TAS Part E4 Stormwater surface and sub-surface drainage systems
The Objective of this Part is to—
- safeguard people from illness, injury or loss (including loss of amenity) due to the failure of a stormwater drainage installation; and
- ensure that a stormwater drainage installation is adequate; and
- conserve water and energy; and
- safeguard the environment; and
- safeguard public and private infrastructure; and
- 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.
Surface drainage systems
A subsoil drainage system must remove excess groundwater and reduce soil moisture levels to prevent loss by changing soil moisture conditions.
- Blockage and uncontrolled discharge.
- Damage from root penetration, superimposed loads or ground movement.
- Entry of sewage and/or liquid trade waste.
- Entry of stormwater into a sanitary drainage.
- Damage to the Network Utility Operator's drainage system
- Foul air and gases accumulating in the stormwater system.
- Loss to buildings or property.
Design, construction and installation
Performance requirements E4P1 to E4P3 are satisfied by complying with E4D2 and E4D3.
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.
Stormwater drains alone may not be adequate as stormwater will often flow over the grate and enter a liquid tradewaste generating area. The total surface water across the site is to be considered and the height of the bund or other feature should be increased where there is a risk of stormwater entering the liquid Tradewaste generating area.
See TAS Figure E3D3 for a typical diagram of roofing and bunding of liquid tradewaste generation areas.
Protection from surface water