APPENDIX A DETAILED PROJECT DESCRIPTION

A.4   Construction ACTIVITIES

The engineering, procurement, and construction (EPC) activities for the proposed Project are expected to be 27 to 30 months in duration. The onsite construction phase of the Project would require approximately 20 months, preceded by 3 to 6 months for demolition of existing onshore structures and site preparation, and followed by 5 to 6 months of startup and commissioning. The San Francisco and Pittsburg converter stations would be constructed concurrently. Installation of the cable systems between San Francisco and Pittsburg would be expected to require about 4 to 5 months. The schedule would begin when a Notice to Proceed was issued to the EPC Contractor, and would be completed when the facility was commercially operational. Construction is currently planned to begin in 2007.

The results of the final engineering design work have the potential to influence construction activities. The final design of the HVDC cable system including operational characteristics would be defined during detailed system studies. All necessary studies to confirm the appropriate performance requirements and ratings of all the equipment would be performed. During the detailed engineering phase all available data would be reviewed and analyzed and incorporated into the final Project design and the issued construction documents. Final engineering activities would include:

The existing data would be examined for accuracy, completeness, and applicability to the required design, and engineered for the installation. This work would also consider the cable burial recommendations and existing utility crossing protection plans. Further, the analysis would include consideration and assessment of critical areas, recommended solutions, laying directions, instructions to control tensions during laying, and any other data required to ensure successful installation of the submarine HVDC cable.

Construction activities would include building the converter stations, installation and connection of HVAC and HVDC transmission systems, substation interconnections, and start-up. Sequential construction activities would include demolition of existing facilities, grading and site preparation, foundation construction, erection of major equipment and structures, installation of electrical systems and control systems, and start-up/testing.

A.4.1   Planning, Engineering, Procurement, and Construction Management

Construction activities would be limited to the worksite dimensions depicted on the site layouts presented in Sections A.2 and A.3. These drawings include the location and boundaries of the access routes and associated construction laydown and parking areas. Temporary construction laydown and parking areas would be located in the temporary construction easements. The boundaries of all work areas would be identified with lath, flagging or other temporary marker/barrier.

The general sequence of construction activities would proceed as follows:

Construction would conclude with start-up and testing activities to ensure reliable operation.

Each converter station would receive a total of six oversized loads (four transformers and two smoothing reactors), beginning in month 12 of the project schedule (see Table A.4-4). The transformers would each be approximately 31.3 feet x 12.9 feet x 16.5 feet, weighing approximately 192 tons. The smoothing reactors would be approximately 12.9 feet x 16.5 feet. Each oversized item detailed above is expected to be loaded on a single trailer.

The proposed Project schedule, estimated construction workforce, construction equipment requirements, construction truck deliveries, and estimated land disturbance during construction are described in the following sections and itemized in Tables A.4-1 through A.4-5.


TABLE A.4-2
ESTIMATED CONSTRUCTION WORKFORCE
Workers per Month


 

Months After Notice To Proceed

Total Worker Months

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

San Francisco Converter Station

16

27

27

20

12

9

11

15

21

31

32

45

37

37

45

45

45

45

45

36

27

15

11

7

7

6

6

3

3

0

686

Pittsburg Converter Station

0

0

0

14

16

7

10

15

21

29

32

45

37

39

44

45

45

45

45

36

27

15

11

7

7

6

6

3

3

0

610

San Francisco and Pittsburg Grand Totals

16

27

27

34

28

16

21

30

42

60

64

90

74

76

89

90

90

90

90

72

54

30

22

14

14

12

12

6

6

0

1,296


TABLE A.4-3
CONSTRUCTION EQUIPMENT UTILIZATION


 

Months After Notice to Proceed (Pieces per Month)

Estimated Total Piece Months

Estimated Total Hours W/
Utilization

Construction Equipment

HP

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

San Francisco Converter Station

                                                                 

Air Compressors - 300 cfm**

90

           

1

1

2

2

2

2

2

2

2

2

2

2

2

2

2

2

1

1

1

1

1

1

1

 

37

1,628

Backhoe***

175

2

2

2

2

2

2

2

2

1

1

1

1

1

1

1

1

1

             

1

1

       

27

2,200

Boom Truck***

220

               

1

1

1

1

1

1

1

1

1

1

1

1

1

1

               

14

1,232

Cranes - 230 Ton***

350

                   

1

1

                                   

2

176

Cranes - 150 Ton***

290

                 

1

 

1

1

                                 

3

264

Cranes - 15 Ton***

130

1

1

1

1

   

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

               

20

1,760

Crane -Truck - 60 Ton***

150

                     

1

1

1

1

                             

4

352

Dozers – D8***

300

1

1

1

1

1

1

1

1

                                           

8

704

Excavator - Loader***

195

2

2

2

2

1

1

1

1

1

1

1

1

1

1

                               

18

1,584

Excavator - Motor Grader***

125

           

1

1

1

                                         

3

264

Forklift - CAT V200***

50

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

                         

17

1,496

HDD Rig – Cat 3412***

550

           

1

1

                                           

2

176

Manlifts - 60 foot***

50

                       

2

2

2

2

2

2

2

                     

14

1,232

Portable Plate Compactors**

10

             

4

4

4

4

4

4

4

4

                             

32

1,408

Vibratory Roller Compactors**

125

         

1

1

1

1

                   

1

1

                 

6

264

Pile Driving Equipment***

300

             

1

2

1

1

                                     

5

440

Tractor for 40 Foot Float***

275

             

1

1

1

1

2

2

3

3

3

3

3

2

1

                   

26

2,288

Trucks - Tandem Dump*

250

3

10

10

10

10

2

2

10

10

10

5

                                     

82

1,443

Trucks - Concrete Mixing*

300

         

6

8

8

6

4

         

2

2

                         

36

634

Trucks - Water***

225

         

1

1

1

                                           

3

264

Trucks - 2 Ton***

225

2

2

2

2

1

 

1

1

1

1

1

                                     

14

1,232

Trucks - Pickup***

175

2

2

2

2

1

1

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

         

48

4,224

Trucks - Winch 100 Ton**

200

                       

1

1

1

1

1

1

                       

6

264

Truck - Lube Oil*

350

1

1

1

1

1

1

1

1

1

1

 

1

 

1

 

1

 

1

 

1

1

                 

16

282

Welding Machines - Portable***

50

1

2

2

1

   

2

2

2

2

2

2

2

1

1

1

1

1

1

1

1

                 

28

2,464

San Francisco Total

 

16

24

24

23

18

17

27

41

38

34

24

21

22

22

20

18

17

14

11

10

9

6

3

3

4

2

1

1

1

0

471

28,450

Pittsburg Converter Station

                                                                 

Air Compressors - 300 cfm**

90

       

