Update on Wainui Stream in Paekākāriki

Thursday 6 August update:

Testing of samples we sent to Hills Laboratory, Hamilton, last week for independent testing were not able to detect any signs of any hydrocarbons up or downstream of the discharge point.

Any odour at the site has dissipated

In consultation with Greater Wellington Regional Council (GWRC), we will be removing the boom and signage from the lower stream.

Wednesday 5 August update:

• Two ecological assessments of the stream, one last Tuesday and the second on Friday, raised no issues of concern.
• Results of samples taken from the stream last week show levels of oil and grease at less than 1 part per million.
• Staff have been at the site every day last week and this week removing any visible scum or oil from the stream (focusing on the area around the booms).
• Staff inspecting Wainui Stream earlier today can confirm there is no scum or oily substance coming out of the stormwater pipe.
• Photos (below) from our site visit earlier today showing the booms in the stream are clear of visible scum and oil. There is also very little, if any, odour on site.
• In consultation with Greater Wellington Regional Council (GWRC), we are proposing to remove the boom and signage from the lower stream but leave the boom directly downstream from the stormwater pipe in place for the moment as a precaution.
• Work remains on hold while GWRC continues its investigations.

Friday 31 July update:

The smell some people are noticing around parts of Wainui Stream is from styrene which is in the resin being used to line the stormwater pipe in the area.

Even at very low levels, styrene smells strong and takes some time to dissipate. It is only dangerous if inhaled in large quantities in a confined space such as a man hole or pipe.

Monitoring of odour by the stormwater pipe this morning shows current levels are below the minimum standard required by industry.

Thursday 30 July update:

This is the latest information we have on the stormwater pipe upgrade work being carried out by Wainui Stream (Paekākāriki) and action being taken around an oily substance found in the stream on Sunday.

• Work to upgrade the stormwater pipe, which discharges into Wainui Stream, commenced in the first week of July by a contractor appointed by council.
• The upgrade work involves lining the concrete pipe with a resin-impregnated liner to strengthen it.
• The liner is being pulled through the pipe by a vegetable oil which acts as a lubricant during the process.
• Many councils in New Zealand have been using this method to upgrade stormwater and wastewater pipes for the last 20 years. The process doesn’t involve digging open trenches to get to pipes, so is much less disruptive to people and the environment.
• We were first told of an oily substance in the stream by a resident on Sunday.
• Greater Wellington Regional Council (GWRC), which is responsible for the water quality of streams and rivers in the region, was notified. They have taken samples from the stream for testing.
• As a precaution, we advised the contractor to stop work until the source of the oily substance is identified and erected warning signs along the stream.
• We also arranged for an ecologist to assess the health of the stream.  His report states his impression was that “no widespread toxicity had occurred in the stream” and there was no evidence of any fish dying recently.
• A further ecological assessment is proposed to be carried out by an independent ecologist.
• Staff from our operations team have:
•  worked to clean up the oily substance
• installed floating booms in the stream to absorb any oily substance and prevent it encroaching further into the stream
• taken samples from the stream for testing by an independent laboratory.
• We are still monitoring the site.

From left, Councillor Janet Holborow, Group Manager Infrastructure Service Sean Mallon and Councillor Gavin Welsh.