Landcom Book 4 Maintenance - WSUD

Water Sensitive Urban Design
Table 4 | Routine monitoring requirement for constructed wetlands.
Item to be
Monitored
Purpose of Monitoring
Performance
Target
Schedule
Maintenance or
Investigation
Immediate
Action Required
Maintenance Action Required
The purpose of the inspection is to
check that the structures associated
with the constructed wetland
(macrophyte zone cells and inlet
zone) are not damaged and function
as designed. Examples of causes of
structural damage include sediment
and/or litter accumulation and large
storms (flood events).
Structures
- GPT / trash rack GPT clear of litter GPT 10 percent full GPT / trash rack
for than 30 percent
full
Notify Cleaning Services
NOTE: If the wetland substrate has
been disturbed during maintenance
activities, ensure bed profile
re-established as designed.
Irregularities in bed profile may have
the potential to act as mosquito
breeding habitats.
- Inlet pipe Clear and
undamaged
- Pipes connecting macrophyte
cells
- Outlet pit
Partially Blocked
Observed damage
Mostly blocked
Severe damage
Schedule removal of debris, or notify
relevant authority within Council for
structural damage.
Inspect for associated erosion and
scour damage within the wetland
and associated structure, and
schedule repair work as required by
Council.
Erosion
Erosion impairs wetland function by
- Changing flow paths through the
wetland
- Smothering wetland vegetation
and biota
- Creation of mosquito habitat
- Contributing to poor water quality
by adding additional sediment
If left untreated, small sites of
erosion can quickly spread over
large areas becoming costly to
repair.
Erosion absent
Erosion damage
visible, but structure
functional
Severe erosion.
Damage impairing
function of device
Schedule investigation into cause
of erosion. Action appropriate
stabilisation response.
Any erosion damage of the
macrophyte zone batters, berms,
and around the inlet and outlet
structures should be noted on the
Inspection Form and remediation
measures undertaken immediately.
Remediation measures may include
surface reinforcement and revegetation.
Sediment
build up
The accumulation of sediment
in the inlet pond of the wetland
is a prescribed function of this
zone. However, sediment must be
regularly removed to ensure that the
sediment trapping performance of
this zone is sustained.
Sediment absent
Sediment
accumulation
appears excessive
Sediment
accumulated to
half the basin
depth
Schedule an investigation into
source of sediment: e.g. localised
erosion or catchment based runoff.
Sediment build up can affect
the hydraulics of the wetland,
and smother aquatic plants,
compromising plant growth.
28 Book 4 | MAINTENANCE