AR & Associates (ARAL) was commissioned to undertake the design of civil engineering and infrastructure works along with the construction supervision, contract administration and certification of the Kowhai Downs development in Pokeno, Northern Waikato. This also included the design of an integrated stormwater management system. ARAL also managed the planning aspect of the project, resource consents for land use, subdivision, earthworks and stormwater discharge; therefore covering both district and regional plans for Waikato.
This subdivision includes the development of a rural block of land, approximately 67.8 hectares and the creation of 125 rural residential lots over 4 stages, following low impact design / water sensitive design philosophies. The site also contains areas of archaeological significance and hence archaeological authority was sought from Heritage New Zealand for the various stages.
The stormwater system being implemented in the Kowhai Downs Development incorporates and encourages the use of natural infrastructure, while focusing on minimising earthworks and conventional engineering methods such as piped networks have been avoided where possible. The work has aimed to retain the rural character of the land, ensure hydrological neutrality and minimise the overall effects on the environment.
Bulk earthworks were avoided by limiting earthworks to the formation of road and accessway corridors only, providing pipeless stormwater systems for conveyance and treatment (through a network of swales, fords and discrete depression / detention areas), along with other initiatives such as the reduction of streetlighting to preserve the rural environment, the preservation of key landscape features and remaining true to the inherent natural features of the site.
The stormwater management systems have been designed to address water quality and stream erosion management, primary and secondary flow conveyance and adoption of WSD principles to minimise environmental effects resulting from the development. Some of the concepts that have been adopted for this development include:
- Maintaining natural ground depressions for the provision of stormwater overland flow paths and discrete storage and detention;
- Slowing the stormwater runoff on site by minimisation of piped networks and using natural methods such as swales, overland flow paths, ford crossings, dipped vehicle crossings and culverts;
- The implementation of a comprehensive riparian planting programme using eco-sourced, non-hybrid native vegetation.
AR & Associates design works included the upgrade and the extension of existing roading infrastructure accessing the subdivision, access ways to individual lots, vehicle crossings and intersections, pedestrian access and pavements and streetlight to enable the subdivision construction. AR & Associates were responsible for supervising the physical works on site and the careful management of physical works operation construction, which was completed to programme and budget.
ARAL’s commitment to open communication and maintaining positive relationships with Waikato Regional Council, Waikato District Council, Heritage New Zealand and other government related agencies throughout the consenting process, was key to the successful and timely acquisition of consents granted to date, which in turn ensured there were no surprises along the way for the developer.
Consultation was undertaken with local iwi, which provided engagement and enabled feedback throughout the design and consenting process. Such consultation was important to enable a full understanding of the cultural and heritage aspects of the site and to accommodate these into the design.