Climate Change Pressures in the Wastewater Sector and Adaptive Planning

E Diack, J Bennett, D de Haas, H Kashkari, S Hartwell - (GHD).

Ministry of Environment (MfE) is leading policy work related to the development
of a proposed new national environmental standard for wastewater discharges and
overflows. To inform their work MfE engaged a joint consultant team of GHD, Beca
and Boffa Miskell to provide a summary of the current state of the wastewater
sector in New Zealand including details on current and emerging issues for
wastewater management.

This paper outlines a portion of this study which explored the current climate
change regulatory requirements and the current tools to estimate greenhouse gas
emissions, in conjunction with the primary risks facing wastewater treatment
plants (WWTPs) in New Zealand with regards to current climate change predictions
and the likely direct and indirect impacts these changes may have.

The wastewater sector is vulnerable to the direct and indirect impacts of climate
change, including coastal inundation and erosion, changing patterns in
precipitation, and drought frequency. Analysis of the location of WWTPs in New
Zealand identified 5% are located within 5 km of coastlines highly sensitive to
inundation and 14% are within 5 km of a segment of coastline highly sensitive to
erosion. A significant number of WWTPs are also located in flood hazard areas,
such as in the Waikato, where 32% of Plants are within a flood hazard zone and
41% within 1 km of these zones.

The localised impacts of climate change, particularly indirect impacts, are difficult
to quantify and predict. From interviews with a representative selection of Local
Government Authorities in New Zealand it was clear that there is a considerable
journey ahead to prepare the wastewater sector to respond to the implications of
climate change. This paper summarises feedback from service providers and
describes what climate change implications interviewees identified were priorities
for them, and the key knowledge gaps and hurdles perceived.

Consideration is given in this paper to the greenhouse gas emissions from WWTPs,
and the associated New Zealand carbon reduction policies. The paper also
describes the emergence and use of adaptation planning for the wastewater sector
and potential to improve its resilience to climate change. By drawing on
international, and emerging domestic case studies, adaptive planning is explored
and its applicability for implementation in New Zealand as a best-practice
approach.