1

1

1

1

2

2

2

2

2

2

2

2

2

2

2

2

2

2

1

1

1

1

1

     

37

1,628

Backhoe***

175

     

1

1

1

1

1

1

1

1

1

1

                   

1

1

1

       

13

1,144

Boom Truck***

220

               

1

1

1

1

1

1

1

1

1

1

1

1

1

                 

13

1,144

Cranes - 230 Ton***

340

                   

1

1

                                   

2

176

Cranes - 150 Ton***

290

                 

1

   

1

1

                               

3

264

Cranes - 15 Ton***

130

     

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

                     

16

1,408

Crane -Truck - 60 Ton***

150

                     

1

1

1

1

                             

4

352

Dozers – D8***

300

       

1

1

 

1

1

                                         

4

352

Excavator - Loader***

195

     

1

1

 

1

1

1

                                         

5

440

Excavator - Motor Grader***

215

           

1

1

1

1

                                       

4

352

Forklift - CAT V200***

50

             

1

1

1

1

1

1

1

1

1

1

                         

10

880

HDD Rig-Cat 3412***

550

                                 

1

1

                     

2

176

Manlifts - 60 foot***

50

                       

2

2

2

2

2

2

2

                     

14

1,232

Portable Plate Compactors**

10

             

4

4

4

4

4

4

4

4

                             

32

1,408

Vibratory Roller Compactors**

125

           

1

1

                     

1

1

                 

4

176

Pile Driving Equipment***

300

             

1

1

1

                                       

3

264

Tractor for 40 Foot Float***

275

             

1

1

1

1

2

2

3

3

3

3

3

3

2

1

                 

29

2,552

Trucks - Tandem Dump*

250

       

2

3

 

1

1

                                         

7

123

Trucks – Concrete Mixing*

300

             

6

8

8

6

4

     

2

2

                         

36

634

Trucks - 2 Ton***

225

       

2

1

1

1

1

1

1

                                     

8

704

Trucks - Pickup***

175

       

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

         

42

3,696

Trucks - Winch 100 Ton**

200

                       

1

1

1

1

1

                         

5

220

Truck - Lube Oil*

350

     

1

1

1

1

1

1

1

1

 

1

 

1

 

1

 

1

 

1

                 

13

229

Welding Machines - Portable***

70

           

2

2

2

2

2

2

2

1

1

1

1

1

1

1

1

                 

22

1,936

Pittsburg Total

 

0

0

0

4

12

11

12

27

30

28

24

22

22

20

20

16

17

13

14

9

9

4

3

4

4

2

1

0

0

0

328

21,490

Marine Operations

                                                                 

Cable Ship Giulio Verne****

2,268

                                         

4

4

             

8

3,465

Cable Barge***

6,000

                                     

1

1

   

1

           

3

1,188

Dredge***

6,000

                                     

2

                   

2

176

Notes:    Equipment hours are based on 176 hours per month except for cable ship and cable barge, which equal 720 hours per month.
             Equipment utilization is assigned as follows: * = 10%; ** = 25%; *** = 50%; **** = 100%.
             Cable ship and cable barge Estimated Total Usage include Capacity Factors of 60% and 55%, respectively. See Air Quality Appendix D for more discussion.


TABLE A.4-4
CONSTRUCTION TRUCK DELIVERIES OF EQUIPMENT AND MATERIALS


 

Months After Notice to Proceed

Total

Construction Deliveries

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

San Francisco Converter Station

                                                             

Contractor Mobilization

       

40

10

15

                                             

65

Demolition Haul & Equipment

40

75

75

75

40

25

25

18

                                           

373

Electrical Bulks

                       

3

6

6

3

3

2

                       

23

Reinforcing Steel

               

5

8

8

10

5

3

                               

39

Excavation for Structures

           

50

100

150

200

200

100

50

50

                               

900

Structural Fill/Stone

             

150

200

150

150

100

10

10

5

           

30

25

20

           

850

Electrical Equipment

                     

75

75

75

75

25

25

                         

350

Concrete

                   

44

44

44

44

44

44

11

11

 

11

                   

297

Mechanical Equipment

                     

11

11

11

11

11

11

11

5

                     

82

Piping/Hangers & Valves

                 

11

11

11

11

11

5

                             

60

Structural Steel

                 

6

11

11

11

5

                               

44

Building Steel Framing

                 

3

10

15

15

5

                               

48

Building Roofing and Siding

                   

11

11

11

                                 

33

Construction Consumables

                 

15

22

22

22

22

22

22

15

10

10

7

6

6

5

5

3

3

3

3

3

 

226

Contractor Demobilization

                                                     

10

10

5

25

Construction Equipment

           

5

5

5

5

5

3

2

                       

5

5

3

3

 

46

Directional Drilling Equipment

           

10

10

                                           

20

Office Supplies/Miscellaneous

               

3

5

5

5

5

5

5

5

5

5

5

5

5

3

3

3

           

72

Piling

           

8

10

8

                                         

26

San Francisco Total

40

75

75

75

80

35

113

293

371

403

477

418

275

247

173

110

70

39

20

23

11

39

33

28

3

8

8

16

16

5

3,579

Pittsburg Converter Station

                                                             

Contractor Mobilization

         

10

15

                                             

25

Demolition Haul & Equipment

     

8

10

5

                                               

23

Electrical Bulks

                       

3

6

6

                             

15

Reinforcing Steel

               

5

8

8

10

5

3

                               

39

Excavation for Structures

           

50

100

150

200

200

100

50

50

                               

900

Structural Fill/Stone

                 

15

25

25

5

5

3

           

30

25

20

           

153

Electrical Equipment

                     

75

75

75

75

25

25

                         

350

Concrete

                   

44

44

44

44

44

44

11

11

 

11

                   

297

Mechanical Equipment

                     

11

11

11

11

11

11

11

5

                     

82

Piping/Hangers & Valves

                 

11

11

11

11

11

5

                             

60

Structural Steel

                 

6

11

11

11

5

                               

44

Building Steel Framing

                 

3

16

16

16

3

                               

54

Building Roofing and Siding

                   

11

11

11

                                 

33

Construction Consumables

                 

15

22

22

22

22

22

22

17

17

17

17

11

11

               

237

Contractor Demobilization

                                                     

10

10

5

25

Construction Equipment

                 

5

11

17

17

17

                               

67

Directional Drilling Equipment

                                 

10

10

                     

20

Office Supplies/Miscellaneous

               

3

5

5

5

5

5

5

5

5

5

5

5

5

3

3

3

           

72

Piling

           

8

10

8

                                         

26

Pittsburg Total

0

0

0

8

10

15

73

110

166

268

364

358

286

257

171

107

69

54

37

33

16

44

28

23

0

0

0

10

10

5

2,522

San Francisco and
Pittsburg Grand Total

40

75

75

83

90

50

186

403

537

671

841

776

561

504

344

217

139

93

57

56

27

83

61

51

3

8

8

26

26

10

6101

Note: All trips are round trips.


