Northstar Vinyl Products and Tensar International recently unveiled the AquaTerra Retaining Wall System, a proprietary new concept that allows sheet piling and geogrid materials to be combined for the first time.
"AquaTerra is a solution for many complicated situations," says Jeff Moreau, President of Northstar Vinyl Products, LLC. "AquaTerra is an excellent option when rock and hard soils present challenges, because in most cases, the sheet piles only need to be placed in a two foot deep trench. The system is also an excellent choice when piping and global stability issues are present because the sheet pile can be driven to a specified depth and then attached to the reinforcement system."
As communities continue to expand, land once considered unusable because of steep grades is now being improved with the use of retaining wall systems. AquaTerra is already having a dramatic effect on how retaining walls are designed and installed. Retaining walls once reserved for steel sheet piling are now being designed with light gauge vinyl or composite sheet piling supplied by Northstar.
Upland retaining walls are currently comprised of two components: a fascia system and a soil reinforcement system. Fascia systems are typically masonry block or pre-cast concrete panel systems. Soil reinforcements are either a geogrid or geotextile material. Using a variety of methods, fascia systems are connected to the soil reinforcement. The purpose of the geogrid is to diffuse the soil load that would otherwise act on the fascia by causing the soil to "stack vertically" as opposed to stacking at its angle of repose. Once the retaining wall is built, there is little soil load against the fascia.
"For years, engineers have known that if they had a method to connect geogrid or geotextile to a sheet pile, the same benefits would apply, and shorter, lighter gauge sheet pile could be used in most retaining wall applications," Moreau says. "Until now, there was not a connection for a 'sheet pile-to-grid' system."
AquaTerra also provides significant benefits to engineers designing tied back sheet pile walls. With AquaTerra, walls once reserved for steel, composite or heavy-gauge vinyl sheet piling can now be built with shorter sections of lightweight vinyl sheet piling. In addition, AquaTerra has no metal components, which is a huge plus in saltwater applications.
The versatility of the AquaTerra system lends itself particularly well to flood control and levee structures. The Modular Levee System is composed of two parallel sheet pile walls supported by layers of geogrid in the core. The geogrid mitigates the soil loading in the sheet piling and in many cases will allow the use of native soil in the core. The Modular Levee System by AquaTerra provides several key benefits:
- The footprint of the levee is dramatically reduced, solving many environmental and easement concerns.
- Lighter and shorter sheet pile sections reduce the cost of getting sheet pile material to remote sites;
- Lighter and shorter sheet pile sections don't require the use of heavy machinery on an existing levee;
- Lighter and shorter sheet pile sections are less expensive that optional materials;
- The geogrid, in many cases, will allow the use of native fill in the core, saving the expense of trucking in non-native fill;
- Whatever the choice of fill, less of it is required; and,
- The AquaTerra Modular Levee System can be installed in less time than conventional designs.
The AquaTerra Modular Levee System is an industry first and is receiving a substantial amount of consideration in places like Louisiana, where major efforts are being made to reduce the risk of flooding in low lying areas.
"The versatility that AquaTerra gives the customer is amazing and we can't wait to see how it can lower the cost of projects and extend what our customers can do with their budgets," Moreau says.
Interested parties can learn more about the AquaTerra solution by visiting www.northstarvinyl.com.