A proper base is essential for the stability of a segmental retaining wall similar to Allan Block. Typical depth of the trench is based on a minimum 6 in (15 cm) deep compacted wall rock base and buried block depth equal to 1 in (2.5 cm) of depth per foot (30 cm) of wall height.
If there are slopes below the wall, a deeper base trench may be necessary.
The base trench should be compacted to the level specified in the geotechnical report and inspected by the on-site soils engineer prior to any base material being placed. (ref. BP, Chapter 2.7)
Allan Block is working to achieve our industry initiative of Zero Wall Failures. With our Best Practices Manual and experience in the industry we are trying to expand the knowledge base for the design of segmental retaining walls (SRW's) by communicating and educating the professionals in the industry. To see the full Best Practices Manual, visit allanblock.com to download today and keep an eye out for more industry Best Practice recommendations here.