APPENDIX A DETAILED PROJECT DESCRIPTION

A.2   Proposed Project Location and Setting

A.2.1   Overview

A.2.1.1   Proposed Submarine Cable Route and Study Corridor

The proposed Project would involve construction and operation of approximately 57 miles of HVDC cable of which approximately 56 miles would be buried in the bottom of San Francisco Bay from near Potrero Point in San Francisco, to Pittsburg (Contra Costa County). The cable would be buried underwater and routed from the San Francisco-based converter station into the San Francisco Bay through San Pablo Bay and the Carquinez Strait to Suisun Bay, and New York Slough to a landing point near the Pittsburg Converter Station. Refer to Figure A.1-1 for an overview of the proposed submarine cable route. Map A.2-1 provides additional detail regarding the proposed HVDC and HVAC cable routes, including delineation of a 500-meter-wide study corridor that is centered on the cable route over the majority of its length. Map A.2-1 consists of an index and 10 strip maps with route mileposts (MP) that begin in San Francisco and end in Pittsburg.

A.2.1.2   Proposed Converter Station Locations

The proposed Project involves construction of HVDC converter stations and associated underground AC cable systems to existing PG&E substations in Potrero and Pittsburg. The proposed 6.8-acre converter station site in San Francisco is known as the HWC Site and is located on 23rd Street south of the existing Mirant Power Plant and adjacent to San Francisco Bay. The site is currently developed and occupied by several businesses. Utilization of this site would require demolition of the existing buildings and facilities prior to construction of the proposed converter station. This site may require some level of subsurface contamination remediation prior to construction of the proposed San Francisco Converter Station. The site is currently zoned Heavy Industrial (M-2).

The proposed 7.5-acre converter station site in the City of Pittsburg is known as the Standard Oil site and is located within a developed industrial area with a mix of industrial and former industrial uses. The only structures on the site are 2 abandoned concrete wastewater storage tanks and a small dilapidated building. The remainder of the site was previously occupied by a wastewater treatment facility and then an automobile storage yard. Prior to construction of the proposed converter station the site would be cleared of all structures and stored materials. There is no vegetation on the site except for a few scattered patches of ruderal species (plants that grow in wasteland, trash, or disturbed ground). The relatively flat site, which is surrounded by a berm, contains no waterways or wetlands. The site is zoned IG (General Industrial).

A.2.2   Proposed Submarine Cable Route and Study Corridor

The submarine cable portion of the Project extends from the Potrero Point area in San Francisco to Pittsburg, California (refer to Figure A.1-1). The proposed HVDC cable system between the 2 terminals consists of a high voltage (HV) transmission cable, a separate medium voltage (MV) metallic return cable, and a fiber optic communication cable (refer to Figures A.2-1 and A.2-2).

The cable system would be buried underwater and extend between the San Francisco Converter Station and the Pittsburg Converter Station, with the exception of approximately 0.9 mile of buried onshore cable connecting to the Pittsburg Converter Station and 0.2 mile along the south side of the San Francisco Converter Station. The proposed submarine system cable route travels from San Francisco to Pittsburg within the floor of San Francisco Bay, San Pablo Bay, the Carquinez Strait, Suisun Bay, and New York Slough. The proposed cable route was selected to avoid shipping channels, anchorages, channel maintenance dredging, dredge disposal areas, and other known obstacles.

Electromagnetic devices would be used to detect and locate existing cables and pipelines that cross the proposed cable system path. Table A.2-1 presents a list of currently known utility crossings, and Table A.2-2 lists other known crossings.

In order to confirm the proposed cable system routing in the Bay, guide selection of cable system burying equipment and procedures, and to confirm that the cable system installation along the proposed route would not stir up contaminated sediments (at levels above regulatory thresholds) that may be present along the proposed route, a 2-tier core-sampling program of bay floor sediments would be implemented to complement and confirm existing data and surveys. The first-tier sampling program of bay floor sediments was performed in September 2005. The survey scope and results are presented in Appendix E of this EIR.


TABLE A.2-1
KNOWN UTILITY CROSSINGS1,2,3

Cable Route Milepost

Map ID

Utility Description

Owner

13.9–14.4

11, 12

Cable Crossing-Point San Quentin to Castro Point

Pacific Telephone and Telegraph

30.5

10

Fiber Optics Conduit (12-inch)

Level 3 Communications, LLC

31.7

9

Communication Line

Pacific Telephone and Telegraph

31.9

8

Two Submarine Communications Cables

Pacific Telephone and Telegraph

36.1

6

Communications Facilities

American Telephone and Telegraph Communications of California Inc.

