Caltrans / Orange County Water Quality Report of Ladd Canyon Bridge


Project Overview

EWC prepared the Water Quality Assessment Report (WQAR) for the bridge replacement project to fulfill the requirements of the National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA) as well as provide information for the National Pollution Discharge Elimination System (NPDES) permitting.



Project Elements

Based on the findings of an in-depth inspection of the Ladd Creek Bridge conducted by the County with Caltrans, the existing bridge for Silverado Canyon Road was classified as “Structurally Deficient.” The project was designed to remove the existing Ladd Canyon Bridge and replace with a new bridge. The elements of the project included:

  • Grading within the vicinity of the bridge in order to tie into the existing slopes and provide drainage improvements where feasible.
  • Use of a pre-cast concrete bridge that provides an expansion from the existing bridge width to provide safe conditions for vehicular traffic and pedestrian access.
  • Keeping portions of the two-lane bridge open during demolition and construction to provide continued vehicular access along Silverado Canyon Road.


Services Provided

  • Coordinated with the project designer to understand the project construction process and project design elements on-site and in the project vicinity.
  • Conducted research on the existing conditions within the local and regional setting, including hydrology and water quality, biological resources, cultural resources, geology and soils, land uses, recreational opportunities, transportation facilities, and visual aesthetics.
  • Defined the regulatory requirements for the project, specifically related to hydrology and water quality.
  • Analyzed the potential effects of the project on the existing conditions with an emphasis on the potential impacts to hydrology and water quality in the project vicinity and the receiving waters.
  • Developed mechanical and operational Best Management Practices (BMPs) that addressed construction activities and the long-term physical changes that would occur with implementation of the project.


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