## SALT RIVER PROJECT NAVAJO GENERATING STATION – UNITS 1, 2, 3

SCR AND BAGHOUSE CAPITAL COST ESTIMATE DESIGN BASIS

Prepared By:

Project No. 12656-001 April 16, 2010 Revision BS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc TOC-1 CONTENTS

1. GENERAL ........................................................................................................................ .1
1.1 Design Basis Scope ......................................................................................................1
1.2 Site Climatic Data..........................................................................................................1
1.3 Design Emissions..........................................................................................................2
1.4 Coal, Ash, and Trace Element Analysis........................................................................3
1.5 Water Analysis ..............................................................................................................3
1.6 Boiler Operating Data....................................................................................................4
1.7 Design Life .................................................................................................................... 6
1.8 Underground Utilities.....................................................................................................6
1.9 Fire Protection...............................................................................................................6

2. MECHANICAL...................................................................................................................6
2.1 SCR Option ...................................................................................................................6
2.2 SCR and Baghouse Option.........................................................................................10

3. ELECTRICAL/I&C ...........................................................................................................13
3.1 SCR OPTION..............................................................................................................13
3.2 SCR AND BAGHOU SE OPTION ................................................................................14

4. CIVIL/STRUCTURAL/ARCHITECT URAL/GEOTECHNICAL..........................................16
4.1 Geotechnical Design Basis .........................................................................................16
4.2 Civil Design Basis........................................................................................................16
4.3 Structural Design Basis...............................................................................................19
4.4 Architectural Design Basis ..........................................................................................21

ATTACHMENTS A. Design Basis Input Document ListS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 1 1. GENERAL

1.1 DESIGN BASIS SCOPE a. The design basis documents the technical and functional requirements on which the capital cost estimate for SCR and Baghouses for the Navajo Generating Station Units 1, 2 & 3 will be based. The design basis covers performance requirements of the equipment, as well as reliability requirements, design life, operating requirements and process technology requirements.

1.2 SITE CLIMATIC DATA

Reference Elevation 4,355 ft MSL
Barometric Pressure 12.49 psia
Relative Humidity 28% - 100%;
annual average =45%
Maximum Ambient Temperature (Design): 109 deg F dry bulb
79 deg F wet bulb
Annual Average Ambient Temperature: 57.6 deg F dry bulb

Minimum Ambient Temperature -11 deg F dry bulb
Freeze Protection (new underground piping installations) Minimum 4 feet cover from the top of pipe per Annex A of NFPA 24
Freeze Protection (existing underground piping) Match existing depthS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 2 Rainfall Duration Storm Return Period 30 Minutes 1 Hour 24 Hours 10-Year 0.62 inches 0.77 inches 1.51 inches 25-Year 0.84 inches 1.04 inches 1.85 inches 50-Year 1.04 inches 1.29 inches 2.12 inches 100-Year 1.28 inches 1.59 inches 2.42 inches

1.3 DESIGN EMISSIONS a. The following emissions rates will govern the design of new emissions control equipment:
a1. NO X Inlet Emissions: 0.24 lb/MMBtu with Low NOx Burners and SOFA modifications only.
a2. NO X outlet emission (permit limit) : 0.09 lb/MMBtu on a 30-day rolling average (to be negotiated with ADEQ).
a3. NO X Outlet Design Emissions: 0.05 lb/MMBtu. The design will be based on the unit specific NO X . a4. Particulate Emissions from existing HESP: 0.03 lb/MMBtu a5. Design Particulate Emissions from Pulse Jet Fabric Filter (PJFF): 0.01 lb/MMBtu a6. Ammonia Slip: 2 ppmvd @ 3% O 2 a7. SO 3 Outlet Design Emissions: No net increase in emissions after installation of SCR with use of sorbent injection. SCR will be designed to operate with ultra-low SO 2 to SO 3 conversion catalyst (<0.125% per layer).
a8. SO 2 Outlet Emissions : 0.04-0.07 lb/MMBtu (depending on coal sulfur content and levels of scrubbing in service). No net increase in emissions after installation of SCR. a9. Mercury - ppmd (wt.) in coal: 0.05 ug/g (dry). No net increase in emission after installation of SCR. a10. Chlorine - ppmd (wt.) in coal: 14 ug/g (dry). No net increase in emission after installation of SCR.
a11. Other Pollutants: N/A b. Future discussions with the EPA may impact the above criteria and will be subject to revisions.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 3 1.4 COAL, ASH, AND TRACE ELEMENT ANALYSIS a. The conceptual design of the new emissions control equipment that would be installed on Units 1, 2, and 3, at Navajo Generating Station will be based on the coal, ash, and trace element analysis provided:

