The Christchurch City Council is currently seeking feedback from the community about new and improved Water Supply, Wastewater and Stormwater bylaws. In particular, the new Stormwater and Land Drainage Bylaw will bring some changes to the way industry treats its stormwater. You can read all the finer details here, but will it deal with zinc polluting the stormwater?
We can feel some reassurance that the likes of car wrecking yards and waste storage yards, in addition to all the usual potentially polluting industries, will be obligated by a new CCC bylaw to have suitable stormwater systems and that these systems will be inspected for compliance.
The draft 2022 Stormwater and Land Drainage Bylaw clearly sets out a regime of registration, assessment, monitoring and audit of trade activities that may pollute our waterways, and gives the Council the power to charge a fee to cover the cost of doing so. The Register of Industrial and Trade Activities, which is contained within the bylaw, lists all such potentially hazardous enterprises.
That is all good, although the underlying issue is that of resourcing: will the Council budget appropriately for sufficient trained and qualified staff, not to mention transport and administrative support, to do the job well. Resourcing needs to be at a level where all industries, but particularly those more at the edge of good practice and management, feel that they are obliged to take seriously their ongoing responsibilities for the quality of stormwater leaving their site.
However, there is a possible blind spot in these regulations if they are to achieve a reduction in the current pollution loading in the Ōpāwaho Heathcote River. Important though accidental, or even deliberate, spills of toxic substances are, they are not the most significant pollution issue.
Zinc is a major pollutant of the river. The CCC Surface Water Quality Annual Report 2020 indicated that a number of monitoring sites on the Ōpāwaho Heathcote River triggered further investigations under the Comprehensive Stormwater Network Discharge Consent (CSNDC) due to the levels of dissolved zinc (and other pollutants) either not meeting the guidelines or having levels statistically increasing over time.
The source of dissolved zinc is tyres and runoff from bare zinc-plated steel roofs. Canterbury University has estimated that 65% of dissolved zinc in our waterways is from the latter. Where is the greatest area of unpainted zinc-plated roofing? In our industrial areas – think of those large, grey warehouses – and our retail malls.
Yet all the retail malls and the many enterprises which are operating in enormous warehouses covered in bare zinc-plated roofing steel will not be captured by the new bylaw because the type of activity taking place in them is not listed in the Register of Industrial and Trade Activities. The stormwater from these warehouses, fed untreated into the council stormwater network, will continue to provide an ongoing supply of dissolved zinc to our waterways.
The drafting of this new bylaw is a precious opportunity to draw these expansive areas of zinc-plated steel into a control system whereby owners of such premises are obliged to remedy the environmental hazard that they cause by either painting their roofs and walls, or by installing a private stormwater treatment system to remove dissolved zinc.
Clause 28 Requirement to apply for an Industrial Stormwater Discharge Licence states:
(3) Where the business activity or area is not captured by the Register, but the Council considers the activity is occurring in a way that may contaminate stormwater, the Council will notify the occupier, setting out a timeframe to apply for an Industrial Stormwater Discharge Licence. The occupier must apply within the timeframe specified in the notification.
It is not yet clear to us whether or not this clause will capture the risk posed by an enterprise that occupies a significant building covered in unpainted zinc-plated steel.
We believe that it should and that the bylaw should state that clearly by indicating that the owner of any non-residential building with a roof area of more than say 200m2 is required to apply for an Industrial Stormwater Discharge Licence.
See also in this series of items relating to the draft Water Supply, Wastewater and Stormwater Bylaws:
