Interlake Tunnel WRA Board Workshop August 25, 2014 1
Agenda Introduction Project Description Background Concept of tunnel operations Engineering and analysis performed to date Preliminary modeling results Permitting approach Preliminary environmental impacts Preliminary biological impacts Project development schedule and budget 3 month look ahead Questions from Board and Public 2
Introduction EPC Consultants, Inc Program and Construction Management (PM/CM) firm Based in San Francisco 26 years in business Specialty is management of public infrastructure projects: Tunnels and underground construction ($7 Bil, 70 miles of tunnels) Water and wastewater Airports Rail Transit California clients include: San Francisco PUC San Francisco MTA Central Subway Los Angeles MTA Regional Connector Program Manager Ron Drake, PE 38 years experience Registered professional civil engineer in CA 3
Interlake Tunnel Introduction Lake San Antonio Monterey County San Luis Obispo County ~ 12,000 of 10 diameter concrete lined, gravity flow tunnel Proposed tunnel alignment
Tunnel alignment concept San Antonio portal San Antonio dam spillway Monterey County San Luis Obispo County Nacimiento portal spillway Nacimiento dam
Interlake Tunnel Project Benefits Adds additional water storage in Lake San Antonio collected during wet years and available to release in dry years. Provides additional flood control measures for the Nacimiento and Salinas Rivers. Maintains a higher, longer term, lake level for recreational use in both Lake Nacimiento and Lake San Antonio. Negligible impacts from tunnel construction and operations.
Background 7
1991 tunnel studies 8
Concept of tunnel operations Nacimiento Reservoir Receives About Three Times More Inflow Than San Antonio Reservoir 9
Interlake Tunnel Transfers Water to San Antonio Reservoir Capturing Additional Water Otherwise Lost to Flood Control Releases Reducing Flood Control Releases from Nacimiento Reservoir Interlake Tunnel Captured additional water 10
Portals and tunnel profile (conceptual) Ground surface Tunnel Nacimiento portal San Antonio portal Portal Elevation (TBD) Spillway elevation ~ 800 Portal Elevation (TBD) Spillway elevation ~ 780
Engineering analysis performed to date Collection of information and data Preliminary feasibility assessment and data analysis Initial reservoir simulation modeling and tunnel concepts testing Identification of environmental permitting requirements Refinement of data Baseline reservoir modeling 12
Preliminary reservoir modeling ECORP Consulting, Inc 13
Modeled 47 year history 14 0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 A c r e F e e t Total releases Nacimiento San Antonio
47 year water year history Wet 15 Normal 19 Dry 13 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Wet Normal Dry 15
1000 Normal year hydrograph Project Operations 400,000 900 800 700 350,000 300,000 Flow, cfs 600 500 400 300 200 100 250,000 200,000 150,000 100,000 50,000 Storage, Acre Feet 0 0 Nacimiento Release Nacimiento Spillway San Antonio Release San Antonio Spillway Combined Release Release Target Tunnel Flow Nacimiento Storage Nacimiento Max Storage San Antonio Storage San Antonio Max Storage 16
1000 Wet year hydrograph Project Operations 400,000 900 800 700 350,000 300,000 Flow, cfs 600 500 400 300 200 100 250,000 200,000 150,000 100,000 50,000 Storage, Acre Feet 0 0 Nacimiento Release Nacimiento Spillway San Antonio Release San Antonio Spillway Combined Release Release Target Tunnel Flow Nacimiento Storage Nacimiento Max Storage San Antonio Storage San Antonio Max Storage 17
Dry year hydrograph 1000 Project Operations 400,000 Flow, cfs 900 800 700 600 500 400 300 200 100 0 350,000 300,000 250,000 200,000 150,000 100,000 50,000 0 Storage, Acre Feet Nacimiento Release Nacimiento Spillway San Antonio Release San Antonio Spillway Combined Release Release Target Tunnel Flow Nacimiento Storage Nacimiento Max Storage San Antonio Storage San Antonio Max Storage 18
600,000 500,000 400,000 300,000 200,000 100,000 Flood releases Flood Spill Releases 14 Years with Reservoir Spill Events over 47 year Period of Record Average Annual Spill Approximately 43,173 Acre Feet 0 Annual Acre Feet 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Nacimiento San Antonio 19
Baseline model results Average Annual Spills, AF Baseline Total, both reservoirs 43,173 Naciamento 40,038 San Antonio 3,135 Years of spill 14 20
4000 3500 3000 2500 2000 1500 1000 500 0 Potential Flows Available for Transfer Tunnel Flow CFS Tunnel hydraulics 12,000 10 Tunnel maximum flow capacity = 1,500 CFS 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 21 Cubic Feet per Second
