TAS Part E4 Stormwater surface and sub-surface drainage systems

The Objective of this Part is to—

1. safeguard people from illness, injury or loss (including loss of amenity) due to the failure of a stormwater drainage installation; and
2. ensure that a stormwater drainage installation is adequate; and
3. conserve water and energy; and
4. safeguard the environment; and
5. safeguard public and private infrastructure; and
6. ensure that a storm water drainage installation is designed and is capable of being maintained so that throughout its serviceable life it will continue to satisfy Objectives (a) to (e).

Buildings and their surroundings are to be provided with a surface drainage and subsurface drainage installation and be constructed in such a manner as to provide protection for people, property and the environment from the adverse effects of stormwater.

(1) A surface drainage system must have capacity to transfer the volume of water anticipated in an annual exceedance probability rainfall event.

(2) The annual exceedance probability must be appropriate to the—

1. importance of the building; and
2. severity of potential damage to property, loss of amenity, illness or injury that would result from the failure of the system.

A subsoil drainage system must remove excess groundwater and reduce soil moisture levels to prevent loss by changing soil moisture conditions.

(1) A surface drainage installation must avoid the following:

1. Blockage and uncontrolled discharge.
2. Damage from root penetration, superimposed loads or ground movement.
3. Entry of sewage and/or liquid trade waste.
4. Entry of stormwater into a sanitary drainage.
5. Damage to the Network Utility Operator's drainage system
6. Foul air and gases accumulating in the stormwater system.
7. Loss to buildings or property.

(2) A surface drainage installation must ensure the following:

1. Access for maintenance and clearing blockages.
2. Stormwater is transferred to a Network Utility Operator's stormwater system or an approved disposal system.

Performance requirements E4P1 to E4P3 are satisfied by complying with E4D2 and E4D3.

A surface and subsurface drainage system must comply with—

1. AS/NZS 3500.3; or
2. Housing provisions 3.3

Surface water must be prevented from escaping a liquid trade waste generating area though the installation of a bund, speed hump or other feature a minimum of 150 mm high surrounding the area.