Westport’s water supply – what happened and what has been done to fix it

Giles Creek, the main source of water for the Westport and Carters Beach town supply has now cleared up following a period of high turbidity.

During the February 2022 severe weather events, significant storm damage was sustained to the Giles Creek area, placing the town at an elevated risk of running out of water.

Council’s Manager Infrastructure Delivery Eric de Boer says “Drawing from Giles Creek again means that the raw water reservoir ponds are beginning to be replenished. The reservoir is currently sitting at 44% capacity.

While we should see some good recovery throughout this settled weather forecast period, it is important to understand that the essential use restriction is to remain in place.

There were slips and storm damage at the Giles Creek catchment area in February this year. The catchment area turned from being a fairly stable, clean source to a muddy mess. We have since been working to fix this area and investigating alternative supplies to ensure the supply remains resilient.”

Emergency works commenced in February during the response phase of the weather events and continued with $1.685 million in Emergency Works funding from Central Government.

Eric de Boer says “This funding enabled essential work to be carried out on the primary water intake and catchment area. Since the event, our team of contractors have been working hard to stabilise and build resilience at the water intake and catchment site.”

Westport Water Supply resilience works from February 2022 to now include:
• Stabilising and repairing the access road to the intake including slips, culverts and crossings.

• Initial intake repairs and maintenance including weir, gates, screens and associated infrastructure.

• Carrying out ongoing intake repairs and maintenance following heavy rainfall events.

• Ensuring ongoing raw water supply including temporary pumping and piping from usable sources

• Construction of a support suspension bridge along a slip effected section of the tunnel supply pipeline.

As noted in the work response above; repairs were required due to a slip between the third and fourth water tunnels (T3-T4), leaving the 600mm diameter pipe unsupported over a 50-metre span. Immediate temporary repairs and interim pipe support were completed to enable water flow and serviceability. Since then, a new, engineered pipe suspension bridge has been constructed to permanently restore integrity and water flow.

There were two major contractors involved in this work. The primary intake and catchment work was undertaken by WestReef Services Ltd. The tunnel pipeline T3-T4 was led by Hadlee & Brunton Ltd, with Abseil Access Ltd constructing the pipe suspension bridge.

Mr de Boer says “The quick response from all contractors under the civil defence emergency and extremely challenging weather and site conditions was outstanding. The work was completed by August, on time and under budget, at no cost to ratepayers.”

In addition to this work, the Westport water supply trunk main replacement project aims to replace the aging trunk main water pipes supplying Westport and Carters Beach residents with water.

Mr de Boer says “The existing gravity-fed trunk main was built between 1903 and 1915. It has exceeded its serviceable life and therefore poses a risk in terms of reliability, resilience, and compliance.

New polyethylene (PE) pipe is replacing the old 8” cast iron and 14” steel pipes which have approached the end of their effective service life. The new PE pipe is thick and engineered for future resilience to seismic events”

This project aims to ensure the Westport and Carters Beach communities have a resilient drinking water supply into the future.

Mr de Boer says “As well as the trunk main replacement, more work is being investigated to further fix up the Giles Creek catchment area to minimise disruptions to the water supply. We appreciate that residents want the issues with the water supply fixed, our team are working on long term solutions to this.”

-ENDS-
further information please contact:
Eric de Boer - Manager Infrastructure Delivery
eric.deboer@bdc.govt.nz