Boulcott/Hutt Project
About the project
As part of the implementation phase of the Hutt River Floodplain Management Plan, Greater Wellington is constructing a new stopbank through the Boulcott and Hutt golf clubs (the Boulcott Hutt stopbank), and undertaking river works to widen the river channel.
The existing stopbank
In this reach of the river, the existing stopbank extends from Melling Bridge to Hathaway Avenue. This section of the stopbank was originally constructed in early 1900s and later upgraded in the 1960s. Following the 1998 floods, emergency repairs were carried out on a section of this stopbank near Connolly Street. There is no existing stopbank from Hathaway Avenue to Fairway Drive but land just south of Hathaway Avenue is high enough to contain about a 100 year flood. The stopbank then start again at the rear of the former National Film Unit building (now the GNS Science building); this short section of stopbank was constructed in the 1970s and is of a good standard.
Failure of the existing stopbank or overtopping at Hathaway Avenue has the potential to cause major flooding of the Hutt Valley.
The new stopbank
The new stopbank will be upgraded to within a 1 in 440 year return period flood and will follow the existing stopbank from east of Mills Street to the Boulcott clubrooms before crossing the Boulcott golf course to meet the boundary of the Boulcott and Hutt golf courses. From the boundary, the stopbank will pass around the front of the Hutt clubrooms, then cross a number of holes, before generally following the residential boundary to Fairway Drive
River works
In this reach of the river, the river channel and floodway, at Transpower’s Melling Substation, narrow significantly. In the feasibility study for the stopbank, significant benefits were found if the river channel was widened in the vicinity of Transpower's Melling substation; the height of flood waters and the erosive force of the river are reduced.
As the benefits of river widening have proven to be significant we are now looking at the design of the river channel between the Kennedy Good and Ewen Bridges.
Project phases
The Boulcott Hutt project will be completed in a 3 phases: feasibility, design and construction; the timing of each phases varies for the stopbank and the river works.
For the stopbank, the feasibility stage was completed in August 2008 when an alignment was chosen after over 2 years of work. We are now in the detailed design phase and expect this piece of work to be completed by November 2009. The final stage is the stopbank construction, which will take place in sections and be spread over four years; construction is due to start in the early part of next year.
For the river works we are in the initial stages of the feasibility study and are currently in the process of consulting with the community.