AVON RIVER BANKS

Press, Volume XCIII, Issue 27987, 6 June 1956, Page 15

AVON RIVER BANKS

Protection Necessary In Lower Reaches

REPORT TO CITY COUNCIL

With the erosion of the Avon river on the sand or clay banks in its lower reaches, protection will ultimately be needed over a long len th of the river at a very high ccfet. is the opinion of the City Engineer (Mr E. Somers), who said in a report to the works committee of the City Council that the work could be spread over many years.

A detailed estimate of the cost of improving and maintaining the stop banks would involve a tremendous amount of careful survey work, keeping a narty busy for several months, he said. The next step would be to determine what flood levels could be anticipated and how much freeboard was necessary, one of the risks with stop banks being that once they were oyer-topped they retarded the flood waters returning when the river levels fell.

Generally, sand available locally should be used as far as possible for protection works. To have any degree of permanence, stop banks close to the river, and specially where the channel had been deepened, would have to be more elaborate. In certain places, this could take the form of loose hand-' placed stone or concrete rubble. In other places possibly more solid protection such as sheet piling or concrete slabs would be required. Temporary protection could be given with building up the banks with suitable clav, the cost of under £ 1000 not being high.

Further flopding took place recently, the worst case being on the right bank near Anthony street. About a dozen yards of stop bank and a stormwater drain with a flap valve were washed out.

Immediate temporary repairs have been authorised. The council has decided that the Christchurch Drainage Board be the local authority responsible for the maintenance of stop banks, the council to meet 50 per cent, of the cost, subject to the boards engineer conferring with the city engineer before any major works are put in hand.