If Manitoba Hydro chooses to string its proposed Bipole III high-voltage power line down the west side of Lake Winnipeg, organic producers in its path may be forced to deal with extra headaches.
That’s because of the need for vegetation control – spraying – underneath the towers, which is forbidden under the rules of certified organic production.
According to Pat McGarry, a senior environmental assessment officer for Hydro, a range of herbicides are typically used to keep woody brush and tree species from interfering with the 500-KV power transmission line that will run 1,300 km from northern generating stations to the Winnipeg area.
Hydro has marked known organic land with red squares along its proposed route, although McGarry said that the public utility’s knowledge of the status of all the farmland is not complete.
“It has been expressed to us from a number of people, about how we treat our rights-of-way through vegetation management. That’s one issue,” he said, in a presentation at the OPAM AGM last week.
Hydro will acquire the land it needs through one-time easement agreement payments, not land purchases, he noted, adding that producers will have up to 18 months to make their concerns heard before a preferred route is chosen.
“In the meantime, this is a good opportunity to have input into the routing and route selection,” he said.
The three currently proposed routes were chosen to avoid irrigated and organic farmland, as well as parks, residences, communi t ies, churches and cemeteries. It also needs to be a minimum of 40 km– and preferably 100 km– from existing Bipole I and II.
Earliest construction is scheduled for 2012.
The 44.4-m lattice-steel towers on farmland will be built without guy wires on a seven-square-metre base, at 480-metre spacing, meaning that one to two towers will span a quarter section, or three to four towers per mile.
Angle towers, on 15-square-metre bases, will be built on slightly larger bases every five to 10 miles, or where a greater than 12-degree turn is required.
Hydro needs an extra transmission line, said McGarry because 75 per cent of its power production is currently routed south on two lines which leaves the province’s electrical supply and exports “hugely vulnerable” to interruptions due to ice storms, forest fires or tornadoes.
Ice storms can collapse towers and forest fires, even if they don’t melt the high-voltage lines themselves, generate smoke and carbon that can create an arc through deionization of the surrounding air.
Also, the F5 tornado that struck Elie in 2007 missed Dorsey Station north of Winnipeg by just five miles, he said.
If the province’s lone DC to AC conversion unit handling power from dams in the north had been hit by the massive twister, power would have been knocked out “for years,” he said. [email protected]