Calculating the required footing depths, will determine whether your proposed work requires POS action to protect nearby gravity pipes:
Determine the shortest distance between the centre-line of our service (whether or not it is concrete encased) and the:
- outer leaf of wall cladding for cottages with standard footings
- edge of the footing for other developments.
The centre-line of the service is indicated on our as constructed plans.
Determine the vertical depth of our service below the:
- finished ground surface level, for cottages with standard footings
- base of the proposed footings, for other developments.
The level of the service is its invert level to Australian Height Datum (AHD).
If the vertical depth is more than the following, POS action will be required:
- for 150mm and 225mm pipes, the distance determined in 1. minus 600mm
- for 300mm to 600mm pipes, the distance determined in 1. minus 1000mm.
For cases involving larger pipes and other soil conditions an assessment by our engineering staff is required.
Action will also be required where at least the following vertical clearance between the finished ground level above the service and the underside of any slab (or other part of the structure) is not maintained by the proposed design:
- for 150mm to 300mm pipes, 2.4m
- for 375mm to 600mm pipes, 2.8m.
Do not build over larger pipes.
Where the proposed work falls within the zone of influence special footings/piles and/or access to our service may need to be provided. Footings/piles are to be taken at least 300mm below the zone of influence or to refusal in unexcavated solid rock.
Where the proposed work falls within the zone of construction, but not within the zone of influence, special footings/piles are not required.