegetation to withstand higher hydraulic forces. They also reduce the amount of soil loss. Design parameters for TRM/HPTRM projects include Hydraulic data such as shears tress and flow velocity, geometry, slope, vegetation type and product specification/properties. Important product properties to be considered are: Design shear stress, design velocity, roughness, resiliency, tensile strength, light penetration and UV resistance. Fibres cross sectional shape and the whole mat s structure can affect the performance of the TRM/HTRM. Propex Landlok Turf Reinforcement Mats (TRMs) and Pyramat High Performance Turf Reinforcement Mats (HPTRMs) are advanced UV-Resistance TRMs with X3 fibre technology and special pyramid 3-D shape which offer maximum performance as an erosion control alternative to hard armour approaches and can replace rock riprap, concrete channels, rock mattress or interlocking concrete block systems with more natural visual appearance and overall cost reduction. X3 fibre technology used in Propex Landlok and Pyramat TRMs/HPTRMs provide extra advantages compared to conventional TRMs. These benefits include: 40% increase in seed germination and plant growth, 60% greater tensile strength, 10% better resiliency, reduction in soil loss by 30% and improvement in vegetation growth by 50%. This leads to a safer design and more reduction in construction and maintenance costs. High resiliency and high tensile strength of Landlok and Pyramat insures the long term performance and stability against possible trafficking such as mowing. References ASTM D4355. Standard Test Method for Deterioration of Geotextiles by Exposure to Light, Moisture and Heat in a Xenon Arc Type Apparatus. American Society for Testing and Materials. ASTM D6524. Standard Test Method for Measuring the Resiliency of Turf Reinforcement Mats (TRMs). American Society for Testing and Materials. ASTM Standard Test Method for Measuring the Light Penetration of a Turf Reinforcement Mat (TRM). American Society for Testing and Materials. ASTM D6818. Standard Test Method for Ultimate Tensile Properties of Rolled Erosion Control Products. American Society for Testing and Materials. Aurecon, Coulthards Creek upgrade Project: Preliminary Construction Envirnmental Managemnet Plan. Coulthards Creek upgrade Project Report. Aurecon PLN-NN Bui, E. N., Hancock, G. J. and Wilkinson, S. N., Tolerable' hillslope soil erosion rates in Australia: Linking science and policy. Agriculture Ecosystems & Environment 144 (1), Chirbas, K., Myrowich, M., Nelsen, R. J., Turf Reinforcement Mattings: An EPArecognized stormwater BMP. Stormwater, Vol. 6, No. 2, March-April ECTC, Standard Specification for Rolled Erosion Controlled Products. Erosion Control Technology Council, Version 2, Rev EPA, Storm Water Technology Fact Sheet: Turf Reinforcement Mats. United States Environmental Protection Agency, EPA 832-F ECSWQM, Erosion Control and Storm Water Quality Manual. BOWEN, COLLINS & ASSOCIATES, Provo City. March 2014.

10 Global Synthetics Propex Erosion Control. Propex: The Exeptional Choice for Sustainable Erosion Control to Replace Hard Armour. Global Synthetics Pty Ltd. GMA, Handbook of Geosynthetics. Geosynthetics Martials Association. Hairsine, P. B., Barson, M., Randall, L. and Wilkinson, S., Identification of areas in Australia where soil loss from hillslope erosion could be reduced. CSIRO Land and Water Report 45/09. Kilgore, R. T. and Cotton, G. K., Design of Roadside Channels with Flexible Linings. Hydraulic Engineering Circular No. 15 (HEC-15). Third Edition, Federal Highway Administration, FHWA-NHI Koerner, R. and Koerner, G., The need for erosion control material specifications. Geosynthetics, February Lancaster, T. and Myrowich, M., ECTC: 14 Years of Guiding and Growing the Rolled Erosion Control Products Industry. Land and Water, Vol. 50 (6), PP 39. Lancaster, T. and Austin, D. N., Classifying Rolled Erosion Control Products: A Current Perspective. Erosion Control Technology Council (ECTC). Propex, Functional Longevity of Turf Reinforcement Mats: Examining the Relationship of Ultraviolet Resistance and Tensile Strength to Long-Term Performance of a Permanent Rolled Erosion Control Product. Technical Bulletin, Propex Operating Co. LLC. Ryan, A., Water erosion in Australia. Caring for our Country Sustainable Agriculture Fact Sheet, Department of Agriculture, Fisheries and Forestry. SI Geosolutions, Landlok Erosion Control Mats. SI Corporation, LL-400. Thornton, C. I, Beasley, J., Vegetative Cover and Turf Reinforcement Mats NDSP Dam Safety, Technical Seminar No. 20: Overtopping of Dams, February UDFCD, Urban Storm Drainage Criteria Manual Volumes 3: Best Management Practices. Urban Drainage and Flood Control District, Denver, CO. Witheridge, G., Erosion and Sediment Control A field Guide for Construction Site Managers. Catchments and Creeks Pty Ltd, Version 2, February Propex, Erosion Control Solutions. Propex Inc., LL-501.

11 Author Biography Amir Shahkolahi graduated in Civil Engineering. He continued his Masters in Environmental Engineering. As a designer and project manager, he has been involved in Geosynthetic and Civil/Geotechnics and Hydraulic Engineering projects over the last 10 years and has also published more than 35 technical papers in national and international conferences and journals. Amir is now the Technical Consultant and Applications Engineer at Global Synthetics. He is also one of the main officers of ACIGS, the Australasian Chapter of the International Geosynthetics Society (IGS). Postal Address: 44 Telford Street, Virginia, QLD amir@globalsynthetics.com.au Alec Tadman is a qualified Civil Engineer with a Masters Degree in Engineering Management. Alec has practiced in various areas of general civil engineering and has specialized in stormwater management and Solid Waste Management. Alec works for Aurecon in the Brisbane Land Infrastructure unit and has held roles previously in private consultancy and Local Government. Postal Address: 32 Turbot Street, Brisbane, QLD Alec.Tadman@aurecongroup.com Jason Crase is a qualified Civil Engineer graduating from QUT in Brisbane in His career development has included design roles within Local Government, Management of a Civil Construction Company in Queensland and most recently in technical design and sale of Geosynthetic materials. With these skills spanning more than 20 years primarily with Geosynthetic based solutions Jason can offer unrivalled experience and design assistance in the application of Geosynthetic products in his role as Regional Manager for Global Synthetics, an Australian owned and operated Geosynthetics Company. Postal Address: 44 Telford Street, Virginia, QLD Jason@globalsynthetics.com.au