Wastewater schemes

There are three types of wastewater schemes provided by the Council - gravity, STEP and pressure.

Gravity Schemes

Wastewater service is provided via gravity through piped reticulation to a large treatment plant often with pump stations within the reticulated area.

For any properties with an on-site septic tank within an urban service area, the tanks are generally owned and maintained by the individual property owners, including any cleaning.

STEP Schemes

Wastewater service is provided by a Septic Tank Effluent Pumping (STEP) system.

Raw sewage is collected in private on-site septic tanks where it receives primary treatment and screening.  The primary treated effluent is then pumped to a treatment plant. The on-site septic tanks are owned and maintained by the individual property owners while the common rising main and treatment plant is owned and operated by the Council.

Pressure Schemes

Wastewater service is provided by a pressure sewer system.

Raw sewerage is collected in privately owned on-site pump stations. These contain a macerating pump which breaks up the raw sewerage into a slurry before pumping into the Council-owned mains through to the treatment plant.

WDC Schemes

SchemeNo. of PropertiesSewer service TypeInitial Treatment PlantPrimary Treatment
Rangiora16,132GravityRangioraAeration basin, oxidation ponds (conveyed to Kaiapoi WWTP for further treatment)
Mandeville/OhokaSTEP and pressure
KaiapoiGravity and pressureKaiapoiAeration basin, oxidation ponds, wetlands and UV disinfection
Pines KairakiGravity
PegasusGravity and pressureWoodendAeration basin, oxidation ponds, wetlands and UV disinfection
WoodendGravity  
Woodend BeachGravity  
TuahiwiSTEP
Waikuku BeachGravity and pressureWaikuku BeachOxidation ponds (conveyed to Woodend WWTP for further treatment)
Oxford
892
GravityOxfordActivated sludge and UV disinfection
Loburn Lea 38GravityLoburn LeaRecirculating sand contactor and UV disinfection
Fernside21STEPFernsideRecirculating sand contactor and UV disinfection
TOTAL17,083   

The Eastern District Sewer Scheme comprises of  Rangiora, Kaiapoi, Pegasus, Woodend, Woodend Beach, Waikuku Beach, Pines Kairaki, Tuahiwi and Mandeville wastewater schemes. The Eastern District Sewer Scheme discharges to the Ocean Outfall in Pegasus Bay. All other schemes discharge to ground.