Statement by Wairoa District Council chief executive Steven May:
The Wairoa District Council would like to offer clarification around the wording of the Hawke’s Bay Regional Council’s Wairoa wastewater resource consent which has now been publicly notified.
The wording in the public notification refers to the discharge of untreated wastewater from the Alexandra Park, North Clyde and Kopu Road pump stations via overflow outlet pipes into the Wairoa River.
The discharge of diluted untreated wastewater from these three pump stations seldom occurs but has happened in extreme and extended rain events which cause flooding.
Council does not want diluted untreated wastewater being discharged into the river. That is why we are going through the consent process, so that we can improve the way we operate.
Overflows at pump stations are a unique occurrence during extreme rain events when there is so much rainwater it infiltrates into the sewer network.
The network physically cannot handle this huge amount of water.
The pressure of the water can cause manhole/utility covers to pop all over town with diluted untreated wastewater spilling out onto land throughout the Wairoa township.
By the discharge going out through the pump stations, it prevents utility covers popping.
The sewer pump station overflow infrastructure is a safety measure for when the sewer network is pushed to its maximum capacity by high rain events.
In a storm event, a pump station overflow is a much lower public health risk as the river is in flood, flowing three to five times above the normal, and the sewer is heavily diluted with rainwater.
Stormwater should not be in the wastewater network, and that is why the work around the Council Inflow and Infiltration Programme is so important.
Inflow and Infiltration can be through house downpipes plumbed into the sewer network, ponding of water on properties that builds up and flows into gulley traps or stormwater getting into the sewer network via cracked or broken pipes.
Council is working to ensure there is no, or minimal, stormwater infiltrating the wastewater system.
To increase reliability Council has also installed Chopper pumps at the sewer pump stations which stops pumps blocking. This year will see the start of a programme to install dedicated generators which will prevent pump station overflows during a power outage.
This will go a long way to eliminating overflow events as historically they have often occurred during power outages.
This is a historical problem, and it is taking time to remedy, but there have been some really good results to date.
Unfortunately, pump station overflows happen all across the country, and most local authorities are addressing this issue.
If the consents are granted, the process will allow Council to formalise the overflow structures and monitor pump station overflows.
A key part of Wairoa’s consent application is that in the long-term, once the project has been completed, the aim is to minimise any overflow into the river.
Discharges have occurred, and like the rest of country are likely to continue to occur, hopefully in a very limited capacity, and we are doing the best we can to address the issue.
Part of the new consent will also allow Council to filter and UV disinfect the wastewater discharge with regards to the wastewater discharge to the river from the oxidation ponds.
This will ensure Wairoa is aligning to the National Policy Statement for Wastewater Overflows.
The application is now open for submissions which will close on Tuesday, 10 September, 2019 at 5pm.
We encourage people to submit, particularly if you have any thoughts on how we can solve this issue.
The application documents, including the assessment of environmental effects, can be viewed at the offices of the Hawke's Bay Regional Council at 159 Dalton Street, Napier and 46 Freyberg Street, Wairoa during office hours, or on Hawke's Bay Regional Council's website.
Anyone can make a submission on the application by going online to the Hawke's Bay Regional Council website and completing the online submission form (Form 13).
Hard copy submission forms can be obtained from HBRC reception or upon request.
8 September 2019
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