6.0 COMPARISON OF ALTERNATIVES

SECTION 6.0

COMPARISON OF ALTERNATIVES

6.1 INTRODUCTION

This section provides a summary comparison of potentially significant impacts for the proposed Project and Project Alternatives, including ancillary facilities. Refer to Section 4.0 (Proposed Project) and Section 5.0 (Project Alternatives) for more information regarding specific impacts and proposed mitigation measures. The No Project Alternative is also included for comparison purposes. Refer to Section A.8.3 in Appendix A for a discussion of alternatives that were considered but eliminated from further consideration, including the rationale for elimination.

The proposed Project and Project Alternatives considered in this comparison of potentially significant impacts are as follows:

Proposed San Francisco HWC Converter Station
Proposed Pittsburg Standard Oil Converter Station
Proposed Offshore DC Cable Route
San Francisco Mirant Converter Station Alternative (three site layouts)
San Francisco Sheedy Converter Station Alternative
Pittsburg West Tenth Street Converter Station (Alternative 1)
Pittsburg West Tenth Street Converter Station (Alternative 2)
Pittsburg Mirant Converter Station Alternative
No Project Alternative

6.2 COMPARISON OF ALTERNATIVES

The potentially significant impact findings (including potential impacts, proposed mitigation measures, and residual impact findings) for the proposed and alternative Project components are summarized in Table 6-1.

As shown in Table 6-1, the identified potentially significant impacts, mitigation measures, and residual impact findings for the proposed and alternative converter station sites (including ancillary facilities) in San Francisco and Pittsburg are very similar, except as noted in Section 6.3. The identified potentially significant impacts associated with the submarine cable installation in the Bay are essentially the same for all converter station sites with the exception of the Pittsburg Standard Oil site as noted in Section 6.3.

6.2.1 San Francisco Converter Stations

The proposed San Francisco HWC Converter Station and alternative San Francisco Mirant Converter Station (three layouts) sites would result in unavoidable adverse significant impacts associated with the required demolition of historic architectural resources (Impact CUL-2), whereas the alternative San Francisco Sheedy Converter Station would not
The proposed San Francisco HWC Converter Station and the alternative San Francisco Sheedy Converter Station would both involve potentially significant impacts associated with potential conflicts with possible future improvements to public access to San Francisco Bay (Impact LU-1), whereas the alternative San Francisco Mirant Converter Station (three site layouts) would not; with implementation of Mitigation Measure LU-1, this potentially significant impact would be reduced to a less-than-significant level
Potential environmental impacts associated with the offshore submarine HVDC cable and for the proposed HWC and alternative Mirant and Sheedy converter station sites are the same and, with implementation of mitigation measures, all identified potentially significant impacts would be reduced to less-than-significant levels

6.2.2 Pittsburg Converter Stations

The proposed Pittsburg Standard Oil Converter Station as well as the Pittsburg West Tenth Street Alternative 1 and Pittsburg Mirant sites would not result in any unavoidable adverse significant environmental impacts, whereas the Pittsburg West Tenth Street Alternative 2 would result in unavoidable significant adverse construction/pile driving noise (Impact NOISE-2) and long-term visual impacts (Impact VIS-5)
While the proposed Pittsburg Standard Oil Converter Station (and ancillary facilities) would not result in any identified unavoidable adverse significant environmental impacts, the proposed Standard Oil site has the following potentially significant impacts that are not applicable to the alternative Pittsburg West Tenth Street sites or the Pittsburg Mirant site:

Water quality impacts from dredging and dredge material disposal (Impact WATER-5) associated with installation of the submarine AC/DC cables between the vicinity of the Mirant Pittsburg Power Plant property and the New York Slough landfall to the east
Potential impacts to the Kirker Creek watershed drainage area (Impact WATER-4)
Potential impacts to vernal pools that provide habitat for special-status biological species (Impact TBIO-1)
Potential impacts to saltmarsh and wetland habitats (Impact TBIO-2)
Potential impacts to wetlands and streams (Kirker Creek) (Impact TBIO-3)
Potential impacts to special-status raptors and birds (Impact TBIO-5)
Potential impacts to Giant garter snake and Western pond turtle (Impact TBIO-4) (note: this potential impact also applies to the Pittsburg West Tenth Street Alternative 2 site)
Potential impacts to special-status plants (Impact TBIO-7)
The northwest portion of the Pittsburg West Tenth Street Alternative 1 site and the entire Pittsburg Mirant site are within the 100-year flood zone (Impact WATER-8) while the proposed Standard Oil and West Tenth Street Alternative 2 sites are not

6.2.3 No Project Alternative

As shown in Table 6-1, the No Project Alternative would avoid the potential environmental impacts of the proposed Trans Bay Cable Project, including those associated with the identified Project Alternatives.