TABLE A.4-5
estimated Land Disturbance


Project Component Item

Unit Area

Proposed Length

Width of Disturbed Area

Construction

Operations

San Francisco Converter Station

     

Site Boundary

5.6 Acres

5.6 Acres

N/A

N/A

Offsite Construction Laydown Used

7 Acres

N/A

N/A

N/A

Pittsburg Converter Station

     

Site Boundary

7.5 Acres1

7.5 Acres1

N/A

N/A

Offsite Construction Laydown Used

7 Acres

N/A

N/A

N/A

Proposed 400 kV Submarine Cable System

Submarine Cable

136 Acres

N/A

56 Miles

20 Feet2

Dredging

10 Acres

N/A

1,000 Feet

400 Feet

Proposed 400 kV HVDC and 12 kV Underground Cable (San Francisco and Pittsburg Combined)

Underground3

6.1 Acres

N/A

1.0 Mile

50 Feet

Proposed Splice Pits (Pittsburg Converter Station)4

Splice Pits (3 Assumed)

0.02 Acre

 

30 Feet

10 Feet

Proposed HDD Pits (Pittsburg Converter Station)4

3 HDD Pits

1.4 Acres

N/A

200 Feet

100 Feet

Proposed 230 kV AC Single-Circuit Submarine Cable (Pittsburg Standard Oil Site Only)

Submarine

10.2 Acres

N/A

4.2 Miles

202

Proposed 230 kV AC Single-Circuit Land Cable (Pittsburg Standard Oil Site Only)

Aboveground

3.6 Acres

1,600 SF/structure

2,100 Feet

75 Feet

Underground

6.1 Acres

N/A

1.0 Mile

50 Feet

Proposed 115 kV AC Double-Circuit Land Cable (San Francisco Only)

Underground

2.2 Acres

N/A

0.3 Mile

50 Feet

Proposed Underground Potable/Fire Water Supply Lines

San Francisco Converter Station

0.7 Acre

N/A

625 Feet

50 Feet

Pittsburg Converter Station

TBD

N/A

TBD

50 Feet

Proposed Underground Sanitary Sewer Lines

San Francisco Converter Station

0.03 Acre

N/A

25 Feet

50 Feet

Pittsburg Converter Station

TBD

N/A

TBD

50 Feet

Proposed Stormwater Discharge Lines

San Francisco Converter Station

0.03 Acre

N/A

25 Feet

50 Feet

Pittsburg Converter Station

TBD

N/A

TBD

50 Feet

1   Includes access roads.
2   Width of disturbed area for buried submarine cable is equal to the Hydroplow wheel base. Kedging anchor lateral deployment may be up to 800 feet from the barge. The cable system trench width is approximately 1 foot.
3   HVDC and MVDC/fiber optic cable system will be in the same right-of-way once onshore.
4   Splice pit(s) and HDD pits at San Francisco Converter Station (proposed HWC site) are within the converter station boundary.
N/A = Not Applicable; TBD = To Be Determined.


A.4.2   Converter Stations

The proposed Project would include installation of the Pittsburg Converter Station, near PG&E's Pittsburg substation, to convert HVAC power into HVDC power and deliver that power through a new approximately 56-mile-long HVDC submarine transmission cable system. The HVDC cable system would terminate at the San Francisco Converter Station, which would convert the HVDC power to HVAC power for delivery to PG&E's Potrero substation and subsequent distribution into the electrical grid in San Francisco.

A.4.2.1   Project Schedule and Workforce

Converter station onsite construction would be based on a 20-month schedule. Construction of the converter stations would be preceded by demolition of existing structures, which is expected to require approximately 3 to 6 months and be followed by 5 to 6 months of startup and commissioning activities.

Construction labor needs would be met using unionized craftspeople. The estimated construction schedule provides for construction craft, supervision, and startup activities, based on an assumed 6-day work week over a 20-month schedule.

While some tasks overlap in scheduling and coordination, converter station construction generally would be planned to be completed as follows

A.4.2.2   Construction Facilities

A.4.2.2.1   Access Roads. No vehicular access to the worksite areas would be permitted until temporary access routes had been defined and/or permanent roads had been constructed. Roads and worksite boundaries would be designated and construction activities would be limited to the designated areas.

Access to the proposed HWC converter station site in San Francisco would be via 23rd Street, which parallels the northern property boundary (refer to Figure A.1-2). No new offsite access road construction would be required. Access to the proposed laydown area (Western Pacific) in San Francisco would be via 25th Street and no new offsite access road construction is proposed. Truck traffic between the HWC site and the proposed laydown area (Western Pacific) would be via Illinois Street between 23rd Street and 25th Street. Expected non-local transportation routes to and from the proposed HWC site as well as the proposed laydown area are discussed in Section 4.10 (Traffic and Transportation).

Two access roads to the proposed Standard Oil Converter Station site and adjacent laydown area are planned. The first, a new permanent access road, would run south from the converter station site to the Pittsburg-Antioch Highway. Refer to Figures A.4-1 and A.4-2 for plan and elevation views, respectively, of this proposed access road. The new road would be approximately 30 feet wide with an asphalt concrete surface (refer to Figure A.4-1). The new road would be located on the existing Standard Oil parcel of land. The new road would require construction of a new bridge over Kirker Creek just north of the Pittsburg-Antioch Highway (refer to Figures A.4-1 and A.4-2). Use of the new access road (e.g., for truck deliveries) would require use of flagmen at the intersection of the new access road and the Pittsburg-Antioch Highway for traffic control and safety during the construction for the converter station.

In addition to the proposed new access road, a second access road would run west from the site and connect the converter station site with Loveridge Road (refer to Figure A.1-3). This access road would likely be used to transport heavy loads (e.g., transformers). The road would be located adjacent to and south of the existing railroad ROW and cross 2 abandoned rail spurs. The road would be approximately 40 feet wide with an asphalt concrete surface. Expected non-local transportation routes to and from the proposed Standard Oil site are discussed in Section 4.10 (Traffic and Transportation).

A.4.2.2.2   Construction Offices. Office space, including mobile trailers, would be located on the San Francisco and Pittsburg converter station sites and would have adequate parking space for construction personnel.

A.4.2.2.3   Site Preparation. Site preparation activities would take place before the start of construction of the converter stations. For planning purposes, site preparation would be divided into 2 phases, pre-demolition and demolition.

Pre-Demolition Activities. Pre-demolition activities would include:

Demolition Activities. Demolition of existing structures would commence following completion of the pre-demolition activities. Demolition would include the following activities:

Demolition would be followed by converter station construction. The transition from site preparation to construction would involve careful management of below-grade soils following excavation of all sub-grade structures and underground utilities. This phase may also include the removal of contaminated soil and/or groundwater, as applicable. Refer to Section 4.14 (Hazardous Materials Handling and Waste Management) for more information.

