Load Block a Projects

V. SYSTEM ADDITIONS AND UPGRADE PROJECTS

V-1 Introduction

Additions and upgrades recommended for the Southern Maryland Electric Cooperative (SMECO) transmission system for this Electric Transmission System Long Range Plan (TLRP) are identified by analyzing system performance during normal and single contingency outage operation for each of the three load blocks. The tables below list the projects recommended for each load block along with cost estimates for each project. Subsections discuss general topics of shunt capacitor banks and 230 kV line construction upon which the individual project costs are based. Subsections under each load block contain further discussion about justification and costs for the projects.

The recommended transmission system additions and upgrade projects are given a project number according to Rural Utilities Service (RUS) guidelines as outlined below:

 5xx Modified Substations  8xx New Transmission Lines  9xx New Switching Stations  10xx Modified Transmission Lines and Switching Stations

Each RUS project number in the following tables also has a letter (A, B, or C) in front of the number. The A, B, or C corresponds to the load block in which that project is recommended for construction.

The Recommended Projects tables contain a Project Priority column that lists the order of projects that should be constructed first should there be constraints on the number of projects to be built.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 1 Costs for 69 kV transmission line terminations at switching stations and substations, estimated to be $410,000, are included in the Transmission System Improvements summary tables below. The termination costs include one 69 kV circuit breaker with disconnect switches and surge arresters. Also included are support structures, foundations, labor (assumes $100/hour) and material. Termination costs are listed for existing stations that are receiving new transmission line connections. New distribution substations and transmission switching stations with transformer additions have the required terminal costs for new lines recommended in the same load block included in the project cost estimates. Cost estimates for the 69 kV transmission line terminations are included in Appendix E, Cost Estimates.

The transformer addition at Hewitt Road Switching Station requires a 230 kV transmission line termination in Load Block C when the 230 kV line from Hellen Creek Switching Station is added. Estimated cost for a 230 kV termination is $600,000 including a 230 kV circuit breaker, disconnect switches, surge arresters, support structures, foundations, labor (assumes $100/hour) and material. Cost estimates for the 230 kV terminations are included in Appendix E, Cost Estimates.

The 230 kV transmission line from Hellen Creek Switching Station to Hewitt Road Switching Station will require a cable crossing of the Patuxent River near Solomons Island. The 230 kV cable will be approximately two miles long and will require jetting or plowing to trench the cable in the river bottom. Estimated cost of the two mile cable installation is $8,000,000.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 2 Table V-1: Load Block A (Year End 2007) Recommended Projects Project Project Project Project Description Len. Estimated Number Priority Type mile Cost A801 1 New Line 69 kV Mount Harmony-Dunkirk, 2.5 $1,175,000 1590 overbuild A501 AAC 69 kV terminal at Mount $410,000 Conductor Harmony A802 2 New Line 69 kV Bolton - Bensville, single 3.8 $1,178,000 1590 circuit A502 AAC 69 kV terminal at Bolton $410,000 Conductor A803 3 New Line 69 kV Indian Bridge - Redgate, 4.0 $1,140,000 556.5 single circuit ACSR Conductor A503 5 Capacitor 36 Mvar Bannister Capacitor $695,000 Bank A504 4 Capacitor 36 Mvar Ripley Switching $695,000 Station

HLY 29-688 Rev 0 (12/07/05) 106869 V - 3 Table V-2: Load Block B (2008-2015) Recommended Projects Project Project Project Project Description Len. Estimated Number Priority Type mile Cost B1001 1 Station 230/69 kV Holland Cliffs $9,370,000 Upgrade Switching Station B801 2 New line 230 kV Chalk Point - Holland 7.7 $1,709,000 2310W Cliffs, double circuit 1590 transmission, existing towers. AAC PEPCO Upgrades at Chalk Point Unknown Conductor B802 11 New line 69 kV Holland Cliffs - Dunkirk, 12.7 $3,940,000 1590 single circuit B501 AAC 69 kV terminal at Dunkirk $410,000 Conductor B803 3 New line 69 kV Holland Cliffs - 5.0 $2,350,000 1590 Huntingtown, overbuild AAC Conductor B804 6 New line 69 kV Huntingtown - 3.1 $1,460,000 1590 Sunderland, overbuild B502 AAC 69 kV terminal at Sunderland $410,000 Conductor B805 10 New line 69 kV Hawkins Gate - Westlake 5.9 $1,830,000 1590 South, single circuit AAC Conductor B806 7 New Line 69kV Hawkins Gate - Heritage 4.7 $2,210,000 1590 Green, overbuild AAC Conductor B807 14 New Line Heritage Green - Marshall’s 6.0 $2,820,000 1590 Corners Substation, overbuild B503 AAC 69 kV terminal at Marshall’s $410,000 Conductor Corner

HLY 29-688 Rev 0 (12/07/05) 106869 V - 4 Table V-2: Load Block B (2008-2015) Recommended Projects (continued) Project Project Project Project Description Len. Estimated Number Priority Type mile Cost B504 8 Station LaPlata GOAB for bypassing to $50,000 upgrade Marshall’s Tap (Structure is already on site) B808 9 New line 69 kV Indian Bridge – 2.0 $620,000 1590 Wildewood, single circuit AAC Conductor B809 12 New line 69 kV Hewitt Road – 5.0 $1,550,000 1590 Wildewood, single circuit AAC Conductor B1002 15 Upgrade 69 kV Mattawoman Tap – 2.2 $820,000 line Mattawoman 1590 With future distribution AAC underbuild B1003 13 Upgrade 69 kV LaPlata to Ripley Switch 7.0 $1,926,000 line 1590 AAC B1004 16 Station Enhanced protection of Chalk $795,000 upgrade Point 69 kV bus, additional 69 kV breakers on PEPCO lines 69101 & 69102 B1005 4 Station Third transformer at Hawkins $3,120,000 upgrade Gate Includes two 69 kV terminals (Westlake South and Heritage Green) B1006 5 Station Third transformer at Hewitt $3,015,000 upgrade Road Includes one 69 kV terminal (Wildewood)