AS RECEIVED DRY % Moisture, Total ASTM D 3302 13.33

% Ash ASTM D 3174/5142 10.36 11.96 % Volatile Matter ASTM D 5142 35.61 41.08 % Fixed Carbon ASTM D 3172 40.7 46.96 Gross Calorific Value (Btu/lb) ASTM D 5865 10418 12020 % Sulfur ASTM D 4239 0.63 0.73 % Carbon ASTM D 5373 59.16 68.26 % Hydrogen ASTM D 5373 4.38 5.05 % Nitrogen ASTM D 5373 1.03 1.18 % Oxygen, (Calc) ASTM D 3176 11.1 12.82 % Sulfur, Pyritic - FOS ASTM D 2492 0.13 0.15 % Sulfur, Sulfate - FOS ASTM D 2492 <0.01 <0.01 % Sulfur, Organic - FOS ASTM D 2492 0.5 0.58

% Potassium Oxide - WSA ASTM D 1428- 56T 0.005 0.005

% Sodium Oxide - WSA ASTM D 1428- 56T 0.118 0.136 Date Sample From 3/1/2009 Date Sample To 3/31/2009 Sample ID N-8 “DMS Shipped”

1.5 WATER ANALYSIS a. The conceptual cost estimate is based on the assumption that the water quality of the existing service water system is acceptable for equipment cooling water. In order to confirm this assumption the following water analysis should be provided by SRP:S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 4 Service Water Cations (ppm) Calcium Magnesium Sodium
Potassium Anions (ppm) Alkalinity Chloride Sulfate Sulfide
Nitrate Phosphate
Fluoride
General TSS (ppm) TDS (ppm) Spec. Cond. (μS/cm) pH Temp (oC)
Ammonia Silica BOD CBOD TOC Kjeldahl N

1.6 BOILER OPERATING DATA a. The boiler data identified in the following table will serve as the basis for new emissions control equipment. Since all three units are similar with respect to size, capacity, and operating conditions, one single set of values will be used as the design basis to allow the same equipment to be used to the fullest extent possible.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 5 Boiler Inputs Value BMCR MW gross 812 Heat Input mmBtu/hr 7,350
Excess Air* 18% Air Heater In Leakage** 22%
* Excess Air is taken from Steam Generator Equipment Data Manual ** Air Heater In leakage is assumed to be 22% to match the stack O 2 levels in the Acid Mist Sampling Summary (7.1% O 2 , dry)

Load Output Source Units 100% 75% 50% GMW Note 1 MW 812 604 403 Coal to Burners Note 1 Mlb/hr 652 513 355

Minimum SCR Inlet Temperature Deg F 580 580 580

AH Flue Gas Outlet Flow Note 1 Klb/hr 7,275 5,763 4,411

AH Flue Gas Outlet Pressure Note 1 INWG -14.9 -9.65 -5.85

AH Flue Gas Outlet Temperature (w/ leakage) Note 1 Deg F 250 235 201

NO X NGS PI Data LB/MMBTU 0.24 - - Stack O 2 Acid Mist Report % Dry 7.1 - -

WindboxFurnace Pressure Note 1 inH2O 3.5 3.1 3.0

Furnace Pressure Note 1 inH2O 0 0 0

Note 1: Data obtained from existing NGS Steam Generator Equipment Data Manual.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 6 1.7 DESIGN LIFE a. All new equipment and components for t he new emissions controls systems will be designed for a 30-year life.