The No Project Alternative would involve taking no action to provide additional electrical transmission capacity to San Francisco-i.e., status quo. Under the No Project Alternative, the potential environmental impacts and benefits of the proposed Trans Bay Cable Project would not occur as a direct consequence of Project implementation. However, the No Project Alternative is incapable of meeting the Project goals and objectives, or the CAISO's objectives for solving the near-term and long-term electrical supply and reliability issues in San Francisco and the northern Peninsula area. One potential consequence of the No Project Alternative would be that the relatively inefficient and polluting Mirant Potrero and Hunters Point power plants may need to continue to run in the future to meet San Francisco's electrical supply needs. Another potential consequence of the No Project Alternative would be the lost potential to save an estimated 20 MW of electrical power that is currently expended in line losses, which would be avoided by the proposed Project. In summary, the No Project Alternative does not constitute a reasonable alternative to the proposed HVDC Project.

6.3 ENVIRONMENTALLY SUPERIOR ALTERNATIVE

The No Project Alternative would result in the fewest environmental effects. However, the No Project Alternative would not meet the Project/CAISO goals and is not considered to be a reasonable or feasible alternative. Numerous "non-Project" alternatives were also considered, as discussed in Section A.8.3 in Appendix A of this EIR. None of the various alternatives evaluated are considered to be capable of meeting all of the Project objectives and the related screening criteria for "feasibility" and "environmental impacts avoidance and minimization." Therefore, none of the potential non-Project alternatives were retained for further consideration in this EIR.

The Trans Bay Cable Project Alternatives are considered by the City of Pittsburg to be the only feasible alternative for meeting the Project and CAISO objectives at this point in time.

It is difficult to determine, however, which of Trans Bay Cable Project converter station site alternatives in San Francisco and Pittsburg is the environmentally superior alternative as, with few exceptions, the sites are very similar to each other in terms of potential impacts. The San Francisco Sheedy Converter Station Alternative would avoid the unavoidable adverse significant impact to historic architectural resources associated with the proposed HWC and alternative San Francisco Mirant sites. However, Mirant plans to demolish the buildings considered to be historic (i.e., Station A Complex) on the San Francisco Mirant property due to their deteriorated condition and seismic safety concerns. Locating the proposed Trans Bay Cable Project San Francisco converter station on any one of the three alternative Mirant site layouts would consolidate the electrical station facilities (i.e., PG&E Potrero Substation and the Trans Bay Cable San Francisco converter station) at one location and would avoid potential conflicts with possible future improvements to public access to San Francisco Bay (Impact LU-1). In addition, the required electrical interconnection (115 kV AC) between the Sheedy Converter Station site and the PG&E Potrero Substation is problematic due to potential conflicts with existing underground utilities along Illinois Street. At this stage of the EIR process, no one site in San Francisco is clearly environmentally superior to another.

Of the proposed and alternative converter station sites in Pittsburg (including ancillary facilities), it is also difficult to determine the clearly environmentally superior alternative at this stage of the EIR process. Due to the unavoidable adverse significant noise and visual impacts associated with the Pittsburg West Tenth Street Alternative 2 site, this alternative site is the least preferable from an environmental impact perspective. The Pittsburg West Tenth Street Alternative 1 and Pittsburg Mirant sites both avoid various potentially significant impacts (e.g., potential water quality impacts due to dredging and potential onshore biological impacts associated with installation of AC/DC cables) that would be associated with the proposed Standard Oil Converter Station site. Accordingly, the Pittsburg West Tenth Street Alternative 1 and Pittsburg Mirant alternative sites are considered to be environmentally superior to the proposed Standard Oil Converter Station site and the Pittsburg West Tenth Street Alternative 2 site. At this stage of the EIR process, it is not possible to clearly differentiate the environmentally superior alternative in Pittsburg between the West Tenth Street Alternative 1 site and the Pittsburg Mirant site.