500,000 450,000 400,000 350,000 300,000 250,000 200,000 150,000 100,000 50,000 Interlake Tunnel Will Reduce Number of Flood Events Flood releases with unconstrained tunnel 7 Years with Reservoir Spill Events with tunnel 50% Reduction in Number of Reservoir Spill Events Average Annual Spill Approximately 35,550 Acre Feet 0 Acre Feet 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Nacmientoi Flood Release San Antonio Flood Release 22
150,000 Interlake Tunnel Annual Benefits, study period 1967 2013, with unconstrained tunnel 130,000 110,000 Water Year Volume, AF 90,000 70,000 50,000 30,000 10,000 10,000 30,000 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 50,000 Reduction in Spills Increase in SRDF Deliveries 11 years with reduction in flood spills 8 years with increased SRDF deliveries Tunnel Avg Annual Spills, AF Benefits Total, both reservoirs 7,624 Naciamento 14,644 San Antonio 7,021 Years of spill 7 Average Downstream Deliveries, AF Deliveries, All Years 5,548 Dry 14,570 Normal 3,462 23 Wet 0
Summary Baseline unconstrained tunnel Difference Average Annual Spills, AF Total, both reservoirs 43,173 35,550 7,624 Naciamento 40,038 25,393 14,644 San Antonio 3,135 10,156 7,021 Years of spill 14 7 7 Average Downstream Deliveries, AF Deliveries, All Years 205,725 211,273 5,548 Dry 164,822 179,392 14,570 Normal 224,483 227,945 3,462 Wet 218,250 218,250 0 24
1000 1995 example Project Operations 400,000 900 800 700 350,000 300,000 Flow, cfs 600 500 400 300 200 100 250,000 200,000 150,000 100,000 50,000 Storage, Acre Feet 0 0 Nacimiento Release Nacimiento Spillway San Antonio Release San Antonio Spillway Combined Release Release Target Tunnel Flow Nacimiento Storage Nacimiento Max Storage San Antonio Storage San Antonio Max Storage 25
1000 1995 with tunnel Project Operations 400,000 900 800 700 350,000 300,000 Flow, cfs 600 500 400 300 200 100 250,000 200,000 150,000 100,000 50,000 Storage, Acre Feet 0 0 Nacimiento Release Nacimiento Spillway San Antonio Release San Antonio Spillway Combined Release Release Target Tunnel Flow Nacimiento Storage Nacimiento Max Storage San Antonio Storage San Antonio Max Storage 26
Next steps engineering / modeling Hydraulic engineering analysis of tunnel options Iterative modeling scenarios to optimize reservoir operations and determine sweet spot for tunnel location, elevation, and diameter Preliminary engineering and development of project description 27
Permitting approach Land Use permit application with Monterey County as lead agency. Mitigated Negative Declaration under CEQA rules. (Federal nexus TBD)
Preliminary environmental impacts Surface impacts: minimal grading at portal sites, intake structure at Lake Nacimiento, and headwall tunnel portal structure at Lake San Antonio. Tunnel muck disposed at site near San Antonio Dam. Noise impacts: Minimal at receptors adjacent to the tunnel construction portal at San Antonio and the intake structure at Lake Nacimiento. Biological impacts: TBD. Related to water diversion from Lake Nacimiento to Lake San Antonio. Paleontological impacts: TBD. Impact zone at tunnel portals only. Geologic/Seismic Hazards: TBD Water resources/flooding impacts: TBD. All water rights and water discharge agreements will not be affected. Project assists with flood control. Recreational /Public Facilities impacts: TBD 29
No impacts expected relative to: Aesthetics/visual resources Agricultural resources Air Quality Cultural resources Energy Fire Protection Hazardous materials Historic resources 30
Preliminary biological impacts White bass predator sport fish prohibited from export (alive) from Lake Nacimiento Quagga and Zebra Mussels transfer from Nacimiento to San Antonio mercury in Lake Nacimiento Bald eagle habitat Downstream releases to maintain steelhead migration (NOAA Fisheries) 31
Project schedule 32
Procurement of services Environmental consultants (Jan Mar 2015) Final design consultants (May July 2015) Contractor (Nov 2015 Mar 2016) 33
Project Budget 34
3 month look ahead Preliminary Engineering Project Description 35
Environmental studies CEQA Neg Dec Application Permitting schedule 36
Questions What is the solution to the white bass problem? Will the lake levels be lower with the tunnel? How do you stop the transgression of mussels to Lake San Antonio? How do you protect the tunnel from intruders (people and animals)? How do you prevent bio fouling (mussels clogging the tunnel). How do you build the tunnel when lake levels are high? How and when will the tunnel operate? What are the seismic concerns for the tunnel and potential for collapse? How will power production at the Nacimiento Hydroelectric plant be affected? 37