ALPINE ROAD TRAIL IMPROVEMENTS PROJECT Draft Initial Study/Mitigated Negative Declaration
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ALPINE ROAD TRAIL IMPROVEMENTS PROJECT Draft Initial Study/Mitigated Negative Declaration Prepared for August 2013 County of San Mateo Department of Public Works ALPINE ROAD TRAIL IMPROVEMENT PROJECT Draft Initial Study/Mitigated Negative Declaration Prepared for August 2013 County of San Mateo Department of Public Works 550 Kearny Street Suite 800 San Francisco, CA 94108 415.896.5900 www.esassoc.com Los Angeles Oakland Orlando Palm Springs Petaluma Portland Sacramento San Diego Santa Cruz Seattle Tampa Woodland Hills D120603.02 OUR COMMITMENT TO SUSTAINABILITY | ESA helps a variety of public and private sector clients plan and prepare for climate change and emerging regulations that limit GHG emissions. ESA is a registered assessor with the California Climate Action Registry, a Climate Leader, and founding reporter for the Climate Registry. ESA is also a corporate member of the U.S. Green Building Council and the Business Council on Climate Change (BC3). Internally, ESA has adopted a Sustainability Vision and Policy Statement and a plan to reduce waste and energy within our operations. This document was produced using recycled paper. Notice of Public Review and Intent to Adopt a Proposed Mitigated Negative Declaration Alpine Road Trail Improvements Project Pursuant to the State of California Public Resources Code and the "Guidelines for Implementation of the California Environmental Quality Act of 1970" as amended to date, this is to advise you that the County of San Mateo (County) has prepared a Draft Initial Study/Mitigated Negative Declaration (IS/MND) on the County’s Alpine Road Trail Improvements Project (proposed project). The County proposes to implement the Alpine Road Trail Improvements Project. The proposed project includes rehabilitation of an approximately 1.84-mile segment of the existing Alpine Road Trail and bank stabilization at three sites along the adjacent Los Trancos Creek. Activities are proposed to occur between the limits of the Town of Portola Valley and the City of Menlo Park in unincorporated San Mateo County. The Draft IS/MND describes the proposed project, analyzes whether the project would result in any potential significant environmental impacts, and describes measures that would mitigate any potential significant impacts to less than significant level, and determines that the project, which incorporates a number of mitigation measures, will not have a significant adverse effect on the environment. In addition, the Draft IS/MND is available online at http://www.co.sanmateo.ca.us/portal/site/parks/ under the “Park Planning” link. Public Comment Period - The period for accepting comments on the adequacy of the environmental document extends from August 16, 2013 to 5:00 P.M., September 15, 2013 . Any comments should be in writing and submitted to either the following address or email address below: Mailing address San Mateo County Public Works 555 County Center, 5th Floor Redwood City, CA 94063-1665 Attn: Karen E. Pachmayer, Principal Civil Engineer Email address [email protected] TABLE OF CONTENTS Alpine Road Trail Improvements Project Initial Study / Mitigated Negative Declaration Page 1. Project Description 1-1 1.1 Introduction 1-1 1.2 Project Background 1-1 1.3 Project Objectives 1-2 1.4 Proposed Project 1-2 1.5 Report Organization 1-12 1.6 Other Approvals 1-12 2. Environmental Checklist 2-1 Environmental Factors Potentially Affected 2-2 Environmental Checklist 2-3 2.1 Aesthetics 2-4 2.2 Agricultural and Forest Resources 2-8 2.3 Air Quality 2-10 2.4 Biological Resources 2-15 2.5 Cultural Resources 2-26 2.6 Geology and Soils 2-32 2.7 Climate Change 2-38 2.8 Hazards and Hazardous Materials 2-41 2.9 Hydrology and Water Quality 2-48 2.10 Land Use and Land Use Planning 2-54 2.11 Mineral Resources 2-57 2.12 Noise 2-58 2.13 Population and Housing 2-63 2.14 Public Services 2-64 2.15 Recreation 2-66 2.16 Transportation/Traffic 2-67 2.17 Utilities and Service Systems 2-75 2.18 Mandatory Findings of Significance 2-78 3. Summary of Mitigation Measures 3-1 Appendices A. Geotechnical Report A-1 B. Air Quality Emissions Estimates B-1 Alpine Road Trail Improvements i ESA / 120603.01 IS/MND August 2013 Table of Contents Page List of Figures 1. Project Location Map 1-3 2. Typical Cross-Section of Wood Railing and Retaining Walls 1-6 3. Typical Cross-Section Soldier Pile Wall with Precast Lagging Proposed at Site 2 1-7 4. Typical Cross-Section of Cast-in-Place Wall Proposed at Site 3 1-9 5. Photos of Alpine Road and Alpine Road Trail 2-5 List of Tables 1. Summary of Construction Requirements for the Proposed Project 1-10 2. Peak Day Unmitigated Construction-Related Pollutant Emissions 2-12 3. Focused List of Special-Status Species Considered for the Alpine Road Trail Improvement Project 2-16 4. Typical Construction Noise Levels 2-58 5. Typical Noise Levels from Demolition/Construction Equipment Operations 2-59 6. Vibration Velocities for