A stretch of the Centennial Trail in Pleasanton has reopened to the public after being temporarily closed for repairs to a damaged bank slide in a flood control channel overseen by the Zone 7 Water Agency.
The trail section between the entrance on West Las Positas Boulevard onto Arroyo Mocho and the bridge by Val Vista Park has been closed since mid-spring, but the U.S. Army Corps of Engineers (USACE) contractor hired for the project wrapped up work this month after several months of construction.
Local flood channels sustained approximately $14 million in damage during the winter storms of 2016-17 such as downed trees, toe erosion, channel bank slides and embankment washouts.
According to Zone 7 representatives, the damage was “so extensive that they have required three summer construction seasons of work and permitting to address.” Much of the damage happened along local creeks and flood channels in Zone 7’s western service area including along the Alamo Canal next to Interstate 680 near West Las Positas and South San Ramon Creek near Dublin High School.
The federal government included the service area immediately afterward in a major disaster declaration, and Zone 7 staff began coordinating with USACE as well as the Federal Emergency Management Agency and the California Office of Emergency Services to repair and rebuild damaged flood control sites. The sites were then assigned different priority levels and added to a monitoring program to ensure those most critically damaged were addressed first.
A total of 96 sites have been repaired since 2017 with another 25 sites up for evaluation and possible repair next year. Originally more than 200 sites with potential issues were identified but Zone 7 General Manager Valerie Pryor told the Weekly that some were less damaged than originally believed and said that could still be the case when inspectors revisit the remaining sites next year.
“Sometimes when you go back, a lot of times those smaller ones, they're not as bad as you thought they were,” Pryor said.
Work completed on the trail included excavating slipping soil, reinforcing and rebuilding the slope with more structurally sound soil than fill, anchoring to the slope and revegetating the area with native plant species.
The trail closure was “unavoidable” because “space on the access road is limited, with equipment and materials occupying its entire width” and “public safety is always a top priority.” Federal and state environmental regulations only allow construction in the channels between April 15 and Oct. 31, and unseasonal rains this spring cut the repair season even shorter.
Three more bank slides farther north are scheduled for repairs between August and October, including the Alamo Canal and South San Ramon Creek sites. The Arroyo Mocho Medeiros Parkway project, a flood protection and habitat restoration plan set along the Medeiros Reach of Arroyo Mocho, has been delayed.
“We were originally hoping to do construction this summer but it doesn’t look like we’ll be able to get all the permits,” Pryor said.
The total repair cost for the Centennial Trail is approximately $1.6 million; $900,000 was funded by USACE and $700,000 came from Zone 7, which funds its flood protection operations with a portion of the 1% property tax revenue.
For more information about Zone 7 flood projects and repairs including an interactive map, visit www.zone7.com.