Impact	Mitigation Measure	Proposed San Francisco HWC Converter Station	Proposed Pittsburg Standard Oil Converter Station	Proposed Offshore DC Cable Route	San Francisco Mirant Converter Station Alternative	San Francisco Sheedy Converter Station Alternative	Pittsburg West Tenth Street Converter Station (Alternative 1)	Pittsburg West Tenth Street Converter Station (Alternative 2)	Pittsburg Mirant Converter Station Alternative	No Project Alternative
Air Quality
AIR-1: Fugitive Dust Emissions
	AIR-1: Fugitive Dust Controls	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
AIR-2: Equipment Exhaust Emissions
	AIR-2: Exhaust Controls	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
AIR-3: Marine Construction – Criteria Pollutants
	AIR-3: Marine Vessel Emission Controls			X
	Resulting Level of Significance			LTS
AIR-4: Marine Construction – Toxic Air Contaminants
	AIR-4: Implement Mitigation Measure AIR-3			X
	Resulting Level of Significance			LTS
Geologic Resources and Soils
GEO-1: Soil Erosion and Compaction
	GEO-1: Design Project for Erosion Control	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
GEO-2: Asbestos-containing Serpentine
	GEO-2: Controls for Excavation of Serpentine	X			X	X
	Resulting Level of Significance	LTS			LTS	LTS
GEO-3: Strong Ground Shaking
	GEO-3: Design to Seismic Design Requirements	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
GEO-4: Liquefaction
	GEO-4: Design Project for Liquefiable Deposits	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
GEO-5: Shrink-Swell/Subsidence
	GEO-5: Design Project for Shrink-Swell/Subsidence	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
Water Resources and Quality
WATER-1: Erosion and Contaminated Runoff
	WATER-1: Erosion Control and Contaminant Source Control	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
WATER-2: Surface Water Quality Impacts from HDD
	WATER-2: Spill Prevention and Control Plan for HDD	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
WATER-3: Groundwater Quality Impacts from HDD
	WATER-3: Use of Pilot Hole and Reaming	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
WATER-4: Impacts to Kirker Creek Watershed Drainage Area
	WATER-4: Kirker Creek Stormwater Management		X
	Resulting Level of Significance		LTS
WATER-5. Water Quality Impacts from Cable Laying Operation
	WATER-5: Avoidance of Sediment Contamination			X
	Resulting Level of Significance			LTS
WATER-6: Water Quality Impacts from Dredging and Dredge Material Disposal
	WATER-6: Dredging Controls and Sediment Testing Program			X
	Resulting Level of Significance			LTS
WATER-7: Water Quality Impacts from Vessel Fuel Spills
	WATER-7: Vessel Fuel Spill Response Plan			X
	Resulting Level of Significance			LTS
WATER-8: Flooding
	WATER-8: Flood Mitigation						X		X
	Resulting Level of Significance						LTS		LTS
Terrestrial Biological Resources
TBIO-1: Trenching Near Pools Providing Habitat for Special-status Species
	TBIO-1a: Avoidance and Prevention Measures for Work Near Vernal Pool Habitat		X
	TBIO-1b: Awareness Training for Workers		X
	TBIO-1c: Biological Monitoring Requirement		X
	Resulting Level of Significance		LTS
TBIO-2: Trenching Near Saltmarsh and Wetland Habitats
	TBIO-2a: Marking Habitat and Implementing Physical Avoidance Measures		X
	TBIO-2b: Monitoring Requirements for Salt Marsh Species		X
	TBIO-2c: Awareness Training for Construction Personnel		X
	TBIO-2d: Halting Work to Remove Endangered Species from Job Site		X
	TBIO-2e: Check Under Parked Vehicles		X
	TBIO-2f: Pre-construction Nesting Surveys		X
	Resulting Level of Significance		LTS
TBIO-3: Disturbance or Fill of Wetlands and Streams
	TBIO-3a : Implement HDD or Comparable Technology Techniques to Avoid Impacts to Kirker Creek and Associated Floodplain Wetlands		X
	TBIO-3b: Wetland and Jurisdictional Waters Delineation Survey		X
	TBIO-3c: Wetland and Pool Avoidance		X
	TBIO-3d: Obtain Streambed Alteration Agreement		X
	TBIO-3e : Implement HDD or Comparable Technology Techniques to Avoid Impacts to Wetlands							X
	Resulting Level of Significance		LTS					LTS
