Rancho Mission Viejo
Geotechnical Project of the Year, Structural Engineering Project of the Year
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Cow Camp Road Design – Phases 1A & 1B

Project Location:

Unincorporated South Orange County, California

Project Description:

Cow Camp Road is a new roadway project located east of San Juan Capistrano in an unincorporated area of Orange County. The project is needed for future development of the Rancho Mission Viejo property, which is currently being used for agricultural purposes. Overall entitlement of the Ranch includes up to 14,000 homes and 5.2 million square feet of non-residential uses over approximately 6,000 acres.

The goal of this project is to provide a vital east–west link between Antonio Parkway and Ortega Highway with sufficient roadway capacity to accommodate all traffic demands, including a Regional Bikeway, and to provide necessary utilities for all Phases of the proposed development.

Phases 1A and 1B of Cow Camp Road included a 7,000 ft. long, 4-lane long roadway with four controlled intersections, and a 1400 ft. long bridge over Chiquita Canyon. The project was completed on an accelerated schedule and took advantage of a favorable economic climate to deliver a very complicated bridge at a very reasonable price. A future “twin-bridge” has been designed and is “shelf ready” for construction when development demands require the increased capacity of Cow Camp Road from 4 lanes to 6 lanes.

Project Justification:

Given the multi-faceted and complex challenges facing the design and implementation of Cow Camp Road, particularly in this phase, the collaboration and innovation of our collective team members was crucial in developing innovating solutions. The multi-disciplined team of Michael Baker International worked very closely with the Rancho Mission Viejo (RMV) Team to gain concurrence with the numerous public agencies involved while addressing the challenges of providing all infrastructure needs. The hillside terrain provides a unique environment, but had to address unique engineering challenges from a grading, drainage, geotechnical, and backbone infrastructure perspective. The 1400 ft. long bridge design over Chiquita Canyon provides an elegant thoroughfare and unique driving experience with context sensitive wooden railings open to views of the beautiful natural canyon surroundings. Columns ranged in clear height from 40 ft. to 70 ft. with 10 ft. diameter drilled shaft foundations ranging in depth from 40 ft. to 90 ft.

Special Circumstances:

Design of this bridge and roadway had many unique engineering challenges. Our team’s solutions to those challenges are described in further detail below.

Flooding, High Ground Water, and Scour | Chiquita Canyon is a major drainage area that is subjected to major flood flows and potential scour of bridge foundations in this deep canyon – This threat was mitigated with deep large diameter drilled shaft foundations within the canyon that accommodate scour depths of 20 ft. This foundation type was selected to mitigate scour effects while minimizing excavation associated with deep pile supported foundations beneath the expected ground water elevations – making bridge construction more economical. This design approach was a direct result of “lessons learned” from construction difficulties associated with other nearby bridges.

Local Seismicity and Geotechnical Concerns | The unique geotechnical conditions included high seismicity, lateral soil spreading, liquefaction, and high ground water. Michael Baker International and GMU Geotechnical Engineering worked together to address these issues by coordinating with Caltrans, County of Orange, and TCA to address the latest known seismic design data at the site. We also implemented the most recent seismic design criteria associated with all approved structural loading combinations. This collaboration with highest level experts resulted in a state of the art design using the most current Seismic Design Criteria (SDC) available and acceptable among numerous agencies.

Utilities and use of 3D Modeling | Backbone utilities included water, sewer, power, and communication throughout the roadway alignment including those that were supported by the bridge. Due to the length of the bridge, a hinge within the bridge was required. Additionally, there were special considerations given to the significant bridge lateral movement from seismic loads. To protect the utilities, detailing required allowances for pipe movement, requiring 3D modeling to show details of how the utilities clear the closely placed reinforcing steel. This led to a coordinated effort with the Contractor to accurately place utilities within the bridge.

