Power pylons in eastern Chch not necessary?

Press, 27 April 1983, Page 7

Power pylons in eastern Chch not necessary?

An electricity supply solution that would eliminate the need to build controversial power pylons through eastern Christchurch has been recommended to the City Council by independent consultants.

Their advice was sought last year after mounting opposition to a proposal that would have meant a pylon line between Bromley and Marhsland, much of it through residential areas. The report by the Auckland consultants, Kingston, Reynolds, Thom and Allardice, Ltd, was recieved by the council’s public utilities committee yesterday. It will be studied over the next month before any decision is made. The consultants recommended an option that would require New Zealand Electricity to rebuild the Municipal Electricity Department’s overhead line between Islington and Bromley when power supply needs warranted it.

Under that option, the preferred method of supplying the northern and eastern sectors of the M.E.D.’s area would be a connection to Belfast and Burwood from the Papanui sub-station.

The over-all cost of the preferred proposal would be $16,430,000-$11,230,000 from New Zealand Electricity and $5.2 million from the M.E.D.

Costs of other options studied ranged from $14,180,000 to $24,750,000.

If the counci chose the $14,180,000 option that had drawn opposition, the consultants recommended a different pylon route from two suggested. “Our investigations have led us to concur with the major environmental concerns raised by the general public in formal submissions, and at public meetings, on this proposed option,” said the report. An alternative pylon route would avoid more residential areas.

“It is a more acceptable practice, to run these lines across open spaces and industrial areas where the visual intrusion and amenity loss is minimal or can be managed,” said the report.

The amendment would alter the pylon route less preferred in the original proposal. From Bromley, pylons would skirt the sew-age-treatment plant and national marae site, remain-

ing south-west of Shortland Street until they cut across Wainoni Road and the Avondale golf course. N.Z.E. and M.E.D. officers had argued that the pylon line proposal was required to achieve a satisfactory security of power supply for eastern Christchurch, especially if there were a power cut.

The consultants admitted that supply reinforcement required in the north and east sections of the M.E.D.’s supply area revolved round new sub-stations that should be built as soon as possible, perhaps by 1986. But the report said that the M.E.D. power distribution system “offers an acceptable level of security of supply to consumers.” At present, the report said, “and given that all the possible effects of wind and ground failure cannot be reasonably designed for, the New Zealand Electricity supply to Bromley substation offers an acceptable level of supply security.” When the Bromley demand exceeded 200 megawatts, perhaps by the year 2000, additional security measures would be needed, and they had to be planned well ahead. The consultants recommended the building of two new sub-stations at Belfast and Burwood. They would be supplied from Papanui by an overhead line with underground cabling through present built-up areas.

A new, double-circuit overhead transmission line from Islington to Bromley, built when the maximum load demanded it, would replace the present overhead line via Halswell and Heathcote over most of its length.

For residential consumers, a loss of power supply for two hours would not necessarily cause any great problems, the report said. “It is our considered opinion that an outage of up to two hours duration, although considered undesirable, is acceptable to the majority of the population,” the report said. If a tower failed, it could take between 24 and 36 hours to replace it with a temporary tower. “However, a major outage of longer than two hours caused by a tower failure or transormer fail-

ure we consider highly unlikely,” said the consultants, “and therefore consider that the risk of this type of fault occurring is an acceptable one.

“A number of total outages at Islington have occurred. These have generally been caused by operator error. Bromley substation has maintained its supply through these outages via the BromleyTwizel line.”

Mr N. F. Pipe, chairman of the Anti-Pylon Action Committee, said he was “really thrilled” about the report. He said the work of a district that had “stuck together” had been a main reason for the recommendation.

Because of information the committee had gathered to dispute some assertions in the original proposal, he thought “this had been on the cards all the time,” he said.

The committee had argued that population growth in that part of the city, even projecting some time into the future, did not call for a project that required an overhead transmission line. The consultants said that planning strategies of the Canterbury United Council regional scheme, and provisions of Christchurch and Waimairi District planning schemes, “clearly indicate that although some urban expansion in the Burwood and Belfast localities will be permitted, it will be controlled in its extent.”

The Travis Swamp area was considered suitable for urban development, the report said, but was “unlikely to be developed because of inherent engineering difficulties.”

Regional green belt restrictions would prevent general urban expansion into Marshland. M.E.D. sub-stations in Grimseys and Winters Roads and in Dallington and New Brighton had sufficient firm capacity to satisfy predicted demands on them until 1995, assuming that present land use and planning strategies and population trends continued.

Because of low-voltage problems in Belfast and Spencerville, “reinforcement of supply” was required immediately, said the report.