San Dieguito River Bridge to be replaced

San Dieguito River Bridge to be replaced
Plans are in the works to replace the San Dieguito River Bridge, but the two-year construction project won’t start until at least 2020. Although the 85-year-old structure is deteriorating and cracking, it has been deemed safe. Photo by Bianca Kaplanek

DEL MAR — Deemed deficient but safe, the 85-year-old bridge that spans the San Dieguito River at dog beach will be replaced, but work probably won’t begin for about three years and is expected to take two years to complete.

To get the project started, council members at the April 17 meeting approved a $1.2 million contract with Kleinfelder Inc. for preliminary engineering work and environmental documentation, a process that is expected to take at least two years, City Engineer Tim Thiele said.

Councilman Dave Druker pulled the item from the consent calendar, which is approved without discussion, to ensure residents they aren’t footing the entire bill.

“To the casual observer it says we’re spending $1.2 million on this,” Druker said. “This really is not coming out of our capital budget. I wanted to make sure people understood that we are spending 11 percent of this, or something like that.”

City Manager Scott Huth said the city will spend about $160,000, or 11.4 percent, for the preliminary work.

“The concept here is that we are going to … redo the bridge,” Druker said. “It’s going to be a long process.

“I just don’t want people to read this and say, ‘Oh, here goes the city spending $1 million on a bridge replacement.’ That isn’t the truth,” he added.

The bridge was built in 1932, widened in 1952 and upgraded in 2000. At that time it was not considered structurally deficient. But in 2006 the sufficiency rating began to decline and in 2010 it was considered deficient mostly because the superstructure is deteriorating.

The reinforced steel is corroding and causing cracks, primarily under the exterior girders that are part of the widened structure and on the tops of braces that span between beams.

A study completed by Kleinfelder in 2012 confirmed the deterioration and identified “several additional items that require corrective action,” the staff report states. The problems include “collapse vulnerability” during a “seismic event.”

“But it would have to be a sizeable earthquake,” Thiele said.

That report concluded it would be more cost effective to replace rather than repair the bridge. The project will be completed one lane at a time to avoid a complete shutdown of the roadway.

“Once we start it will be under construction for about two years because it would increase the cost to start and stop to avoid work during the summer,” Thiele said.

On the plus side, he said, there will be half as many piers in the water — five rather than the existing 10 — so water will flow better under the bridge.

Thiele said public outreach will be conducted so residents can provide input on the design. He said he expects the new bridge to be similar to the existing structure but with a slimmer profile when looking at it while standing on the beach.

Traffic and bike lanes should remain about the same width.

The total project cost is estimated to be $22 million. Federal funding will provide about $19.5 million. The rest will be paid with local matching funds.

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