Waste Water

Description

Background and history

195. We are currently seeking further information on this.

Assets

196. The total volume of wastewater produced approaches 345 million cubic metres per year for the surveyed territorial authorities. Many large industrial sites also have private discharge arrangements with regional councils, rather than discharging to a reticulated system. The percentage of waste water can be broken down by source and is shown in the diagram that follows.

Current Wastewater Volumes by Source

Source: PricewaterhouseCoopers Surveys of Territorial Authorities (eproduced from the MED Infrastructure Stocktake 2004)

Institutional arrangements

197. The ownership and responsibility for the delivery and maintenance of water network infrastructure varies across territorial authorities. Many provincial and rural councils retain full control over all aspects of their water networks. A number of large councils use council-controlled trading organisations to deliver bulk and/or reticulated supplies to one or more councils (e.g. Watercare Services). A number of arrangements also exist for maintenance and operation.

198. In Papakura, management and operation of the water and wastewater networks are contracted out to a private firm (United Water).

199. There are a large number of discrete wastewater systems, although a lower proportion of the population is connected to the wastewater system than is supplied by water reticulation systems. This is particularly the case for rural councils that tend to have more water than wastewater schemes. As with drinking water, metropolitan councils also have far fewer individual wastewater schemes than provincial and rural councils and a much greater length of reticulation, again reflecting more intense development. The table below indicates the differences.

Source: DIA Water network infrastructure report

200. Wastewater systems are not interconnected across the country. Each reticulated system has assets to collect untreated wastewater from customers and transport it to facilities for the treatment and disposal of wastewater effluent, which includes liquid, solids and gas.

201. Wastewater reticulation capacity is measured by assessing the number of recorded overflows that are related to either wet weather or dry weather overflows. For the majority of the country, this is not an issue. Some systems have designed overflows, which enable the system operator to control system overflows. The Auckland region has the highest proportion of wet weather overflows (largely due to stormwater inflow), particularly (but not solely) in the part of the system that combines wastewater and stormwater flows. The separation of wastewater and stormwater systems to prevent overflows is an ongoing issue for many local authorities.

202. As noted above, the peak day capacity in most areas is determined by high inflow and infiltration in wet weather and, as a result, treatment plants have a much higher peak day capacity than average day capacity. This is due to the high water content on peak days diluting the wastewater and enabling resource consent requirements to be met. A number of councils are also providing for wastewater storage to enable better control of discharge and a capacity to respond to breakages.

203. Estimates of asset condition suggest that in general, wastewater systems appear to have more life remaining than drinking water assets, especially in rural areas.

Funding and pricing

204. Local authorities fund water network infrastructure from a variety of sources including rates (directly and indirectly), loans, subsidies (where available) and through development contributions. The latter are levied to cover the impact of increased demand on existing infrastructure. The graph below indicates that, of the territorial authorities using development contributions, a significant proportion of this revenue is used for drinking water, wastewater and stormwater.

Meridian Development Contribution Charge by Group of Activities

Source: Source: Department of Internal Affairs: Analysis of 2007/08 Development Contribution

Planning

205. Water infrastructure plans are set out in LTCCPs.

Analysis

206. The level of wastewater treatment varies from council to council. In contrast to drinking water quality, which is monitored centrally by the Ministry of Health, resource consents for discharge of wastewater are managed by regional councils (based on guidelines set by the Ministry for the Environment). These consents are valid for a number of years, and decisions to upgrade often coincide with the need for a council to renew its consent (together with public pressure).

207. Wastewater is treated using a mix of primary, secondary and tertiary treatment. Many systems produce “good” quality outflow. However, around 23 per cent provide only primary treatment. While these will probably meet their current resource consents, increased requirements mean that capital upgrades may be required on expiry. Some small communities may face financial difficulties meeting these costs, especially if they also have to upgrade their water supplies.

208. In recent years, local authorities have made significant capital investments in wastewater collection, treatment and disposal infrastructure. Many larger plants have been (or are being) substantially upgraded, and a large number of upgrades have been identified in the 2009/10 LTCCPs. This is reflected in the fact that forecast capital expenditure for wastewater is greater than for water for the next 10 years (see the chapter on Planned Investment).