37.6–37.8

5

Two Petroleum Pipelines and One Discharge Pipeline

Exxon Corporation-Assigned to Valero Refining Co.

45.2

4

To Be Determined

Shell Oil Co. Multiple reassignments to Chevron USA Inc, Venoco Inc.

49.4

3

Refined Petroleum Product Line (8-inch)

Chevron USA Inc.

49.7

2

CPN Natural Gas Pipeline

Shell Oil co-reassignments – Shell Cal Prod. Inc, Shell Western E&P Inc, Cal Resources LLC. AERA Energy LLC

1   Refer to Map A.2-1 for approximate crossing locations.
2   Source: State Lands Commission lease documentation review conducted in 2005.
3   Note: numerous bay crossings have been identified. The information in this table will be revised and updated, as required, when the need for a crossing consent has been confirmed.

TABLE A.2-2
OTHER KNOWN CROSSINGS1

Milepost

Utility Description

Owner

3.1

Oakland Bay Bridge

Caltrans

3.4

Trans Bay (BART) Tube

Bay Area Rapid Transit

13.9

Richmond Bridge

Caltrans

30.8

Carquinez Bridge

Caltrans

37.5

Benicia Bridge

Caltrans

1  Refer to Map A.2-1 for approximate crossing locations.

A.2.3   Proposed Onshore Cable/Electrical Interconnection Routes

A.2.3.1   San Francisco

The proposed onshore route for the HVDC cable system entry into the San Francisco Converter Station from San Francisco Bay would parallel the southern property line of the converter station for approximately 1,000 feet from the bore pit, to enter the DC hall at the proposed converter station site (refer to Figure A.1-2). Refer to section A.4.4.1.5 for more information regarding horizontal directional drilling (HDD).

The double-circuit 115 kV HVAC interconnecting cable system could exit the proposed San Francisco Converter Station to the north approximately 900 feet from the easterly line of Illinois Street, then west along the north side of 23rd Street for 600 feet. The HVAC cable would then turn north in former Michigan Street paralleling the existing PG&E Potrero Substation for approximately 375 feet, where it would enter the substation to interconnect with the PG&E transmission and distribution system. Another proposed route involves keeping the 115 kV HVAC interconnecting cable system on the south side of 23rd Street (on HWC property for a portion of its westward path until it reaches a point roughly adjacent to Mirant Potrero's western boundary). It would then turn north, cross 23rd Street, and proceed north on Mirant property.

A.2.3.2   Pittsburg

The proposed HVAC and HVDC cable system routings would begin at the Pittsburg Converter Station (Standard Oil Site) in Pittsburg, California. Both the HVDC and HVAC cable systems would run approximately 0.3 mile to the northeast to an existing paved access road associated with the Delta Energy Center (south of the Burlington Northern Santa Fe [BNSF] right-of-way [ROW]) (refer to Figure A.1-3 and Map A.2-1, Sheet 10 of 10). This initial section of the cable routes would be installed via HDD (for detailed information on HDD, see Section A.4.4.1.5 of this appendix). The route (buried in conduit) then would parallel the existing paved access road in an easterly direction for a distance of approximately 0.25 mile, and then turn north for approximately 0.5 mile along the Delta Diablo outflow access road ending at a splice box approximately 100 to 500 feet south of New York Slough on Winter Island property. The submarine cable system would be drawn in from the bay side, and joined to the underground cable system in this splice box or transition to aboveground.

To avoid aquatic habitat and protect the cable system at the shore crossing, the proposed cable system would enter the bay floor through casings placed by HDD. The casings would terminate offshore and direct burial in the bay floor would begin at the exit of the casings.

The proposed Pittsburg Converter Station 230 kV HVAC cable system interconnect with the PG&E Pittsburg Substation would exit from the southernmost bay of the 230 kV switchyard, bearing west-northwest for approximately 850 feet, and then on a north-northeast bearing for a distance of 650 feet to casings installed by means of HDD. The casings would terminate offshore. The proposed HVAC cable system would enter New York Slough approximately 500 feet west of Mirantís Pittsburg Power Plant Unit 7.


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