Introduction

The Plumas County Public Works Department is proposing to replace the structurally deficient one-lane bridge over Spanish Creek on County Road (CR) 422, which serves access to US Forest Service and private lands. The existing bridge was built in 1938 and is supported by abutments consisting of steel piles, steel panels and concrete panels. The bridge was originally used as the Rock Creek bridge before being moved to its present location in the mid 70's after the Rock Creek bridge was replaced with present concrete structure.  The California Department of Transportation (Caltrans) inspection report has classified the bridge as Structurally Deficient, with a sufficiency ration of 37.9, making it eligible for replacement with federal funding through the Federal Highway Administration’s Highway Bridge Program (HBP).

Project Location

The Snake Lake Road Bridge (9C-0148) is located approximately 6 miles west of Quincy on Bucks Lake Road at latitude 39.94 North and 121.04 West.  The bridge crosses over Spanish Creek a short distance downstream from the confluence with Wapaunsie Creek

Project History

Snake Lake Bridge over Spanish Creek is a single-lane, clear span steel pony truss with high abutment walls comprised of precast concrete panels with tieback anchors and was constructed in 1969. The County has obtained funding through the Federal Highway Bridge Program (HBP) to replace the bridge. Work is currently underway to determine the replacement bridge configuration.   

Need for the Project

The existing bridge was classified as structurally deficient by Caltrans as a result of their biannual inspection. The panels comprising the abutment wall were identified as having failed. The superstructure of the bridge was coded as being in a serious condition, indicating deterioration affecting primary structural components. The crossing is currently posted for a truck speed limit of 15 MPH. The bridge provides access to U.S. Forest Service and private lands east of the unincorporated community of Meadow Valley. The new bridge will enhance traffic safety and improve conditions in Spanish Creek by providing an increased flow area.

Proposed Replacement

The replacement bridge is proposed as a two-lane, single span structure 80 to 120 feet in length. The project will also include limited stream bank modification in order to improve in stream channel and reduce the potential for scour at the bridge site.

 

Special Considerations

As part of the project a temporary detour will be constructed to maintain access to lands north of Spanish Creek.

Project Consultants

MGE Engineering, Inc. of Sacramento is the prime consultant.

Sub-consultants:

 
AECOM – Environmental

Blackburn Consulting - Geotechnical

 

Steven C. Devin, Civil and Geotechnical Engineering Services – Hydrology and Hydraulics

 

BRG Engineering – Independent Design Check

 

Project Timetable
                                          

Report/Study/Analysis	Due Date
Preliminary Design	June 2012
Environmental Clearance	December 2012
Final Design	June 2013
Right of Way	June 2013
Advertise for Construction	February 2014
Construction	June through October 2014