24 September, 2018
Wastewater overflows are tracking downwards across the Waikato district, but there is still more work to be done.
2014-16 data showed that 81% of overflows were caused by blockages. This has increased to 90% of overflows district-wide
in 2018. This may seem like Council is going backwards, a percentage increase in blockages resulting in overflows shows
that the network itself is becoming more resilient. This is as a result of investment in the telemetry system that
identifies and responds to alarms quicker, asset grade assessments which prioritise critical areas for replacement or
upgrade and large scale cleaning of the network. As we know, blockages are largely due to objects entering the
wastewater system which are not meant to be there.
Council’s work in this space stems from its Continuous Improvement Programme which was established in 2016 after a
number of overflows in Raglan caused the Whaingaroa Harbour to be closed several times. The programme looks to deliver
on a number of tasks including:
• employing more specialist water and wastewater staff;
• the purchase of standby generators;
• improved wastewater operational knowledge and control across the district;
• a proactive network jetting and condition assessment programme;
• and a district wide public education programme.
Two years into the programme Council is already seeing results. In 2017, the district had 171 overflows. For 2018 to
date there have been 73 overflows compared to 113 at the same time last year. In Raglan, there have been 13 overflows so
far this year compared to 34 for 2017. These 13 overflows have been minor and have not seen any wastewater discharged
into water bodies. This means the harbour has stayed open.
Wastewater overflows are caused by:
• foreign objectives within the network or at pumping stations
• inadequate capacity within the network, relative to the flow being transported – this is normally an issue in
• failure of key equipment (e.g. pumping stations) or power at pump stations
The effects or consequences of wastewater overflows include:
• pollution of waterway (streams, rivers and harbour)
• public health issues, if next to people or where they swim,
• a loss of utility for sanitary services for customers
Waikato District Council Waters Manager Karl Pavlovich says while Council interventions will undoubtedly lead to
positive results, the community’s support and action will improve these results.
“For that reason, the district’s communities are being asked to do their bit through a public education programme.
“As part of this public education work, material will soon be distributed to all public toilets in the district and all
households will receive information letting them know what should and shouldn’t be put down the loo and kitchen sink,”
Council aims to do all it can to reduce overflows, but is realistic in knowing that achieving zero overflows is not
possible. “Council and the community working together is the only way we can reduce the impacts of overflows on the
environment,” Mr Pavlovich says.