HLY 29-688 Rev 0 (12/07/05) 106869 V - 5 Table V-3: Load Block C (2016-2025) Recommended Projects Project Project Project Project Description Len. Estimated Number Priority Type mile Cost C901 3 New 230/69 kV Switching Station $7,455,000 station near Hellen Creek C801 4 New line 230 kV Holland Cliffs – Hellen 23.5 $19,436,000 1590 Creek, double circuit AAC Conductor C802 9 New line 230 kV Hellen Creek – Hewitt 10.5 $7,963,000 1590 Road, single circuit on double AAC circuit tower Conductor C803 10 Cable 230 kV Patuxent River crossing 2.0 $8,000,000 near Solomons Island 230 kV terminal at Hewitt Road $600,000 C804 8 New line 69 kV Hewitt Road – Willows, 4.0 $1,240,000 1590 single circuit C501 AAC 69 kV terminal at Hewitt Road $410,000 C502 Conductor 69 kV terminal at Willows $410,000 C805 12 New line 69 kV Wildewood – Hollywood, 3.1 $961,000 1590 single circuit C503 AAC 69 kV terminal at Wildewood $410,000 C504 Conductor 69 kV terminal at Hollywood $410,000 C806 1 New line Hawkins Gate – Bensville 9.0 $2,790,000 C505 1590 69 kV terminal at Hawkins Gate $410,000 C506 AAC 69 kV terminal at Bensville $410,000 C807 2 New line 69 kV Bensville – Accokeek, 3.5 $1,085,000 1590 single circuit C507 AAC 69 kV terminal at Bensville $410,000 C508 Conductor 69 kV terminal at Accokeek $410,000 C1001 5 Upgrade 69 kV Bryantown Switching 1.5 $465,000 line Station – Bryantown Substation 1590 AAC. C1002 11 Upgrade 69 kV Hughesville – Cedarville 9.4 $2,917,000 line 1590 AAC C509 7 Capacitor 36 Mvar Bensville Substation $695,000 C510 6 Capacitor 36 Mvar Westlake South $695,000 Substation

HLY 29-688 Rev 0 (12/07/05) 106869 V - 6 V-2 Load Block A

Mount Harmony Substation to Dunkirk Substation 69 kV Line RUS No. A801 and A501

Justification: The Dunkirk Substation will initially be energized by a 69 kV, 1590 MCM AAC line from the Mount Harmony Substation. This is the shortest path and least problematic construction to get power to Dunkirk Substation. The line will be an overbuild of existing distribution lines and will not require significant new right-of-way. Estimated length of the line is 2.5 miles. The 1590 MCM AAC conductor will allow for future loop feeding through this line.

Cost: Estimated cost for 1590 MCM AAC 69 kV overbuild of 12.47 kV distribution lines is $470,000 per mile. This estimate is based on the costs for the Hughesville south Line 6750 overbuild project. The Mount Harmony Substation to Dunkirk Substation 69 kV line is approximately 2.5 miles and is estimated to cost approximately $1,175,000.

Bolton Substation to Bensville Substation 69 kV Line RUS No. A802 and A502

Justification: The Bensville Substation will be constructed during Load Block A. It is located near a PEPCO 500 kV transmission line the runs near both Bensville and Bolton Substations. The Bensville Substation will initially be energized with a new 1590 MCM AAC 69 kV line from the Bolton Substation. The PEPCO right-of-way may be used for the new 69 kV transmission line.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 7 Cost: Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Bolton Substation to Bensville Substation 69 kV line is approximately 3.8 miles long and is estimated to cost $1,178,000.

Indian Bridge Switching Station to Redgate Substation 69 kV Line RUS No. A803

Justification: The Redgate Substation will be energized from the Indian Bridge Switching Station on Line 6740. The Indian Bridge Switching Station will also serve the new Willows Substation to be energized during Load Block B. The Indian Bridge Switching Station to Redgate Substation 69 kV line requires new right-of-way through Saint Mary’s County.

Cost: Estimated length of the line is 4.0 miles. This will be a new 556.5 MCM ACSR 69 kV line. Estimated cost for this line construction is $285,000 per mile based on cost for the Hughesville north Line 6720 is $1,140,000.

Bannister Substation 36 Mvar Capacitor Bank RUS No. A503

Justification: Shunt capacitor banks are needed on SMECO’s transmission system to support system voltage during outage contingencies and to improve the system power factor for compliance with the bulk power supplier’s requirements. Power factor on the system supplied from Hawkins Gate Switching Station in most need of improvement. The

HLY 29-688 Rev 0 (12/07/05) 106869 V - 8 Bannister Substation is normally fed from Hawkins Gate Switching Station. During contingency outages of Line 6715 between Hawkins Gate Switching Station and Bannister Substation, Bannister may be fed through a long path from Hawkins Gate through the Waldorf, Westlake and Saint Charles Substations. In this case, the Bannister Substation capacitor bank will provide needed voltage support.

The Bannister Substation is located in the Saint Charles area of Charles County east of Saint Charles Lake Parkway along Saint Paul’s Drive. The substation has an area of about 25,200 square feet inside the existing fence. The capacitor bank may be connected to either the Hawkins Gate Switching Station Line 6716 or Saint Charles Substation Line 6723 side of the Bannister Substation. If either side is equally convenient for the connection, it is recommended that the capacitor bank be connected to the Saint Charles Substation Line 6723 side. Then if the Bannister Substation high side bus is split by opening the disconnect switches, the capacitor bank will stay on the weaker side of the substation where voltage support may be needed most. Since transmission normally (and during outage contingencies considered in this TLRP) loops through the substation the capacitor bank connection can be made according to engineering layout requirements of the substation.

