We have a number of decisions that will need to be made over the coming years to ensure our infrastructure will still be providing the levels of service our community expect and need beyond 2031.
The main factors that we have taken into account when drafting our plan are: compliance with regulations; sufficient infrastructure to meet the demand and growth of our district; infrastructure that is resilient and can withstand and recover quickly from disruptions; and that our spending is affordable for our community.
Our main focus in the short-term is around installing district wide water meters and upgrading the Methven, Mt Somers, Methven-Springfield and Montalto drinking water schemes to comply with the new drinking water standards. We’re also continuing to progress our plans for the second urban bridge across the Ashburton River.
In the 2030s, our wastewater resource consents come up for renewal, and we’re likely to see higher standards and expectations for nutrient loadings. To pre-empt this, we have made strategic land purchases near existing facilities and we’re looking at different ways to deal with wastewater disposal at our treatment plants, including subsurface irrigation.
We know our assets pretty well, but there is also a lot we don’t know. Some of our assets were built a hundred years ago, and it’s not always easy to understand the condition they’re in or to predict exactly when they’ll fail. In the last five to ten years a lot of work has gone into improving our knowledge and understanding of our assets. In particular, we have implemented a new asset database for the three waters and have thoroughly checked and corrected the information we hold on all of our assets, both water and transportation.
Roads, bridges, footpaths and other transportation assets are inspected regularly for defects and condition to inform the upcoming renewal programme.
We carry out a closed-circuit television (CCTV) survey of a selection of our wastewater pipes each year to assess their condition and refine our renewals programme. We have not carried out formal condition assessment for our non-reticulated three water assets however. Instead we use incidental inspections (such as looking at assets and listening to motors) to warn us when assets may be close to failure. We accept that there are risks with this approach and that it could result in disrupted levels of service, unplanned renewals costs and potentially increased maintenance costs.
Our renewal strategy for three waters infrastructure is based on age (when assets like underground pipes reach the end of their useful life), material and criticality with modifications made based on analysis of maintenance records and customer complaints. This means we are generally funding our renewals in line with depreciation. We will need to keep monitoring our rates of failure to ensure that our renewal programme remains responsive to our infrastructure needs.
We’re also looking ahead at where new developments are happening and where we may need to extend our drinking water infrastructure.
To be able to write our plans, we have to make some assumptions based on the best of our knowledge. This includes estimating how fast our population will grow (or not), what challenges we’ll have in the future and how these will affect us. We also have financial assumptions, such as what our interest rate will be on our loans.
