The city of San Diego worries some of its dams “may be nearing completion of their beneficial life span” and is spending up to $5 million to see how they’re doing.
In 2015, city officials worked with an engineering company to do in-depth checkups on each of the city’s 9 dams. Carlsbad-based GEI Consultants has been working quietly ever since on a study that might use up to five years.
Most city dams are 80 years or older.
Brent Eidson, a spokesman for the city water department, stated the research study might ultimately find that no considerable work is needed on the dams.
Officials currently have a few concerns, however. In fall 2014, for instance, the city restricted the amount of water it can save in the lake formed by the El Capitan Dam near Alpine, which is the city’s second-largest tank.
That’s because authorities spotted water permeating out from below the dam. Some seepage is typical, but it could also suggest problems.
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Up until now, there hasn’t sufficed rain to raise the dam above that limitation, so the city hasn’t been forced to spill any water to keep the lake low, said Isam Hireish, the deputy director of water system operations.
” We are listed below the level of constraint– barely there, however we are there,” he stated.
But if there were ever enough downpours, the city is just permitted to keep the dam full temporarily. That indicates El Capitan, which has the capacity to store as much water as 900,000 people utilize in a year, can just keep about half that much water for any prolonged duration.
No one understands for sure if El Capitan is a security issue yet. Engineers prepare to do numerous different tests to determine the condition of the 83-year-old dam and the soil and rock on which it sits.
It’s unlikely the suggestion would be so drastic as to require the dam to be gotten of service, said Rania Amen, an assistant director of the water department.
” They’re not going to inform us the dam is no great,” she said. “Those dams are developed to last forever– sort of.”
Other problems at other dams are not serious enough to need operational limitations, which in dam security parlance are called “fill limitations.”
Yet, that doesn’t imply there may not be expensive dam retrofits in coming years.
The state Division of Dam Safety has actually “recognized dam safety deficiencies that might possibly require costly modifications to city dams,” the city’s engineering expert stated in a report. “The dam security concerns that have the greatest potential for costly adjustments are related to: stability of concrete, rockfill and hydraulic fill earth dams; stability and capacity of outlet towers; and possible for overtopping of dams during the design flood.”
A dam’s outlet tower houses the controls that allow water to be launched from the tank.
Authorities are already planning to invest $22.5 million to fix the seismically unsteady tower at the city’s earliest dam, the Morena Dam near Campo.
Officials also discovered a deficiency with the dam’s spillway, the flood control channel that notoriously fell apart at the Oroville Dam in Northern California earlier this year, however Morena remains in no real risk of spilling water: It’s 91 percent empty today.
The outlet tower at Savage Dam, which keeps back the Lower Otay Reservior, is likewise a problem. The tower is seismically unstable, inning accordance with the city’s engineering specialist.
Some of the possible upgrades remain in anticipation of issues– things like pipelines, ladders, hatches and instruments are old, so they have to be fixed up prior to they become security problems. Other concerns have currently been recognized either by the city, which does routine inspections of its dams, or by state regulators, who do annual inspections.
The city’s biggest dam, the San Vicente Dam near Lakeside, is recently redesigned. The city of San Diego and the San Diego County Water Authority interacted to raise the dam in 2014 so that the lake it forms might hold more water to obtain the region through droughts and emergency situations for several years to come.
This article associates with: Infrastructure, Science/Environment, Water