Cost: The Shunt Capacitor Bank section of this TLRP indicated that the estimated cost for the 36 Mvar shunt capacitor bank is $695,000. This cost does not include the purchase of additional land at Bannister Substation.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 9 Ripley Switching Station 36 Mvar Capacitor Bank RUS No. A504

Justification: Shunt capacitor banks are needed on SMECO’s transmission system to support system voltage during outage contingencies and to improve the system power factor for compliance with the bulk power supplier’s requirements. Power factor on the system supplied from Hawkins Gate Switching Station is in most need of improvement. The Ripley Switching Station is normally fed from Hawkins Gate Switching Station. During contingency outages of Line 6713 or Line 6717 between Hawkins Gate and the Ripley Switching Stations, Ripley and the substations that it supplies may be fed through a long path from Farmington through the Accokeek and Masson Springs Substations. In this case, the Ripley Switch Station capacitor bank will provide needed voltage support.

The Ripley Switching Station is located in Charles County southeast of Route 225 on the north side of Ripley Road. The capacitor bank should be connected to the common switching bus so that it will be available for energization either from Mason Springs Substation or Marshall’s Tap.

The switching station has an area of about 14,500 square feet inside the existing fence. Lines radiate out from the fenced area in three directions. It is likely that capacitor bank engineering for this location will require space in addition to the existing fenced area.

Cost: The Shunt Capacitor Bank section of this TLRP indicated that the estimated cost for the 36 Mvar shunt capacitor bank is $695,000. This cost does not include the purchase of additional land.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 10 V-3 Load Block B

Holland Cliffs Switching Station 230/69 kV Upgrade RUS No. B1001

Justification: A 230 kV upgrade is recommended at Holland Cliffs Switching Station to provide a regulated source for northern Calvert County. A 69 kV regulated bus at Holland Cliffs Switching Station is required to provide adequate voltage for the substations in northern Calvert County during normal and contingency system operation. The firm capacity of the 69 kV Chalk Point metering point is limited by the existing PEPCO 230/69 kV transformer capacities and SMECO’s combustion turbine. SMECO’s load on this metering point must be relieved during Load Block B. The upgraded Holland Cliffs Switching Station will be the beginning of a 230 kV loop to a switching station in southern Calvert County (near Hellen Creek) and on to the Hewitt Road Switching Station in Saint Mary’s County. SMECO has approximately seventeen acres at the existing Holland Cliffs Switching Station site to accommodate this station expansion.

Cost: Cost estimates for the recommended Holland Cliffs Switching Station upgrade are in the table below. These costs include the 230 kV switchyard with six 230 kV circuit breakers needed to form a 230 kV ring bus. The ring bus provides for connecting two lines from Chalk Point, two lines to a new Hellen Creek Switching Station in southern Calvert County, and two 230/69kV transformers to serve northern Calvert County. These three phase 230/69 kV transformers are rated at 135/180/224 MVA each. The 69 kV side of the Holland Cliffs Switching Station includes nine 69 kV circuit breakers arranged in a breaker and a half arrangement for connection of the two transformers and four 69 kV transmission lines. Sectionalizing switches are included on both sides of the transformers between the transformers and the circuit breakers.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 11 Costs assume a labor rate of $100 per hour, removal of the existing 69 kV switching station, grading of the land and a chain link fence around the station. For maximum reliability, transformers should not be connected to adjacent breakers on the 230 kV ring bus or in the same bay of 69 kV breakers. A cost estimate summary is included in Appendix E, Cost Estimates.

Table V-4: Holland Cliffs Switching Station Estimates of Probable Cost Description Estimated Cost Outdoor Equipment $5,775,000 Tubular Steel Structures $477,000 Foundations $735,000 Cable and Conduit $163,000 Control House $610,000 Site Improvements $440,000 Testing and Energization $117,000 Subtotal $8,317,000 Contractor Mobilize and Demobilize $25,000 Construction Management $250,000 Engineering $332,000 Subtotal $8,924,000 Contingency $446,000 Total Estimated Cost $9,370,000

HLY 29-688 Rev 0 (12/07/05) 106869 V - 12 Chalk Point to Holland Cliffs 230 kV Line Costs: In addition to the upgraded Holland Cliffs Switching Station, there are transmission line upgrades associated with the 230 kV lines from PEPCO’s 230 kV switch yard at Chalk Point to Holland Cliffs. Estimated additional costs associated with SMECO’s 230 kV lines 2310E and 2310W are shown in the table below. It is assumed that the existing line 2310E is already insulated for 230 kV operation. Note that this cost does not include work or equipment required inside PEPCO’s 230 kV switchyard. The existing Line #2310E has a few wooden poles near the Chalk Point complex that are currently routed to the SMECO 69 kV switchyard. Replacement of these few wooden poles and re-routing the pole line over to the PEPCO 230 kV switchyard will require some engineering and is not included in the table.

Table V-5: 230 kV Chalk Point-Holland Cliffs Lines Estimates of Probable Cost Description Estimated Cost Insulator assemblies for new line 2310W $100,000 Conductor for line 2310W $462,000 Miscellaneous Material $30,000 Construction $925,000 Subtotal $1,517,000 Contractor Mobilization and Demobilization $25,000 Construction Management $46,000 Engineering $40,000 Subtotal $1,628,000 Contingency $81,000 Total Estimated Cost $1,709,000

HLY 29-688 Rev 0 (12/07/05) 106869 V - 13 Chalk Point Station to Holland Cliffs Switching Station 230 kV Line RUS No. B801

Justification: The Holland Cliffs Switching Station will need a 230 kV source from Chalk Point Station. The existing SMECO Line 2310 structures are designed for double-circuit 230 kV operation. Line 2310 is constructed with one circuit and that circuit is presently operated at 69 kV. In Load Block B the existing line will be converted from 69 kV operation to 230 kV operation. Also, in Load Block B a the second circuit will be added to the Line 2310 structures between Chalk Point Station and Holland Cliffs Switching Station; both circuits will be operated at 230 kV.

