If you are lodging a DA with council, the local councils regulations will determine if you require a Geotechnical Report. Regulations vary slightly between councils but the issues that trigger the requirement for a Geotechnical report are generally as follows:1. The property is on a steep slope.2. A cliff face cuts or is close to the property.3. There is a documented history of ground movement on the site or in the surrounding area.4. The property falls within the potential landslip area as mapped by the local council. (Usually mapped as such due to points 1-3 above).5. As part of the proposed development excavations are planned that extend beyond a depth of 2.0 to 3.0 metres (the depth requirement that triggers the need for a report varies between councils). 6. As part of the proposed development excavations near the boundary are planned, where the distance from the ground surface to the base of the excavation (the excavation height) is greater than its closest horizontal distance to the boundary.