County to Shore up Trabuco Creek Bed

A second outside agency will soon undertake another major construction project in San Juan Capistrano.

Already, Caltrans has two projects in town, the bridge widening and off-ramp at San Juan Creek Road and Camino Capistrano – scheduled for completion by January or February of next year – and the , scheduled to begin construction just as the other project is wrapping up.

Now comes the Orange County Flood Control Division, which will start this summer to shore up Trabuco Creek and prevent future flooding, according to Phil Jones, manager of flood control design for the division.

Jones gave a presentation to the City Council this week to explain what the year-long project will entail.

Without the addition of sheet pile beneath the concrete channel, the creek bed is likely to dissolve “like wet Kleenex in the raging waters,” Jones said.

Currently, there’s nothing but earth beneath the concrete, he added. The sheet pile, which interlock, will be placed between 35 and 54 feet underground. Placement will vary to allow water to percolate to underground tables.

Jones shared a number of images from previous breaches in the creek. The may be most recent in memory, but the creek also failed in 1969, 1998 and 2005, causing damage and prompting evacuations, he said.

The section to be improved is between Del Obispo Street south to where Trabuco Creek joins San Juan Creek, Jones said.

Because homes line the west side of the creek, the county will employ a “press-in” method with a machine called a Giken Silent Piler to drive the sheet piles into the ground with a lot less noise and vibration, Jones said.

Workers on the east side of the creek, however, will employ the normal, noisier and less expensive methods of construction, he added.

Residents along the creek and employees who work nearby will hear noise and experience vibration, Project Design Engineer Hugo Pineda said, but for residents in the Mission Point tract and San Juan Mobile Home Estates, the impacts should be minimal.

Bike trails will temporarily close but will reopen fairly quickly, Pineda said. There will be no net loss of bike trails upon completion. Descanso Park, with the flood control division owns and leases rent-free to the city, will serve as the construction staging area.

The bike trail along San Juan Creek and the pedestrian bridge will also close, but reopen within two weeks to a month, he added.