Construction Equipment 2-60 7. Estimated Maximum Daily Vehicle Trips for Project Construction 2-68 Alpine Road Trail Improvements ii ESA / 120603.01 IS/MND August 2013 SECTION 1 Project Description 1.1 Introduction San Mateo County (County) proposes to implement the Alpine Road Trail Improvements Project (proposed project) within unincorporated San Mateo County, California. The proposed project includes rehabilitation of an approximately 1.84-mile segment of the Lower Alpine Road Trail and bank stabilization at three sites along the adjacent Los Trancos Creek. Activities are proposed to occur between the limits of the Town of Portola Valley and the City of Menlo Park. This document is an Initial Study/Mitigated Negative Declaration (IS/MND) that analyzes the potential environmental impacts of the trail rehabilitation work and bank stabilization work. This IS/MND is prepared in compliance with Public Resources Code Section 21000 et seq., California Environmental Quality Act (CEQA) of 1970 (as amended), and Title 14, Chapter 3 of the California Administrative Code. In accordance with the CEQA Guidelines, California Code of Regulations Title 14, Chapter 3, Section 15070, a Mitigated Negative Declaration shall be prepared if the following criteria are met: There is no substantial evidence that the project may have a significant effect; or Where there may be a potentially significant effect, revisions to the project would avoid or mitigate the effects to a point where clearly no significant effects would occur. In accordance with Section 15073 of the CEQA Guidelines, this document is being circulated to local, state and federal agencies and to interested organizations and individuals who may wish to review and comment on the report. Written comments may be forwarded to: Karen E. Pachmayer, Principal Civil Engineer County of San Mateo, Department of Public Works 555 County Center, 5th Floor Redwood City, CA 94063-1665 Alpine Road Trail Improvements 1-1 ESA / 120603.01 IS/MND August 2013 1. Project Description 1.2 Project Background Introduction and Background The Lower Alpine Road Trail is a multi-use trail that extends from Santa Cruz Avenue at Junipero Serra Boulevard in Menlo Park to Alpine Road at Portola Road in Portola Valley. In 2011, the Town of Portola Valley renovated and realigned sections of an approximately 5,500-foot segment of the trail and performed creek bank stabilization along Los Trancos Creek banks from the Town’s northern border within unincorporated San Mateo County to Arastradero Road, just south of the proposed project site. The proposed project would consist of trail rehabilitation work on the adjacent segment to the north, where the existing pavement is in need of rehabilitation and where in some areas the uprooting of tree roots have degraded the trail surface. The project would also stabilize Los Trancos Creek banks at three locations where bank failures have narrowed or threaten to narrow the trail and affect the adjacent roadway and critical utilities (i.e., Pacific Gas and Electric [PG&E] gas main sanitary sewer main, and water main) a few feet away. 1.3 Project Objectives The main objectives of the proposed project are to rehabilitate the segment of the Alpine Road Trail within unincorporated San Mateo County, stabilize the bank along the trail and Los Trancos Creek at three identified locations to prevent further erosion and trail narrowing, protect adjacent critical utilities as well as Alpine Road, and improve the trail surface for trail users. 1.4 Proposed Project 1.4.1 Project Location The County’s proposed trail rehabilitation work would occur along a 1.84-mile stretch of the existing Alpine Road Trail. The trail rehabilitation work would extend from the northern limits of the Town of Portola Valley (approximately 1,000 feet south of the Alpine Road and La Mesa Drive intersection) to the southern limits of City of Menlo Park, just south of the Alpine Road and Rural Lane intersection. The existing asphalt Alpine Road Trail roughly parallels the northbound side of Alpine Road. As shown in Figure 1, the trail segment south of Interstate 280 (I-280) is immediately adjacent to Los Trancos Creek. North of bank stabilization Site 3, the trail diverges from the creek and parallels Alpine Road to the north. Alpine Road Trail Improvements 1-2 ESA / 120603.01 IS/MND August 2013 Stanford University Golf Course S R A CITY OF MENLO PARK U N R T A SAND HILL RD A A L SAN MATEO CO L C L N L A A R R A A C C O STOWE LN O 280 VALLEJO NOVATO ALPINE RD SAN CONCORD RAFAEL RICHMOND WALNUT BERKELEY CREEK OAKLAND 680 SAN ALAMEDA SAN FRANCISCO RAMON 580 DALY CITY HAYWARD Pacific Ocean ncisquit 280 ra o C FREMONT F reek SAN an MATEO 880 S REDWOOD CITY MOUNTAIN 101 VIEW Project Site 280 SAN JOSE UES A C T L A D R L L o o ALPINE RD s s T r a n R c LA D o M SA s E C r r e e e e k k LIMIT OF PROPOSED ALPINE ROAD TRAIL IMPROVEMENTS LOCATION OF PROPOSED BANK STABILIZATION WORK ALONG LOS TRANCOS CREEK S SAN MATEO CO A N TA C TOWN OF PORTOLA VALLEY L A R A A 0 1000 C C O O Feet Alpine Road .