MONTREAL - Those who enjoy zooming back and forth from the South Shore on the metro are in for a lingering season of deprivation, as the first of 25 consecutive weekend closures of the three-station yellow line is set to begin on March 8.

Crews have to do $10 million of work repairing leaks in the tunnel's ceiling, a job expected to take more than 200 days in total.

The prospect of water seeping into a transportation tunnel under the raging St. Lawrence River might seem unsettling, but the top local transit executive isn't panicking.

"It's not dangerous it's completely normal," said STM chairman Philippe Schnobb. "In every subway all over the world you have water infiltration and we have pumped all over the network because we are under the river but in every station we have that kind of situation."

Commuters can expect weekend closures from March until May 25, and then resume on September 13 and continue until Dec. 14, 2014. In each case the metro will shut down on Friday evenings and only re-open on Monday mornings.

When the metro is not running the STM plans to run shuttle buses along three routes between Berri-UQAM and Longueuil, with stops along the way.

Those buses will run every 4 to 10 minutes, the same scheduled departures as the metro.

Schnobb said previously the work is essential but not urgent, and if the Champlain Bridge faces any additional emergency closures next year the work can be postponed.

Almost 20,000 commuters take the metro's Yellow Line on weekends.