Sustainable engineering solutions for natural disaster rehabilitation

Review of Part 1:

The Engineering solutions for natural disasters include:

1. Sustainable engineering solutions for quick and economical yet technical and durable rehabilitation and repair of the damage and failures from natural disasters.

2. Resilient infrastructures that can withstand and manage/prevent natural disasters such as floods and bush fires.

This blog series will cover both of the above categories, including:

Part 1 (TO REPAIR DAMAGE FROM NATURAL DISASTERS):

• Shallow plane slope failure repair

• Major slope failure repair

• Explore our comprehensive review of sustainable engineering solutions in Part 1.

Part 2 ( TO PREVENT AND/OR REDUCE DAMAGES FROM NATURAL DISASTERS):

• Resilience flood protection levees.

• Resilience stormwater channels.

• Bush fire resistance and permanent erosion control techniques.

Part 2 – To Prevent and/or Reduce Damages from Natural Disasters:

Through innovative engineering solutions, it is possible to build flood-resilient infrastructures that can withstand and manage floodwaters. For instance, resilience flood protection levees and stormwater management systems can help prevent flooding and protect critical infrastructure.

A. Resilient flood protection levees: Resilient flood protection levees should prevent water infiltration through the dam as well as downstream slope erosion due to rain, wind and/or overtopping:

Preventing water infiltration:

To avoid failures due to water infiltration inside and below a dyke, the most effective passive method is to prevent any interaction between the water and soil. The sustainable method to do this is using barrier materials such as geosynthetic clay liners (GCL), which also serve as protection for the underlying soil. The advantage of these systems is the flexibility to adapt to deformations developing after the lining installation. The use of geosynthetics also allows for the construction of a dyke out of higher permeability fill and local available material than would normally be adopted for dyke construction [1, 12].

Photo: Installation of Bentofix® GCL on Levee, Oder, Germany, Section 51 (Courtesy: NAUE)

Additional information and detailed insights regarding the performance of the Armormax® system in flood protection levees.

Explore detailed insights into Bentofix® GCL (both PE coated and non-coated variants)

• Preventing downstream slope erosion due to rain, wind and/or overtopping

Armoured levees are intended to provide protection of earthen construction from erosion caused by overtopping. Adding resilience to earthen flood protection structures such as dams and levees is critical to future risk mitigation. Finding alternative solutions to traditional hard armour solutions such as rock, which can reduce the costs and provide the same or better performance is always a goal for clients.

Armormax® is an armouring system consisting of Pyramat® high-performance turf reinforcement mat (HPTRM) with Engineered Earth Anchors (EEA) that work together to lock soil in place and protect it against hydraulic stresses. This system provides dynamic erosion control and slope stabilisation solutions.

Testing and field monitoring by US Army Corps of Engineers (USACE) since 2005 through one of the largest and most comprehensive public works projects in American history to provide a 100-year level of risk reduction have showed that using Armormx® system has performed substantially better than all other systems in protecting against erosion.

Armormax® helps restore levees, rivers, floodplains, wetlands, living shorelines and soil stabilisation. It is the first and only verified carbon footprint product by an independent third-party organization. The carbon footprint of the HPTRM is up to thirty times smaller than traditional solutions such as rock riprap and concrete.

This system is bushfire resistance and highly UV stabilised and can be used either to promote vegetation or unvegetated and exposed with providing permanent erosion protection for up to 100 years.

Photo: Armormax® installation on New Orleans Levee, USA (Courtesy: Propex/Solmax)

Additional information and detailed insights regarding the performance of the Armormax® system in flood protection levees.

For further information about Armormax®, please visit the official website of Global Synthetics: Armormax®

B. Resilience stormwater channels

Selecting the right stormwater channel stabilisation method is critical to prevent soil erosion and high sediment loads, water clarity reduction, and increase in the levels of contaminants in surface waters. Performance criteria and field performance of channel stabilisation methods include both hydraulic parameters such as shear stress and flow velocity, as well as non-hydraulic factors.

While their traditional purpose has focused on water conveyance and efficient hydraulic design, recent environmental legislation imposed by Environmental Protection Agencies (EPAs) for water quality, sustainability requirements and trends favoring Low Impact Development (LID) have forced engineers to consider other system components in developing solutions.

