DRAFT REPORT CONCEPTUAL ENGINEERING for REMOVAL of SUNOL and NILES DAMS Alameda County, California
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DRAFT REPORT CONCEPTUAL ENGINEERING FOR REMOVAL OF SUNOL AND NILES DAMS Alameda County, California Prepared for: San Francisco Public Utilities Commission 1155 Market Street, 7th Floor San Francisco, California 94103 July 2003 Project No. 6959.021 July 17, 2003 Project No. 6959.021 Ms. Barbara Palacios San Francisco Public Utilities Commission 1155 Market Street, 7th Floor San Francisco, California 94103 Subject: Draft Report – Conceptual Engineering For Removal of Sunol and Niles Dams Alameda County, California Dear Ms. Palacios: Geomatrix Consultants, Inc. (Geomatrix) and HDR Engineering, Inc. (HDR) are pleased to submit the enclosed revised draft report, which presents the findings of our geologic/geotechnical assessment and presents conceptual engineering recommendations for the removal of Sunol and Niles dams. The study, conducted by Geomatrix and HDR, involved reviewing available information, conducting site-specific field investigations, laboratory testing, and developing conceptual-level engineering recommendations for the removal of both dams. Our study also involved evaluating potential socioeconomic and community issues (performed by Mara Feeney & Associates), along with potential traffic impacts on the local communities (performed by CHS Consulting Group). This revised draft report incorporates the PUC’s comments from review of our first draft report, dated June 2, 2003. Geomatrix and HDR have appreciated this opportunity to work with you. Please contact the undersigned if you have any questions about this report. We will finalize the enclosed report upon receipt of the PUC’s written review comments. Sincerely yours, GEOMATRIX CONSULTANTS, INC. Faiz Makdisi, P.E. Todd Crampton, C.E.G. Principal Engineer Senior Geologist TAC \\sf3\deptdata\Project\6000s\6959.021\draft_report_02\.doc Enclosure TABLE OF CONTENTS Page EXECUTIVE SUMMARY...........................................................................................................1 1.0 INTRODUCTION.............................................................................................................2 1.1 PURPOSE AND SCOPE ...............................................................................................2 1.2 REPORT ORGANIZATION ..........................................................................................3 1.3 PROJECT TEAM AND ACKNOWLEDGEMENTS ............................................................3 2.0 ALAMEDA CREEK WATERSHED ...............................................................................4 2.1 PREVIOUS STUDIES..................................................................................................4 2.2 COMMUNITY ISSUES (PREPARED BY MARA FEENEY & ASSOCIATES)........................5 2.2.1 Local Parks and Wilderness Areas............................................................7 2.2.2 Community and Local Environmental Groups..........................................7 2.2.3 Other Groups .............................................................................................8 2.2.4 Roadwork Planned for Highway 84 in Sunol Area...................................9 2.2.5 Summary of Conversations .......................................................................9 2.2.6 Preferred Methods of Communication ....................................................10 2.2.7 Individuals Contacted..............................................................................10 2.3 GEOLOGY..............................................................................................................10 2.4 HISTORICAL MINING ACTIVITIES IN THE WATERSHED ............................................12 2.5 DREDGING ACTIVITES IN THE WATERSHED ............................................................13 2.6 CREEK FLOWS .......................................................................................................14 3.0 SUNOL DAM REMOVAL.............................................................................................16 3.1 DESCRIPTION OF DAM............................................................................................16 3.2 SITE INVESTIGATIONS ...........................................................................................17 3.2.1 Review of Aerial Photographs.................................................................17 3.2.2 Geologic Mapping...................................................................................18 3.2.3 Sediment Sampling..................................................................................19 3.2.4 Laboratory Testing ..................................................................................20 3.3 SEDIMENT MANAGEMENT .....................................................................................20 3.3.1 Sediment Volume Estimates....................................................................20 3.3.2 Removal Strategies..................................................................................21 3.4 PROPOSED CREEK DIVERSION AND DEWATERING SYSTEMS ...................................23 3.5 CONCEPTUAL DESIGN OF DEMOLITION PLAN .........................................................26 3.5.1 Extent of Dam Removal ..........................................................................26 3.5.2 Demolition Method .................................................................................27 3.5.2.1 Dam Removal..............................................................................28 3.5.2.2 Dewatering & Diversion System Installation..............................31 3.5.2.3 Sediment Removal.......................................................................31 3.5.3 Construction and Staging Access ............................................................32 3.5.3.1 Staging Areas...............................................................................32 3.5.3.2 Fuel Handling and Equipment Maintenance ...............................33 3.5.3.3 Temporary Power and Telephone Service ..................................33 L:\Project\6000s\6959.021\report\draft_report_v02.doc i TABLE OF CONTENTS (continued) 3.5.4 Traffic Impacts ........................................................................................33 3.5.5 Other Construction Issues........................................................................33 3.5.5.1 Site Access...................................................................................33 3.5.5.2 Work Adjacent to UPRR Main Line ...........................................33 3.5.5.3 Disposal Options .........................................................................34 3.6 COST ESTIMATES AND CONSTRUCTION SCHEDULE.................................................34 3.6.1 Cost Estimate...........................................................................................34 3.6.2 Construction Schedule.............................................................................35 3.7 RECOMMENDATIONS .............................................................................................36 4.0 NILES DAM REMOVAL...............................................................................................38 4.1 DESCRIPTION OF DAM............................................................................................38 4.2 SITE INVESTIGATIONS ...........................................................................................39 4.2.1 Review of Aerial Photographs.................................................................39 4.2.2 Geologic Mapping...................................................................................40 4.2.3 Sediment Sampling..................................................................................42 4.3 SEDIMENT MANAGEMENT .....................................................................................42 4.3.1 Sediment Volume Estimates....................................................................42 4.3.2 Removal Strategies..................................................................................43 4.4 PROPOSED CREEK DIVERSION AND DEWATERING SYSTEMS ...................................44 4.5 CONCEPTUAL DESIGN OF DEMOLITION PLAN .........................................................45 4.5.1 Extent of Dam Removal ..........................................................................45 4.5.2 Demolition Method .................................................................................46 4.5.2.1 Dam .............................................................................................46 4.5.2.2 Dewatering & Diversion System Installation..............................46 4.5.2.3 Sediment Removal.......................................................................47 4.5.3 Construction and Staging Access ............................................................47 4.5.3.1 Staging Areas...............................................................................47 4.5.3.2 Fuel Handling and Equipment Maintenance ...............................47 4.5.3.3 Temporary Power and Telephone Service ..................................48 4.5.4 Traffic Impacts ........................................................................................48 4.5.5 Other Construction Issues........................................................................48 4.5.5.1 Site Access...................................................................................48 4.5.5.2 Discussion of Access Alternatives ..............................................51 4.5.5.3 Disposal Options .........................................................................52