Landcom Book 4 Maintenance - WSUD

Water Sensitive Urban Design
6.1.2 Stage 2: Building phase protection (or sediment and erosion control)
Stage 2 involves the construction of temporary measures to protect the functional elements
of the system. As stated, two options are typically considered, either diversion of flows
away from the functional elements to allow plant establishment, or the establishment of
temporary sedimentation basins (within or upstream of the main functional part of the
WSUD element).
The main activities required as part of stage 2 are:
Bioretention basin Constructed wetland Sedimentation basin / pond
Bypass of stormwater flows / isolation of functional design
Install bypass structure. The
system will typically involve
one of the following:
1) Completely bypassing
the inlet pipe around the
filter media area
2) Partitioning the systems
such that the inlet and
outlet only are engaged
Isolate macrophyte zone
from the inlet zone by
blocking the connection
pipe between the two zones
Stabilise the high flow
bypass either with turf or
reinforced turf
Ensure the entire perimeter
of the wetland is protected
by sediment fences
Construct non-wetland
related hardscapes, such as
boardwalks and pathways
Sedimentation Basins
Generally not considered for
sedimentation basins
Ponds
Isolate pond from downstream
treatment devices by blocking
connecting pipework
Ensure the entire perimeter of the
pond is protected by sediment
fences
Establishment of temporary sediment protection devices
Protect the filter media with
a filter cloth or 25 to 50 mm
of course sand plus 25 mm
of topsoil and turf
The entire constructed
wetland footprint is allowed
to operate as a sediment
basin
Sedimentation Basins
Ensure earthworks are stabilised
immediately post construction
(basin profile should be stabilised
through sterile grasses, while
terrestrial planting established
around the basin perimeter)
Ensure overflow from basin
disconnected from any
downstream treatment devices
(such as wetlands)
The protective measures identified above should be removed only when 80 to 90 percent of
construction works in the catchment have been completed. If a distributed water sensitive
design process has been implemented, treatment systems can be brought online gradually
without having to wait for all development to cease.
Landscaping can be established in areas isolated from stormwater flow. For constructed
wetlands, special attention is required in manipulating the water level during plant
establishment within the macrophyte zone such that plants are not ‘drowned’. The specific
plant establishment requirements for constructed wetlands are detailed in the Water by
Design documentation.
42 Book 4 | MAINTENANCE