Masonry Magazine June 2004 Page. 26
INSTALLATION TIPS
The National Concrete Masonry Association offers installation guidelines in the Segmental Retaining Wall Installation Guide. However, Anchor Wall Systems provides a brief overview of the recommended installation for Anchor products:
Step One
Using a shovel or a skid loader, dig a trench about 24 inches wide and deep enough to accommodate the required amount of buried block and compacted base. For walls four feet high and shorter, bury one course of units. Total wall height includes the height of any buried courses.
Step Two
Firmly compact the soil in the bottom of the trench. Lay six inches of compactable base (eg, sand and gravel) in the bottom of the trench and compact.
Step Three
Place the first layer of Anchor units without lips on the prepared base (lips must be manually knocked off units before placement). Position the units side-by-side, in full contact with the base, and level in both directions using your carpenter's level. Backfill with free draining aggregate.
Step Four
Anchor recommends using a filter fabric, which should be placed directly behind the wall extending from the bottom of the base course to the middle of the top course.
Step Five
Continue assembling additional courses in a running bond pattern, pulling each unit forward until secure. Use free-draining aggregate to backfill each additional course as it is installed.
Step Six
Place drain tile behind the wall at grade to allow water to drain from the backfill (organic or clay-type soils are not recommended). Outlet the drain tile through the wall at every low point, or every 75 feet of wall length and around the ends of the wall. Backfill with free-draining gravel 12 inches behind the wall, in six-inch layers.
Step Seven
Fill any remaining areas behind the wall with soil. Compact every 12 inches. Repeat steps four through seven until the wall reaches the desired height.
Step Eight
Firmly compact native soil every 12 inches behind the wall. Do not compact directly on top of the units.
An engineer should evaluate every retaining wall project, even those lower than four feet. When geosynthetic reinforcement is required, an engineer can specify the appropriate materials, number of layers and correct placement of geosynthetic reinforcement based on the particular site conditions and your project design.
The result was a whole new look for the property: a retaining wall, curved with a natural stone look, terraces for plants and flowers, and vertical blocks to vary the look, all while effectively channeling the water run-off from the steep hillside. Before building your retaining wall project, Anchor Wall recommends key steps to take into consideration in planning, on-site evaluation and installation.
Planning
THE FIRST STEP in building a retaining wall is thorough planning. A site plan, design soils information and a wall construction plan are essential before getting started on a retaining wall project.
Site Plan
THE SITE PLAN is a detailed drawing of the site including wall location, length, elevations, information on grading, underground utilities, erosion control and storm water management.
Design Soils Information
THE DESIGN SOILS information identifies the kinds of soils on your construction specifications.
Wall Construction Plan
THE WALL CONSTRUCTION plan is a blueprint of the wall you're going to build, and has five requirements: wall, toe and crest elevations, reinforcement location and length; soil conditions and parameters; drainage and other wall details, and wall construction specifications.
When creating a wall construction plan, it is important to consult with an engineer, as it is their job to determine the length and the number of geosynthetic reinforcement material that is required to stabilize a site-specific segmental retaining wall system, as well as provide drawings that show how a wall should be constructed. Geosynthetic reinforcement is a sheet material made from high-tensile strength polypropylene, polyethylene or polyester that, when used properly, helps to support the retaining wall system.
The need for geosynthetic reinforcement depends upon many factors, including wall height, soil conditions, expected loads and earth movement. To determine whether geosynthetic reinforcement is warranted, an engi-