2024. 3. 15. 12:11ㆍ카테고리 없음
3.1.2.0
Performance Requirement P2.2.1 is satisfied for drainage if the drainage is designed and constructed in accordance with AS 3500.3 - Stormwater drainage installations.
3.1.2.1 Application
Compliance with this Part satisfies Performance Requirement P2.2.1 for drainage of-
(a) roofs in areas subject to 5 minute duration rainfall intensities of not more than 255 mm per hour over an average recurrence interval of 20 years (as per Table 3.5.2.1) where a drainage system is required; and
(b) sub-soil areas where excessive soil moisture problems may occur; and
(c) land adjoining and under buildings,provided the stormwater drainage system otherwise complies with AS 3500.3.
Drainage requirements
Drainage systems must be installed as follows-
(a) areas adjoining and under buildings - surface water drainage in accordance
with 3.1.2.3;
(b) where site conditions exist that create a need for subsoil water to be diverted
away from footings, basements, retaining walls etc - sub-soil drainage in
accordance with 3.1.2.4;
(c) where underground drainage from roof areas is required or permitted -
underground stormwater drainage in accordance with 3.1.2.5;
(d) excavation for drains adjacent to existing footings must be within the area
described in Figure 3.1.2.1 as being safe for excavation.
3.1.2.3 Surface water drainage
Surface water must be diverted away from Class 1 buildings as follows:
(a) Slab-on-ground finished ground level adjacent to buildings
The external finished surface surrounding the slab must be drained to move surface water away from the building and graded to give a slope of not less than 50 mm over the first 1m from the building (see Figure 3.1.2.2).
(b) Slab-on-ground - finished slab heights
The height of the slab-on-ground (measured at the slab edge) above external
finished surfaces must be not less than150 mm above finished ground level or 100 mm above sandy, well-drained areas and 50 mm above paved or concreted areas that slope away from the building in accordance with (a).
(c) The ground beneath
suspended floors must be graded so that the area beneath the building is above the adjacent external finished ground level and surface water is prevented from ponding under the building (see Figure 3.1.2.3).
3.1.2.4 Subsoil drainage
Where a subsoil drainage system is installed to divert sub-surface water away from the area beneath the building it must comply with the following:
(a) The depth to the top of the drain must not be less than 400 mm into the soil and not less than 100 mm below any adjacent pavement level and footing base.
(b) Trench bases (as appropriate) must be graded to a uniform fall to suit the following parallel with pavement grade and parallel with overall grade of footings and not less than 1:300.
(c) The bottom of the trench must be well compacted and evenly graded.
(d) The drain must be laid true to line and gradient on the bottom of the trench or where rock is encountered, on compacted bedding.
(e) Silt pits or sumps of a suitable size for expected water flow, must be provided at the outlet end of each subsoil drain before it discharges into an impervious drainage line.
(f) Outlets must be installed through walls of silt pits not less than 50 mm below the lowest point of the inlet (see Figure 3.1.2.4).
(g) Drainage trenches in clay soils using sand filters must be constructed in
accordance with Figure 3.1.2.5.
3.1.2.5 Stormwater drainage
Where a stormwater drainage system is installed, it must comply with the following:
(a) The position and manner of discharge of the stormwater drainage system
must be to the satisfaction of the appropriate authority.
(b) The stormwater drainage system must be designed so that any overflow
during heavy rain periods is prevented from flowing back into the building.
(c) Cover to stormwater drains
The cover to 90 mm UPVC stormwater drains installed underground must be
not less than
(i) under soil - 100 mm; or
(ii) under paved or concrete areas - 50 mm; or
(iii) under reinforced concrete to light vehicle traffic - 75 mm
(iii) under paved to light vehicle traffic - 100 mm