Styx floodgates proposed

Press, 31 March 1980, Page 15

Styx floodgates proposed

Floodgates to be installed on the Styx River .would prevent serious flooding of properties adjoining the lower reaches of the river end its basin, said the re-; gional engineer of the North j Canterbury Catchment Board (Mr M. J< Bowden). - 1 The board’s water com-, mittee has recommended the installation of the floodgate structure, 30m downstream of r het existing gates, and the diversion of the river through the I floodgates. -. ~ The floodgates are part of major programme of! works to improve and: strengthen flood defences on the Waimakariri River. The existing floodgates were built in 1934 and had given very good service, said Mr Bowden. The structure was now of very doubtful strength and its replacement was a matter of some urgency, he said. The floodgates formed a vital part of the flood protection system on the Waimakariri River and prevented overflows from the river into the Styx Basin. ■ •- The gates also reduced the tidal influence on drainage of the large area of land in the Styx Basin by being lo-

cated in the tidal estuary of the river system. ; The replacement gates ! were to be. of the same gen- ; eral design as the old struc- < ture, but provisions would 1 be made for stop-logs toi (ensure that repairs and! I maintenance could be carried, out. Mr Bowden said. I 1 An application for water; .rights had been made and! should provide an adequate!, forum for public comment.! To date no objections had: been received, he said. j It was expected that ten-; Iders for the construction (would be called early in the, 11980-81 financial year and; I that work would extend on* ito the 1.981-82 year. i The .new river channel re-‘ quiring stop-bank construction, and minor' site developments were to be carried out by the board using its own contractors, plan, and labour. The' stop-banks for the Waimakariri River would be joined across the new floodgate and the old gates would be completely removed. The new structure would be a short distance downstream from the present site, on the line of the main Waimakariri River stopbanks in a place where construction could be easily carried out in dry conditions.

Responsibility for work and maintenance in the Styx River upstream of the floodgates rested with the Christchurch Drainage Board, Mr Bowden said. i The board had been investigating a scheme for improved protection from (flooding of land fronting on ;to the Styx ’River and its (lower reaches. |. The floodgates were the i downstream control or startI ing point for any improvejment scheme on the Styx ißiver and close liaison had been maintained between the i two boards. The Drainage Board had ’already agreed to extend its area of responsibility to the ‘site of the new floodgates, said Mr Bowden. Disturbance of the area was to be kept to a minimum during diversion of the river and construction of the stop-banks. It was planned to fill some of the channels with culverting so that a walking track could be established, he said. This would enhance public enjoyment of the area and it was hoped that the tidal backwaer created downstream of the new gate would be used for. recreation, Mr Bowden said.