XXXXXXXXXXX Solar (XXX) Generation Interconnection

Facility Study For XXXXXXXXXXX Solar (XXX) Generation Interconnection Prepared For: Randy Harlas, Substation Manager El Paso Electric Company El Paso, TX September 2010

Table of Contents 1. GENERAL... 1 2. FOREWORD... 1 3. DISCLAIMER... 1 4. SCOPE OF WORK... 2 Transmission Diablo to Santa Teresa 115 kv Line Tap... 2 Station XXXXXXXXXXX Solar 115 kv Switching Station... 2 Table 1 Network Upgrades Material Costs... 5 Table 2 EPE Interconnection Facilities Material Costs... 6 5. COST SUMMARIES... 6 Table 3 Network Upgrades Installation Costs... 7 Table 4 EPE Interconnection Facilities - Installation Costs... 7 6. CONCLUSIONS... 8 Project Schedule-Transmission... 8 Project Schedule-Switching Station... 8 Overall Project Cost... 8 7. LIST OF ATTACHMENTS... 8 Documents... 8 Substation Preliminary Design Drawings... 8

CERTIFICATION Texas State - Certification I hereby certify, as a Professional Engineer in the state of Texas, that the information in this document was assembled under my direct personal charge. This report is not intended or represented to be suitable for re-use by El Paso Electric Company or others without specific verification or adaptation by the Engineer (Burns & McDonnell). This certification is made in accordance with the provisions of the laws and rules of the Texas State Board of Engineers Administrative Code. Electrical Engineer Approved P.E. Seal (Electrical) Kirk Saint Alwyn Powell, P.E. TX License No. 91951 Date: September 30, 2010 Civil/Structural Engineer Kristie J Green, P.E. TX License No. 97622 Date: September 30, 2010 Approved P.E. Seal (Civil/Structural)

1. GENERAL El Paso Electric Company (Transmission Provider) has requested Burns & McDonnell Engineering (Engineer) to provide a Facilities Study to estimate the Transmission Provider s system upgrades required for the interconnection of the proposed XXXXXXXXXXX Solar Thermal Generating Station (Interconnection Customer) to Transmission Provider s Electric Transmission System. The Interconnection Customer proposes to connect an ultimate 99.8MW solar thermal steam generation facility to Transmission Provider s electric grid. The proposed interconnection requires the installation of a new 115kV Switching Station by tapping the existing Diablo-Santa Teresa 115kV transmission line approximately 5.7 miles from the Diablo Substation and 3.2 miles from the Santa Teresa Substation. The Point of Interconnection (POI) will be located at this Facility. Per the attached preliminary oneline diagram (XX_OOL), the POI has been designated to be the point at which the Interconnection Customer s Electrical Facilities connect to the Transmission Provider s 115 kv bus. The following tasks and associated costs are not included in this Facility Study and are assumed to be the responsibility of the Interconnection Customer: Land Acquisition and Surveying. Design and installation of the new 115kV transmission line from the Interconnection Customer s Generation Facilities to the line terminal at the POI. 2. FOREWORD This estimate has been prepared with +/- 15% accuracy as requested by the Transmission Provider. A 10% contingency has been added to the estimate which is to be applied before any adder is considered. All assumptions are clearly defined within this document and should be duly noted. Due to market conditions, costs (material and labor) have been increasing. The equipment and labor costs included in this document reflect budgetary quotes received from prospective construction contractors. These are the most up-to-date costs to the Engineer s knowledge, but are subject to change based on market conditions. Due to market conditions, prices of both copper and construction labor have been fluctuating. 3. DISCLAIMER Estimates, forecasts, projections, and schedules relating to costs, quantities, demand pricing (including but not limited to, property costs, construction, operation or maintenance costs, and/or energy or commodity demand and pricing), are opinions based on the Engineer s experience, qualifications and judgment. In using the term Network Upgrades in this report, it is assumed that all facilities at or beyond the Point of Interconnection are Network Upgrades. The Engineer has not evaluated and has formed no opinion on whether the facilities described as Network Upgrades are integrated with and support EPE s overall transmission system for the general benefit of all users. 1 P age

