Silverado Canyon Bridge (No. 55C-0177) Replacement Project

2 Documents in Project


SCH Number
Lead Agency
Orange County
Document Title
Silverado Canyon Bridge (No. 55C-0177) Replacement Project
Document Type
MND - Mitigated Negative Declaration
Present Land Use
The Land Use Designation at and near the proposed Project is Rural Residential with 0.025 – 0.5 Dwelling Units (DU) per acre and Suburban Residential with 0.5 – 18 DU per acre.
Document Description
Orange County Public Works, in cooperation with the California Department of Transportation (Caltrans), is proposing to replace the Silverado Canyon Road Bridge (Bridge No. 55C-0177) over Silverado Creek. The Silverado Canyon Road Bridge is located in Silverado Canyon surrounded by the Cleveland National Forest. The existing bridge is a single span and crosses over Silverado Creek. The proposed Project will replace the existing substandard steel bridge; a portion of the construction funding is provided by the Highway Bridge Program (HBP). The proposed replacement structure as of date is a single span prestressed, precast concrete voided slab girder bridge. The bridge will be raised approximately three feet to increase hydraulic conveyance. However, the bridge will only be able to pass the approximate 5-year storm event. Raising the bridge higher would greatly impact residents to the east of the bridge. The abutments, similar to the existing bridge, will be set on spread footing foundations. Bridge barriers will be side mounted open metal railing, Type ST-70SM. The replacement bridge will have 12-foot wide lanes and will include a 4-foot shoulder on the north side and 6-foot shoulder on the south side, for a minimum total barrier to barrier width of 34 feet. There are no nearby pedestrian facilities or future plans to place sidewalks along Silverado Canyon Road, but portions of Silverado Canyon Road have sufficient dirt shoulders to provide room for pedestrians. To keep with the rural setting, there will not be sidewalks on the bridge. Silverado Creek is an intermittent stream that flows west under the existing bridge. The narrow road and limited right of way requires the replacement structure be placed in the same location as the existing structure. There is no viable detour available. The bridge will be replaced utilizing staged construction with approximately ½ the bridge replaced in each stage. The existing 4 girder bridge allows half the bridge to be removed, supporting the remaining half on two girders. Contractor staging areas are limited. The contractor may stage on the closed portion of the existing road approaches. Additional staging locations may need to be utilized. Utilities include a waterline attached to the south side of the bridge and overhead telecommunication lines which cross the bridge diagonally. The overhead telecommunication lines will need to be relocated temporarily for construction. The waterline will need to be relocated to the new bridge. Typical equipment for roadway construction would include heavy construction earthmoving equipment, dump trucks and pavers. Typical bridge construction equipment would include cranes, excavators, rock hammers, generators, and concrete pumps.

Contact Information

Sam Tieu
Agency Name
Orange County Public Works
Job Title
PE | Civil Engineer
Contact Types
Lead/Public Agency


Cross Streets
Silverado Canyon Road and Oak Lane

Notice of Completion

State Review Period Start
State Review Period End
State Reviewing Agencies
California Air Resources Board (ARB), California Department of Conservation (DOC), California Department of Fish and Wildlife, South Coast Region 5 (CDFW), California Department of Forestry and Fire Protection (CAL FIRE), California Department of Parks and Recreation, California Department of Transportation, District 12 (DOT), California Department of Water Resources (DWR), California Native American Heritage Commission (NAHC), California Natural Resources Agency, California Regional Water Quality Control Board, Santa Ana Region 8 (RWQCB), California Transportation Commission (CATC), Department of Toxic Substances Control, Office of Historic Preservation, State Water Resources Control Board, Division of Drinking Water
Development Types
Transportation:Local Road (Bridge Replacement)
Local Actions
Bridge Replacement
Project Issues
Aesthetics, Agriculture and Forestry Resources, Air Quality, Biological Resources, Cultural Resources, Energy, Geology/Soils, Greenhouse Gas Emissions, Hazards & Hazardous Materials, Hydrology/Water Quality, Land Use/Planning, Mandatory Findings of Significance, Mineral Resources, Noise, Population/Housing, Public Services, Recreation, Transportation, Tribal Cultural Resources, Utilities/Service Systems, Wildfire
Local Review Period Start
Local Review Period End


Draft Environmental Document [Draft IS, NOI_NOA_Public notices, OPR Summary Form, Appx,]
Notice of Completion [NOC] Transmittal form

Disclaimer: The Governor’s Office of Planning and Research (OPR) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at or via phone at (916) 445-0613. For more information, please visit OPR’s Accessibility Site.

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