All excavations should be completed close to but not within the intended location of the percolation area.
A total of 7 excavations are required.
This allows an assessment of the profile of the soil to a depth of 3m.
A single trial pit is required – excavated as shown below. It should be a minimum of 1m wide with the face of the pit stepped to allow access for inspection. The pit should be 3m deep.
The T-test assesses the soakage in the subsoil.
Three Number holes are required.
Each hole should be 1m wide and 2m long with one end benched.
The depth of the hole depends on site conditions but should be a minimum of 450mm deep.
Within each hole a “Sump” 300mm x 300mm should be excavated to a depth of 400mm.
This test assesses the soakage in the topsoil and therefore is completed at the existing ground level.
Three Number Holes required for the P-test.
Holes are 300mm square and 400mm deep.