SCH Number 2022110262

Project Info

Title

Chalk Mountain Road Over North Fork Cache Creek Bridge Replacement Project (Bridge No. 14C-0048)

Description

The existing bridge has a sufficiency rating of 26.7 and has been designated as structurally deficient per the Caltrans Structure Maintenance & Investigations, Local Agency Bridge List (February 2015). In its current condition, the foundations of the existing structure are unknown, the nearest structure Bridge No. 14C0051, Wolf Creek Road over Wolf Creek, was constructed in the same year, with the same engineer, and part of the same development. Flows in Wolf Creek in the spring of 1968 caused the Wolf Creek Road Bridge to settle some six inches. Similar substructure vulnerabilities may exist with the Chalk Mountain Road Bridge. In addition, the slope protection at Abutment 1 is undermined with pier 2 scour exposure at the top of footing. Caltrans has reviewed the preliminary details of the project and supports a full replacement scope. The purpose of the proposed project is to provide a replacement structure that is consistent with appropriate Caltrans structural design standards, is placed on a road alignment that meets the appropriate AASHTO roadway geometry standards, and is hydraulically capable of passing and clearing the design storm events (50-year storm plus 2 feet of freeboard and 100-year storm). The replacement bridge will be wider to comply with current AASHTO standards for local rural roads, including 9-foot travel lanes and 2-foot shoulders, plus crash-tested vehicular barriers. A Class 1 bike trail is also proposed. The replacement structure will be approximately 230 feet long. It is anticipated that deep foundations will be needed to support the replacement bridge. The underlying formation of the soil is rock overlaid by alluvial and fan deposits which have washed down from the mountains. The upper materials are subject to scour; this is often best suited for concrete piles, as they can be designed to act as columns if the soil material scours away. The most feasible pile type will be determined during the type selection process, when further geotechnical information is available. The proposed project also includes a separated (Class 1) multi use path in the design of the bridge deck width of the replacement bridge. The Class 1 train is needed to support the local non-motorized traffic from the adjacent Spring Valley Community Center, camping areas, and parks. The Class 1 Trail is also needed to be in compliance with the Cache Creek Coordinated Resources Management Plan (CRMP) for Zone B. Under the National Environment Policy Act (23 USC 326), a categorical exclusion was signed on July 20, 2020, by Caltrans for the proposed project. Per the California Code of Regulations, Title 14, Division 6, Article 5, an initial study has been prepared for this project.

2 documents in project