Cost: Estimated length of the line is 7.7 miles. The existing Line 2310 circuit will be converted to 230 kV operation. The second 230 kV circuit will require adding insulators and conductors to the existing structures. Both circuits will be 1590 MCM AAC conductor except for the Patuxent River crossing where the conductor (already installed) is 1590 MCM ACSR. The ACSR conductor was used at the river crossing due to its additional strength for this long span. Estimated cost for this line construction is $1,709,000.

Holland Cliffs Switching Station to Dunkirk Substation 69 kV Line RUS No. B802 and B501

Justification: The Dunkirk Substation is initially energized radially from Mount Harmony Substation by way of a radial connection from Chalk Point Switching Station (Line 2310E) through Holland Cliffs Switching Station (Line 6783), and Sunderland Substation (Line 6785). A contingency outage of any of these lines will leave at least Dunkirk Substation without service. This new Holland Cliffs Switching Station to Dunkirk Substation 69 kV line is

HLY 29-688 Rev 0 (12/07/05) 106869 V - 14 required to provide an alternative loop feed to northern Calvert County. The line should be fed from the new 230/69 kV Holland Cliffs Switching Station. This will be a regulated voltage source and provide a good source to Dunkirk, Mount Harmony, and Sunderland Substations during both normal and contingency conditions.

Cost: Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Holland Cliffs Switching Station to Dunkirk Substation 69 kV line estimated at 12.7 miles long with a cost of $3,940,000.

Holland Cliffs Switching Station to Huntingtown Substation 69 kV Line RUS No. B803

Justification: Recommended service to the Huntingtown Substation is from a 69 kV line from the new 230/69 kV Holland Cliffs Switching Station. The planned location for the Huntingtown Substation is on Route 524 in northern Calvert County. This location is not near any existing transmission line. The closest line is Line 6782 between Holland Cliffs Switching Station and Sunderland Substation. Distance to the line is approximately 3.5 miles. A Line 6782 loop through the Huntingtown Substation would add about seven miles to the main transmission path serving northern Calvert County and produce additional problematic voltage drop. If the Huntingtown Substation is relocated, system performance should be re-evaluated from both distribution and transmission considerations.

Cost: The new 1590 MCM AAC 69 kV transmission line from Holland Cliffs Switching Station to Huntingtown Substation will be an overbuild of existing 12.47 kV distribution lines. Estimated cost for the overbuild based on the Hughesville south Line 6750 cost is

HLY 29-688 Rev 0 (12/07/05) 106869 V - 15 $470,000 per mile. The Holland Cliffs to Huntingtown line will be approximately 5.0 miles long and is estimated to cost approximately $2,350,000.

Huntingtown Substation to Sunderland Substation 69 kV Line RUS No. 804 and B502

Justification: The line from the new Huntington Substation to the Sunderland Substation will be part of the loop feed options for the Huntingtown Substation and northern Calvert County. It will allow Huntingtown Substation to be fed from either the new 69 kV line from Holland Cliffs Switching Station or this new Huntingtown Substation to Sunderland Substation 69 kV line.

Cost: The new 1590 MCM AAC 69 kV transmission line from Holland Cliffs Switching Station to Huntingtown Substation to Sunderland Substation will be an overbuild of existing 12.47 kV distribution lines. Estimated cost for the overbuild based on the Hughesville south Line 6750 cost is $470,000 per mile. The Huntingtown Substation to Sunderland Substation 69 kV line will be approximately 3.1 miles long and is estimated to cost approximately $1,460,000.

Hawkins Gate Switching Station to Westlake South Substation 69 kV Line RUS No. B805

Justification: The Westlake South Substation is in the Waldorf high growth area. More transmission capacity is needed for this area both to support normal load growth and to allow for contingency operation during outages of Line 6713 from Hawkins Gate Switching Station to Bannister Substation or Lines 6733 or 6710 from Hawkins Gate Switching

HLY 29-688 Rev 0 (12/07/05) 106869 V - 16 Station to Forest Park and Waldorf Substations. This new 69 kV line goes into the heart of the high growth commercial area where more power will be need during Load Blocks B and C. From Westlake South Substation, the new line can supply power south toward Saint Charles Substation or north toward Waldorf Substation. The base case system configuration for Load Block B shown in Appendix B has this new line normally feeding the Westlake South 1, Westlake, and Waldorf Substations.

Cost: Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Hawkins Gate Switching Station to Westlake South 1 Substation 69 kV line is estimated at 5.9 miles long with a cost of $1,830,000.

Hawkins Gate Switching Station to Heritage Green Substation 69 kV Line RUS No. B806

Justification: The new Heritage Green subdivision will be located in LaPlata north of Saint Charles Street and east of the Consolidated Rail Corporation rail road track. A new Heritage Green Substation is required to serve the new subdivision. The new line to serve Heritage Green Substation will come from the Hawkins Gate Switching Station.

Cost: Construction along the longer route (Route 488 and Route 6) will be an overbuild of existing 12.47 kV distribution line. Estimated cost for the overbuild based on the Hughesville south Line 6750 cost is $470,000 per mile. The Hawkins Gate Switching Station to Heritage Green Substation 69 kV line will be approximately 4.7 miles long and is estimated to cost approximately $2,210,000. The cost could vary depending on the exact location of the substation and the entry and exit routes to the site.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 17 Heritage Green Substation to Marshall’s Corner Substation 69 kV Line RUS No. B807 and B503

Justification: A new 69 kV line from the Heritage Green Substation to the Marshall’s Corner Substation is needed to provide loop service to the Heritage Green Substation and to the Marshall’s Corner Substation. The line will also provide an alternate path to serve the Marshall’s Corner, McConchie and Grayton Substations during contingency outages of Line 6613 from Hawkins Gate Switching Station to LaPlata Substation or Line 6717 from the LaPlata Substation to Marshall’s Tap.

