Landscape Technical Specification - OPW14/0197

Doonella – Stage C


4.       STORMWATER AND DRAINAGE



4.1.1    GENERAL

The Contractor shall be responsible for all aspects of coordination with Hydraulic works by other trades.
Refer also to Hydraulic Engineers drawings

Drainage locations shown on but not limited to: Landscape Plans

Landscape Plans are indicative only. All drainage requirements are to be checked, confirmed and
documented by the Hydraulic Engineer.

Refer to Hydraulic Documents for actual drainage requirements for type, size and capacity. Refer to this
specification for grate type/ finishes only. Submit samples for approval prior to installation. Refer to
Engineers drawings for load capacity requirements.

4.1.2    CROSS REFERENCES

General: Conform to the General requirements section.

4.1.3    MATERIALS

Subsoil: To AS 2439.1.

Pits and Channel Grates: Located with reference to the Landscape Levels and Drainage Plans. Refer to
Engineer’s details for type, size and capacity.



4.1.4    STORMWATER

General: Refer to Engineer’s details

4.1.5    SUBSOIL DRAINS

General: Provide subsoil drains to intercept groundwater seepage and prevent water build-up behind walls
and under floors and pavements. As required or as shown on the drawings. Connect subsoil drains to
surface drains or to an approved stormwater drainage system as applicable. Points and method of
connection to stormwater system to Hydraulic Engineers details.

Subsoil drainage shall be constructed in accordance to AS/NZS 3500.3:2003. Unless specified otherwise,
subsoil drainage trenches shall incorporate geotextile material lining the trench.

Trench width: ≥ 450 mm.

Pipe depth: Provide the following minimum clear depths, measured to the crown of the pipe, where the pipe
passes below the following elements:

100 mm below sub-grade level of the pavement, kerb or channel.

100 mm below the average gradient of the bottom of footings.

450 mm below the finished surface of unpaved ground.

4.1.6    SUBSOIL DRAINAGE GEOFABRIC MATERIAL

Geotextile material used in subsoil drains shall be a non-woven type and shall have the following properties
prior to exposure to sunlight at the site.

Geotextile strength rating (G) of greater than 900

Flow rate under 100 mm constant head as determined using the Permittivity Test procedures stated in AS
3706.9 of greater than 501/m2/s.


AECOM                                        1