A 10-year, $13 million project to improve Inglewood’s wastewater system will see work start in the town this month.

This is the first major project that’s come out of NPDC’s digital modelling of Inglewood’s wastewater flows, where upgrade options could be ‘made live’ and their effectiveness reviewed before approval.

Inglewood has had persistent issues with its wastewater system being overloaded during heavy rainfall. This is primarily caused by cracks and defects in sewer pipes due to their age, the town’s soil conditions and its high water-table, says NPDC Project Delivery Lead Gordon Davenport.

“The existing wastewater main on Carrington Street has a number of defects that are letting in groundwater and stormwater, especially during heavy rainfall, so stage one of the project will see it replaced with a new and larger pipe,” he says.

“Later on in stage two, we’ll lay a new main down Rata Street, which will halve the wastewater load on the existing Humphries Street pipe by taking on the wastewater load from the town’s southern areas.”

Planning the project included extensive on-the-ground testing to find out where stormwater and groundwater was getting into the wastewater pipes, then running upgrade scenarios in the digital model of Inglewood’s pipe network.

“We were able to see if installing a larger pipe or adding a new connection would cause an issue elsewhere in the network. As a result, we’re confident that the project’s budget is being spent in the right places for the most effective solutions for the town,” says Gordon.

Stage one construction will run until June (weather permitting).

The 10-year project is in addition to several improvements at specific sites in the town that have already been completed in recent years, including on Pukatea, James, Richmond, Kowhai and Konini streets.

At a glance:

• NPDC is investing $289m over 10 years to 2034 to fix the district’s plumbing.
• Inglewood’s wastewater is treated at the New Plymouth Wastewater Treatment Plan, along with wastewater from New Plymouth, Bell Block, Waitara and Ōākura.
• The New Plymouth Waste Water Treatment Plant handles an average of 25 million litres of wastewater each day.

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