31 March 2022
Media: Local Democracy Reporter
Topic: Discolouration of Whakarewarewa Forest waterway
Enquiry
*NOTE: The following enquiry was received yesterday [30 March 2022]
We've enquired with the regional council about some discolouration in Puarenga Stream.
We understand the district council informed the regional council there had been a breakage in the treated wastewater irrigation pipe in the Whakarewarewa Forest land treatment system and the burst pipe caused erosion and is likely to be the cause of the discolouration.
That's according to the regional council.
Could the district council please answer:
- Whether the district council advised the regional council of the incident before or after the regional council enquired about it?
- Why, when and how did the pipe burst and has it been fixed yet? Is there any risk wastewater reached the stream?
- What actions is the council taking to prevent future incidences?
- Why it hasn't the council notified the public about this incident?
- If the council has investigated if the discolouration in the water has any risk to human health and what the outcome of that investigation was?
I am after answers to these questions by 2 pm tomorrow please.
Response
*NOTE: Article was published on Rotorua Daily Post online HERE (time stamped 7.36am) today based on information provided by Bay of Plenty Regional Council yesterday [30 March 2022
Whether the district council advised the regional council of the incident before or after the regional council enquired about it?
Council and TRILITY proactively investigated whether there was a potential problem with the spray irrigation system in the forest after being informed of the discolouration of the Waipa stream by Red Stag. We understand that at that stage, Bay of Plenty Regional Council staff were in the mill area investigating other possible causes of the issue, having been notified by other parties. As per agreed protocols, TRILITY notified the regional council as soon as the pipe break was found and other stakeholders were also notified.
Why, when and how did the pipe burst and has it been fixed yet? Is there any risk wastewater reached the stream?
The cause of the broken pipe is not yet known but will be investigated.
As soon as the break was found the flow of recovered water (ie treated wastewater) to that spray block was shut down with immediate effect on the discolouration. (see more below)
There is no risk that wastewater (ie raw sewage) reached the stream. What is pumped from the wastewater treatment plant to the forest for spraying in the forest is fully treated wastewater and our wastewater is treated to a high standard. The treated wastewater is clear in colour.
Initial investigations suggest recovered water (ie fully treated wastewater) from the pipe break made its way overland to the stream, carrying silt with it, causing temporary discolouration of the stream. The recovered water is clear in colour
What actions is the council taking to prevent future incidences?
Both Council and TRILITY have comprehensive asset management systems in place for all critical assets, including condition monitoring and maintenance programmes designed to minimise any failures and mitigate any risks to the environment and public health.
These types of occurrences are rare but occasional and unforeseen failures are to be expected in any network so there is a strong focus on effective response and we follow protocols that were developed jointly with the Regional Council and other Local Authorities in the region.
As well as cooperating with the regional council’s investigation, we will undertaken our own investigation, with TRILITY, and will undertake repairs and any additional mitigation works deemed necessary.
In the meantime, that spray block – which is one of 16 in the forest – will remain out of commission. This will not affect the forest irrigation programme as use of the blocks is rotated. They are never all in use at once
Why it hasn't the council notified the public about this incident?
The focus in responding to such incidents is minimising any adverse effect on the environment and/or risk to public health and agreed and accepted response protocols are followed.
The level of notification is dependent on the situation and the level of risk to the environment and public health and/or safety.
In this case signage was erected in a number of places cautioning against entering the water, as a precaution, and stakeholders including forest stakeholders and Whakarewarewa Village representatives were notified and will be kept informed.
If the council has investigated if the discolouration in the water has any risk to human health and what the outcome of that investigation was?
The silt that is the likely cause of the temporary discolouration of the stream poses very low risk to human health. Bacterial testing of the Puarenga Stream at Whakarewarewa Village shortly after the break was found showed E.coli levels to be within recommended bathing water guidelines.
Monitoring of the turbidity (which is a measure of discolouration) showed it dropped quickly within a matter of hours after the flow to the spray block was stopped. Turbidity has continued to improve since then and it may take a few more days for the sediment in the stream to settle fully and the stream to be back to normal.
From the Bay of Plenty Regional Council
The regional council was asked about the stream discolouration yesterday [30 March] and provided the following information:
Is the council aware of this and what has caused it?
Bay of Plenty Regional Council received a call from a member of the public yesterday (29 March 2022) at 1pm regarding discoloured water in the streams at the Waipa Mill side, near the Whakarewarewa forest. Council staff promptly visited the site to take samples and, with support from the local businesses, investigated upstream to find the source of the issue.
During this time, Rotorua Lakes Council informed us that they had identified a breakage in a treated wastewater irrigation pipe in the Whakarewarewa Forest land treatment system; the burst pipe caused erosion at the source, which is likely to be the main cause of the discolouration in the stream.
What, if any, plans are in place to fix the issue?
RLC advised that they had shut off irrigation to that area of the forest to ensure no further discharges would occur. Regional Council has commenced an investigation into the discharge, and will be conducting follow-up inspections and monitoring the discharge point over the coming days.
In response to a follow-up question to the regional council today [31 March] about the potential environmental impact of the incident, the regional council provided the following response:
Please attribute the comment below to Toi Moana Bay of Plenty Regional Council Compliance Manager, Alex Miller:
As this matter is still under investigation, we are unable to comment on the effects (actual or potential) until we receive the sample results back.