Cost: Estimated cost for the overbuild based on the Hughesville south Line 6750 cost is $470,000 per mile. Overbuild construction of existing 12.47 kV distribution lines from the Heritage Green Substation to the Marshall’s Corner Substation will be approximately 6.0 miles long and is estimated to cost approximately $2,820,000. The cost could vary depending on the exact location of the Heritage Green Substation and the entry and exit routes to the site.

LaPlata GOAB Installation RUS No. B504

Justification: The LaPlata GOAB switch is required during contingency outages of any section of Line 6717 between LaPlata and Mason Springs Substations. It is also necessary to allow the new Hawkins Gate to Heritage Green to Marshall’s Corner line to feed on to Ripley Switching Station without having to supply the LaPlata Substation load. The switch will allow the LaPlata Substation load to be fed from the Morgantown metering point along with Tompkinsville, Newburg, and Faulkner Substations.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 18 Cost: The LaPlata GOAB switch will provide bypass capability similar to that at the Forest Park Substation. The pole for mounting the switch is already at the LaPlata site. Estimated cost for the additional hardware and labor to install the switch is $50,000.

Indian Bridge Switching Station to Wildewood Substation 69 kV Line RUS No. B808

Justification: The Wildewood Substation will be initially loop fed by lines from Indian Bridge and Hewitt Road Switching Stations. The normal supply for Wildewood Substation will be the new 69 kV line from Hewitt Road Switching Station. The Indian Bridge Switching Station to Wildewood Substation to Hewitt Road Switching Station 69 kV line will be available for contingency outages of Line 6740 between Hewitt Road and Indian Bridge Switching Stations or the same line (6740) between Hughesville and Leonardtown Substations.

Cost: The new line from Indian Bridge Switching Station to the Wildewood Substation is expected to be approximately 2.0 miles of new construction. Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The two mile Indian Bridge Switching Station to Wildewood Substation 69 kV line will cost approximately $620,000.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 19 Hewitt Road Switching Station to Wildewood Substation 69 kV Line RUS No. B809

Justification: The Hewitt Road Switching Station to Wildewood Substation 69 kV line will be the normal source of power for the Wildewood Substation. The line will also provide contingency power for Leonardtown Substation during outages of Line 6740 from Hughesville Substation and contingency power for Valley Lee, Piney Point and Redgate Substations during outages of the same line (6740) between Hewitt Road and Barefoot Acres Switching Stations.

Cost: The new line from Hewitt Road Switching Station to Wildewood Substation is expected to be approximately 5.0 miles long. Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Hewitt Road Switching Station to Wildewood Substation 69 kV line will cost approximately $1,550,000.

Mattawoman Tap to Mattawoman Substation 69 kV Line Upgrade RUS No. B1002

Justification: This 30 year old 336.4 MCM ACSR conductor is a weak link between 1590 MCM AAC conductors. It can not carry the required Mattawoman, West Brandywine and Cedarville substation loads during a contingency outage of Line 6720 from Hughesville Substation to Cedarville Substation. During Load Block C the Mattawoman Substation load will exceed the normal operating design level of the 336.4 MCM ACSR conductor.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 20 Cost: Line 6715 is 2.2 miles long and should be upgraded to 1590 MCM AAC conductors. It should be constructed on poles to allow a 12.47 kV distribution line underbuild. Estimated cost for new 1590 MCM AAC 69 kV line upgrade construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The cost is assumed be approximately 20% higher to provide for a 12.47 kV distribution circuit underbuild. The Mattawoman Tap to Mattawoman Substation line upgrade will cost approximately $820,000.

LaPlata Substation to Ripley Switching Station 69 kV Line Upgrade RUS No. B1003

Justification: Line 6717 from LaPlata Substation through Marshall’s Tap to the Ripley Switching Station is 556.5 MCM ACSR conductor. The lines on both ends of these sections are 1590 MCM AAC conductors. Upgrade of the line is required to supply the load from LaPlata Substation to Accokeek Substation during a contingency outage of Line 6620 from Farmington to Accokeek.

Cost: Line 6717 from LaPlata Substation through Marshall’s Tap to the Ripley Switching Station is 7.03 miles. The section from LaPlata Substation to Marshall’s Tap is 2.81 miles long and was built in 1971. The section from Marshall’s Tap to the Ripley Switching Station is 4.22 miles long and was built in 1992. It is assumed that the older 2.81 mile section from LaPlata Substation to Marshall’s Tap will require work similar the Hughesville north Line 6720 and cost approximately $310,000 per mile. The 4.22 mile section from Marshall’s Tap to the Ripley Switching Station is newer and it is assumed that some of the poles can be reused. Considering this possible savings, cost for construction may be 20% less than the cost of the Hughesville north Line 6720 or

HLY 29-688 Rev 0 (12/07/05) 106869 V - 21 approximately $250,000 per mile. Total cost of the Line 6717 upgrade from the LaPlata Substation to the Ripley Switching Station is estimated to be $1,926,000 (2.81*$310,000+4.22*$250,000).

Chalk Point Switching Station 69 kV Breaker Additions RUS No. B1004

Justification: Presently the only circuit breakers protecting SMECO’s 69 kV Chalk Point Switching Station bus are on PEPCO’s end of the Lines 69101 and 69102 in PEPCO’s station. SMECO should not rely completely upon PEPCO/Mirant for protection of the 69 kV Chalk Point bus. It is not practical to build additional lines to mitigate this problem. Hence, it is recommended that SMECO’s 69 kV Chalk Point Switching Station be enhanced by additional circuit breakers on PEPCO’s Lines 69101 and 69102 with relay protection for SMECO’s switching station. This will give SMECO control over operation of these lines and protection of the Chalk Point Switching Station to minimize the risk of outages associated with this connection to the PEPCO system.

