ArmorMax stands up to Hurricane Gustav and IKE
When Hurricane Katrina made landfall on August 29, 2005 it caused devastating flood damage to large portions of southeastern Louisiana—but it was not the only hurricane to hit the area that year. Hurricane Rita made landfall in late September, causing catastrophic tidal inundation to the community of Lafitte as it passed south of Jefferson Parish, Louisiana. One of the many levees that needed rehabilitation was the Penn Levee. The LADOTD and the Lafitte Levee Board made the decision to incorporate the ArmorMax anchored reinforced vegetation system into the project design. The Decamp Street Levee which intersects the Penn Levee was also armored with ArmorMax. Not only did the ArmorMax system offer a cost-effective approach to armoring the levees, but the innovative approach offered immediate protection from erosion and scour forces caused by wave overtopping and storm surge similar to what happened from Katrina. When wave overtopping occurs, the levee soil surface is subject to severe erosion and scour that can lead to breaches causing catastrophic failure. The ArmorMax system is an engineered armoring solution that provides permanent erosion protection to the levee resisting soil movement and uplift that can occur.

The design for the 1.8 mile (2.90 Km) long Penn Levee included the use of the ArmorMax system to armor the levee crest (top) and down the backside slope to the Borrow canal. The project was installed in two phases. Phase I installation was completed in July 2007 with the ArmorMax system installed starting 5 feet (1.52 m) from the sheet pile wall to 18 feet (5.49 m) across the levee crest. Phase II installation started in May 2008 and started where Phase I ended 25 feet (7.62 m) down the back side of the slope. Prior to installation the levee was prepared by “scalping” the vegetation with a mower and then back-dragging it to fill in any depressions and remove any obstructions. The HPTRM component was then installed and secured with Type 2 earth percussion anchors in a checkerboard grid pattern at five feet (1.52 m) centers. The earth percussion anchors act as a tie-down mechanism with 500 lbs (227 Kgs) of maximum pull-out strength for greater factors of safety. The ArmorMax installation in both phases was complete in 6 weeks each time versus typical installation of rock riprap which could take 4 to 5 months. The DeCamp Street Levee was an additional 1300 feet (396.24 m) of ArmorMax installed from the front toe of the levee over the crest and down to the backside toe.

In September 2008, the Penn Levee was subject to heavy rain from Hurricane Gustav and a 12-foot (3.66 m) storm surge from Hurricane Ike. The ArmorMax system held its ground during the severe overtopping and storm conditions resisting erosion and scour.

During the heavy rainy season of 2004/2005 a steep cut 1:1 slope along Highway 26 in Caleveras County, California became saturated, creating a shallow plane failure. Two possible solutions were considered to repair the slope: The ArmorMaxTM anchored reinforced vegetation system; and rock slope protection. Rock slope protection would not be possible due to the height (approximately 120 feet) and angle (approximately 45°) of the slope as well as the high cost. The ArmorMaxTM system was specified because it was low impact, required only handheld equipment for installation and provided an instantly attractive finish to the slope creating a natural looking environment. It also meant that there was no need to purchase additional right-of-way or close the lane of the highway, making it the most cost effective option.

The ArmorMaxTM design included earth percussion anchors with a 4.5 foot stainless steel tendon to be driven through the high performance turf reinforcement mat (HPTRM) protection layer on a checker board grid pattern at 5 feet centers. In August 2005, installation was complete in just 10 days. By early September vegetation was starting to emerge. The X3® fiber technology utilized in the HPTRM material construction trapped in the morning dew, providing moisture for the seed germination. The project was particularly successful due to the speed and simplicity of the ArmorMaxTM installation and construction, the elimination of heavy equipment that would have been necessary to install the rock slope protection and the rapid vegetative establishment properties of the HPTRM component in the ArmorMaxTM system.

In early 2007, a bypass channel was constructed to allow the Clark Fork River to flow through the reservoir area without cutting into toxic sediments and to prevent the contamination from washing downstream to minimize the impact on fish and other wildlife. The bypass channel is 4100 feet (1249.7 m) long and 100 feet (30.5 m) wide and built to withstand a 100-year flood level event.

With construction of the bypass channel, there was a need to reinforce the soil from movement into the river flow. ArmorMax was used to reinforce the channel banks from erosion. As the site was not intended to be vegetated, a Propex nonwoven geotextile was used as a lining underneath the ArmorMax system to keep soil fines from filtering through.

The ArmorMax system consists of a high performance turf reinforcement mat (HPTRM) and earth percussion anchors. The HPTRM is a woven-three dimensional fabric that exhibits a high tensile strength surface protection layer of 4000 lb/ft (58.4 kN/m), which exceeds the U.S. EPA’s definition of a High Performance Turf Reinforcement Mat. It has a high resistance to ultraviolet light which is an important factor as the project design is for the river bank to remain unvegetated. The Type 2 earth percussion anchors were driven through the hard surface 2ft (0.61 m) below the rocky soil to securely anchor the HPTRM to the subgrade. The anchor foot provides 200 pounds (90.7 Kgs) of tie down capacity per percussion earth anchor. The lightweight armoring system allows for easier handling and rapid installation and is approximately 50% of the cost of traditional hard armor methods. The ArmorMax system is engineered to provide permanent erosion and soil reinforcement protection for long-term design life.

The construction of the bypass channel was complete in March 2008 and water from the Clark Fork river was diverted into the channel. With the Clark Fork River diverted to the bypass channel the amount of material scoured from the reservoir area will be reduced by 60 percent and no contaminated sediments will be sent downstream. The river will remain in this channel until the contaminated sediments are removed and a new natural channel is built through the old reservoir area.

The Border Road and Fence Project is a 2,000+ mile (3219 km) project being constructed along the U.S.-Mexico Border from San Diego, CA to Brownsville, TX. The project is unique in that this road is being constructed with respect to political boundaries regardless of terrain. This presents unique challenges to the design and construction of this road as it crosses streams, rivers and mountainous terrain in ways where traditional civil design and construction might avoid. The ArmorMax system has been instrumental in providing permanent erosion control for cut and fill slopes that have resulted from the construction. In addition, there are drainage ways where the ArmorMax is being used to provide permanent erosion control as well.

The ArmorMax system is comprised of a high performance turf reinforcement mat (HPTRM) and earth percussion anchors. Key challenges include UV Exposure- the vast majority of this road lies in arid or semi-arid climates where very little vegetation can establish and the HPTRM meets the most stringent UV stability requirement of 90% at 6000 hours. In addition, the high tensile strength of the HPTRM provides long-term protection against erosive forces – 10 times stronger than first generation turf reinforcement mats. The earth percussion anchors, made of corrosion resistant aluminum alloy, are connected to a stainless steel rod/tendon to fully enhance the corrosion resistance at the soil/air interface to ensure that the anchors meet the permanent design life required by the project. The ArmorMax system offers the necessary material properties needed to provide the permanent erosion protection designed for this rugged environment.