Unless the site conditions require over-excavation, it should be avoided as natural soil typically provides the most stable base for system components. Use a laser and verify proper elevations throughout the excavation process to limit the need for imported backfill material for pipe and tank support.There are many reasons over-excavation can occur on a job site. It may be intentional due to the removal of materials such as bedrock, trees or rocks. In addition, organic, loose or rapidly settling soils do not provide a stable base for onsite wastewater treatment system components. Work should only occur when the soil is