Three dimensional (3D) modeling of all utilities throughout the site was conducted so that accurate locations of all utilities were coordinated – allowing for future connections while minimizing costs associated with potential conflicts. Further, design of the project gave special consideration to the existing water line in Chiquita Canyon to provided adequate clearance of bridge foundations and maintenance access roads to the canyon from the roadway.

The project also incorporated extensive hydrology and hydraulic engineering to design a storm drain system, with the main outfall being a 102-inch diameter pipe with a jack and bore segment under the existing 66-inch diameter South County Pipeline.

Phasing Improvements | The multi-year phasing associated with the community development plans was closely coordinated with the RMV Team. Building the infrastructure including roads, utilities, and the future “twin-bridge” crossing Chiquita Canyon was carefully planned among the planning and engineering team members. Careful coordination among design team and utility providers was initiated early to ensure the improvements in the first phases (1A and 1B) allowed for future phases of development.

Environmental Planning and Implementation | From the early design stages, special attention was given to the environmental compliance issues, which included storm water capture and filtration using the most current methods of Best Management Practice by implementing BMPs in final design plans for the regional and local drainage areas. Careful attention was given to the construction in Chiquita Canyon during the construction of the bridge including wildlife monitoring, as well as treating groundwater associated with deep shaft foundation excavations. 

Resiliency | The engineering challenges associated with this project were met to provide a safe structure in an area that has a high potential to experience flooding and earthquake events. It meets the most stringent design requirements of the statewide Caltrans bridge specifications that provides for Non-collapse at high level earthquake. In addition, the design satisfied additional design requirements of the Transportation Corridor Agencies (TCA) that requires the bridge to remain elastic (no-structural damage) so that the bridge is completely operational after a lower level earthquake to provide access to the nearby local highway system. This approach of Performance Based Design incorporated a higher level of design requirements to ensure the bridge will remain functional and allow for transportation access to nearby residents after a seismic event.

Multi- Agency Coordination and Cooperation | Success of this project started with “early and often” meetings with the affected stakeholders and agencies that had jurisdiction of project approval. Those agencies included the County of Orange, TCA, Department of Fish and Wildlife, US Army Corps of Engineers, and State of California Regional Water Quality Control Board.

Construction and Engineering Teaming | The success of this Project culminated with the construction of all improvements on-time within an expedited delivery of 18 months and within the anticipated budget.  Significant cost savings were realized as a result of close coordination with the Ranch staff, Engineering Consultants, and Construction Team during construction. The Team placed an emphasis on close coordination during construction with frequent team meetings on site, expedited review of submittals, and discussions with the County of Orange for final approvals. Significant project cost savings occurred during placement of deep drilled shaft foundations and the expedited reviews during the superstructure construction of the bridge and roadway improvements.

Project Attachments:

None at this time.

Award Citation::

Cow Camp Road is a vital east-west arterial critical to the development of Rancho Mission Viejo’s overall Ranch Plan in South Orange County. It is a major regional and local infrastructure link for traffic movements. Phase 1 included a new 7,000 ft. long roadway with four controlled intersections and a 1,400 ft. long, 8-span twin-bridge structure over Chiquita Canyon.

Suggested Award Summary:

Cow Camp Road is a vital east-west arterial critical to the development of Rancho Mission Viejo’s overall Ranch Plan located in South Orange County. It is a major infrastructure link for both regional traffic movements as well as locally into the current and future Planning Areas within the Ranch.  Phases 1A and 1B are the first of Cow Camp Road, and included a new 7,000 ft. long roadway with four controlled intersections. The project also incorporated a major twin-bridge structure over Chiquita Canyon with significant geotechnical features, utility and access road envelopes, and seismic considerations. The bridge is a 1,400 ft. long, 8-span structure that faced numerous design challenges and site constraints.  Columns ranged in clear height from 40 ft. to 70 ft. with 10 ft. diameter drilled shaft foundations ranging in depth from 40 ft. to 90 ft. Michael Baker International coordinated with TCA, County of Orange, and Rancho Mission Viejo for all approvals and permits. Phases 1A and 1B were successfully completed in 2015.

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