The Engineer has no control over the weather, cost and availability of labor, materials and equipment, labor productivity, energy or commodity pricing, demand or usage, population demographics, market conditions, change in technology, and other economic or political factors affecting such estimates or projections. The Transmission Provider acknowledges that actual results may vary significantly from the representations and opinions herein. Nothing herein will be construed as a guarantee or warranty (actual or implied) that rates, demand, pricing, costs, performance schedules, quantities, technology, or any other related items will not vary from the opinions contained in the report prepared by the Engineer. 4. SCOPE OF WORK Transmission Diablo to Santa Teresa 115 kv Line Tap This new substation will require the 115kV Diablo-Santa Teresa Line to turn into the new substation in an in-and-out configuration. Turning the 115kV line into the new station will require the line to pass under the existing 345kV Luna to Diablo transmission line. The proposed two transmission towers shall be self supporting structure. The structures shall be capable of supporting 3 phases of 2-bundled 954 kcmil ACSR Cardinal conductor with one OPGW. The foundations for the dead-end structures shall be drilled shaft concrete foundations with steel reinforcement. Geotechnical information is not available, so foundation sizes and costs were estimated based on data from other projects previously performed in the area. Transmission Engineering Assumptions The location of the new XXXXXXXXXXX Switching Station shall be immediately adjacent to the existing 115 kv Diablo to Santa Teresa transmission line ROW. Two (2) dead-end structures will be required to terminate the line adjacent to the new XXXXXXXXXXX Switching Station and no modification of the existing structures is required. The conductors shall be in a horizontal bundle configuration and will require spacers and dampers. All hardware assemblies shall use polymer insulators. The dead-end assemblies shall use compression fittings. Station XXXXXXXXXXX Solar 115 kv Switching Station The new XXXXXXXXXXX Solar 115 kv Switching Station is proposed to be installed as shown below: One (1) three-position ring bus. o o Two (2) positions designated for the termination of the Transmission Provider s 115 kv transmission lines to Diablo and Santa Teresa substations. One (1) position designated for the termination of the 115 kv transmission line to the Interconnection Customer s Generation Facilities. It is assumed that the Interconnection Customer s incoming transmission line will be slack-spanned into the switching station. 2 P age

Control building (20 x 28-6 ) with the necessary power, relaying and communication equipment One (1) lot of 115 kv Revenue Metering equipment to be installed on the 115 kv line to the Interconnection Customer s Facilities. Metering equipment includes PT/CT combo units, foundations and support structures for the PT/CT units, Metering Panel, cables, etc. The costs for metering equipment are included in Table 2 below. Site Survey The Engineer will secure the services from a Transmission Provider-approved Survey company to perform a site and access road survey. Survey data will be used in grading design, soil cut-and-fill calculations and transmission structure positioning. Geotechnical Field Investigations and Engineering The Engineer will secure services from a Transmission Provider-approved Geotechnical Firm to perform field investigations. Geotechnical investigations and engineering calculations will be performed to establish the design basis for foundation and electrical grounding design. Site Preparation, Grading and Drainage Design The proposed XXXXXXXXXXX Solar 115 kv Switching Station location will require the installation of an approximately 2 mile gravel drive to provide all weather access from an existing public road to the site. It is proposed that the new access road will be an upgrade of an existing dirt track starting where the 345 kv Diablo to Luna transmission line crosses the Pete Dominici Blvd (Hwy 136) and continuing roughly in an easterly direction to the POI. It is assumed that the existing dirt track is within the existing transmission ROW and no land purchases are required. The proposed 20-foot wide access drive will consist of 8-inch well-graded crushed stone. The estimated 4,498 square yard substation will require a gravel surface assumed to consist of 3-inch thick gap-graded aggregate with a base of 4-inch thick well-graded crushed stone. The station site is assumed to be crowned in the center to drain across the surface of the site outward. Because of the remote location of the station site, a detention pond is not envisaged. Drainage structures may include driveway culverts, rip-rap rocks, detention pond outlet structures, or grate inlets with outlet pipes if necessary. An 8-foot chain link fence will be constructed around the perimeter of the station site. Civil/Structural Design Engineer shall design the required foundations as shown on the layout drawing and according to Transmission Provider s or Engineer s specifications. Refer to the substation major materials list and preliminary design drawings for the various foundations to be installed on this project. Engineer shall perform the studies necessary to assure that the bus system is adequately supported by the structures, fittings, and insulators selected when placed under the site specific environmental and short circuit fault forces. 3 P age