Removal of existing foundations would be required and the location of these foundations would be identified during detailed construction design. It is anticipated that groundwater control would be provided for these excavations such that the base would be stable for placing structural fill. Structural fill would be brought up to the new converter station finished grade. Some construction activities may take place prior to bringing structural fill to finished grade. These activities may include ground improvement measures, deep foundation construction or constructing foundation mats.

It is estimated that up to approximately 15,000 cubic yards of material would need to be excavated at each converter station site. Maximum excavation depths are estimated to be approximately 15 feet associated with foundation and sump installations under each of the four transformers at each converter station.

A.4.2.2.4   Erosion and Sediment Control. Temporary erosion control devices would be installed in accordance with the required Construction Storm Water Pollution and Prevention Plan (SWPPP) before initial site clearing and would be visually inspected during the regular site environmental compliance inspections.

Paved surfaces would be periodically washed to remove soil during dry periods and water would be applied to soil stockpiles and unpaved areas at regular intervals during the earth-moving and construction phases. Access roads/exits/entrances would be inspected regularly for spillage or carryout of loose dirt or mud. Corrective actions would be implemented as necessary to minimize any such spillage or carryout.

A.4.2.2.5   Spoil Control for Excavation. The boundaries of all ROWs and work areas would be identified.

Topsoil stripping would be undertaken on the area anticipated to be disturbed by excavation, grading, and/or piling of excavated subsoil/rock. Stripped topsoil would be segregated from subsoil and stockpiled in temporary storage areas on the property from which it was removed. All areas to be disturbed by excavation and backfilling would be enclosed within silt fencing or other temporary marker/barrier to define the allowable limits of disturbance.

Material removed from site grading and excavations would be stockpiled adjacent to the excavation. Material would be inspected and tested as necessary to determine its suitability for reuse. If the material were found to be reusable, silt fencing and/or other soil erosion controls would be used to prevent erosion of stockpiled material.

Excavated subsoil and rock would not be stockpiled or spoiled on unapproved sections of the converter station sites. Excess excavated subsoil and rock, or that which is not suitable as backfill, would be removed from the site.

Surface water "ponding" and soil erosion would be avoided. Backfill would consist of excavated subsoil and rock, whenever possible. If this material were determined to be unsuitable as backfill, engineered fill would be used.

A.4.2.2.6   Chemical and Waste Storage and Spill Prevention and Control. The onsite management and offsite disposal of non-hazardous solid wastes generated during construction of the converter stations would be governed by the regulations of a solid waste management plan for the Project. The onsite management and offsite disposal of hazardous wastes would be governed by the regulations of a hazardous waste management plan for the Project. Waste would be stockpiled temporarily before disposal offsite. The local fire departments and emergency management teams would be provided a list of the waste material expected to be generated and stored onsite.

All vehicles and construction equipment would be inspected to ensure that there are no leaking fluids (e.g., oil, hydraulic, lubricants, or brake fluid) and that all fuels and fluids are stored in proper, labeled containers. Any observation of spills, leaking fluids, or improperly stored fluids may trigger the issuance of a "stop work" notice until the problem is resolved, including the removal of any soil contaminated by vehicle fluids. All applicable regulations governing the storage, transport, use and disposal of fluids, and all reporting requirements for spills would be enforced.

A.4.2.2.7   Hazardous Materials Handling and Disposal. Petroleum products and chemical substances (termed "hazardous materials") would be managed in such a manner as to minimize the potential for threats to human health and the environment. Hazardous waste may be generated during the course of Project construction. The details regarding the management of hazardous waste onsite would be contained in the Hazardous Waste Management Plan.

A.4.2.2.8   Public Road Traffic Control and Safety. Construction (excluding 3 to 6 months for demolition of existing buildings at the San Francisco site) would be expected to take 20 months to complete, with the peak construction activity occurring over a 4- to 5-month period. During construction, two categories of vehicular trips would encompass the construction activity: 1) worker trips, and 2) equipment/supply deliveries. It is anticipated that during the 4- to 5-month peak period of construction activity, approximately 30 construction and equipment-related trips/deliveries to the converter station sites would occur on a daily basis. Peak morning traffic would likely occur between the hours of 7:00 and 8:00 a.m. and peak evening traffic would be expected to occur between the hours of 5:30 and 6:30 p.m.

Construction activities would occur over the course of 1 shift scheduled between the hours of 7:00 a.m. to 8:00 p.m. Extensions of the basic workday, or moderate amounts of evening work, where allowable, might occasionally occur. It is expected, however, that any evening activities would require only a small number of workers.

Truck movements for materials delivery and removal would be spread throughout the day on weekdays, and would generally occur between the hours of 7:30 a.m. and 6:00 p.m., depending on the period of construction and except to the extent required to accommodate oversized deliveries or nighttime work. In order to minimize the potential for Project-related traffic issues to occur, state and local transportation agencies would be consulted, not less than weekly, about traffic conditions near the converter station sites.

Detailed traffic controls (as necessary), parking (onsite and offsite), and equipment delivery plans to the converter station sites, including overweight and permit-required loads, would be developed and coordinated with local highway officials for submission with detailed construction drawings.

A.4.2.2.9   Pedestrian Access and Bikeway Traffic Control. The construction sites would be protected and secured with a temporary fence, to be replaced by permanent fencing and walls upon completion of construction. Access during both construction and operation would be only via designated, gated, and secured access points.

A.4.2.2.10 Nighttime Construction Provisions. Work at the sites would be restricted between the hours of 7:30 a.m. and 6:00 p.m., unless the work were entirely within an enclosed building. Work performed within an enclosed building outside of the normal work hours could be done between the hours of 6:00 p.m. and 10:00 p.m. without any additional lighting or noise controls. From 10:00 p.m. to 7:30 a.m., work done within an enclosed building could only be performed as long as the noise levels did not create a disturbance and lights did not illuminate adjacent property areas.

Cable installation in the bay would be carried out on a 24-hour basis, 7 days per week. Some onshore cable installation activities may be conducted on a 24-hour basis consistent with applicable regulations.

A.4.2.3   San Francisco Converter Station

The proposed San Francisco converter station at the HWC site would occupy 5.6 acres on the overall 6.8-acre parcel on 23rd Street, just south of the Mirant Potrero Power Plant. A 64-foot-high valve and converter transformer building would occupy approximately 23,000 square feet on the site. The balance would be occupied by outdoor-air cooled radiators, transformers, and AC filters. The proposed site currently has 3 structures that would need to be demolished as part of the site preparation. A fourth structure on the site is 1 of 4 structures on the Potrero Power Plant site included with Mirant's Application for Demolition Permit.

