How to evaluate a retaining wall project

In addition to SRW, options such as Timbers, Natural Stone, H-pile, Vegetated Walls, Cellular Containment Systems, Concrete Masonry Units (CMU) and Poured Concrete can be considered.

Factors to evaluate include cost, longevity, aesthetics, site access, machine access, complexity of construction and the ability to be engineered.

Cost can be evaluated by estimating the materials and labor required to install a hypothetical wall of x Height, y Width, and z Depth. Remember that some types of walls benefit more from Economies Of Scale than others.

Longevity can vary greatly based on factors including site conditions, manufacturing processes/quality control and installation details. A properly installed timber retaining wall may well outlast a poorly designed and installed poured concrete wall.

Aesthetics is a matter of personal opinion combined with site characteristics. A SRW may blend as poorly in a traditional Zen garden as a timber wall in a formal garden.

Site and Machine access are more important for some walls than others. Depth of excavation both vertical and horizontally into the bank need to be considered. Some larger SRW systems weigh upwards of 200 lbs apiece and require machines to move and set, while smaller SRW units can be light enough to be hand carried by one person and poured concrete has to be moved into place with chutes, pumps or buggies.

Due to the sheer volume of literature available from manufacturers, SRWs rate very well on complexity of construction and the ability to be engineered, . In addition, their lack of traditional footing and "Level-and-Go" style of construction make them very accessible to DIY projects. Natural stone is easy to install but hard to install well. The artistic aspect of beautiful dry-stack work often takes years to master and the variable nature of the material makes for difficult engineering.

Two options not mentioned before are Structural Shotcrete (or Gunite) and Gabion Walls.

Shotcrete and Gunite are non-traditional methods of placing traditional concrete. Both use pumping equipment to blow the concrete at high velocity onto the work surface. Traditional formwork is replaced with one-sided forms with the operator's side being open.

Shotcrete is mixed with water prior to being put into the pump and pressurized. Gunite is pumped as a dry powder through the hose to the nozzle and then is mixed with water at the nozzle or within a few feet of the hose end.

Premixing Shotcrete at the pump produces a more consistent product at the nozzle than Gunite, since Gunite is mixed with water at the nozzle and the amount of water can be adjusted by the nozzleman, proper mix is more difficult to control. The primary benefit of Gunite is the ability to start and stop the operation without worrying about the mix drying in the supply line.

With proper Engineering and installation, Shotcrete and Gunite can obtain the same structural integrity as traditional formed systems.

Gabion Basket Walls are large wire mesh cages filled with stone or rubble.