Segmental retaining walls handle various landscaping designs, but they maintain a clean, attractive appearance while playing a role within a landscaping team concept. Two recent sports-facility projects attest to segmental wall versatility.
Lebanon Valley College of Annville, Pa., had to do something about a hillside in the middle of the site of its planned McGill Field in fall 1997. A major state highway on the other side of the hill made an earth-retention system essential. Looking at a segmental wall, the president saw it would be possible to have multiple retaining walls-including an attractive 9-foot-high vertical outfield wall-built at a reasonable cost. The Versa-Lok system worked as part of a site-improvement team, bringing out possibilities for other site features.
Matching split-face units were used for planters, walkways, dugouts, and even walls for elevated bullpens integrated into the outfield wall. Seating for 500 also has a segmental wall as a veneer, and the configuration allows integration of other split-faced masonry units into the walls. The results were so positive that Derck & Edson, the landscape architect, used the system for bleachers and players' benches at a soccer facility next to McGill Field.
It's hard to imagine a site worse than the one Johnson C. Smith University recently had prepared for a football and track facility in Charlotte, N.C. One end borders a highway and required 30 feet of cut on solid granite, and another end required 25 feet of fill on decomposing trash and alluvial soil. Landscape architects helped design a soil-retention system that included wick drains to soak up water, a geosynthetic drainage blanket foundation, and a 30,000-square-foot retaining wall.
"Segmental block systems seemed to work the best because of their ability to function flexibly and to be resistant to the problem of differential settlement of the soil," says geotechnical project engineer Donnie Barrier of Barrier Engineering.
The cut side of the site presented other challenges, with vertical seams of granite just below the soil surface that required blasting, interspersed with soft soil. The contractor cast a concrete cut-off trench to hold the sheet piles in place. Two 15-foot segmental walls complete the system. The wall could be built immediately following the groundwork.
The article includes a description of how Fircrest, Wash.-based WestBlock Systems designed and licensed an adaptable segmental retaining wall system that uses interlocking components.