A.4.2.3.1   Laydown and Storage. An area of up to approximately 7 acres would be located on the approximately 11-acre Western Pacific site and would be devoted to equipment and materials laydown, storage, parking of construction equipment, small fabrication areas, and office trailers for the San Francisco Converter Station site. The site has no standing buildings or structures and lies on land that was reclaimed from San Francisco Bay early in the twentieth century.

A.4.2.3.2   Construction Parking. During construction, parking would be permitted outside of the active work zone in designated areas within the converter station site boundaries and/or offsite at adjacent properties. Onsite parking areas would be designated as necessary during construction activities. The parking areas would be fenced and controlled by security personnel during normal work hours.

A.4.2.3.3   Construction Utilities. During construction, temporary utilities would be provided for the Project sites and laydown areas. Temporary construction power would be supplied initially by generator and, when available, by a temporary connection to the local distribution system. Area lighting would be provided and strategically located for safety and security.

Water for construction would be provided by the City of San Francisco. Portable toilets would be provided throughout the site for sanitation purposes.

A.4.2.4   Pittsburg Converter Station

The proposed Pittsburg Converter Station would occupy 5.4 acres of a 7.5-acre parcel (the Standard Oil site) in the City of Pittsburg. The site 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 dilapidated building. The site was most recently occupied by an automobile storage yard. Before construction of the proposed converter station commenced, the site would be cleared of all structures and stored materials.

A 64-foot-high valve and converter transformer building would occupy approximately 23,000 square feet at the site. Outdoor air-cooled radiators, transformers, and AC filters would occupy the balance of the site. The site would receive an architecturally appropriate treatment in areas that are visible to the public on the south and west sides. An acoustical barrier approximately 10 feet high would be erected around a portion of the converter station and an acoustical barrier approximately 13 feet high would be erected around a portion of the emergency generator. If final design determined that an acoustical barrier were unnecessary, it would not be required.

A.4.2.4.1   Laydown and Storage. An area of up to approximately 7 acres would be located on vacant property adjacent to and north of the site and would be devoted to equipment and materials laydown, storage, parking of construction equipment, small fabrication areas, and office trailers for the Pittsburg Converter Station site. Temporary construction parking, staging, and storage areas would be developed by clearing/grubbing/ removing topsoil from unimproved areas that would receive vehicular traffic and laydown. Minor leveling of the laydown area would be performed, as necessary. Topsoil would be stockpiled in windrows or piles adjacent to the staging area. The exposed subsoil would be covered with stabilized fill, as necessary. Upon completion of construction, the temporary laydown area would be restored.

A.4.2.4.2   Construction Parking. General construction parking details would be similar to those described in Section A.4.2.3.2 for San Francisco.

A.4.2.4.3   Construction Utilities. During construction, temporary utilities would be provided for the Project sites and laydown areas. A portable generator would supply temporary construction power initially. When available, construction power would be supplied by a temporary connection to the local utility distribution system. Area lighting would be provided and strategically located for safety and security.

Water for construction would be provided by the City of Pittsburg. Portable toilets would be provided throughout the site for sanitation purposes.

A.4.3   Construction Equipment and Materials Delivery

Table A.4-3 provides an approximate tabulation of construction equipment to be used for the Project. Truck deliveries of equipment and materials would normally occur only during daylight hours. There could be need for offloading and or transporting to the sites on the weekend, but not as a general rule. The estimated average daily frequency of truck deliveries is presented in Table A.4-4.

Materials such as wire and cable, fuels, reinforcing steel, and small tools and consumables would be delivered to the site laydown areas by truck. The heavy equipment items would be transported by ship to the marine terminal at the Port of Oakland. Standard sized containers (approximately 700 total) would be used to the maximum extent possible. Containerized equipment and material would be off-loaded at the marine terminal and transported to the site by truck. Heavier and/or breakbulk items (e.g., transformers) would be offloaded at the marine terminal and transported by rail and/or truck to the site. Approximately 1,330 tons of equipment would be shipped for each converter station.

A.4.3.1   HVDC Cable Transportation

The Prysmian cable ship (C/S) Giulio Verne (refer to Figure A.4-3) is equipped with a state of the art turntable platform for the storage of the HVDC power cable and laying equipment, and would be rigged to allow the stowage of the medium voltage (MV) metallic return and optical cables. Upon completion of all the rigging operations the submarine cables would be loaded onboard the C/S Giulio Verne.

An installation barge could be used for cable laying in shallow water, therefore, part of the cables would be unloaded on board the cable installation barge before starting the laying activity.

In the event that the cables were to be shipped from the factory to the site by means of a transportation vessel other than the C/S Giulio Verne, a complete cable transfer to the laying vessel and/or to the installation barge would occur prior to starting the laying activity.

A.4.4   HVDC Transmission Lines

The Project would use a variety of construction methods for the HVDC transmission line. The particular method used for a specific segment of the project would depend upon several factors, including being landside or offshore, distance from shore, sediment characteristics, and depth of water and depth to bedrock.

The main HVDC, metallic return, and fiber optic cables would be bundled and laid simultaneously. Over the proposed route, protection to both the cable and the environment would be accomplished through:

A.4.4.1   Submarine Cable Installation Equipment and Procedures

Specialized equipment and procedures developed for efficient installation of buried submarine cables would be utilized.

A.4.4.1.1   Submarine Cable Laying Vessels. The proposed Project would use Prysmian HVDC cable design and installation technology.

The C/S Giulio Verne would be used from San Francisco landfall to the west end of Pinole Shoals and from the east end of Pinole Shoals to the west end of Suisun Bay across the Carquinez Strait.

Cable installation across Pinole Shoals and from the west end of Suisun Bay to Pittsburg landfall would be carried out by a cable installation barge.

The above laying scenario involves the assembly at sea of 3 joints on the cable system: 1 joint at the west end of Pinole Shoals, 1 joint at the east end of Pinole Shoals and 1 joint at the west end of Suisun Bay.

Alternative cable laying scenarios are under consideration which may require a minor number of joints to be assembled in the bay (from 0 to 3 joints). One scenario includes the possibility of laying the cable across Pinole Shoals with C/S Giulio Verne (basically cable laying with C/S Giulio Verne from San Francisco landfall to the west end of Suisun Bay and laying with the installation barge from this point to Pittsburg landfall). Another scenario includes laying the cable across the Carquinez Strait with the installation barge up to the west end of Pinole Shoals (basically cable laying with C/S Giulio Verne from San Francisco landfall to the west end of Pinole Shoals and cable laying with the installation barge from this point to Pittsburg).

The final selection of the laying set-up would be defined once the marine survey data were available.

