In accordance with the Australian Standards AS4678-2002 Earth Retaining Structures, the sleeper retaining wall calculations in ClearCalcs takes the soil conditions into account for both backfill and footing soil.

The different types of soil conditions provide different levels of uncertainty as shown in AS4678-2002 Table 5.1. These apply uncertainty factors to the soil properties specified.

The conditions of soil on site are split according to the following:

• Controlled Fill Class I - pertains to soil, rock or other inert material that has been placed on site in a controlled fashion such that the average compacted density is 98% (no less than 95%) of the maximum dry density when tested in accordance with AS1289.5.1.1.
• Controlled Fill Class II - pertains to soil, rock or other inert material that has been placed on site in a controlled fashion such that the average compacted density is 95% (no less than 92%) of the maximum dry density when tested in accordance with AS1289.5.1.1.
• Uncontrolled fill - pertains to soil, rock or other inert material that has been placed on site without the compaction density as defined for either control fill.
• In-situ material - pertains to natural soil found on site.