Impacts on Stormwater Management Arising from Subdivision Modifications During Development

The red-zoning of significant portions of eastern Christchurch as a result of the Canterbury earthquakes has seen the proliferation of new subdivision developments on greenfield sites around Christchurch and other satellite towns in the Canterbury Region.

This paper will focus on the authors’ recent experience during the development of a large subdivision in North Canterbury. During the planning and consenting phase of this development, an initial stormwater design which met the requirements of the subdivision was prepared and the system was later constructed. However, market demands, requirements for infrastructure improvements and the incorporation of additional development area resulted in modifications to the subdivision design well into the construction phase. These modifications have entailed changes to the initial stormwater system design and variations to the stormwater discharge consent.

The challenge was to provide an efficient stormwater system, in terms of both treatment requirements and space availability, while working within the constraints of a site where space had already been allocated for sections and internal roads.