Reinforced vegetation using Turf Reinforcement Mats (TRMs) have been proven to provide a sustainable solution for stormwater channels. They provide various advantages compared to traditional hard armour solutions such as rock riprap and concrete in different aspects including engineering, economy and environment.

Landlok® and Pyramat® Turf Reinforcement Mats (TRMs) provide reinforcement to the natural vegetations which can improves the shear resistance of the channel bed compared to natural unreinforced vegetation by up to 50 times. They can outperform rock riprap with average size of 90cm if designed and installed properly. Reinforced vegetative solutions support living shorelines, whereas rock riprap and concrete can decrease streamside vegetation and adversely impact fish populations.

Photo: Pyramat® stabilized stormwater channel, Richlands, QLD

This system can be even used with limited or no vegetation, and for coastal areas.

Photo: Oyster Lake Outfall coastal flood protection, USA (Courtesy: Propex/Solmax)

The carbon footprint of Landlok® and Pyramat® TRMs is up to thirty times smaller than traditional solutions such as rock riprap and concrete. They have been recognized by the Environmental Protection Agency (EPA) as a Best Management Practice (BMP) to improve water quality.

For comprehensive details regarding the design and performance of stormwater channels with TRMs, please refer to : Stormwater 2020

Free software for TRM stormwater channel design (EC Design)

Free webinar on Advanced Stormwater Channels Erosion Control Design with reinforced vegetation:

For details on Landlok® and Pyramat® TRMs and more erosion control products, visit: Global Synthetics – Erosion Control

C. Bush Fire Resistance Permanent Slope Erosion Control Techniques

Erosion potential is reduced by minimising rainfall and wind impact and by reducing the velocity and depth of surface water flow. Erosion control techniques are activities or practices, or a combination of practices that are designed to protect an exposed soil surface, to prevent or reduce the release of sediment to environmentally sensitive areas, and to promote revegetation as soon as possible.

Reinforcing vegetation with TRMs has become an acceptable, performance proven, cost effective and environmentally friendly alternative to rock riprap and other forms of non-vegetative materials (EPA, 1999; Lancaster and Austin, 2003; Rivas, 2006).

TRMs provide immediate erosion protection and act as a barrier to minimise soil displacement and erosion by wind and during hydraulic flows both, prior to and while vegetation is being established (EPA, 1999). TRMs also reduce evaporation and insulates the soil, reduce soil moisture loss, moderate soil temperature, prevent crusting and sealing of the soil surface and may increase infiltration (ECSWQM, 2014).

Landlok® and Pyramat® Turf Reinforcement Mats (TRMs) consist of various non-degradable UV stabilised flame resistance synthetics fibres and filaments processed into permanent, high-strength, three dimensional matrices. These TRMs are designed to impart immediate erosion protection, enhance vegetation establishment and provide long-term functionality by permanently reinforcing vegetation during and after maturation.

Photo: Landlok® and Pyramat® TRM erosion protection (installed-left, and after vegetated-right), Palmwoods-Montville Rd, QLD, Australia

Being highly UV stabilised, Pyramat® HPTRMs can be used exposed in arid and semi-arid areas without vegetation with design life of up to 100 years.

Photo: Pyramat® HPTRM Slope erosion protection, Solomon Primary Crushing Hub, Australia

Photo: Pyramat® HPTRM Slope erosion protection, Solomon Primary Crushing Hub, Australia

The unique structure and high strength of the Pyramat® HPTRMs make these material a suitable erosion control solution even for steep slopes.

Photo: Pyramat® HPTRM with EEA, St. Maurice River Pipeline Cap de la Madeleine, USA

Propex Pyramat® TRMs are now engineered to mitigate fire risk and increase the resilience of wildfire prone areas using non-halogen fire retardant technology.

Landlok® and Pyramat® erosion control systems provide resilience solutions against natural disasters:

For insights into slope erosion control techniques and design considerations, check out our document.

Free software for slope erosion control (EC Design)

For details on Landlok® and Pyramat® TRMs and more erosion control products, visit: Global Synthetics – Erosion Control

Free webinar on Resilient flood protection systems and rehabilitation solutions.