Why our infrastructure is important

Purpose of the water supply network

The purpose of the water supply network is to protect public health by delivering adequate quantities of safe water to water users. Clean drinking water is essential for public health and for the safe and productive operation of many businesses. The DCC provides drinking water services to protect the health of its residents and visitors and to support economic activity.

What’s involved in supplying water?

The DCC manages the collection, supply, treatment and distribution of water to domestic and commercial residents in Dunedin. The below list covers the main aspects of the water supply system.

• Catchment: an area where water is collected by the natural landscape. The DCC holds 21,000ha of water catchment within its territory, and most of this land is in the protected Deep Stream and Deep Creek catchments.
• Untreated (raw) water: water that is collected from the catchments.
• Water supply: the main supply pipelines that carry raw water from the catchments to the raw water reservoirs or directly to the treatment plants.
• Treatment: raw water is treated at one of Dunedin’s six water treatment plants.
• Distribution: the main pipelines between the treatment plants and the treated water reservoirs.
• Reticulation: pipelines that distribute water from the treated water reservoirs to the property boundary.

How our water supply infrastructure works

Water supply level of service measures

The water supply network provides the following levels of service:

• the water is safe to drink
• service calls are responded to promptly
• the water tastes and looks pleasant
• water is supplied at adequate pressure
• the water supply is reliable
• the Council is responsive to customer concerns
• water resources are used efficiently and sustainably.

Purpose of the wastewater network

Wastewater is taken from commercial and domestic properties via pipes and pumps to one of seven waste water treatment plants in the district. The wastewater system aims to protect the health of the community by providing cost effective, reticulated wastewater services throughout the urban area, and to treat wastewater to a high standard before it is discharged into the environment.

What’s involved in the wastewater network?

The DCC manages the collection, treatment and disposal of wastewater from residential and commercial customers across Dunedin. The below list covers the main aspects of the wastewater system.

• Reticulation: the network collects wastewater from domestic and commercial private lateral connections. The majority of the 918km of publicly owned wastewater reticulation system operates via gravity, with pipe size varying from 150mm to 1800mm in diameter.
• Pump stations: there are 79 wastewater pump stations throughout the reticulated network that pump wastewater from low points back into the gravity network. A critical pump station located at Musselburgh accounts for half of the wastewater pump station asset base (by value).
• Treatment: the DCC owns seven wastewater treatment plants. The population served by each plant varies from fewer than 100 for the smallest plant (Seacliff) to more than 83,000 for the largest plant (Tahuna). Treated wastewater is then returned into the environment.
• Biosolids: (or sludges) are the major by-product of the wastewater treatment process. They are the organic material that remains after sludge is treated. The vast majority of biosolids are generated by 3 waters wastewater treatment processes (with a small amount from the drinking water treatment process). Currently, Dunedin’s biosolids are incinerated at the Tahuna wastewater treatment plant or disposed of at Green Island Landfill.

How wastewater infrastructure works

Wastewater level of service measures

The wastewater network provides the following levels of service:

• sewage is managed without adversely affecting the quality of the receiving environment
• service calls are responded to promptly
• the wastewater service is reliable, and the Council is responsive to customer concerns.

Purpose of the stormwater network

The stormwater network collects rainwater from the roofs of houses and buildings, footpaths and roads and diverts it to the ground, into waterways or the ocean. Effective management of stormwater is essential to prevent flooding of properties and businesses. Controls are necessary to ensure stormwater does not become excessively contaminated leading to pollution of watercourses, the harbour or the ocean. The DCC is not engaged in flood protection and control works except where it relates to stormwater or to protect assets such as roads.

What’s involved in the stormwater network?

The DCC provides reticulated stormwater services to the city and to most areas that also receive reticulated wastewater. When an area is developed, stormwater generally increases due to runoff from impermeable surfaces (e.g. roofs, roads, car parks, or compacted soil). It flows naturally from higher to lower ground, and ultimately discharges into natural watercourses such as wetlands, creeks, rivers or the sea. Land development results in the creation of both private and public stormwater systems. These networks exist co-operatively to collect and transfer stormwater to waterways, and in some cases the marine environment, efficiently minimising damage to downstream assets.

The below list covers the main aspects of the stormwater system.

• Reticulation: the reticulated network collects stormwater from domestic and commercial connections, mud tanks and some watercourses, and discharges stormwater into watercourses, streams and the sea. Most of the 378km of publicly owned stormwater reticulation system operates via gravity, with pipe size varying from 100mm to 2700mm in diameter.
• Pump stations: there are 11 stormwater pump stations throughout the reticulated network that pump stormwater from low points back into the gravity network or to discharge points. The most critical pump stations are in South Dunedin and Mosgiel.
• Overland flow paths: structures such as swales direct and convey stormwater overland into the stormwater system.

How stormwater infrastructure works

Stormwater level of service measures

The stormwater network will provide the following major levels of service:

• stormwater services perform adequately and reliably
• stormwater is managed without adversely affecting the quality of the receiving environment
• service calls are responded to promptly.

Purpose of the transport network

The role of a transport network is to provide access to move people and goods to destinations such as centres of employment, services, and amenities. Transport assets allow people choice about how they move around the city for either commuter or recreational purposes. Roading infrastructure also connects Dunedin to national and international road, rail, shipping and air transportation networks. Land transport investment promotes keeping people in employment, improves productivity, and supports economic growth and connected communities.

What’s involved in the transport network?

The DCC manages a large network of transport infrastructure which includes roads (both sealed and unsealed) footpaths, cycle ways, streetlights, traffic signals, signs and road markings, retaining walls, bridges, culverts and seawalls.

The below list covers the main aspects of the transport network

• 1071km of sealed roads
• 695km of unsealed roads
• 968km of footpaths
• 261 bridges
• 42km of seawall
• 8478 mud tanks
• 5742 culverts.

Our transport network

Transport levels of service

The transport network provides the following levels of service:

• the transport network facilitates safe travel
• the transport network facilitates active travel
• the transport network facilitates comfortable travel
• the transport network facilitates accessibility
• the transport network facilitates efficient travel
• the transport network facilitates sustainable maintenance
• the transport network is maintained in a responsive manner
• The use of electric vehicles (EV’s) is supported
• Minimising transport disruption during and after the construction of the new Dunedin Hospital rebuild will be supported through the Shaping Future Dunedin project.