Huge retaining wall installed at Virginia Military Institute
14 Apr, 2011 LDB SolutionsThe 6-acre drill field and complex features a quart-mile-long retaining wall.
By Karl Bremer
When the Virginia Military Institute (VMI) wanted to convert an unusable valley on its Lexington, VA, campus to a drill field and shooting range complex, it turned to Versa-Lok Retaining Wall Systems for a 34-ft.-tall segmental retaining wall over a quarter-mile long holding up more than 100,000 cubic yards of fill to create a 6-acre level field.
The $17 million complex comprises three drill fields measuring about 1,200 ft. by 200 ft. each. The center field has synthetic turf and lighting to allow for year-round use. The outer two fields are both natural turf. In addition, there is an obstacle course and baffled firing range with 30 positions. Besides the large wall, there are several smaller decorative walls on the site.
According to Lt. Col. Keith Jarvis, deputy director of construction for VMI, the wall design went through several permutations before they settled on Versa-Lok’s Weathered Square Foot product in a Granite Blend color.
“It was vastly less expensive to build than a poured concrete retaining wall,” Jarvis says. “The cost savings played a huge part in the selection. We chose the type and the weathered look of the stone because it matched existing stone on site and gave us a rustic fieldstone look.”
The project began in October 2009, and the final touches on landscaping will be completed in Spring 2011. The main wall itself took about seven months to erect and comprises nearly 50,000 sq. ft. of block.
Jerry DeVault, project manager with general contractor Branch & Associates, Inc. of Roanoke, VA, says his firm is experienced with large retaining walls, but even by their standards, he adds, “this one’s pretty massive.”
The VMI site presented some challenges as well.
“There’s a river, then a hill beside it that drops down to a creek — this horrible place that was like a little valley,” he says. “We built the wall and leveled off the top of the hill, then moved about 100,000 yards of fill behind the wall.” Some rock had to be blasted out.
The walls were built on a crushed-gravel base. Geogrid soil reinforcement in lengths of about 22 ft. was laid behind the wall on every other course, with 2-in.-minus crushed rock used on top of the grid layers.
“We had to bring in all the material to backfill on top of the grid for the whole distance,” says DeVault. “We backfilled behind them as they went up with the wall.”
Eckhart Construction Services Inc. performed the actual wall construction.
“There was really a lot of competition for the block work,” says Mark Eckhart, vice president. “Early on, it seemed like everyone and their brother on the manufacturing side was a VMI graduate, or a had a relative who was. We weren’t quite sure what the ultimate selection and block facing was going to be.”
Once the product and manufacturer—Chandler Concrete of Christiansburg, VA—was selected, Eckhart says, “We were very concerned early on about establishing a criteria for determining which units were acceptable and which units were to be culled. I wanted the culls to be culled at the plant, not the job site. But we had very, very few culled units—so few it wasn’t even worth reporting.”
Ken Tucker, hardscape sales territory manager for Chandler Concrete, says their special process for manufacturing Weathered Square Foot minimized production problems.
“We beefed up our Square Foot unit by filling in the voided area between the back ‘ears’ of the units with solid material,” he explains. “This helped reduce culls during the tumbling process. High quality standards were established from the end of the tumbling line to the cuber to the trucks leaving the yard.”
The entire 50,000-sq. ft. lot of retaining wall units was done in a single production run to ensure consistency in color, strength and texture.
Karl Bremer is editor at Versa-Lok Retaining Wall Systems, Oakdale, MN.
Please send any technical comments or questions to our webmaster.