This site was a vacant bush site in the Birdwood Urban Concept Plan area. The site was approximately 13.8 ha with moderate to steep slopes. The site constraints lead to a range of lot densities over the development. Typically the clearer and more gently sloping area offered suitable land for 450 – 500m2 sites, the steeper, higher quality vegetated areas were better suited to large lots of 1200-3500m2. The lower part of the site (containing significant bush area) bounding the Swanson Stream was vested in Council as Recreation Reserve. A non-complying application was lodged and granted for 59 Lots.
The extent of vegetation on site, existing topography and geotechnical constraints the made the provision of drainage services challenging. The design used an existing stormwater pond on an adjacent site for the upper site. The lower half of the site with no reticulation and steep heavily vegetated slopes above the stream led to an innovative design using flexible polyethylene stormwater and sewer pipes laid overland through the bush. Lines were also thrust beneath the bush to the existing trunk sewer and to direct the stormwater to a mitigation device.
The stormwater discharge created a major difficulty and Cato Bolam identified a small gully feature and proposed a filter strip including small check dams, minor shaping and revegetation.
How we assisted
Cato Bolam Consultants provided full development project management, engineering, planning and surveying services working closely with the client. Furthermore seasonal restrictions and timing of resource consents required a variable procurement process and construction program over the winter months. Cato Bolam worked closely with the contractor and council to complete the design and obtain the engineering approval ahead of construction.
We completed the subdivision design and feasibility study; provided the Resource Consent application; we designed all engineering and managed construction; we completed land transfer and as built surveys and achieved titles.