Segmental concrete retaining walls (SRWs) tame steep hillsides, create decorative planters and water fountain displays. The availability of choices in color, shapes and textures have made SRWs a popular landscape product for residential and commercial applications. Prior to the growth explosion of the segmental retaining wall industry, retaining structures were limited to poured concrete, railroad timbers, or natural stone. Standard concrete walls by today's standards are gray, drab and boring. Expansive concrete slab walls can crack due to the ground movement beneath and are also subject to graffiti vandals. Railroad timbers offer a dated look and become unattractive due to wood rot. Natural stone are still an attractive choice, but prove to be a very heavy product and difficult to work with for anyone other than the most skilled laborer. The manufactured concrete segmental retaining wall industry provides an attractive, natural stone look but affordably priced. Available in easy-to-install modular units, SRWs are now available in earthtone blends and a variety of shapes and textures. Some have a straight face, some a beveled edge, still others a more broken, natural stone-like face. Because there are so many beautiful concrete wall systems to choose from, a contractor can provide the customer with retaining structure options that allow for a world of landscape possibilities. This equates to increased revenue potential for the Landscape Contractor. "There are two types of retaining walls: gravity and reinforced walls," Pat Williams, Pavestone Company, Kansas City, explains. "A reinforced wall can be thought of in terms of a tall wall more than 3 feet tall that can reach heights of up to 40 feet. Typically this wall is found in large commercial applications. It will require an engineer, a wall construction plan, soil testing and a reinforcement fabric. "A SRW gravity wall typically averages 2 to 4 feet in height and can be a standalone product. That is, it resists the forces of soil though the weight and set-back of the stones. Gravity walls are common residential applications such as slope stabilization, tree rings and terraced gardens. Some of the new SRWs, such as the tumbled rectangular and square stones that modulate together, provide additional creative applications such as bar-b-que grilling encasements, water fountain features and even columns that can contain outdoor lighting features. The same is true for wall caps and coordinating steps. These items enhance the outdoor living spaces while affording the contractor the opportunity for increased selling features and greater profitability." The first step is to help the customer select the SRW that will most complement the project. In each wall category, reinforced tall and gravity walls, one will find a variety of SRW shapes, textures and colors to select from. For the purpose of this feature, the focus will be primarily on gravity retaining walls. Selecting SRW Color SRW color selection can be made to complement the home's color scheme. Or it can be to contrast a specific feature such as a dark retaining wall to match a dark roof offsetting a light color home. Contrast SRWs to the concrete pave stones. If you have a dark pave stone for the driveway, use a light, complementary color for the wall. Texture can help complement the home's architecture. For example, brighter colors and the beveled face wall stone work well with a modern home. A brick home may be best accented by a straight-faced wall. A tumbled wall can provide a fresh landscaping update while preserving an older home's historic integrity. Softscape Considerations Softscapes provide more than just "curb appeal" in landscape design. Beyond the obvious aesthetic value, the addition of softscapes adds practical aspects as well. Properly placed trees provide shade relief from the intensity of the sun, reducing house temperatures in the summer, and allowing the air conditioner to operate more efficiently. In fact, according to the Department of Energy, carefully positioned trees can save up to 25 percent of a home's energy for heating and cooling. Additionally, they offer privacy, block street noises and reduce flare glare of passing headlights. Because softscapes are living plants, there are a few important things to consider in SRW design and installation. Be careful so not to disturb the roots in the tree's "drip line" as they deliver critical nutrients to the tree. The drip line is the invisible circle on the ground directly below a tree's branch tips. Do not pile soil against the tree's trunk, as it will restrict oxygen and possibly retain moisture that is dangerous to the stem of the tree. Place mulch up to 3 to 4 inches deep around inside the tree ring; the porous material will allow the tree to breathe. Today, SRWs are designed to achieve aesthetic appeal, install with ease and efficiency, and deliver a structurally sound retaining structure. Williams provides the following brief overview of the installation process for segmental retaining wall installation for gravity wall applications. Site Preparation Stake out the project with tall stakes. Place an accurate level string line at the estimated final wall height and mark the stake with a pencil. Small walls, three courses or less, require the first course to be partially buried (approx. 3 inches). Excavation For small gravity walls, dig a minimum 3-inch deep trench. Firmly pack the floor of this trench with a compactor or hand tamp. Base Preparation & Leveling Add 1/2 inch of coarse sand to the bottom of the trench. With a Carpenter's Level, level the surface in both directions. Place a level string line where the top of your first course will be. Laying Stones Always begin at the lowest point of the wall. Position the wall units side-by-side, with lip removed on the prepared base. Level each stone in both directions with a carpenter?EUR??,,????'???s level. Verify each placement with your string line. Once the base course is complete, continue assembling additional courses by positioning the units in a staggered pattern to the course beneath. Pull each forward to secure. Backfill in 4- to 6-inch layers (depending on the height of the wall product) with your approved backfill. In a seven year period from 1995 to 2001, the SRW market saw a 342 percent increase in millions of face feet sold in the US. Landscape Contractors choose SRWs as the retaining structure of choice for their ease-of-installation, aesthetic beauty, consumer appeal and wide variety of applications. Alva D. Longsdon is the Director of Marketing for Pavestone