A.4.4.1.2   Submarine Trenching and Cable Burying Machines. The cable would be buried using the Hydroplow burial machine or other equivalent cable-laying technology whose sediment disturbances are similar to those of the Hydroplow. The working principle for the Hydroplow would be to fluidize the seabed materials in a narrow path and to a predetermined depth without displacing the majority of the material and therefore minimizing the suspension of sediment in surrounding waters. The fluidizing effect would provide relatively low and controlled towing forces. The method has been positively shown to place fiber optic cables and power cables at a consistent required depth of embedment in all jettable bottom conditions.

During cable installation (refer to Figures A.4-4 and A.4-5), the Hydroplow would straddle the cable, create a trench below the cable and guide the cable into the trench. The trench would then partially collapse after the passage of the burial machine and the remaining part would be generally filled by natural sediment deposition.

The Hydroplow is capable of both simultaneous lay and burial operations and post-lay burial operation. In the first case, the Hydroplow would be operated and towed by the cable laying vessel/installation barge. The cable would then be simultaneously laid and buried during the same operation. The sediment plume and local water turbidity levels created by the Hydroplow water jet cable burial machines vary with burial depth, tide, current, and soil characteristics. Additionally, natural turbidity is often prevalent in the areas where cables are to be installed. Typically, a light sediment plume surrounds the Hydroplow in full operation, and the plume quickly dissipates as the Hydroplow proceeds, leaving little or no spoil ridges alongside the trench. It is estimated that approximately 10-20 percent of the disturbed sediment would be dispersed into the bay. This percentage is an indicative figure which could vary depending on soil conditions, trench depth, etc.

The Hydroplow would be towed by the laying vessel/barge in case of simultaneous lay and burial operation or a support vessel/barge in case of post-lay burial operation. The support vessel/barge can be propelled with dynamic positioning or kedging on anchors.

A.4.4.1.3   Dredging. While there are several locations where the cable route would cross dredged shipping channels, there are only two locations where dredging would be required to bury the cable at an adequate depth to ensure that future dredging (e.g., by the U.S. Army Corps of Engineers [USACE]) does not encounter the cable. A standard clamshell dredge (or hopper dredge) could be used to create a deep trench at ship channel crossings. To obtain maximum efficiency and minimize interference with vessels using the shipping channels, this trenching would normally be completed before the cable-laying vessel began its work. If the dredged material was not replaced in the excavation, natural sediment deposition would likely completely fill the excavated areas in less than 2 years.

A.4.4.1.4   Direct Cover with Protective Mattresses. At several locations, the HVDC cable route would cross existing cable and pipeline crossings or rocky bottoms, where a trenching machine (e.g., Hydroplow) may not be used. In these locations, a protective cable cover would be provided by laying protective mattresses (e.g., concrete mattresses filled with mastic grout and internally lined with a geotextile) or other protective materials over the cable on the bay floor. Where an existing cable or pipeline would be exposed, mattresses may also be placed on the bay floor on top of the existing pipe or cable before the proposed Project cable system was laid in order to provide a physical separation between the utility to be crossed and the Proposed project cable system (refer to Figures A.4-6 and A.4-7). Separation sleeves installed directly on the proposed project cable system could also be used in place of mattresses to provide physical separation.

A.4.4.1.5   Horizontal Directional Drilling (HDD) at Cable Landfall. The method being considered for installing the HVDC cable as it crosses the shoreline is installation of conduits by means of HDD. Photos of typical HDD operations are shown on Figure A.4-8. At the landfall near Potrero Point in San Francisco, the proposed HDD operation is shown on Figure A.4-9. The proposed HDD installation of AC and DC cables at the landfalls at the east end of New York Slough and at the Mirant Pittsburg Power Plant site in Pittsburg are shown on Figures A.4-10 and A.4-11, respectively. The following typical HDD installation methodology is expected to be used subject to final engineering.

If this method were used, the DC and AC cables would have a clear passageway from the water to the land that would not disturb the sensitive environmental conditions that often exist along shorelines. Two holes would be drilled and a steel or high density polyethylene (HDPE) pipe installed to accommodate the HVDC, MVDC, and fiber optic cables at the Pittsburg landfall. A larger third bore would be drilled for the installation of the 3, 230 kV AC cables. A single hole would be drilled at the Mirant Pittsburg Power Plant crossing for bringing the 230 kV cables ashore to interconnect with the Pittsburg substation. If a single bore solution were infeasible due to final cable design and/or soil conditions, it could be necessary to use a 3-bore solution.

An area up to 100 feet by 200 feet would be required to set up the drilling rig and associated equipment. In the event the soil at the drilling site were found to be contaminated or to have too much concrete and metal debris content, a cofferdam consisting of a steel casing would be driven into the soil at a shallow angle. The interior of the casing would be excavated, limiting the volume of contaminated soil for disposal and isolating the bore hole from contamination. At the completion of the operation, the casing would be grouted and left in place, providing a barrier against contaminant migration.

Special fluid would be used to lubricate the drill head and remove the waste from the hole. There would be a system at the site for collecting the cuttings that came out of the drill hole and for recovering the drilling fluid (also known as drilling mud). A Spill Prevention Control and Countermeasures Plan would be prepared and implemented for all HDD operations.

Two rigs would be used, 1 ashore and 1 on a barge. A pilot hole would be drilled initially and a guidance and monitoring system would be used to control the direction of the pilot hole. With the pilot hole completed and the drill bit "punched out" onto the Bay floor, a small quantity of drilling fluid may be released. As an alternative, a conductor barrel can be installed in the Bay floor and the drilling fluid brought to the surface and collected on the barge. The drill stem would be recovered from the waterside. The pilot hole would be reamed out to the required size and the steel or HDPE pipe installed. Cuttings would be stored at the drilling site and disposed of at an approved waste facility. After completion of the reaming and the pipe installation, the ends of the pipes would be sealed until the cables were ready to be installed. Other containment systems (curtain system, etc.) may be considered as an alternative.

This technology would also be used to install a portion of the proposed AC/DC cable route between the proposed Standard Oil Converter Station site in Pittsburg and the crossing of Kirker Creek and adjacent wetlands (refer to Map A.2-1; Sheet 10 of 10 for approximate location).

A.4.4.2   Survey and Route Design

Surveying for construction of a transmission line segment would include engineering and property line surveys, and in this application, marine surveys. The engineering survey collects topographic and feature detail for use in the design of the transmission structures. Land surveys would be performed to develop legal descriptions of the ROW easements. The survey corridor covers a buffer area on either side of the centerline of the route.

A detailed survey of the bay floor will be performed along the proposed cable route to evaluate geology and topography as well as possible obstacles. To guide selection of cable burying equipment and procedures, a core-sampling program for bay floor sediments would be implemented. This sampling program would be used in conjunction with existing data and surveys (e.g., TBC environmental survey already performed, and USACE data associated with the bay maintenance-dredging program). Sonar devices would be used to detect both natural and man-made obstructions. Electromagnetic devices would be used to detect and precisely locate existing cables and pipelines that cross the cable path. The proposed cable route was selected to avoid shipping channels, anchorages, dredge disposal areas, and other known obstacles.

