Drainage Inadequacies Shown By Storm

Press, Volume CVIII, Issue 31662, 24 April 1968, Page 1

Drainage Inadequacies Shown By Storm

Inadequacies in drainage works were clearly shown in the Sumner main drain, the main outfall drain, the south Canal Reserve drain and the Heathcote and Cashmere Valley areas, said the chief engineer (Mr P. J. McWilliam) in a report to the Christchurch Drainage Board last evening on the recent storm.

Mr McWilliam said that several points had come to light which would require careful investigation.

Urgent consideration was being given to a flood-warning system. Because of the short length of the Heathcote River and its tidal nature and because other areas subjected to more major periodic fleod-

ing were not directly connected to the river it might be hard to devise an automatic warning. . An alternative, said Mr McWilliam, was a patrol with a radio-equipped vehicle or vehicles. "The extensive flooding also stressed the importance of land drainage works and the need for improvement or relief in many areas,” he said. “Some of these are already

being investigated, including the Estuary and the lower reaches of the rivers, but there is a tremendous amount of work to be done in many other areas.” In areas near the sea, the Estuary and the lower reaches of the Avon and Heathcote rivers, high tides during the storm added considerably to flooding by holding back discharge from rivers and drains. Mr McWilliam said that during the storm, and in some cases for several days after, sewer pumping stations were working at maximum capacity. Many sewers were gorged, and the sewer overflow at Fitzgerald Avenue operated for a time. Three other overflows probably occurred. A few pumping stations were affected by loss of power. The longest break was at Southshore, where a fuse blew and the inadequacy of the alarm system delayed action. Mr McWilliam said he would report later in more detail.

The board’s rainfall readings between April 9 and 14 showed totals ranging from 5.08 in at Riccarton to 10.42 in at Woolston.

The chairman (Mr F. R. Price) said that records taken during the storm had been sent to the Wallingford Research Station to help in its investigations on the Estuary and rivers.

Members paid tribute to the efforts of Mr McWilliam and the staff during the storm, and it was agreed to thank the Post Office for its work in restoring communications.