La Pata Avenue Gap Closure

The project was awarded Project of the Year by the Orange County branch of the American Society of Civil Engineers, earned the No. 2 award in Roads & Bridges magazine’s Top 10 Roads list, and was awarded the Design Quality Partner Award by the Southern California Chapter of the Construction Management Association.

Project Highlights:

  • Geotechnical Engineering
  • Mass Grading
  • Removal of Landslides
  • Instrumentation and Remote Sensing
  • 1.8 Miles of Roadway Widening
  • 2 Miles of New Roadway
  • 2 New Bridges

Ninyo & Moore provided geotechnical consulting services during construction of the La Pata Avenue Gap Closure and Camino Del Rio Extension Project, which involved widening 1.8 miles of La Pata Avenue in San Juan Capistrano, constructing 2 miles of new roadway to connect La Pata Avenue to Avenida La Pata in San Clemente, connecting Avenida La Pata to Camino Del Rio via 0.4 mile of new roadway, and constructing two bridges and two long-span structural plate steel undercrossings. Our services included observation and compaction testing during 12 million cubic yards of mass grading that involved removal of landslides and construction of buttresses. We performed geologic mapping of remedial grading bottoms and temporary backcuts for buttresses, observed canyon subdrain and buttress backdrain construction, performed in-grading exploratory borings to evaluate removal of landslide deposits, and prepared geologic cross sections for slope stability analyses to evaluate adequacy of buttresses and preparation of revised buttress configurations. We also performed settlement analyses of deep fill, and prepared geotechnical field memoranda and as-graded reports. We also implemented a slope monitoring plan to observe the stability of temporary remedial grading cuts adjacent to SDG&E and SCE transmission lines. The plan included the design and installation of thirteen continuously monitored in-place inclinometer and tilt meter systems that were solar powered and transmitted data via cellular modem to a web-based monitoring service. The plan established automatic alert levels based on ground or tower/pole movement and recommendations for actions. Our services included review and maintenance of the monitoring system and implementation of actions following automatic alarms.

Project Details


County of Orange Public Works c/o Hill International


Orange County, California

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