A.4.4.2.1   Pre-lay Grapnel Run. The pre-lay grapnel run would be carried out before the cable installation if deemed necessary during the detailed engineering process. Prior to cable installation, a small vessel would be equipped with grapnels designed to be towed along the cable route.

The grapnel would catch and remove small debris on the seabed surface, such as wire ropes and nets, that may interfere with the installation of the new cables. Discarded wire ropes would be caught with the grapnel and would either be parted at the seabed or be recovered to the surface and cut. Other debris would be caught and moved off the route centerline.

A.4.4.3   Submarine Cable Installation

The proposed HVDC cable would be buried underwater in San Francisco Bay, San Pablo Bay, the Carquinez Strait, Suisun Bay, and New York Slough. Typical target burial depths for the cable would be 3 to 6 feet, with the potential for local burial to greater depths if required, in areas of the bay containing soft sediments. Depths are expected to vary in response to the geophysical makeup of the bay floor sediments. If appropriate, as determined by existing conditions of the Bay floor, portions of the cable would be placed on the surface of the Bay floor and a system of concrete mattresses would be placed over the cable to provide added protection.

A preliminary description of the DC cable laying operation is presented in this section. The following assumptions are made:

Alternative cable laying scenarios are under consideration as discussed in Section A.4.4.1.1. Operations of the C/S Giulio Verne and the installation barge would be executed either simultaneously or one vessel first and the second one after depending on the laying scenario that was implemented.

During the final engineering process, detailed installation procedures would be developed for the chosen alternative (Refer to Section A.4.4.1.1). These may differ from the preliminary procedures described below.

A.4.4.3.1   Cable Laying with Installation Barge. Suisun Bay and probably Pinole Shoals are too shallow for the cable ship Giulio Verne to operate. In these areas cable installation by barge is foreseen.

A transportation vessel or the C/S Giulio Verne would arrive with the cables to be transferred to the cable installation barge. This loading would be performed continuously until the appropriate length of cable was aboard the cable installation barge.

Mooring of Cable Installation Barge. The cable installation barge would be towed to the starting point of the barge laying operation. With the cable installation barge held in position by 1 tugboat, the second tug would receive an anchor from the cable installation barge. The tug would position the anchor in a pre-determined location as mooring wire attached to the anchor is deployed from the cable installation barge's mooring winch. This anchor deployment would be repeated until all anchors were deployed. In addition to the cable installation barge mooring wire attached to the anchor shank, each anchor would have a wire leading to a buoy floating on the surface. These wires would allow the anchor tug to lift the anchor to the surface and re-position the anchor to a new location.

Deployment of Cable Ends. The cable ends would be sealed with caps. A stopper would be applied on board on the cable end and connected to a steel wire of appropriate length. At the end of the steel wire a dead weight would be attached in order to keep the steel wire in position and to ease the recovery operation at the beginning of the following phase of the cable laying operation. The positions of cable end and dead weight would be logged.

The cable installation barge would deploy the dead weight first, then it would move along the cable route as the steel wire is paid out and laid on the seabed. The cable heads would be paid out as the cable installation barge continued to move along the cable route. This cable end deployment would allow the C/S Giulio Verne to return to the position of the steel wire and then recover the cables for splicing to the cables for the following cable laying operation.

Simultaneous Barge Cable Lay and Burial. The cable installation barge would stop to deploy the Hydroplow on the cable route when an appropriate length of cable was laid on the seabed. The Hydroplow tow wire, water hose, and umbilical line would be connected to the Hydroplow before launching. A crane would lift the Hydroplow from the deck and place it on the Bay floor where divers would disconnect the crane and the Hydroplow would be prepared for cable burial.

The cable installation barge would tow the Hydroplow along the cable route, the water jets would be activated, and the stinger would be lowered down to full burial depth. The cables would be paid out through the cable chute positioned at the stern of the cable installation barge.

A combination of GPS and the telemetry system which provides all Hydroplow data (attitude, burial depth, location) would be monitored as the Hydroplow buries the cable system. As the cable installation barge was moved along the cable route, the anchor handling tugs would be recovering anchors and re-positioning them to accommodate cable installation barge movement. The mooring winches would be pulling and paying out the anchor wires in a coordinated sequence to move the cable installation barge along the route.

The navigation/survey computers would be displaying and recording positioning data of the cable installation barge and Hydroplow during the cable laying sequence. Telemetry parameters would also be displayed and recorded. This recorded data would be used to produce the as-built reporting.

Ship Channels. A limited dredging effort would be required to install the HVDC and HVAC cables where the routes cross ship channels in New York Slough. The dredging would occur in 2 locations. The first location would be at the west end of the West Reach, northeast of the Mirant Pittsburg Power Plant at approximately MP 52.5 of the HVDC cable route (and approximately MP 1 of the HVAC cable route). The second location would be just east of the Dow Chemical Plant property in Pittsburg as shown on Map A.2-1, Sheet 10 of 10, at approximately MP 56 of the HVDC cable route (and approximately MP 4.5 of the HVAC cable route). At these locations, the 2 cables would cross the existing shipping channel in New York Slough. The channel in these areas is between 45 and 50 feet deep. The USACE routinely performs maintenance dredging of the channel in these areas to a depth of 37 feet and, therefore, dredging below the routine dredge depth would be required to allow installation of the cables at a safe depth.

The requirement to excavate a cable trench would be similar in both areas. At each location, it would be necessary for the dredge to excavate approximately 38,000 cubic yards of material. These excavations would provide a trench approximately 400 feet long by 30 feet wide at the bottom of the excavation by 15 - 20 feet deep beneath the bay floor, in which the 2 cables would be installed. The sides of the trenches would be sloped at 4 feet horizontal to 1 foot vertical. The trench would be backfilled after the cables were installed.

The dredging method would utilize a barge-mounted crane excavating with a clamshell bucket. Excavated material would be brought to the surface and deposited on a barge. The USACE and private firms regularly use this method to perform maintenance dredging of shipping channels and ship docks in the bay. An alternative would be to carry out dredging by using a hopper dredging system.

During the dredging process, material excavated and loaded on the barge would be sampled and tested in a laboratory to determine its acceptability for reuse as backfill. Preliminary results for sediment samples taken at the 2 proposed dredge locations as part of the TBC Bay Survey indicate that the material to be dredged would be acceptable for backfill in the excavated dredge areas. If the excavated material were ultimately determined to be acceptable, the material would be stored on the barge until the HVDC and HVAC cable installation was complete. At that time, the excavated material would be taken off the barge and returned to the sea bottom as backfill. If testing determined that the material was unacceptable for reuse as backfill, the material would be transported to an acceptable disposal site. One possible use for such material would be to support on-going wetland reclamation projects in the area.

