River, land, sea discharges in the mix

The likely options for future management of Palmerston North’s wastewater have been whittled down to three as the city council invites public feedback on the multimillion-dollar project.

The options are expected to cost between $290m and $415m upfront, with varying ongoing treatment costs, and will add between $330 and $450 to residential ratepayers’ bills each year.

Mayor Grant Smith is asking people to consider what is most important, with cost being just one of the values the council wants to hear about.

It wanted to know what weight people wanted to give to issues including public health, Māori cultural values, the natural environment, resilience and growth and more.

‘‘All of these values factor into the final decision-making, but getting a good grasp of what matters to our community can help shape that decision.

‘‘The challenge for us will be to determine the most cost-effective option that strikes an appropriate balance between environmental, cultural, social and financial considerations.’’

The options that have risen to the top of the list the council and its technical advisers have been considering include discharges to the Manawatu¯ River, to land and to the ocean.

The first option is a significant upgrade to treatment standards based at the existing Totara Rd wastewater treatment plant to remove nitrogen as well as phosphorus before discharging the bulk of the wastewater through wetland to the river.

When the river was at low levels, about 75 per cent of the discharge would be diverted to land, requiring pipes to be laid to carry it to an area of about 670 hectares.

Although cheaper than some options to set up, at $290m, it would be expensive to operate.

The second option would also be a hybrid between discharge to the river, 45 per cent of the flow, and 55 per cent to land, specifically during summer.

It would require 1740 hectares of land, which would make it the biggest land discharge in New Zealand.

It would cost $260m to set up, and $315m over its 35-year lifetime.

The third option was for all treated wastewater to be discharged to the ocean, at the end of a pipeline at least 30km long.

Pipeline costs would contribute to making it the most expensive to set up, at $343m.

The council wants to hear from people in Manawatu¯ and Horowhenua about the options, as well as city dwellers.

The council has to come up with a plan for future wastewater management because its current discharge consent is coming to an end, and it has to apply for a new one by June next year.

There will be public meetings and drop-in sessions for people who want to learn more.

The Palmerston North public meeting is at the Conference and Function Centre in Main St at 5.30pm on Thursday, April 22.

Submissions close on Sunday, May 9.