Cost: Estimated cost for the enhanced protection of the Chalk Point Switching Station is $795,000. This estimate includes two 69 kV circuit breakers with disconnect switches on both sides, line side surge arresters, a new control building, support structures, foundations, labor and materials. Labor rate assumed is $100 per hour with no unusual site conditions. Removal of existing equipment is included along with heavy grading and surfacing of the entire substation (assumed 400 ft x 400 ft). The cost estimate summary is included in Appendix E, Cost Estimates.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 22 Hawkins Gate Switching Station Third 230/69 kV Transformer Addition RUS No. B1005

Justification: Load on the Hawkins Gate Switching Station exceeds the rating of a single transformer. Two transformers are needed to handle maximum load conditions. A third transformer is required to mitigate a single contingency outage of one transformer.

Cost: Estimated cost of adding a third 230/69 kV 135/180/224 MVA at Hawkins Gate Switching Station is $3,120,000. This estimate includes the transformer, one 230 kV circuit breaker with a motor operated disconnect switch and a line side surge arrester. The transformer will be tapped off an existing 230 kV line running through the station. The estimate includes one additional 69 kV bay position (one spare bay position exists) and two 69 kV circuit breakers with disconnect switches. Also covered are moderate site grading, a new control building, support structures, foundations, labor and materials. Labor rate assumed is $100 per hour. The cost estimate summary is included in Appendix E, Cost Estimates.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 23 Hewitt Road Switching Station Third 230/69 kV Transformer Addition RUS No. B1006

Justification: Load on the Hewitt Road Switching Station exceeds the rating of a single transformer. Two transformers are needed to handle maximum load conditions. A third transformer is required to mitigate a single contingency outage of one transformer.

Cost: Estimated cost of adding a third 230/69 kV 135/180/224 MVA at Hewitt Road Switching Station is $3,015,000. This estimate includes the transformer, one 230 kV circuit breaker with motor operated disconnect switches. The estimate includes one additional 69 kV bay position (one spare bay position exists) and two 69 kV circuit breakers with disconnect switches. Also covered are moderate site grading, a new control building, support structures, foundations, labor and materials. Labor rate assumed is $100 per hour. The cost estimate summary is included in Appendix E, Cost Estimates.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 24 V-4 Load Block C

Hellen Creek Switching Station 230/69 kV RUS No. C901

Justification: Southern Calvert County needs an additional transmission line to carry the required load predicted to develop during Load Block C and some method of voltage support. Southern Calvert County also needs additional loop feed options for contingency outages of either the connection from Hewitt Road Switching Station in the south or the connection through Dukes Inn Substation in the north. Solutions were considered at 69 kV with an additional line from Holland Cliffs Switching Station to Saint Leonard Substation, a regulating transformer on the new line at Saint Leonard Substation, and a shunt capacitor bank at the Solomons Substation. A 138 kV solution was also considered. None of these southern Calvert County solutions addressed the need for a 230 kV loop to the Hewitt Road Switching Station or provided for significant load growth beyond 2025. The 230/69 kV switching station in southern Calvert County is recommended for the long term operation of the transmission system.

Cost: Cost estimates for the recommended new Hellen Creek Switching Station are included in the table below. These costs include the 230 kV switchyard with five 230 kV circuit breakers needed to form a 230 kV ring bus. The ring bus will be designed for a sixth circuit breaker that may be added sometime after 2025 when a second 230 kV line to Hewitt Road Switching Station is required. The ring bus provides for connecting two lines from Holland Cliffs Switching Station, one line/cable to the Hewitt Road Switching Station in Saint Mary’s County, and two 230/69 kV transformers to serve southern Calvert County.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 25 The three phase 230/69 kV transformers are rated at 105/140/175 MVA each. Larger 135/180/224 MVA transformers could be purchased if it is desired to have the transformers like the Hawkins Gate, Hewitt Road and Holland Cliffs units. It is estimated that the larger transformers would cost an additional $600,000. Sectionalizing switches are included on both sides of the transformers between the transformers and the circuit breakers.

The 69 kV side of the Hellen Creek Switching Station includes six 69 kV circuit breakers in a breaker and a half arrangement for connection of the two transformers and two 69 kV transmission lines. Space should be allowed in the 69 kV switchyard for connection to an additional substation. This may be desirable instead of double ending the Saint Leonard Substation.

Costs assume a labor rate of $100 per hour, moderate land grading, no removal of existing equipment (greenfield site), and a chain link fence around the station. For maximum reliability, transformers should not be connected to adjacent breakers on the 230 kV ring bus or in the same bay of 69 kV breakers. A cost estimate summary is included in Appendix E, Cost Estimates.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 26 Table V-6: Hellen Creek Switching Station Estimates of Probable Costs Description Estimated Cost Outdoor Equipment $4,650,000 Tubular Steel Structures $368,000 Foundations $600,000 Cable and Conduit $149,000 Control House $439,000 Site Improvements $313,000 Testing and Energization $91,000 Subtotal $6,610,000 Contractor Mobilize and Demobilize $25,000 Construction Management $200,000 Engineering $265,000 Subtotal $7,100,000 Contingency $355,000 Total Estimated Cost $7,455,000

Holland Cliffs Switching Station to Hellen Creek Switching Station Double Circuit 230 kV Line RUS No. C801

Justification: This is the first section of a line through Calvert County that will form a 230 kV loop from PEPCO’s Chalk Point Switching Station through Calvert County to the Hewitt Road Switching Station in Saint Mary’s County. The line will supply power to a new switching station near Hellen Creek that will serve the distribution stations in southern Calvert County. A double circuit line is required for this section to supply both the southern Calvert County Hellen Creek Switching Station load and the Hewitt Road Switching Station load during a single contingency outage of the Ryceville Switching Station to Hewitt Road Switching Station Lines 2320E and 2320W. These lines (2320E and 2320W) are considered a single contingency outage because they are on the same transmission line structures.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 27 Cost of the 230 kV double circuit line is estimated to be $826,000 per mile plus a $25,000 contractor mobilization and demobilization cost as discussed in the 230 kV Double Circuit Transmission Lines section of this report. The suggested route is approximately 23.5 miles and the estimated cost is $19,436,000. This cost does not include expenses associated with right-of-way acquisition or clearing.

