Sandia Creek Drive Bridge Replacement and Fish Passage Project

PDS2020-LDGRMJ-30309; PDS2020-LDPIIP-60093; Log No. PDS2021-ER-21-02-005

The project consists of the removal and replacement of an aging low-flow and flood-prone concrete box culvert river crossing over the Santa Margarita River on Sandia Creek Drive. The box culvert crossing, which has created a significant fish passage barrier on the Santa Margarita River, will be removed following construction of a new steel and concrete span bridge. The new bridge will span the river (574 feet in length), with an abutment including wing walls at either end of the bridge and two piers in between. Thus, the bridge will have three sections, the first section of which will span 214 feet (over the main Santa Margarita River channel), and each of the two remaining sections will span 176 feet. The bridge will provide two paved traffic lanes (12 feet wide) with two shoulders (8 feet wide) within a 68-foot-wide road right-of-way. The road surface of the bridge will range in elevation from just over 354 feet above mean sea level (amsl) at the northern abutment to just over 359 feet near the center of the bridge. In comparison, the ordinary high-water elevation of the river is 331 feet amsl, while the 100-year water surface elevation is just over 346 feet amsl. The new bridge is designed to pass the 100-year peak discharge with one foot of freeboard pursuant to the San Diego County Hydraulic Design Manual. The new bridge will be constructed about 160 feet downstream of the existing box culvert crossing. The existing box culvert crossing on Sandia Creek Drive will remain open to traffic during construction of the new steel bridge. Construction of this span bridge and removal of the existing crossing will occur over a period of approximately two years. A temporary trail approximately eight feet in width and 600 feet in length will be constructed south of and above Sandia Creek Drive between the south end of the construction zone at Sandia Creek Drive and the existing parking lot for the Santa Margarita Trail Preserve to maintain trail access around the site and to trails upstream and downstream of the project site.

The project is located approximately two miles north of the village area of Fallbrook, 160 feet southwest of the intersection of Rock Mountain Drive and Sandia Creek Drive where Sandia Creek Drive crosses the Santa Margarita River (APN 102-250-24-00) in the Fallbrook Community Planning Area of unincorporated San Diego County, California.

Please direct any questions or formal comments to the project contact below.

Project Contact: Rob Hingtgen | Robert.Hingtgen@sdcounty.ca.gov | (619) 323-8701