16-001014-02A (Ultimate SCMMP)

Plants
Plants play an important role in the efficiency of the WQCP treatment system for a number of reasons as outlined below:
   Dense stands slow the velocity of stormwater moving through the system and facilitate sedimentation;
   The plants themselves provide uptake of nutrients and metals;
   They provide a media upon which biofilms develop and it is this site and organisms that are responsible for much of
    the soluble nutrient removal capability of ponds;
   Decayed plant material increases the organic content of the sediments which, in turn, promotes anaerobic
    decomposition and improved nitrogen removal.
Replanting of vegetation is to be carried out to replace dead or damaged vegetation, vegetation that has been removed
by scour or erosion or vegetation that is being re-planted following tilling. Removed vegetation should be replaced by
plants of equivalent size and species, or as indicated on the appropriate Landscaping Plans.
Water Birds
Ponds are a major bird habitat especially in dry periods, and they will become a haven for water birds. These birds will,
even in normal times, impact on the constructed WQCP. This impact may lead to a decrease in the performance of the
WQCP, particularly with respect to decreased water quality. Birds such as purple water hens, ducks, and reed warblers
inhabit the WQCP permanently while others are itinerant. Some birds cause severe damage to the plants by trampling,
eating shoots and the more succulent leaves and using plant parts for nesting material. As long as this occurs on a
limited basis, little detrimental effect on the constructed WQCP and its performance will occur. However if significant
impact is evident, professional advice should be sought.
Mallards, muscovy and other domestic ducks and domestic geese should be removed. Check with governing authority for
approval to harvest the birds, and the appropriate method of doing this.
Feeding of waterbirds should be vigorously discouraged. Residents should be educated not to feed the birds nor
release domestic waterfowl into the system. Grassed verges should be kept to a minimum, vegetated foreshores
encouraged and low bushes used to discourage the birds grazing in areas adjacent to the water.
The densely vegetated marsh zone, proposed for this WQCP, is not a favoured habitat for waterfowl. Maintaining this
densely vegetated separation between the shore and deeper water is a key issue to preventing the birds concentrating in
one area and eroding the foreshore as they move from the land to the water.
Algae (Filamentous and Blue Green)

Algae will occur naturally in the WQCP as a result of nutrient concentrations in stormwater inflows and the nutrients
released from sediment and decomposing organic matter.
Filamentous algae usually grow in shallow vegetated zones and open zones, forming dense floating mats that limit light
penetration into the water column. Excessive filamentous algal biomass may cause blockage to hydraulic structures,
damage to vegetation health (smother or facilitate displacement of vegetation), and lead to oxygen depletion of the pond
when the algae dies or decays. Unless amenity is an issue it is not generally necessary to take action when sighting
small areas of filamentous algae biomass. If the algal mat covers more than 10% of the constructed WQCP area on
inspection action is to be taken. Filamentous algal biomass may be physical removed using rakes or with specialist
machinery.
Planktonic algae, including cyanobacterial blooms (often known as blue-green algae), usually grow in open water areas.
They produce toxins, which pose a potential public health risk. Further investigation is required if Planktonic algae is
sighted during inspection. Refer to Section 2.3.3 for further details of management of cyanobacterial blooms.
Accumulation of Toxicants
Research suggests that metals and phosphorus and organic substances are tightly bound in or to the sediments and
media placed in a pond and do not become mobilised back into the water column over long periods of time (depending
on sediment type).
The removal of sediment accumulated in the vegetated areas of the WQCP is not proposed, as the potential to remobilise
toxicants into the water column is high and will result in significant environmental harm.




16-001014-02A | SMCMP | PALM LAKE RESORTS                        COOROY RETIREMENT COMMUNITY, TRADING POST
                                                                                             ROAD, COOROY                   |7