Work Starts on the Belmont Wetland Pilot

This week work began on RiverLink's Belmont Wetland Project. Mulching existing river berm vegetation to remove blackberry and all existing berm trees within the site footprint in preparation of new lower wetland planting.

In the week commencing 26 August environmental controls, fencing and signage will be in place. Topsoil and filling mounds will be stripped for the upper wetland and excavation of the upper wetland will commence. This material will form mounds in the river berm for planting.

RiverLink is piloting riverbank revegetation, stream improvements and partial diversion of stormwater through constructed wetlands within the immediate floodplain of Te Awa Kairangi / Hutt River. This pilot project is designed to test the feasibility of constructed wetlands within the modified river corridor to improve the mauri of the stream, habitat for indigenous flora and fauna, stormwater quality and control and understand the short- and long-term maintenance requirements.

The proposal includes the partial diversion of stream flows from the Belmont catchment through a tiered wetland system. The existing modified stream will continue to carry baseflows up to 5 Litres per second to support fish passage to the upper headwaters. Above this, flows will split between the existing channel and the constructed wetland system to improve water quality.

To split the proposed stream flow and protect the wetland system, two forebays will be constructed. The first controls flows into the wetland and the second helps trap sediments and spread flows across the full width of the wetland. The wetland comprises a mix of shallow and deep habitats to support a range of indigenous plants specifically chosen to improve water quality. This achieved by a mix of physical settling of sediments as well as complex biological and chemical processes to reduce urban contaminants including metals and nutrients.

Other features include a podocarp treeland, native shrub river edge protection, pedestrian and vehicle access and carparks, a forebay service area and a grassed areas for gathering and interpretive signage.