The Forestry Road Redevelopment Project:

21 Forestry Rd is a 17.2 ha property that was occupied by Carter Holt Harvey from 1966 to 1996 as a sawmill and timber treatment facility. Although CHH ceased operations in 1996, other industrial activities continued to occur until the current redevelopment.

Dainty Alderton Consulting Engineers were engaged to provide engineering design and construction supervision services for the proposed redevelopment of the property. The property is being subdivided into 22 new commercial/industrial lots, two reserve areas and a public road to be vested with Rodney District Council. Auckland Regional Council and Rodney District council codes of practice as well as Environmental Court rulings related directly to the subject property were assessed and addressed as part of the design process.

Stormwater runoff from the property discharges to the lower Wautaiti Stream 3.5 km upstream from the Upper Waitamata Harbour. Stormwater quality treatment is required to protect the waterways from any possible contaminates present in the run off from the redeveloped site. The focus for the stormwater management was on removal of pollutants of concern (i.e. Copper, Lead, Zinc, Cadmium (from automobile tires) and hydrocarbons) which can decimate marine biota.

Two separate wetlands were designed to effectively treat all the stormwater runoff from the property prior to discharging it into the larger catchment. The constructed wetlands provide stormwater quality treatment through sedimentation, filtration, oxidation, biological uptake and decomposition. The wetland plants will reduce runoff velocity and lower the carrying capacity of the water, reducing suspended solids and decreasing erosion. The wetland will also provide more surface area for small particle adhesion i.e. clay sized particles which act as a sink for metals such as phosphorus and other soluble contaminants.

As Dainty Alderton Consulting Engineers examined the possible plant species to populate the wetland it was determined that habitat for several native species that were declining nationally could be provided. It was the vision of the developer and the engineers to provide wetlands which would act as a visual amenity to those who would spend time in the industrial park as well as stormwater management. While the wetland is still in the planting stages watch this space.