TBIO-4: Potential Impacts to Giant Garter Snake and Western Pond Turtle
	TBIO-4a: Avoidance of Habitat and Timing of Construction		X					X
	TBIO-4b: Worker Training for Giant Garter Snake and Western Pond Turtle		X					X
	TBIO-4c: Biological Monitoring for Giant Garter Snake and Western Pond Turtle		X					X
	TBIO-4D: Avoiding Impacts to Wetlands and Habitat							X
	Resulting Level of Significance		LTS					LTS
TBIO-5: Potential Impacts to Special-status Raptors and Birds in Construction Laydown Area
	TBIO-5: Pre-construction Nesting Surveys at Construction Laydown Area		X
	Resulting Level of Significance		LTS
TBIO-6: Potential Impacts to Special-status Plants
	TBIO-6a: Rare Plant Surveys		X
	TBIO-6b: Avoidance of Rare Plant Populations		X
	Resulting Level of Significance		LTS
TBIO-7: Potential Impacts to Special-status Plants from Laydown Areas
	TBIO-7a: Rare Plant Surveys in Laydown Areas		X
	TBIO-7b: Avoidance of Special-status Plants		X
	Resulting Level of Significance		LTS
Marine Biological Resources
No potentially significant impacts
Cultural Resources
CUL-1: Disturbance of Archaeological Resources
	CUL-1a: Archeological Resource Testing	X			X
	CUL-1b: Archaeological Resource Data Recovery	X			X
	CUL-1c: Archaeological Resource Construction Monitoring	X			X
	Resulting Level of Significance	LTS			LTS
CUL-2: Demolition of Historic Architectural Resources
	CUL-2a: Recording Architectural Resources	X			X
	CUL-2b: Architectural Resource Interpretive Display and/or Interpretive Material	X			X
	CUL-2c: Architectural Resource Salvage Opportunities	X			X
	Resulting Level of Significance	RS			RS
CUL-3: Offshore Cable Route Archaeological Resources
	CUL-3a: Archaeological Resources Geophysical Survey			X
	CUL-3b: Archaeological Resources Avoidance			X
	CUL-3c: Archaeological Resources Supplemental Underwater Investigation			X
	Resulting Level of Significance			LTS
Land Use and Recreation
LU-1: Potential Conflict with Public Access Improvements
	LU-1: Public Access	X				X
	Resulting Level of Significance	LTS				LTS
LU-2: Exceedance of Height Allowance
	LU-2: Height Allowance		X				X	X
	Resulting Level of Significance		LTS				LTS	LTS
LU-3: Potential Conflict with Kirker Creek Policy
	LU-3: Kirker Creek Policy		X
	Resulting Level of Significance		LTS
LU-4: Increased Vessel Traffic
	LU-4a: Vessel Crew Procedures			X
	LU-4b: Coast Guard Coordination			X
	Resulting Level of Significance			LTS
LU-5: Potential Conflict with Local Plans and Policies
	LU-5: Local Plans and Policies Coordination			X
	Resulting Level of Significance			LTS
Commercial Fishing and Marine Transportation
MTRANS-1: Vessel Navigation Hazards
	MTRANS-1a: Project Registration, Information and Pilotage			X
	MTRANS-1b: Compliance with Navigation Rules			X
	MTRANS-1c: Precautionary Area			X
	Resulting Level of Significance			LTS
MTRANS-2: Interference with Commercial Fishing Operations
	MTRANS-2a: Commercial Fishing Avoidance			X
	MTRANS-2b: Project Information			X
	Resulting Level of Significance			LTS
MTRANS-3: Interference with Commercial Sport Fishing Operations
	MTRANS-3a: Commercial Sport Fishing Avoidance			X
	MTRANS-3b: Project Information			X
	Resulting Level of Significance			LTS
Traffic and Transportation
TRAFFIC-1: Cumulative Traffic Impacts
	TRAFFIC-1: Coordination to Reduce Cumulative Traffic Impacts	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
TRAFFIC-2: Oversized Loads
	TRAFFIC-2: Coordination of Oversized Loads	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
TRAFFIC-3: Temporary Street Closures Affecting Traffic, Bicycle, and Pedestrian Circulation
	TRAFFIC-3: Signage for Temporary Street Closures	X			X	X
	Resulting Level of Significance	LTS			LTS	LTS
TRAFFIC-4: Impacts on Metro East Light Rail Facility
	TRAFFIC-4: Reducing Impact on the Movement of MUNI Light Rail Vehicles into and out of the Metro East Maintenance Facility	X			X	X
	Resulting Level of Significance	LTS			LTS	LTS
TRAFFIC-5: Traffic Impacts During Construction
	TRAFFIC-5: Improve Vehicular Safety		X
	Resulting Level of Significance		LTS
