Dunedin City Council 3 Waters Strategy

NZ Inaugural Infrastructure Summit

Mayor Dave Cull

Context

Urban centre with large rural hinterland c 125,000 people, including 23,000 students Heritage, culture and biodiversity

Before the Strategy

Previous strategy focussed on water and wastewater quality

Single issue; Single solution;

High service; High cost

Identified gap in strategic planning capability

Integrated improvement strategy •Departmental restructure

• 3 Waters Strategy project

Development Approach

Review strategic drivers

Review technical constraints of existing infrastructure

Engaged with the community on their concerns and priorities

Produced strategic timeline of issues and potential solutions

Developed strategic principles to guide future decision making

Dunedin’s Water Challenges Limited growth

Shift in economy away from water intensive industry

Excess capacity in parts of our infrastructure

Gravity fed water supplies

Climate change predicted to increase catchment yield (although more seasonal)

Dunedin’s Water Challenges

Increasing flood risk

Sea level rise – rising groundwater

Vulnerable to single point failures in our critical infrastructure.

Relative isolation requires greater resilience

Dunedin’s Water Challenges

Infrastructure is ageing

Some pre 1900 infrastructure still in use.

Renewals peak is looming

Renewals forecast as at 2010

Dunedin’s Challenges

High sunk infrastructure costs

Looming renewals requirements

Slow growth

Environmental and other pressures

= Affordability challenges

Strategic Priorities

7 high level statements

Outline long term principles and commitments to guide future planning and decision making.

Deals with uncertainty by allowing us to adjust and respond as change happens

How does this affect decision making?

Change of thinking

•More focus on using and rationalising existing assets

• Integrated approaches to give multiple benefits

• Flexibility and resilience for different potential futures

• Improved cross council planning e.g. 2nd generation district plan

Security of Supply – System Overview

INSERT SCHEMATIC MAP OF MAJOR PIPELINES AND TREATMENT PLANTS

Security of Supply Strategy

2008 - Previously unrelated problems and projects

Serious lifelines risk – 2 main raw water supply pipes over same, vulnerable, 1936 bridge.

Only one source of water supply for the Hill suburbs

Deep Creek Pipeline Renewal programme ($15m+ budget)

High future costs to maintain and renew two raw water pipelines (gravity fed = low OPEX).

Ross Creek Dam Stability problems

Risk of losing consents for un-utilised water resources

2014 - One Integrated Solution

2008 : Second Taieri Crossing

Initial budget c$6m

Cost estimates escalating up to $15m

Time for a rethink!

Ross Creek Dam Stability

Disused water reservoir Well used community recreation asset Dam stability problems have led to lowering of water levels

2014: Integrated thinking

What we are doing

•Stabilise Ross Creek Dam (in progress)

•Build pumping station from Southern Treatment plant to Mount Grand Treatment Plant (in progress)

•Bring some redundant water infrastructure back into supply (2018-2020)

• Future rationalisation of 2 supply pipelines to one (c2036)

What we are NOT doing

No second crossing across the Taieri Required

Not renewing the Deep Creek Raw Water Pipeline (decommission when Deep Stream pipeline requires renewal)

• The criticality of the infrastructure will be reduced to such a level that we can provide continuous supply without them (at higher cost, and with some restrictions)

Benefits All parts of metropolitan Dunedin can be served

by 2 treatment plants and any of 4 water supply sources

Resilience to loss of any single part of the supply system, including the Taieri Bridge Crossing or either one of the treatment plants.

High level of resilience to catchment drought or fire

Dam stabilised and Ross Creek amenity value restored

Asset lifecycle costs significant reduced

Savings of $12m in the first 10 years.

In Conclusion

Infrastructure challenges need to be seen in the right local context.

Dunedin’s 3 Waters Strategy responds to our local context by:

• Ensuring integrated decisions

•Rationalising infrastructure

• Increasing flexibility and resilience

•Doing more with less…