Hellen Creek Switching Station to Hewitt Road Switching Station Single Circuit 230 kV Line RUS No. C802 and C803

Justification: This is the second section of a line through Calvert County that will form a 230 kV loop from PEPCO’s Chalk Point Switching Station through Calvert County to the Hewitt Road Switching Station in Saint Mary’s County. The line/cable will supply power to the Hewitt Road Switching Station during single contingency outages of Lines 2320E and 2320W from Ryceville Switching Station to Hewitt Road Switching Station. Only a single circuit is required for this section to supply the Hewitt Road Switching Station load.

Cost: Cost of the 230 kV single circuit overhead line is estimated to be $726,000 per mile plus a $25,000 contractor mobilization and demobilization cost. This cost assumes that phase conductor costs will be $60,000 per mile less than the double circuit line and that the construction costs will be $10,000 per mile less than the double circuit line. Double circuit lines are discussed in the 230 kV Double Circuit Transmission Lines section of this report. The overhead line length is estimated to be 10.5 miles and the estimated cost is $7,963,000. This cost does not include expenses associated with right-of-way acquisition and clearing.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 28 Estimated cost of the 230 kV Patuxent River crossing cable section of the line is $4,000,000 per mile. Cost of a two mile section is estimated to cost $8,000,000.

230 kV Double Circuit Transmission Lines

This TLRP recommends a new 230 kV double circuit transmission line between the upgraded Holland Cliffs Switching Station in northern Calvert County and a new Hellen Creek Switching Station in southern Calvert County. It further recommends that a new 230 kV transmission line/cable be built from the Hellen Creek Switching Station to the Hewitt Road Switching Station in Saint Mary’s County. Both lines should have double circuit towers. Both circuits should be installed between Holland Cliffs and Hellen Creek Switching Stations. Only one circuit is needed in Load Block C from the Hellen Creek Switching Station to the Hewitt Road Switching Station to provide backup for the Hewitt Road 230 kV lines; 2320E and 2320W. The second circuit may be needed in the future and it is recommended that the towers be designed and constructed for the future addition of a second circuit.

A general estimate for the cost of new 230 kV lines is provided in the table below. The estimate assumes ten steel single pole double circuit structures per mile. Right-of-way expenses are not included in the estimate. Exact line costs will depend upon the nature of the terrain, obstructions, and other factors. These estimates are based on a 230 kV line through a hilly area with existing right-of-way and assumes that permits are already obtained. When a single circuit line is to be constructed with provisions for a future second circuit, estimated costs have the conductor expense reduced by half to $60,000 per mile and the construction expense reduced by $10,000 per mile to $330,000 per mile.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 29 Table V-7: 230 kV Double Circuit Line Estimates of Probable Costs Description Estimated Cost $ per Mile Steel Structures $222,000 Insulator Assemblies $24,000 Conductor (6 – 1590 MCM Al) $120,000 Shield Wire $3,000 Fiber Optic Shield Wire $10,000 Miscellaneous Material/Hardware $16,000 Construction $340,000 Subtotal $735,000 Construction Management $22,000 Engineering $29,000 Subtotal $786,000 Contingency $40,000 Total Estimated Cost per Mile $826,000 Contractor Mob/Demob $25,000

Hewitt Road Switching Station to Willows Substation 69 kV Line RUS No. C804, C501, and C502

Justification: This line will supply power to the Willows 2, Ridge, Pax River 3 and Pax River 4 Substations during normal operation. It is needed to avoid overloading of Line 6779 from Hewitt Road Switching Station to Lexington Park Substation or Line 6760 from Hewitt Road Switching Station to Patuxent Park Substation during contingency outages of one of these two lines.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 30 Cost: The new line will be constructed on dedicated single circuit towers. It is expected to be approximately 4.0 miles long. Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Hewitt Road Switching Station to Willows Substation 69 kV line will cost approximately $1,240,000.

Wildewood Substation to Hollywood Substation 69 kV Line RUS No. C805, C503, and C504

Justification: This line is needed to supply backup power to Hollywood and Saint Andrews Substations in the event of a contingency outage of Line 6750 between Hewitt Road Switching Station and Hollywood Substation or contingency power to Oakville, Mechanicsville and Golden Beach Substations in the event of an outage of Line 6750 between Hughesville and Oakville Substations.

Cost: The exact location of the Wildewood Substation has not been established. The new line will be approximately 3.1 miles long. Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Wildewood Substation to Hollywood Substation line will cost approximately $961,000. This estimated cost does not include right-of-way expenses.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 31 Hawkins Gate Switching Station to Bensville Substation 69 kV Line RUS No. C806, C505, and C506

Justification: This line will supply power to Bensville, Accokeek, Mason Springs 2 and Indian Head Substations during normal Load Block C operation. The line provides a loop feed to Bensville Substation and relieves loading on Line 6733 from Hawkins Gate Switching Station to Forest Park Substation serving Mattawoman, Waldorf, and Bolton Substations. It will also be part of a new loop feed from Hawkins Gate Switching Station to Accokeek Substation required to keep the Farmington supply point below its firm capacity.

Cost: Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Hawkins Gate Switching Station to Bensville Substation 69 kV line is approximately 9.0 miles long and will cost $2,790,000. This cost estimate does not include expenses associated with acquiring new right-of-way.

