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Introduction
The slope adjacent to the athletic fields at Saint Mark Catholic School in Huntersville, N.C. was the site of fairly severe surface erosion. A project to restore the slope with reinforcing geogrids was completed in 2010.
The athletic field slope that had been failing was restored and Saint Mark Catholic School was able to continue using the field without continued slope failures. The slope was reseeded at the conclusion of the project and several weeks later it had full vegetation.
Project plan
What do you do when your Field of Dreams turns into a nightmare of erosion?
Engineers on this case in Huntersville, N.C. decided on a solution that involved driven soil anchors and a turf reinforcement mat for veneer stability. The geogrid selected was an ideal fit for the turf reinforcement because of its high tensile strength at low elongations.
The plan for repair of the athletic field slope consisted of installation of slope reinforcement and erosion-control measures. After all existing vegetation and unsuitable soil was stripped, the slope was re-graded to a 2horizontal:1vertical slope.
A 12-in. berm was constructed at the top of the slope. Catch basins with slope drains helped divert site runoff from eroding the repaired slope. Surface/slope reinforcement materials were then installed to prevent further surface erosion and surficial slope failures.
The stabilization and reinforcement materials consisted of a driven soil-anchor system with the turf reinforcement mat. After the slope surface was prepared and seeded, the geogrid was anchored at the top of the slope. Then it was simply unrolled down the face of the slope. The soil anchors were then installed, eliminating the need to pin the geogrid in place.
Conclusion
This erosion-control project was completed in the spring of 2010. The athletic field slope that had been failing was restored and Saint Mark Catholic School was able to continue using the field without fear of continued failures. The final step was reseeding the slope and it soon was fully vegetated.
Geogrid
The geogrid on this project was a flexible, three-dimensional reinforcement grid made from high-tenacity, low-creep polyester with the additional function of protection against soil erosion. A polymeric coating provides protection against ultraviolet degradation and mechanical damage. A high-tenacity geogrid provides reinforcement against soil slippage on a slope, such as described above. The geogrid improves soil retention on a vulnerable slip plane surface and its tensile strength carries the loading forces imposed on the anchorage zone. The surface stability of the structure is increased, resulting in a safer and more economical construction method.