The Christchurch City Council (CCC) is currently seeking feedback from the community about new and improved Water Supply, Wastewater and Stormwater bylaws. You can read all the finer details here. In particular, the new CCC Stormwater and Land Drainage Bylaw will bring improvements to requirements for private stormwater systems and the powers that the Council has to ensure that these are maintained in working order. But is it enough to stop architectural copper polluting stormwater?
With its undulating copper roof, wrapping down over a series of concrete pavilions, the 2021 Master Builders Supreme House of the Year (shown above; Fendalton, Christchurch) is not only unashamedly modern, it also requires a special filtration system to prevent it from being toxic to its environment.
Most people are probably not aware that rainwater running off a copper roof and/or gutter will generate dissolved copper concentrations of up to 7500 micrograms per litre of water, mostly present as free ions which are toxic to macrobiotic life. Without a filtration device, the rain runoff from this copper roof would pollute the local waterways with dissolved copper for the life of the house.
Fortunately, the Christchurch City Council is aware of the environmental issue of architectural copper. As a condition of the building consent, the owner was required to install a filter to lessen the level of dissolved copper from the roof entering the council stormwater system which empties into the local urban waterway.
.We trust that the home’s owners, the current ones and those to come during the life of the house, will maintain the filtration system continuously, replacing the consumable filtration media as necessary. Such filter systems can remove more than 89% of dissolved copper in ideal circumstances.
As an important improvement on current CCC regulations, the draft 2022 Stormwater and Land Drainage Bylaw clarifies that the council has the power to require owners to maintain private stormwater devices to achieve the purpose for which they were installed.
Clause 26 (1) states:
Where the Council has required an occupier to install a privately-owned stormwater device, the occupier must maintain the device in good operating condition.
This needs to be read in conjunction with Clause 24 (1):
The occupier(s) of any property with a private stormwater system must discharge stormwater from the site or sites in accordance with any controls the Council specifies (including any operative resource consent)
and Clause 24 (2):
The occupier(s) of any property with a private stormwater system must, on request by the Council, provide information to demonstrate that the stormwater system is operated and maintained to achieve its purpose, and carry out any works that are required to ensure the stormwater system meets its purpose.
While this all assumes that the Council has the staffing and record systems to be able to identify appropriate private stormwater installations to inspect, as well as the will to pursue owners whose systems require maintenance, at least with the adoption of its draft 2022 Stormwater and Land Drainage Bylaw, the CCC will be in a better regulatory position to do so.
As the focus on water quality in our waterways intensifies nationwide, there needs to be an informed debate about the use of architectural copper. There may well be sustainability factors that counter the environmental toxicity of copper polluting stormwater.
See also in this series of items relating to the draft Water Supply, Wastewater and Stormwater Bylaws: