Sewer upgrade advances

18:38, Nov 14 2012

Contractors aim to complete the first step of upgrading the sewer line from Waikawa Bay to an outfall into the Picton Harbour at Kaipupu Point by January next year.

Marlborough District Council contractors Hawkins Infrastructure are laying 1700 meters of concrete sewer pipe along Dublin St, connected to the Picton sewage treatment plant, along Lagoon Rd and out to a new outfall into Picton Harbour at the start of Kaipupu Point.

The existing outfall pipeline, which runs along the Kaipupu Point shoreline, will be removed by Christmas.

The work, estimated to cost $3.8 million, should be completed by January and is the first stage in council plans to upgrade the whole trunk sewer line from Waikawa Bay to the outfall.

The council sub-contracted Crafar Crouch Construction and N-Viro to assist with the project.

Council project engineer Bruce Oliver said the upgrade would reduce the amount of wastewater overflows and the risk they posed to public health, and increase the town's capacity for growth.


"This is the first part of an overall sewer upgrade through Picton."

Treated water will be pumped to the sea via a diffuser pipeline created near the former Carey's Boatyard site.

The size of the piping should be large enough to avoid overflow rising up to street level through sewer grates. The pipeline up to the treatment plant will be designed to manage up to 130 litres of wastewater per second. Excess wastewater up to 390 litres per second will be pumped through a fine screen to a bypass treatment unit and disinfected with ultraviolet radiation before being rejoined to the line and pumped to the harbour. Wastewater up to 570 litres per second will be treated in the same way but excess will be flushed into the Waitohi Stream.

Construction was staged to meet Port Marlborough's need to cater for ferry traffic and logging work at Shakespeare Bay.

The next stage of the work will involve the construction of a new pump station and associated pipe work on Dublin St in 2014.

New pump stations at Surrey St and Fishermans Wharf will be constructed in 2015, and construction on upgrading the pump stations at Beach Rd and Waikawa Beach will be started by 2016.

The Marlborough Express