In the event of a massive pipe failure, about half of the city's homes could be left without water, officials said.
"We have very limited control right now," said Peter Kavounas, assistant general manager for Glendale Water & Power. "If there were a natural disaster like an earthquake, we would have a very difficult time isolating the reservoir, and would have to sit by and watch the water drain."
Under the project approved Tuesday, officials will oversee the construction of a second pipeline, made out of welded steel. In addition to preparing for emergencies, the second pipeline will allow for the repair of the current pipeline, officials said.
The new pipeline is one of only a few capital improvement projects to move forward this year. Most have been postponed for at least five years as officials grapple with tight budgets.
While many postponed projects are classified as critical, Kavounas said the reservoir project is simply too pressing to put off.
"This is by far the facility we felt not only is most likely to fail, but also the one that would have the greatest consequence if it did fail," Kavounas said.
The work at Diederich reservoir comes in the same year that officials lauded the completion of the $30-million replacement of the Chevy Chase reservoir, which was deemed essential after city engineers determined cracks in the concrete had significantly compromised the structure's integrity.
Such projects, said Mayor Ara Najarian, show important work is moving forward despite budget difficulties.
"What I think it shows is that the city is committed to maintaining its infrastructure, the most critical elements," he said. "In this case, it's our water supply."
Utility officials will return to the City Council with a recommended contract later this year. Construction is slated to begin in December and finish in July.