Project Name: Slope Stabilization & Landscaping Project
Project Location: Walnut Creek, CA
Project Background & Challenge:
Project owners at a California medical center were faced with the challenge of stabilizing a steep 0.5:1 slope (63.5°) located between a fence and concrete drain. To further complicate things, the slope contained several exposed tree roots that would need to be addressed without damaging the trees.
The contractor reached out to Presto Geosystems to receive a complimentary project evaluation, then arranged a meeting with a landscape contractor, along with a local geosynthetics distributor, Reed & Graham, for installation support.
The GEOWEB® Slope Stabilization System with a vegetated infill was selected as the site solution to stabilize and protect the slope’s surface and prevent future erosion. Additionally, the GEOWEB system would also provide the necessary support to the trees and fence located along the top of the steep slope.
After contractors did some slight re-grading of the slope, they placed a six-ounce non-woven geotextile over the slope’s surface, then installed 6-inch-deep GEOWEB sections over the top, securing the panels with the patented ATRA® Keys. The ATRA Key connection devices are three times faster to install and three times stronger than staples, providing a more secure and permanent load-transfer connection at mechanical junctions.
The installers used TP-93 tendons to suspend the GEOWEB material over the geotextile, providing additional reinforcement against sliding. The ATRA Tendon Clips were used in conjunction with the tendons to transfer the load from the GEOWEB panels to the tendons. The ATRA Tendon Clips’ turn-and-lock design engages the clips securely with the GEOWEB cell wall, and also allows for off-slope preassembly, which can be especially helpful for steep or difficult-to-access slopes.
The contractors wanted to secure tendons with anchors as close to the fence as possible, so they opted to place the anchors on the opposite side of the fence. This allowed the GEOWEB panels to fit snugly against the bottom of the fence in order to spread the infill material higher and more evenly across the top of the slope.
Once the GEOWEB system was in place, the geocells were infilled with sandy clay and gravel. Typically, an engineered fill consisting of topsoil and gravel would be used for a vegetated surface. However, due to the steepness of the slope, cohesive infill material was required in order to protect against washout.
Benefits of the GEOWEB Slope Stabilization System:
The GEOWEB system’s 3D cellular network stabilizes topsoil for sustainable vegetation on steep or complex slopes. In the case of the medical center project, installing a vegetated slope helped meet landscaping goals by providing an aesthetically pleasing green solution. The GEOWEB system will also protect the surrounding trees and fence installed at the top of the slope and eliminate the potential for future erosion behind the fence.
The GEOWEB vegetated slopes are a green solution ideal for Low Impact Development (LID) and Green Infrastructure (GI) designs. The system reduces environmental impacts by allowing stormwater infiltration, thereby limiting impacts from runoff and sedimentation in stormwater management systems and waterways.