Drainage problem ‘not typical’

Press, 8 March 1984, Page 9

Drainage problem ‘not typical’

An “inverted siphon” design for property stormwater drains to raised streetside channels should cause few problems if the new system was maintained properly, the Christchurch City Council works and traffic committee was told yesterday. Cr Mollie Clark said last month that such a system could cause problems for residents along Hereford Street, between Linwood Avenue and Olliviers Road, where the street is being reconstructed.

Drains leading from houses to the side channel have dips in them to compensate for a reduced fall to the street.

The ability of such drains to carry water was “not necessarily impaired,” said the council’s Deputy General Manager (works), Mr H. E. Surtees.

“Provided they are regularly flushed, and provided the level of the outfall is below the level of the intake, there should be no problems,” he said. It was estimated that property drainage from 20 to 30 per cent of the older parts of the city depended to some degree on drains using the inverted siphon method.

Mr Surtees said he was not aware of any problems on a general basis. It was more common for problems to stem from other factors, such as tree roots in the drains.

The only practicable alternative to inverted siphons would be an addi-

tional stormwater collection pipe system in the footpath, he said.

That could cost $1 million a year extra if all projects provided such a service. When situations arose such as the one in Hereford Street, the council and Drainage Board should be expected to meet the extra expense of a separate system, said Cr R. H. Arbuckle.

Mr Surtees said that residents were genuinely concerned, but the problem had been “somewhat exaggerated.” Cr D. C. Close said that council officers should provide clear, preferably written advice on how problems with inverted siphon systems could be fixed. He mentioned a case in the reconstructed stretch of Hereford Street where water had pooled in the bacll yard of a property. The City Engineer, Mr J. A. Ince, said that that section was low and should have been raised. It was “not typical at all.”

Kellys Road

A District Scheme designation showing Kellys Road stopped at its eastern end, at the junction with Hills, Briggs and Innes Roads, should remain, said Mr H. J. sder, chairman of the new alter Park Residents’ Committee. He said that a more recent suggestion that Kellys Road could be realigned at that end and directed through part of the yetundeveloped park, would not be supported by residents.

The traffic engineer, Mr M. L. Gadd, said that traffic pressure on Kellys Road could be reduced by removing the street from the intersection, but it would be preferable to have it closed from a traffic and environmental point of view.

Mr Tyler said that traffic in Kellys Road had increased in volume and speed since Ranger Street was extended to form a link with McFaddens Road.