People’s safety is Council’s priority when it comes to addressing flooding problems.
Tauranga City Council reviewed its level of service for stormwater through the 2015-25 Long Term Plan. The council’s stormwater level of service is now focussed on “safety to persons”. Areas where flood water flows fast and deep enough to pose a danger to people’s safety are given the highest priority. (The flood water safety threshold is calculated using depth x velocity.)
This approach provides for the following:
- A ‘safety to persons’ focussed level of service
- Regulation and policy amendment to ensure no increased risk occurs, and over time risk is reduced
- Education to enable private individuals to make informed decisions
- Residual risk and emergency management to ensure an appropriate service is provided to flood affected landowners following flood events
- Reactive response capacity to aid flood affected landowners following flood events.
Residential and rural residential zoned private property takes priority, then non-residential/non-rural residential private properties.
This level of service does not provide for a reduction in the risk of flood-related damage to buildings, nor does it allow for changing climate conditions or address the risk of flooding from rivers or streams.
More about stormwater
Stormwater is the water that runs off surfaces such as houses, roads, driveways and footpaths when it rains. In the city it runs down drains into stormwater pipes or channels and is carried to the sea. Changing weather patterns and the effects of climate change are leading to longer and heavier bursts of rain that can overwhelm systems and increase the risk of flooding.
Stormwater is traditionally piped away from buildings, roads and carparks. The pipes discharge the stormwater into the nearest waterway (e.g. stream, beach, harbour, wetland). It is usually not treated in any way. Beneath our city streets, there is a complex network of stormwater pipes that carry stormwater downhill to discharge points. For most, the only visible signs of this network are the familiar kerb drains and perhaps pipes at the local beach.
The two main risks in the city are the amount and the quality of stormwater, and their respective effects.
Flood risk areas
Most flooding and stormwater issues tend to occur within older, established areas of the city constructed prior to 1990, or where inappropriate residential development occurred in low lying parts of the city prior to 1989. This particularly applies to houses that were built in the bottom of gullies in Tauranga and in the base of swales between dunes on the Coastal Strip, or to buildings (mainly industrial) built on old swampy harbourside sites in Mount Maunganui and Tauranga.
Stormwater is contaminated by air pollution, herbicides, garden fertilisers, rotting lawn clippings, motor vehicles, detergent from car washing, domestic animal faeces, or illegal and accidental spills/dumping into stormwater drains. Our modern lifestyle contributes to stormwater pollution, often unwittingly.
What do we do to reduce the risk of flooding?
Council has three 35-year consents for stormwater structures and managing discharges from across the city. Council has developed city-wide catchment management plans to deal with stormwater and stormwater quality issues as they arise. These also provide a programme of renewals and maintenance of existing stormwater infrastructure so we make sure the system is fit for purpose.
What structures do we have in place?
- 583km of stormwater mains
- 5 stormwater pump stations
- 250ha of ponds and wetlands
- 135 stormwater ponds
- 61km of identified overland flowpaths in public and private ownership
- 55480 properties are serviced
Stormwater works vary depending on the issue we need to resolve. Often they will include the construction of large infrastructure pipes underground. They can also involve reshaping roads to convey the water away from private property (these are called inverted roads).
What can you do to prevent flooding on private property?
There are many ways to reduce the risk of flooding on private property. These include using rain tanks, limiting the amount of paved surfaces on your property, and regularly cleaning out guttering and soakage holes. All of these will help reduce the risk of flooding.
What do we do to prevent stormwater pollution?
To prevent contamination of stormwater we need to create awareness within our community. Here are a couple of initiatives we have led to put this message across:
Stormwater signs in reserves
Council has produced a series of four signs covering what stormwater ponds are for, how they work, and ways people can prevent stormwater pollution. You can find these in Gordon Carmichael Reserve, Bethlehem Wetlands, Carlton Street Reserve and Matua Salt Marsh as well as at three separate locations in Papamoa. Poster versions of the signs are also available.
Bluefish on drains
The Bluefish on drains programme is designed to reinforce the message that 'The drain is just for rain'.
Last Reviewed: 05/06/2020