Bensville Substation to Accokeek Substation 69 Line RUS No. C807, C507, and C508

Justification: This line is required provide service to Accokeek, Mason Springs 2 and Indian Head Substations during normal operation to keep the Farmington supply point below its firm capacity. The line will also provide power for Mason Springs 1, Grayton and McConchie Substations during contingency outages of Line 6717 between Marshall’s Tap and Mason Springs Substation.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 32 Cost: Estimated cost for new 1590 MCM AAC 69 kV line construction without overbuilding distribution lines is $310,000 per mile based on costs for the Hughesville north Line 6720. The Bensville Substation to Accokeek Substation 69 kV line is approximately 3.5 miles long and will cost $1,085,000. This cost estimate does not include expenses associated with acquiring new right-of-way.

Bryantown Switching Station to Bryantown Substation 69 kV Line Upgrade RUS No. C1001

Justification: The portion of Line 6730 from the Bryantown Switching Station to the new Bryantown Substation must be upgraded from 2/0 ACSR to 1590 MCM AAC to serve the new Bryantown Substation loads. Line 6730 from the Bryantown Switching Station to the Holland Cliffs Switching Station was constructed in the 1950s. The old 2/0 ACSR line does not have the capacity or reliability required to serve the new Bryantown Substation. The portion of Line 6730 from the new Bryantown Substation east to Holland Cliffs Switching Station will be connected (switched) to the Bryantown Substation 69 kV bus and remain as it is on the right-of-way on to Holland Cliffs. This section is presently not required for normal or single contingency outage operation. It is recommended that the line remain in place to maintain the existing right-of-way for possible future line upgrading or new line construction.

Cost: The exact location of the Bryantown Substation projected for construction by 2025 during Load Block C has not been established. It is expected to be near Line 6730 and within about one and a half miles of the Bryantown Switching Station. Upgrade of Line 6730 from the Bryantown Switching Station to the Bryantown Substation is assumed to

HLY 29-688 Rev 0 (12/07/05) 106869 V - 33 be similar to the Hughesville north Line 6720 project and cost approximately $310,000 per mile. Cost for the 1.5 mile upgrade is estimated to be $465,000.

Hughesville Substation to Cedarville Substation 69 kV Line Upgrade RUS No. C1002

Justification: Line 6720 from Hughesville Substation to Cedarville Substation is 336.4 MCM ACSR conductor and was built in 1951. The line normally serves the Cedarville Substation and West Brandywine Substation loads. During Load Block C, the load will increase to the point it can not be served by the 336.4 MCM ACSR conductor and the line will require upgrading. Line 6720 from Cedarville Substation through the West Brandywine Tap to Burches Hill will not require larger conductor unless the firm capacity at the Burches Hill supply point is increased. The Burches Hill supply point is of limited capacity and is not used for normal system operation during any of the three load blocks considered in the TLRP.

Cost: Line 6720 from Hughesville Substation to Cedarville Substation is 9.41 miles long. This construction is expected to be similar to the 2005 Hughesville north bypass project and cost approximately $310,000 per mile. Estimated cost of this upgrade is $2,917,000.

Bensville Substation 36 Mvar Capacitor Bank Addition RUS No. C509

Justification: Shunt capacitor banks are needed on SMECO’s transmission system to support system voltage during outage contingencies and to improve the system power factor for compliance with the bulk power supplier’s requirements. Power factor on the system

HLY 29-688 Rev 0 (12/07/05) 106869 V - 34 supplied from Hawkins Gate Switching Station is in most need of improvement. The Bensville Substation is normally fed from Hawkins Gate Switching Station.

The new line from Hawkins Gate Switching Station to Bensville Substation is approximately nine miles long. When heavy load is supplied through this line, the Bensville Substation shunt capacitor bank will compensate for voltage drop in the line. During contingency outages of Lines 6733 or 6710 between Hawkins Gate Switching Station and Waldorf Substation the capacitor provides needed voltage support.

The Bensville Substation is located in Charles County near Billingsley Road and Route 229. The Bensville Substation is being designed with a single 69-12.47 kV distribution transformer. Space should be allowed for the capacitor bank installation during Load Block C when the new Hawkins Gate Switching Station to Bensville Substation 69 kV line is constructed. The capacitor bank could be installed when the Bensville Substation is built and switched to regulate the Bensville voltage during both normal and contingency conditions.

Costs: The Shunt Capacitor Bank section of this TLRP indicated that the estimated cost for the 36 Mvar shunt capacitor bank is $695,000. This cost does not include the purchase of additional land.

Westlake South Substation 36 Mvar Capacitor Bank Addition RUS No. C510

Justification: Shunt capacitor banks are needed on SMECO’s transmission system to support system voltage during outage contingencies and to improve the system power factor for compliance with the bulk power supplier’s requirements. Power factor on the system supplied from Hawkins Gate Switching Station is in most need of improvement. The

HLY 29-688 Rev 0 (12/07/05) 106869 V - 35 Westlake South Substation is normally fed from Hawkins Gate Switching Station. During contingency outages of Line 6716 between Hawkins Gate Switching Station and Bannister Substation, Line 6733 between Hawkins Gate and Forest Park Substation or the new line between Hawkins Gate and Westlake South Substation, the Westlake South capacitor bank will support system voltage.

The double ended Westlake South Substation will be located along Line 6712 near the Westlake Substation. The shunt capacitor bank should be connected to the Westlake South 1 bus on the Westlake side of the substation as indicated on the single diagram in Appendix C. This will allow the capacitor bank to stay on the heavily load Westlake side of the Hawkins Gate loop when Westlake South Substation high side bus is split. Space should be allowed for the Westlake South capacitor bank when the substation is designed and built in Load Block B. The capacitor bank could be installed during Load Block B and switched to regulate the Westlake South capacitor voltage during normal and contingency conditions.

Cost: The Shunt Capacitor Bank section of this TLRP indicated that the estimated cost for the 36 Mvar shunt capacitor bank is $695,000. This cost does not include the purchase of additional land.

HLY 29-688 Rev 0 (12/07/05) 106869 V - 36