A.4.4.3.2   Pittsburg Landfall. The cable installation barge would be maneuvered to start the final cable landing operation at the pre-installed conduit ends (as described in A.4.4.1.5 above). Each cable would be floated separately, 1 cable at a time. The distance to the end on land, including the conduit, would be measured. The length of cable required to reach the end on land would be calculated in order to cut the cable at the correct position.

Each cable would be paid out from the cable installation barge with floats attached. This floating cable would be in the shape of a circle or omega as the entire final length of cable was paid out from the cable installation barge. Small boats would manage the configuration of this floating cable. When the final end of the cable reached the stern of the cable installation barge, it would be connected to the pulling wire. Each cable would be pulled separately.

A shore-pulling winch would begin to pull the cable ends into the conduit. Divers would monitor the entry of the cable into the conduit. The divers would remove floats from the cable just before the cable reached the conduit end. The cables would be suspended in catenaries between the water surface and the conduit as the floats were removed and the cable pulled. When cable-pulling operations were completed, the offshore section of cable would be buried by Hydroplow or by divers using hand-jetting systems.

A.4.4.3.3   Cable Laying with C/S Giulio Verne. The C/S Giulio Verne would move to the location where the cable ends had been previously left on the seabed by the cable installation barge. The cable ends would be recovered by grappling the wire inserted between cable end and dead weight. The operation would be carried out directly by the lay vessel.

Once the cable ends were secured on board, the splicing operation between cable lengths from sea and cable lengths on board would take place. The splicing operation would take approximately 10 days.

Simultaneous Lay and Burial. The Hydroplow would be launched as described above. The Hydroplow, towed by the C/S Giulio Verne, would activate the water jets and begin burial. The vessel would move along the cable route as the cables were paid out, laid on the seabed and buried by the Hydroplow. The C/S Giulio Verne would use dynamic positioning (DP) control system; anchors as described the cable installation barge method would not be required.

During the laying operation, the main parameters such as vessel position along the route, cable payout length, water depth, and cable tension would be monitored and recorded. Control of the cable laying operation would be based on the evaluation of the continuously monitored data.

The C/S Giulio Verne would continue the cable lay and burial operation up to MP 0 near Potrero Point in San Francisco.

A.4.4.3.4   San Francisco Bay Shore End. As the vessel approached the final landing position it would turn parallel to the bay shore. Once in position, the cable landing operation would start. The cable ship would be dynamically positioned at an approximate water depth of 35 feet (about 2,000 feet off shore) in line with the exit conduit coming from shore. The ship would maintain position using its own thrusters controlled by its dynamic positioning system. No anchors, spuds or other devices touching the sea bottom would be used.

The distance to the end point on land would be measured for the cable cut. Each cable would be floated separately. The cable would be paid out from the C/S Giulio Verne. Floats would be attached to each cable as it left the C/S Giulio Verne. These floating cables would be in the shape of circles or omegas as the entire final length of cables was paid out. Small boats would manage the position of the floating cables. It is possible that a barge would be used to assist C/S Giulio Verne during the cable floating operation.

When the ends of the cable reached the stern of the vessel the cable ends would be floated and taken to the conduit ends by a service boat. When the cable ends approached the conduit end each would be connected to the main pulling wire that would extend from a shore winch through the conduit.

The cables would be pulled to shore each through a conduit separately, 1 cable at a time. The shore-pulling winch would begin to pull the first cable end into the conduit. Divers would monitor the entry of the cable into the conduit. The divers would remove floats from the cable just before the cable reached the conduit end. The cable would be suspended in catenaries between the water surface and the conduit as the floats were removed and the cable was pulled.

A similar operation would be performed for the metallic return and fiber optic cables. When the cable pulling operation was completed, the section of cable remaining exposed on the Bay floor would be buried using the Hydroplow or by divers using hand-jetting systems.

A.4.5   Landside Underground HVDC Cable Installation

A short length of HVDC cable connecting the submarine cable to the landside cable is required. This connection would occur with a sea/land joint between submarine and land cable (close to the exit on land of the conduit) which would extend up to the cable termination at the converter station. In some cases, it may be possible to install the submarine cables up to the termination point at the converter. In this event, a joint would be unnecessary.

A.4.5.1   Landside Cable Trenching and Burial

The elements of typical landside underground construction include ROW clearing, excavation and/or trenching, shoring, bedding and laying of cable, backfill and compaction, and restoration.

Typical cut-and-cover trenching and burial techniques would be used to bury the cable to a depth of approximately 4 feet. Backfill with appropriate thermal properties would be installed up to a certain level to protect the cable and ensure heat dissipation during operation. The remainder of the trench would then be backfilled with indigenous excavated material.

A.4.5.2   HDD

HDD or comparable technology may be used in several locations to install landside cable (e.g., in areas between the proposed Standard Oil Converter Station in Pittsburg and south of the BNSF Railroad ROW). A drill pit approximately 75 feet square would be prepared on each end of the area to be drilled. HDD equipment would be placed in the pit and used to bore a hole from the pit to a predetermined point on the opposite end. A pipe casing would be pushed or pulled through the borehole to maintain the opening and provide a protective conduit and path for installation of the cable. The process would finish by pumping bentonite clay slurry to fill the annular space around the cable and to provide positive heat dissipation.

A.4.6   HVAC Interconnections Construction

The proposed Project would require HVAC interconnections between the San Francisco Converter Station and Pacific Gas and Electric Company's (PG&E) Potrero substation and between the Pittsburg Converter Station and PG&E's Pittsburg substation.

A.4.6.1   San Francisco

A.4.6.1.1   Three-phase Transmission Line. A double-circuit, 3-phase 115 kV underground transmission cable or above ground transmission line would deliver AC power approximately 0.3 mile from the AC switchyard at the San Francisco Converter Station to the PG&E Potrero Substation.

A.4.6.1.2   Tie-in to PG&E Potrero Substation. The double-circuit AC line would connect into the existing Potrero substation.

A.4.6.2   Pittsburg

A.4.6.2.1   Three-phase Underground and Submarine Transmission Cable. A new 3-phase 230 kV underground transmission cable would deliver AC power from the Pittsburg substation to the AC switchyard at the Pittsburg Converter Station. The 5.5-mile-long cable route includes 4 miles of offshore line and 1.5 miles of onshore line. Onshore and offshore portions would be installed using the same techniques as described previously for the HVDC cable.

A.4.6.2.2   Tie-in to PG&E Pittsburg Substation. The proposed HVAC cable would connect into the existing PG&E Pittsburg Substation. PG&E would be responsible for engineering and for construction oversight and approval. PG&E may procure equipment and construction or may have the Project Proponent provide procurement and construction.


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