September 25, 2015

Don’t Underestimate the Importance of Your Soil

The soil on your site is a critical aspect to your retaining wall project.  Among the ways your soils can affect your overall project cost are:

  • Geogrid Requirements
  • Increased Effort to Compact
  • Cost of Importing Additional Material and Removing Existing Soils


Clay Soil
A wall built in clay will have an increased need for geogrid when compared to the same wall build on a sandy site.  This is because clay will “push” on the wall more than sand.  This geogrid will be used to create a mass of soil large enough to overcome these forces.




Sandy Soil
Clays and silts resist compacting due to the shape of each grain of soil.  They to trap water more and make proper compaction more labor intensive.  It is important to achieve proper compaction to reduce future settlement and to increase the stability of the reinforced soil mass.  To achieve the required compaction, you may need to compact more frequently with smaller lifts of soil, or use specialized compaction equipment.




Organic Soil

When your site does not meet the minimum requirements suggested on the planning your retaining wall  page on the Allan Block website, it may be required to remove the existing soil from the site and use select fill for the area within the geogrid.  You may also find it necessary to increase the width of your base to compensate for poor soils under the wall.