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Jacksonville to assess water system seismic risk

Jacksonville is about to launch a study of the seismic risks facing the city’s water system.

The study will include recommendations for potential capital improvement projects to deal with earthquake impacts. The study could lead to installation of automatic shutoff valves that would isolate its four tanks from other parts of the system should leaks develop after an earthquake, City Administrator Jeff Alvis told Jacksonville City Council when he detailed a $20,000 grant the city has received to fund the study.

Jacksonville has tanks of a million gallons and 250,000 gallons located near the Britt Festival grounds. There’s a million-gallon tank in the Coachman area on the eastern end of town, and a 200,000-gallon tank in Westmont on the west side.

“The small one by Britt is over 100 years old. It’s still holding its own, but it probably wouldn’t hold up in an earthquake,” said Alvis. He would like to get a 750,000-gallon replacement tank, which would meet the city’s anticipated water needs for the next 20 years.

“Part of the grant is just to survey the system for structural and physical strengths,” said Alvis. “From that we will look into adding in warning devices or automatic valves for pressure zones that might be able to shut down more quickly than others.”

Because the city’s current master water plan is only 5 years old, further work on data is not necessary, Manny Ramos of Civil West Engineering Services, Inc., in Eagle Point, wrote to Alvis. The firm will complete the study and then update the master plan, which should be a simple process, he wrote.

The grant came from Business Oregon, the state agency that is administering funds available for Seismic Risk Assessment and Mitigation Plan studies that come from the U.S. Department of Agriculture. Jacksonville already has been awarded $20,000 for its study, because it had a newer master plan in place, Alvis said.

A major emphasis will be on resilience of elements in the system when a Cascadia Subduction Zone event occurs. The region has not experienced a Cascadia earthquake since 1700. On average a Cascadia quake of 8.0 magnitude or greater occurs about every 500 years.

The Oregon Resilience Plan requires the ability of water systems to maintain 20-psi pressure at crucial supply points following a quake, the ability to meet fire flow needs, 20 to 30 percent of capacity restored within a day, 50 to 60 percent within three days, and 80 to 90 percent within 7 to 14 days.

Talent and Phoenix are each seeking similar grants. Neither city has received notification of a grant award.

Talent is nearly finished with a new water master plan.

Phoenix Public Works Director Ray DiPasquale was scheduled to talk with a consultant about the town’s water master plan this week, City Manager Aaron Prunty reported. RH2 Engineering, Medford, is doing the master plan studies for both cities.

Talent has started the process of replacing a 1970s 1.5-million-gallon water tank in the Belmont Road area that has been identified by a seismic engineer as needing major structural repair or replacement. Work is nearly finished on a pipeline to a new reservoir site off Helms Road, said City Manager Sandra Spelliscy. Bids for the new tank will be sought sometime this spring.

Reach Ashland freelance writer Tony Boom at tboomwriter@gmail.com.

Jacksonville is about to launch a study of the seismic risks facing the city’s water system.