New stopbanks in flood plan

FLOOD PROTECTION: Queen Elizabeth Park oval, with Cecille in the Park cafe in the background, is the focus of new proposals. PHOTO/LYNDA FERINGA.

Planning to combat Masterton's vulnerability to a devastating river flood has resulted in the framing of some wide-ranging options, including building stopbanks throughout parts of Queen Elizabeth Park.

A series of options has been developed by a subcommittee of Greater Wellington Regional Council and chaired by former Masterton mayor Bob Francis.

These are outlined in a draft paper which will form the basis of a plan to involve the people of Masterton through an extensive programme of public meetings starting on October 5.

They revolve around ways of overcoming flood problems in the Waipoua River with the baseline being a one-in-100-year return flood.

The most controversial option among those aimed at protecting the urban area between the bridge over State Highway 2 at the town's northern entrance and the Colombo Rd river bridge is one which would see large sections of existing stopbanks on both sides of the Waipoua taken away.

The stopbanks would disappear from 200m downstream of the SH2 bridge on the Lansdowne side and 12m downstream of the bridge on the Queen Elizabeth Park side.

New sections would then be built connecting the existing stopbanks to the river terraces.

On the Lansdowne side a new 100m stopbank would run along the alignment of the footpath from the swingbridge and the section of stopbank between SH2 and the swingbridge would need 70m of gabion raising.

At Queen Elizabeth Park, a new stopbank would be built along the southern edge of the skate park, connecting to the cricket oval before turning to run close to the cafe, bowling green and connect with the river terrace at the edge of the cemetery. From there it would follow the alignment of the old river terrace.

That option would involve 940m of stopbanks from a height of 2m near the skate park, dropping to under a metre near the cafe and half a metre near the cemetery.

A totally different option, known as the narrow option, would see the existing stopbanks along the Waipoua raised by between 1 metre and 2 metres in height, effectively to contain high floodwaters.

A potential problem with this option would be the extra loading a huge flood would place on the stopbanks. Two other options have been included on the draft development plans to be discussed at the meetings.

One is a variant of the option that would impact on the park, with a small stopbank along the alignment of the existing stopbank to protect the park and its lake from a one-in-20-year flood and to help the lake function as a stormwater management pond.

The final option is a hybrid of two others protecting the park from a one-in-100-year flood but taking away the stopbank on the Lansdowne side of the river, allowing the Red Star rugby ground to flood.

The public meetings are aimed at giving people an opportunity to be involved in the options debate before a final proposal is chosen by the end of the year.

Mr Francis said yesterday the flood protection measures finally adopted could cost between $5 million and $6 m.

The subcommittee believes people may not be aware of aspects such as the risk of disruption to the urban water supply in a large flood and everyone should be involved in a management plan acceptable to the entire community.