Note. Custom structures will be designed by the Engineer as required however the Engineer assumes that all structures installed will be per Transmission Provider s Standards and current practices. The requirement of customized structures will translate to additional project costs which are not covered herein. Electrical Design Engineer shall design the substation per Transmission Provider s Standards. The following are general tasks required to complete the electrical design: Install the electrical facility and equipment as indicated on the preliminary design drawings. Install the required insulation, conductors and fittings to inter-connect new equipment in the substation. Install a new station ground grid to adequately protect personnel and also the Transmission Provider s electrical infrastructure. Engineer will perform grounding calculations to verify that the new grid layout provides adequate personnel and equipment protection. Grounding installation shall be per Transmission Provider s standard practices. Install lightning protection (shielding) to adequately protect the new equipment. Perform the necessary calculations to design and verify the adequacy of the lightning protection. Install lightning masts as required. Install static wire between structures as needed. Lightning masts and line terminals will be fitted with 15 lightning spires on top (of each leg). Protection and Control Design The protection and control design shall follow Transmission Provider s Standards. The design is intended to provide a means of local and remote control of the equipment and electrical system (by means of switching) by the Transmission Provider. It is also intended to fulfill the purpose of protecting human life, electrical infrastructure under abnormal system conditions and minimize system outages and disturbances. The following are general tasks required to complete the protection and control design: Install a new control house which will be used to store all control and communication equipment, the batteries and associated equipment for the DC system (located in a separated area of the house), personnel safety equipment, etc. Install three (3) new Transmission Provider Standard transmission line protection racks for the new 115 kv transmission lines at this new station. Relay communication for the transmission lines to Santa Teresa and Diablo shall as well as for the transmission line to the Interconnection Customer s Solar Thermal Generation Facilities will be over Fiber Optic conductors. Install revenue metering for the 115 kv line to Interconnection Customer s Solar Generating Station. Install a Digital Fault Recorder (DFR) also known as a Transient Recorder. Install a new Communications Rack. Install relay serial communications as needed to connect the new relays to the communication rack. Provide relay settings for all new relays. 4 P age

Install fiber optic cables, conduit and termination equipment for all three (3) transmission lines at the new switching station. Install SCADA control, monitoring and indication per Transmission Provider s standard practice. Install a new AC/DC Station Power system. Both the AC and DC systems will be designed and installed with redundancy (for reliability purposes). There shall be two sources of AC and two DC battery systems installed. These systems will provide the necessary auxiliary power for the station. Both the primary and back-up AC Station Service will be connected to the 115 kv bus at XXX station. An automatic transfer switch shall be installed between the two sources. Connect the new equipment, racks, yard lights to the new AC/DC station service systems as needed. Install a new raceway system from the control house to the new field equipment. The raceway system will be comprised of cable trench, one large pull box and 3 PVC conduit installed per Transmission Provider s current practices. Install the necessary control and power cable using this raceway system to connect the field equipment to the control house equipment. Install floodlight assemblies in order to provide adequate lighting for the substation equipment. Lights will be installed at lightning masts and line terminal structures. Table 1 Network Upgrades Material Costs Equipment Description XXXXXXXXXXX Solar 115 kv Switching Station 1,2 Unit Est. Qty. Lead Time (Weeks ARO) Unit Cost ($) Total Cost ($) 115kV 2000A GCB's EA 3 26 50,000 150,000 Structural Steel LOT 1 24-26 195,560 195,560 115kV, 2000A, Disc. Sw. EA 8 14-16 11,000 88,000 50KVA Station Service XFMR EA 2 14-16 25,000 50,000 115kV CCVT's EA 6 8-10 3 6,000 36,000 115kV Surge Arresters EA 6 6-8 1,191 7,146 Other Elect/Site Materials 4 LOT 1-1,274,294 1,274,294 Station Materials (Sub-Total) 1,801,000 Diablo-Santa Teresa 115 kv Transmission Line Tap 1,2 3-Pole Dead-end Structures EA 2 20-26 45,000 90,000 Dead-end Assemblies EA 18 14-16 550 9,900 954kcmil ACSR "Rail" FT 14,500 12-14 1.90 27,550 3/8" EHS 7-Strand OHGW FT 2,500 12-14 0.45 1,125 OHGW Deadends EA 6-110 660 OPGW 24-Count FT 3,000 14-16 1.50 4,500 OPGW Deadends EA 6 350 2,100 Fiber Optic Splice Box EA 2 750 1,500 5 P age

