The minimum recommended width is 600mm.
GAP 20 or GAP 40 are probably the best options. Otherwise, use non-cohesive compactible gravel with less than 5% passing the #200 sieve, and a particle size of no more than 40mm.
The minimum embedment is 150mm. However, it is easier when constructing to use a minimum of 200mm, which is the height of the Rocklok units. This minimum embedment applies to retaining walls with a total wall height of 1.8m.
For retaining walls over 1.8m use the following formula:
????????? (?) = ????? ???? ℎ???ℎ? (?)/8
For example, the embedment depth of a 3m high retaining wall would be 3.0/8 = 0.375m.
Note: Unless specified by a chartered professional engineer, the embedment depth is to a maximum of 0.6m (three blocks). Poor soils, toe slopes, or seismically active areas may require extra embedment.
I am building on a slope. Can I use the standard embedment depth?
No. Normally walls built on slopes or with toe-slopes require additional buried blocks. Typically, the minimum distance between the face of the first Rocklok block and daylight should be at least 1.5m (minimum bench). For example, the necessary embedment of a Rocklok retaining wall with a 3H:1V (Run:Rise) slope in front of the wall would require 0.5m (2.5 blocks).