Wastewater plant – making affordable decisions
Published on 11 December 2014
11 December 2014
Mayor Annette Main today said the Wanganui District Council has decided it is necessary to delay the construction of the new wastewater treatment plant.
“This week the Council acknowledged that factors which have arisen during the process to finalise the design mean we simply do not have enough information and certainty at this time to be able to give the go-ahead for work to start,” Mayor Main said.
“We are confident that we have a design that meets the requirements of our community. What is now being determined is the affordability of that design and the impacts on households, businesses and future users.
“It is necessary to fully understand the impact of the operating costs of the proposed plant on the affordability of the project. The only responsible thing for the Council to do is to delay the construction until we have worked through those matters.
“We now have more work to do to verify information and to talk to key businesses, organisations and the wider community. These decisions will have a long-term impact on our community so it’s important to get it right. We must have complete and accurate information available to make the right decisions.”
The issues
Design of upgraded treatment plant
The approved design by Cardno BTO is based on our district’s unique wastewater profile. Our wastewater load is heavily influenced by our industrial users and subject to large peaks during the height of the summer season. It needs to have the capacity to cope with the equivalent of a population of 300,000 at peak times.
The design is also driven by the current resource consent conditions set by Horizons Regional Council.
The design has been peer reviewed and it has been confirmed to the Council that it will work. What is at issue are the operating costs driven by outputs (sludge) which are the result of our unique wastewater profile.
Following the Council’s approval we commenced work to incorporate design amendments arising from the peer reviews which required reassessment of sludge production in the operational and financial models. We have worked to ensure a robust process and this refinement was necessary. Best practice requires that we have certainty over both the quantity of sludge production and the cost of disposal before further advancing the project.
Operating costs
The Council believes that, based on information to hand, the ongoing operating costs of the plant may cause the plant to become unaffordable to households, businesses and trade waste users.
Sludge
The key challenge relates to uncertainty about sludge disposal options and costs.
Sludge is a by-product and major cost driver of all wastewater treatment plants and, because of our unique wastewater profile, our modelling currently shows increased levels of sludge outputs.
Work has started on a ‘sludge strategy’. This will provide more options around sludge disposal. There is a range of possible alternatives with varying costs and these will be investigated further.
Wastewater Advisory Group
The Council is working with our major industrial users and has formed a Wastewater Advisory Group which includes representatives of current trade waste producers, councillors and the business community. This group has agreed on principles for wastewater and trade waste rates and is now considering how these principles will be applied to future charging for trade waste. The group’s agreed priority principle is on a wastewater treatment plant and charging regime that is affordable for all users.
Next steps
During the next few months more work will be done to:
- Verify key assumptions and variables on the treatment plant operating costs
- Complete a ‘sludge strategy’ and the impacts on capital and operating costs for presentation to the Council in February
- Produce a cost allocation model based on the principles from the Wastewater Advisory Group.