Noise and Vibration
NOISE-1: Converter Station Operations Sound Levels
	NOISE-1: Noise Barrier Installation for Converter Station		X				X	X	X
	Resulting Level of Significance		LTS				LTS	LTS	LTS
NOISE-2: Construction Sound Level
	NOISE-2: Construction Noise Control Measures							X
	Resulting Level of Significance							RS
Public Services and Utilities
PS-1: Construction Fire Hazards
	PS-1: Construction Fire Prevention	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
PS-2: Existing Onshore Underground Utilities
	PS-2: Utility Survey	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
PS-3: Operations Fire Hazards
	PS-3: Operations Fire Prevention	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
PS-4: Water Service
	PS-4: Water Service		X						X
	Resulting Level of Significance		LTS						LTS
Visual Resources
VIS-1: Converter Station Domination of View
	VIS-1a: Plan Submittal Requirements for Building Materials and Colors	X	X			X	X		X
	VIS-1b: Plan Submittal Requirements for Landscaping	X	X			X	X		X
	VIS-1C: Landscaping Plan		X
	Resulting Level of Significance	LTS	LTS			LTS	LTS		LTS
VIS-2: Converter Station Will Create Substantial Light and Glare
	VIS-2: Plan Submittal Requirements for Lighting	X	X		X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS
VIS-3: Creation of Visual Clutter
	VIS-3: Landscaping Plan	X
	Resulting Level of Significance	LTS
VIS-4: Converter Station Domination of Entrance to Warm Water Cove Park
	VIS-4a: Landscaping					X
	VIS-4b: Common Fence Design					X
	VIS-4c: Street Lighting along 24th Street					X
	Resulting Level of Significance					LTS
VIS-5: Converter Station Domination of View
	VIS-5a: Street Yard Setback							X
	VIS-5b: Street Yard Landscape							X
	VIS-5c: Architectural Design and Building Colors							X
	Resulting Level of Significance							RS
Hazardous Materials and Waste Management
HAZ-1: Removal of Potentially Hazardous Building Materials Resulting from Demolition
	HAZ-1: Complete an ACM Abatement Plan and an LBP Abatement Plan	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-2: Soil Removal
	HAZ-2: Soil Removal Protocols	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-3: Construction-phase Hazardous Materials Use
	HAZ-3: Reduction of Hazards During Construction Phase	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-4: Construction-phase Waste Streams
	HAZ-4: Management of Construction-phase Waste Streams	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-5: Construction-phase Accidental Spills
	HAZ-5: Construction-phase Spill Prevention, Control, and Countermeasure	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-6: Construction-phase Dust and Volatilization of Contaminants
	HAZ-6: Reduction of Construction Dust and Volatilization of Contaminants	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-7: Contaminated Groundwater
	HAZ-7: Contaminated Groundwater Control	X	X		X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS
HAZ-8: Operations-phase Hazardous Materials Usage
	HAZ-8: Control of Operations-phase Hazardous Materials	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-9: Operations-phase Waste Streams
	HAZ-9: Manage Waste Generation, Storage and Disposal During Operations Phase	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-10: Operations-phase Accidental Spills
	HAZ-10: Operations-phase Spill Prevention, Control, and Countermeasure	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-11: Operations-phase Fire and Explosion Risk)
	HAZ-11: Reduction of Fire and Explosion Risk and Emergency Support During Operations Phase	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
HAZ-12: Impacts from Seismic Activity
	HAZ-12: Manage Seismic Activity	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS
Paleontological Resources
PALEO-1: Disturbance of Fossil Resources
	PALEO-1: Potential Fossil Resources Protection	X	X		X	X	X	X	X
	Resulting Level of Significance	LTS	LTS		LTS	LTS	LTS	LTS	LTS

X = Applicable; Blank = Not Applicable; LTS = Less than Significant; RS = Residual Significant Impact.