Home  Sustainable Land Development Today April 2007
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Retaining Walls Featured on Residential and Commercial Projects |
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Written by Karl Bremer
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Thursday, 04 January 2007 |
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Residential “tier-ful” project in Wisconsin wins first place in national contest.
With much of the prime real estate already gobbled up in many communities, it is not a surprise to see more challenging parcels now being developed. Many of the challenges involve slopes and/or significant topographical drops. These often present hydrological conditions that need to be professionally addressed as well.
As a result, it is not uncommon any more to have developers budgeting and designing retaining walls and similar structures to support these new challenges. And, just like other necessary components of a development project, many creative designers and developers are turning these functioning structures into amenities – on both residential and commercial projects. In addition, the increase in use has resulted in newer and more efficient products to install.
Residential Applications
Jim Christensen’s award-winning landscape design for a rural Wisconsin residence will bring tiers to your eyes, but that’s a good thing. Christensen, senior landscape architect for Villa Landscapes (Oakdale, MN) won first place in the Interlocking Concrete Pavement Institute’s National Concrete Paver Design Contest for his stunning multilevel design of a backyard in the St. Croix County (WI) countryside.
A large paver patio featuring a pair of circular patios overlooks a broad expanse of farm fields and anchors the lower level of this complex. The twin patios — one a sunken fire pit with tiered seating around the edge and the other a raised dining area — are partially ringed with freestanding walls and create a pleasing symmetry on the landscape.
The lower patio area is connected by a walkway to a massive three-tiered series of gardens of various shapes and sizes on the other end of the house. Filled with colorful plantings, the gardens are bisected by offset stairs that weave between them with landings at every level. Freestanding columns capped with natural stone accent each landing. Stepped serpentine walls wrap around the end of the house and tie the tiered garden complex back into the slope of the yard and the driveway above.
“This is a magnificent site that begs for taking advantage of the wide open spaces,” says Christensen. “The twin circular patios provide comfortable gathering areas while the spacious patio around them offers plenty of room for other activities.”
“We had to tame a slope to allow for a gentle stepped transition between the lower patio and the garage and house above,” explains Christensen concerning the other end of the yard. “Instead of straight tiered walls and stairs, I opted for a more sculpted look by offsetting the stairs and landings and adding some curves, corners and columns. As a result, the entire structure has much more visual appeal and looks less imposing.”
About 2,000 square feet of Versa-Lok Standard retaining wall units in a chestnut blend color were used for the walls, raised patio base, columns and stairs throughout the project. Nearly 2,000 square feet of Willow Creek paving stones in a matching chestnut blend color were used for the paved surfaces — Circlestone for the sunken fire pit and raised dining area and random-pattern Cobblestone for the remaining paved areas.
“The flexibility of the Versa-Lok wall product makes it an easy system to design with,” explains Christensen. “With one unit you can design a plethora of elements — retaining walls, freestanding walls, planters, benches, columns, stairs. There’s really no other retaining wall system that can do that.”
Christensen, with 38 years experience as a landscape architect and over 10 years with Villa Landscapes, notes that the ability to match colors between walls and paved surfaces made Willow Creek the natural choice for paving stones.
“Willow Creek’s quality is consistent in color and durability and is an excellent complement to Versa-Lok’s appearance,” says Christensen. “Together, they are a nice pallet from which to work.”
Commercial Applications
For contractor Arvid Jereczek, building a segmental retaining wall using traditional 100-pound units is child’s play. However, building a wall with a new 4,500-pound system presented a whole different challenge. But, after completing his first wall of this design, the Eau Claire (WI) contractor can’t wait to get started on his next one.
“I wish we would have had them about four years ago,” Jereczek enthused.
Jereczek’s company, American Express Transport, has installed a lot of segmental retaining walls. But they had never worked with blocks as large as VERSA-LOK’s new 4,500-pound Bronco Segmental Retaining Wall (SRW) system until this project at a commercial office building parking lot came along.
“We probably would have gone with a regular segmental retaining wall,” says Jereczek, because there wasn’t a whole lot of (total installed) cost difference between the two products. But, the time savings was the biggest factor in going with Bronco.”
Bronco is installed much like any other SRW. Each unit weighs about 4,500 pounds and displays 14 square feet of face area with a four-panel, natural-stone relief appearance. Bronco units are made in four different face patterns. By alternating the four patterns, a random pattern can be achieved throughout the wall.
Bronco units are wet-cast using approximately 1.25 cubic yards of concrete per unit. Steel-cable pick rings are cast into the top and back of the unit for easy placement using appropriate lifting equipment. Alignment knobs molded into the top of units and channels molded into the bottom ensure correct near-vertical positioning and allow for tight, variable-bond construction. Cap units are designed to allow for landscaping to the face of the wall at the top.
Although Bronco units can be set on an 8-inch granular road-base leveling pad, Jereczek’s crew installed their wall on a “lean” concrete footing.
“The very first course is the hardest because you’re trying to get them exactly level. By using a concrete leveling pad, you put them down and you’re done,” says Jereczek. Once the base-course is in place, each one is leveled front to back and side to side with adjacent blocks and shimmed up if necessary.
Bronco units are placed using a backhoe and chain to hoist them. Once placed, they can easily be nudged into position with the backhoe bucket.
“We were figuring it would take us five minutes per block,” says Jereczek. “But it was even faster than that. We had one placed about every three minutes.”
Because Bronco can be built up to 10 feet tall without geogrid, it’s ideal for installations with site constraints. However, Jereczek says that wasn’t an issue on this project and had no bearing on choosing Bronco.
“It was the time savings. We saved at least a week-and-a-half” by using Bronco over a conventional SRW, he notes. The project was installed in October, so it was imperative that they have time on their side before the Wisconsin winter set in. “Plus, we wanted the random-pattern look that Bronco has.”
Two walls were built to create parking areas adjacent to the office building: one 135-foot wall and one 80-foot wall. The walls used 97 full Bronco units, six half units and 37 caps for a total wall surface of just over 2,000 square feet.
Jereczek will soon be staining the wall and he looks forward to completing more wall projects with these large units. LDT
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