Blenheim Wastewater Treatment Wetlands
Combining Wastewater Treatment with Wildlife Habitat
Adding a 2km long 25ha wastewater treatment wetland to an existing system of wastewater ponds seems a great idea for a passive treatment system. When this is in a large natural estuarine wetland teeming with large amounts of large bird life then the challenges arise.
The upgrade project created new wetlands and storage ponds so in future only highly treated wastewater will be discharged on to surrounding land during summer months or pumped into the Wairau Estuary on the outgoing tides.
As part of the huge project, a new wildlife habitat was created, with 25 hectares of new wetlands of ecosourced plants. The upgrade allowed better public access for recreational use of the lower Opawa River and Wairau Estuary and walkways through the area to share the power and beauty of estuarine wetland ecosystems.
Ecosystem: Nothing is Wasted in Natures Economy
The construction of the wetlands and irrigation system was overseen by local iwi and provided additional useful information on the cultural and archaeological values of the area. The upgrading of the Wastewater plant has provided community with a win-win situation.
The long wetlands which convey pond effluent from the treatment plant, also provide further polishing treatment, habitat enhancement and storage to allow discharge on the ebb tide.
During the wetter periods, when land discharge is not sustainable, well-treated effluent is discharged to the Wairau Estuary, where it quickly reaches the open waters of Cloudy Bay. There are no longer any discharges to the poorly flushed reaches of the Opawa River.
Ecovitalism: The Challenge of Concept and Reality
The concept of combining a wastewater treatment facility, public walkways, and access all in the middle of a thriving estuarine wetland is applaudable. The building and establishing a treatment wetland in a wildlife habitat is where reality teaches us that Nature is brutal.
A newly establishing wetland is a green grocers store to our web-footed owners.
The establishment process was costly and time consuming. The large areas had to be netted in an impenetrable design. Swans, Geese, Pukeko’s, Spoonbills and ducks all fancied the tender shoots of the wetland plant and tried breaking through the fences on a 24/7 basis.
After 12 months the nets were removed, and the wetlands were mature enough to withstand the wildlife pressures of grazing. These ecosourced wetlands although in a wastewater treatment network, they have naturalized into the surrounding ecosystem and are habitat and sanctuary to an important coastal life-giving paradise.
