Where are we as a Water Sensitive City? A Case Study on a Sustainable Development

Development in Auckland is becoming more intensive to meet the city’s growth needs and the lifestyle desires of its residents. Intensive residential development is encouraged in the Auckland Unitary Plan, but comes with environmental and infrastructure challenges such as the provision of three-water services.

A three level residential development, ‘Element’, is proposed at 20 Pukerangi Crescent, Ellerslie, Auckland, on land that is currently occupied by a single house. Element seeks to incorporate a high level of sustainable, environmentally friendly features and, as part of this, proposes to adopt on-site water management solutions and reduced potable water demand from Auckland’s water supplier, Watercare Services Ltd. The philosophy for the water management is to manage stormwater runoff on-site and reuse it as a resource.

For the water management design, a continuous simulation water balance model was used, based on 60 years of historical rainfall record. The model simulated the performance of the water reuse tanks taking into account the runoff, on-site potable and irrigation reuse, and the available infiltration. The design includes for water supplementation from the town water supply. The Building Management System (BMS), which includes the management of the pumping and treatment plant of the potable reuse supply, will play an important role in maintaining non-stagnant conditions and ensuring that the dual supply system is maintained correctly.

Water Sensitive Design promotes viewing stormwater as a resource. To become a Water Sensitive City is seen by some as the ultimate goal in Management. The recently adopted Auckland Unitary Plan embraces some of the principles of Water Sensitive Design, helping Auckland to progress beyond being a Water Supply, Sewered and Drained city to being a Waterways City. This case study is an example of a development which embraces numerous principles of Water Sensitive Design, progressing beyond the policy requirements for stormwater management in Auckland.