Planning for Sustainability, QLDC's Wastewater Story

Reuben Bouman, Evie Wallace (Beca), Trent Beckman-Cross, Calum Pringle (Queenstown Lakes District Council)

Due to years of substantial growth, Queenstown Lakes District Council (QLDC) has been upgrading nearly all its wastewater treatment plants. At the same time QLDC has been developing the implementation of sustainability principles in its capital works projects. This paper outlines the methods QLDC have used to do this including Sustainability in Design (SustID) workshops. This paper will give practical examples of how these workshops were run and the initiatives developed and implemented. This process has been successfully applied to the upgrade projects for the Shotover WWTP in Queenstown and Pure WWTP in Wānaka. More recently it has also been used for the Hāwea to Pure wastewater pipeline.

The initiatives developed in the SustID workshops were categorised by ease of implementation, scale of impact, and ownership. The initiatives discussed cover a wide range of topics including greenhouse gas (GHG) emissions from construction materials and methods, GHG emissions from liquid and solids treatment processes (including a review of N2O emission from sequencing batch reactors (SBRs)), waste minimisation (from a design and construction perspective), water reuse opportunities, tree planting within the project, and reuse of materials such as pond sludge onsite. Detailed carbon assessments were then used to help determine which sustainable design solutions should be implemented. For example, tapering of the concrete reactor walls to reduce the quantity of concrete and reinforcing steel, and high efficiency aeration blower and diffuser types.

This experience, along with work with other suppliers and stakeholders, has helped enable QLDC to develop sustainability KPIs for its Three Waters Panel, for both professional services and physical works. How these KPIs will impact and inform sustainability throughout both design and construction is also discussed in the paper.

As the Project Pure upgrade moves into the construction phase, a sustainability in construction workshop has been scheduled to discuss the protocols for waste management and carbon accounting. It is valuable for designers and constructors to work together with QLDC, to implement and build upon opportunities established in the design phase, and add additional construction related sustainability initiatives.

Another opportunity in doing these upgrades has been the chance to plan the space for future upgrades. This was particularly the case for the Shotover WWTP where the planned decommissioning of the ponds has created a large area for potential development with many parties interested in the use of the land. This paper will detail the importance and collaborative method for developing these master plans, and how space for future sustainability initiatives has been
incorporated.