Los Angeles' Water and Power Commission voted unanimously today to change the city's water rationing schedule, which experts have cited as a factor in a rash of pipeline breaks last summer.
The proposed changes will go into effect once approved by the City Council, a process which could take a few weeks. The mayor's office has waived consideration of the matter.
James McDaniel, senior assistant general manager for the Department of Water and Power's water system, called for amending the city's Emergency Water Conservation ordinance so residents of odd-numbered addresses can activate their sprinklers on Mondays and Thursdays, while residents at even-numbered addresses can irrigate on Tuesdays and Fridays.
Addresses ending in 1/2 or any fraction would conform to the permitted uses for the last whole number in the address.
McDaniel said the proposed changes "would reduce the magnitude of pressure fluctuations throughout the DWP water distribution system while still providing the necessary water conservation levels.''
He added the DWP would maintain its water conservation targets, noting "our ordinance has been very effective and I think it's been very crucial to us meeting our demands while wisely using water in the state.''
Under the draft ordinance, if the DWP decides to ease the restrictions so residents can water three days a week, odd-numbered addresses would add Saturdays and even-numbered addresses would add Sundays.
But if the DWP decides to tighten restrictions, odd-numbered addresses would irrigate only on Mondays while even-numbered addresses would irrigate only on Tuesdays.
The proposed changes come weeks after a study led by Jean-Pierre Bardet, chairman of USC's Department of Civil and Environmental Engineering, found that banning residents from turning on their sprinklers except on Mondays and Thursdays was a major factor in the 101 water main breaks reported from July through September last year -- double the normal number for that time period.
The experts concluded that DWP's water rationing schedule created drastic changes in water pressure that put stress on corroded cast-iron pipes and caused them to break, causing severe flooding in several areas of the city.
One pipeline break even created a massive sinkhole that nearly swallowed a fire truck.
The experts were the first to propose a change in the water rationing schedule.
When the study was released last month, DWP criticized it, saying, "The model presented is simplistic as noted by the author. The explanation provided is certainly possible or contributory, but is not tested to the level of definitive or conclusive.''
Today, however, McDaniel said, "One of Professor Bardet's recommendations was to minimize pressure fluctuations in the pipeline and we've gone back and forth and talked to the expert panel about a lot of the different things that cause pressure fluctuations, but fundamentally, I think we're in
agreement that minimizing pressure fluctuations is a good thing.''
Bardet hailed the proposed changes, saying there are "weak links'' in the pipeline.
"These weak links keep appearing and they are here now and they are ready to break and create another rash in the summer if we don't prevent the (pressure) fluctuations,'' he warned.