To: Board of Supervisors
From: John Kopchik, Director, Conservation and Development
Report Title: Authorization to construct retaining wall/culvert retrofits within a restricted development area on the property located at 1545 in the unincorporated Lafayette area.
☒Recommendation of the County Administrator ☐ Recommendation of Board Committee
RECOMMENDATIONS:
1. ACKNOWLEDGE that the Zoning Administrator adopted the Mitigated Negative Declaration and Mitigation Monitoring and Reporting Plan for the Project, and FIND that the preparation of an EIR is not required.
2. APPROVE and AUTHORIZE, under the terms of the attached grant deed of development rights held by the County, Rich Francis of The Olympus Group, Inc. on behalf of VTR Countrywood LP, to conduct site improvements, including grading and construction of a retrofit of two existing, failing retaining walls and a culvert forming a bridge structure on Assessor's Parcel No. 169-090-002, located at 1545 Pleasant Hill Road in unincorporated Lafayette, in accordance with Development Plan permit CDDP20-03005.
FISCAL IMPACT:
There is no fiscal impact. The applicant has paid the necessary application deposit and is obligated to pay supplemental fees to recover any and all additional costs associate with the application process.
BACKGROUND:
The proposed grading and construction of retrofits to two failing retaining wall structures and a culvert forming a bridge structure will be located on Assessor’s Parcel No. (APN) 169-090-002, located at 1545 Pleasant Hill Road in the unincorporated Lafayette area of the County. Pursuant to the Conditions of Approval (COA) of Development Plan CDDP85-03050 (COA #12-L), the development rights over the natural watercourse and scenic ravine traversing the property have been dedicated to the County of Contra Costa, a governmental subdivision of the State of California, necessitating the Board to authorize improvement on this property.
A congregate care facility was constructed in 2003 on the subject property and is currently in operation as the Atria Park of Lafayette assisted living facility. Public and employee access to the facility is via a two-lane, approximately 250-foot-long driveway from Pleasant Hill Road near the intersection of Taylor Boulevard. The driveway is supported by two block-type retaining walls forming a bridge across a ravine. An ephemeral, seasonal stream flows through an open-bed, arch culvert constructed within the bridge structure. Based on the geotechnical reports prepared for the project and on staff site visits, there is evidence of differential displacement of the retaining walls which is causing the bridge to sink, and in turn causing major roadway rutting and potholing. In addition, due to multiple and significant rainfall events in the 2022/23 winter season, heavier than normal creek flows through the channel caused scouring and significant erosion of the open culvert bed. Thus, there is a potential for the culvert footings to be undermined in such a way that they could collapse and cause additional damage to the bridge structure and roadway above.
On February 21, 2020, Rich Francis of The Olympus Group, Inc. submitted a Development Plan modification application (CDDP20-03005), and on October 17, 2023, submitted revised drawings, to allow a non-substantial modification to County File #CDDP88-03007 for the construction within the area grant deeded to the County of the subject parcel of a retrofit of two existing retaining walls ranging from approximately 2 feet to approximately 29 feet in height and the retrofit of the existing culvert that together form a bridge for the primary driveway from Pleasant Hill Road to the existing assisted living facility. The application also includes a Tree Permit to allow the removal of ten code-protected trees and to allow work within the driplines of seven code-protected trees, also within the area grant deeded to the County of the subject parcel.
The matter was heard by the County Zoning Administrator on October 21, 2024, during which testimony was accepted from the applicant and members of the public. Based on the accepted testimony and project analysis provided by County staff, the County Zoning Administrator approved the Development Plan permit with modifications to conditions of approval (COA) including new conditions related to the use of Diablo View Road, a publicly maintained road, as a detour of regular operational and emergency vehicles during construction of the retaining wall/bridge retrofits, signage to be posted during construction, notification of all property owners and occupants of Diablo View Road and of dead-end streets that connect to Diablo View Road of the bridge closure, pavement surveys/analysis of the detour route, and roadway repairs of the detour route if needed after construction is completed. The modified conditions (COA #10, #45, #48, #49, and #59) and new conditions (COA #60 to #63) have been incorporated in the conditions of approval as directed by the County Zoning Administrator. Therefore, staff recommends the Board of Supervisors authorize the site improvements and to allow the retrofit of the two failing retaining walls and culvert (bridge) structure and the removal or alteration of code-protected trees located at APN: 169-090-002, where the development rights have been granted to the County.
CONSEQUENCE OF NEGATIVE ACTION:
If not approved, COA #6 of Development Plan permit, County File CDDP20-03005, will not be satisfied and building permits for the retaining walls would not be issued. Therefore, if not approved, the applicant will not be able to construct retrofits to the failing retaining walls and culvert forming a bridge structure as needed for the property identified as 1545 Pleasant Hill Road in the unincorporated Lafayette area.