Retaining walls have become a necessary part of the landscape, as highways, driveways and paths are cut through sloping hillsides. There are options to the heavy, cast concrete walls that can be seen alongside every major highway. These alternatives to retaining walls should be carefully considered, because they blend into the surrounding landscape rather than create an eyesore.
Reinforced Soil Slopes
This simple and quick construction method uses a geotextile or wire made of polyethylene or polypropylene to lock up the existing soil material and create a reinforced mass with no fill dirt required. This method can be used on slopes with a grade of less than 45 degrees, and offers a soft face that can quickly be covered over with ground covers and native plants.
To blend a wall in with the existing surroundings, try using what nature has provided by incorporating local stones into the wall. Anchor the base by digging a footer and pouring a shallow concrete pad for the stones to sit on. Base stones can be mortared together, to prevent bowing when you backfill with soil.
Treated wooden timbers or railroad ties treated with creosote provide a natural look and can last a long time without rotting. Timbers are especially good for building raised beds or for terracing a hillside. Add a fast-spreading ground cover such as bishop's weed, sweet woodruff, creeping phlox or crested iris for fragrance and a pop of color.
Segmental Retaining Walls
This is a good-looking and less expensive alternative to a poured concrete wall. Identical pieces of precast concrete are interlocked and anchored into the backfilled soil. This design is more flexible than poured concrete, and is often used in conjunction with geotextiles where the slope is greater than 45 degrees.
These wire cages are used where water flow is an issue. The cage is filled with native rock or stone. Quick-growing vegetation can cover the wire cage, but water can flow freely down the hillside without impediment.
Soil Bioengineered Wall
Using living materials as part of its construction, this relatively new type of wall uses cut branches which are combined with natural rock or a geotextile covering. The branches provide immediate support and begin to root in the soil, as well as providing an unusual texture to the wall. Those portions of the branches that are exposed to light will begin to host new vegetation and will create a natural covering.