Construction of Low Impact Design Solutions at Long Bay

After the Environment Court hearing in 1996 allowed urbanization of the Long Bay catchment, there was 10 years of planning to prepare the Long Bay Structure Plan, a council hearing in 2005, another Environment Court process from 2007 to 2011, the Long Bay Structure Plan became operative on 6th October 2011. Significant bulk infrastructure has been constructed and the first subdivision Stage has been legalized. Due to the sensitive receiving environment and the desire for more sustainable and effective stormwater management to protect the ecological values of the existing natural streams, a number of innovative low impact design stormwater management practices have been incorporated into the final constructed streetscape.

The Long Bay Structure Plan is a greenfield development of some 360 hectares to house up to 7,500 people in the northern east coast of Auckland. It fronts onto the Long Bay Regional Park and the Long Bay/Okura Marine Reserve. Due to the sensitive receiving environment and the desire for more sustainable and effective stormwater management to protect the ecological values of the existing natural streams, a number of innovative low impact design stormwater management practices have been incorporated into the final constructed streetscape.

Of particular interest is the construction of the developments first Subdivision Stage which includes on-site bioretention gardens and tree pits, all located within the road reserve to manage the stormwater runoff from the road surfaces. The paper will describes the methodology, options and layouts that were put through their design paces and reasons for the final choices to make an aesthetically pleasing and practical stormwater solution.

The focus of this paper is the design and construction of the bio-retention devices (rain gardens and tree pits) to manage the stormwater runoff from the roads being built in the first stages of construction in the SP-B area.