Other XMS Materials LOT 1-26,365 26,365 Transmission Materials (Sub-Total) 163,700 Total Major Material Costs - EPE Network Upgrades 1,964,700 Table Notes 1. This table is included to show major substation equipment lead times and associated costs only. 2. No installation (labor) costs are included in this table. Labor costs are included in the cost summary unless otherwise noted. 3. Number of weeks after drawing approval. 4. Other Elect/Site Material cost include estimated pricing for geotechnical investigations, site preparation, foundations, grounding, bus work, fittings and connectors, control house, raceway, station service minor equipment, DC system, protective relay racks, SCADA racks, communication equipment, etc associated with Network Upgrades. These materials generally have shorter procurement lead times. Table 2 EPE Interconnection Facilities Material Costs Equipment Description XXXXXXXXXXX Solar 115 kv Switching Station 1,2 Unit Est. Qty. Lead Time (Weeks ARO) Unit Cost ($) Total Cost ($) Structural Steel LOT 1 24-26 72,000 72,000 115kV, 2000A, Disc. Sw. EA 1 14-16 11,000 11,000 115kV CT/PT Combo Unit EA 3 24 20,000 60,000 115kV Surge Arresters EA 3 6-8 1,191 3,573 Other Elect Materials 3 LOT 1-133,427 133,427 Total Major Material Costs - EPE Interconnection Upgrades 280,000 Table Notes 1. This table is included to show major substation equipment lead times and associated costs only. 2. No installation (labor) costs are included in this table. Labor costs are included in the cost summary unless otherwise noted. 3. Other Elect Material cost include estimated pricing for foundations, grounding, bus work, fittings and connectors, protective relay racks, Revenue Metering System (PT/CT units, Metering Panel and associated equipment) associated with Interconnection Facilities. These materials generally have shorter procurement lead times. Milestone Schedule Please refer to Attachment No. 1 and conclusions. 5. COST SUMMARIES The estimated project Network Upgrade and EPE Interconnection Facilities costs are outlined below. 6 P age

Table 3 Network Upgrades Installation Costs Project Task Cost ($) Transmission Labor 1 180,250 Transmission Material 2 163,700 Transmission Construction Management 3 35,000 Transmission Engineering 4 35,000 Transmission Installation (Sub-Total) 5 413,950 Station Labor 6 1,519,000 Station Material 6 1,801,000 Station Construction Management 7 240,000 Station Engineering 8 300,000 Station Installation (Sub-Total) 3,860,000 Total Network Upgrade Cost 4,273,950 Contingency @ 10% 427,395 Total Network Upgrade Cost w/contingency 4,701,345 Table Notes 1. Transmission Labor Cost includes all labor required to construction transmission line including erection, foundations, stringing, right-of-way preparation, construction incidentals and grounding. 2. Transmission Material Cost includes all material required to construction transmission line including, steel, hardware, conductor, dampers, spacers and other miscellaneous material. 3. Transmission Construction Management Costs include costs associated with procurement, bidding, construction supervision and management of the construction process. 4. The Transmission Engineering Line Item includes costs associated with transmission line design, owner s overhead engineering costs, survey, geotechnical investigations, construction support, environmental evaluations and permit applications. 5. Transmission Right-of-way acquisition and land management costs are not included in the Total Installed Cost. 6. Station Labor and material costs include Site Preparation costs. 7. Station Construction Management cost includes supervision and management of the construction process. 8. Station Engineering costs are budgetary. Final engineering costs will be provided when an RFP is issued to Engineer. Table 4 EPE Interconnection Facilities - Installation Costs Project Task Cost ($) Station Labor 99,000 Station Material 280,000 Station Construction Management - Station Engineering - Total Interconnection Facilities Cost 379,000 Contingency @ 10% 37,900 Total Interconnection Facilities Cost w/contingency 416,900 7 P age

6. CONCLUSIONS Project Schedule-Transmission With only two (2) structures to be installed, the transmission schedule is incorporated into the switching station schedule. Project Schedule-Switching Station The attached preliminary Milestone Schedule assumes a project start date (Notice-to- Proceed) of January 2, 2011. The estimated duration of the project is fifteen (15) months from Notice-to-Proceed to project completion at the end of March, 2012. Overall Project Cost The overall estimated project costs for the installation of XXX Switching Station is approximately US$5,118,245 which includes 10% contingency. 7. LIST OF ATTACHMENTS Documents Attachment No.1 XXXXXXXXXXX Solar 115 kv Switching Station Project Milestone Schedule Substation Preliminary Design Drawings XXXXXXXXXXX Solar Switching Station Operation One-Line Diagram XX_OOL XXXXXXXXXXX Solar Switching Station General Location Plan XX_GLP 8 P age