Highway Embankment Construction Using PYRAWALL Wrap-Face Vegetated Wall System

Pend Oreille County needed to remove a culvert on Indian Creek that was preventing Bull Trout from traveling upstream to spawn.  The Bull Trout are a threatened species under the U.S. Endanger Species Act and the stream is considered environmentally sensitive.  Additionally, the county needed to address the road’s aging condition. Its alignment was for a 35 mile per hour road, but the speed limit is 50 miles per hour.  It was determined to realign the road and replace the culvert with a 58-foot, single-span bridge to allow the fish to more easily move upstream and to correct the road condition. Limited physical and right-of-way access dictated that the earth-fill embankment approaches required for the new bridge would need steep wing-walls.

The owner considered using steel sheet pile walls, but the cost quickly exceeded the project’s budget. Vinyl sheet pile walls were considered, but they did not meet the strength criteria.  Another deciding factor was that residents and a local Indian tribe wanted a solution with a natural, vegetated look rather than a concrete wall along the wetland.  PYRAWALL™ was selected because it is an engineered wrap-face, vegetated solution that costs less than a concrete retaining wall.  The system combines the robust protection of PYRAMAT® High Performance Turf Reinforcement Mat with fiber-composite internal bracing to deliver permanent erosion control and mechanical slope stabilization.

In addition to offering long-term durability, PYRAWALL is a vegetated solution.  It is designed with patented triolobal X3® Fiber Technology to promote rapid root mass development, yielding a fully vegetated installation.  In addition to yielding a natural look, the system’s bracing is all internal creating a smaller footprint overall.  PYRAWALL can also withstand animal loading expected from deer, antelope and moose in the area.

PYRAWALL was used to build an east-approach embankment that is 210 feet long and 14 feet tall, and the west-approach embankment that is around 340 feet long and 18 feet tall.  On-site soil was used for infill, eliminating the cost and carbon footprint of importing soil.  Seeds were planted within the wall to further establish vegetation. Within months of installation, vegetation was visible along the constructed wall, and within four years it is expected to be 85%-90% vegetated and will provide erosion control protection for up to 75 years.

In addition to creating  wrapped-face mechanically stabilized earth structures, PYRAWALL can be used for reinforced soil slopes, stream bank stabilization, landslide remediation, vegetated facing for soil-nail or ground-anchored slopes, landscaping enhancements for residential and commercial properties, and wing walls for Geosynthetic Reinforced Soil – Integrated Bridge Systems (GRS-IBS). PYRAWALL features flexible setback and alignment, allowing it to be customized to unique site conditions.  Plus, it is easy to transport, making it ideal for sites that are difficult to access.

For more information on how PYRAWALL can benefit your next project contact Propex GeoSolutions at  800 621-1273 or visit our website at www.PropexGlobal.com. Also, make sure to attend our webinar on PYRAWALL on May 30th at 1 p.m. (EST).

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