1.8 UNDERGROUND UTILITIES a. Existing underground utilities will be relocated to support installation of new structures. Relocated utilities will be designed for above ground installation onto existing or new pipe racks as requir ed, it is assumed existing systems have sufficient capacity to support utility relocation.

1.9 FIRE PROTECTION a. Fire protection for new emissions control equipment will be provided by the existing NGS fire protection system; this includes fire pumps, yard piping, hydrants, etc. It is assumed the existi ng fire protection system has sufficient capacity to meet these new demands. a1. SCR fire protection requirements: Fire protection for the SCR and auxiliary equipment will require fire hydrants located within 50 feet of the SCR structure. a2. Baghouse fire protection requirements: Fire protection for the baghouse and auxiliary equipment will require fire hydrants located within 50 feet of the baghouse structure. The baghouse will be designed with polyphenylene Sulfide (PPS) fabric bags to minimize fire potential. PPS fabric bags are neither flammable nor combustible. A fire water standpipe will provide water to the penthouse area with a hose connection for use during outages when flammable materials may be present.

2. MECHANICAL

2.1 SCR OPTION
a. SCR Preliminary calculations indicate the following equipment will be required for an SCR system:
a1. SCR Reactor: 2 x 50% for each unit. a2. The SCR reactors will be of a 4-catalyst layer design with 2 layers initially filled. a3. Catalyst Type: Plate / honeycomb a4. The SCR reactors will be designed with provisions for catalyst removal, i.e. monorail, trolley, jib cranes, etc. a5. The SCR system will be designed without flue gas bypass provisions around the reactor.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 7 a6. The SCR reactors will be low-dust reactors with sonic horns utilized for mitigation of dust buildup on the catalyst layers. a7. An economizer side flue gas bypass will be required to maintain the flue gas temperature above 580F for load conditions between minimum load and approximately 700MW. a8. Reagent for the SCR system will be anhydrous ammonia. The anhydrous ammonia is vaporized to gaseous ammonia. Approximately 550 lbs/hr of gaseous ammonia will be required per unit. b. Reagent Unloading and Storage b1. Anhydrous ammonia will be delivered to the site via truck to a common ammonia unloading area. Anhydrous ammonia is unloaded (via onboard truck pumps) into a storage tank. The unloading area is sized to accommodate simultaneous deliveries to the ammonia tanks. b2. The ammonia storage facility will utilize three (3) horizontal tanks sized for 14 days of continuous operation at full load for the site. b3. Four (4 x 33%) transfer pumps are provided to transfer the ammonia solution for use in the vaporizers. b4. Four (4) steam vaporizers (2 x 100% per reactor) will be provided for each unit. 1,500 lbs/hr of low pressure steam is required per vaporizer. b5. Ammonia dilution air heater and blower: 1 x 100% skid per reactor; each skid consists of 2 x 100% blowers and heaters. The ammonia dilution air heaters will be sized to provide enough air to dilute the ammonia to 5% of the total injected air flow. The air will be heated to 300 oF to match the ammonia temperature out of the vaporizer. c. Sorbent Injection System (Trona or Hydrated Lime). c1. The sorbent injection system will be designed per the following basis: c1.1 The sorbent injection system will be sized for a feed rate of 200 lbm/hr. c1.2 The sorbent injection system consists of the following equipment and components:

EQUIPMENT QTY/REDUNDANCY

STORAGE SILO 1 X 100% (PER UNIT)

SORBENT INJECTION BLOWER S 2 X 100% (PER UNIT)

SORBENT INJECTION LANCES BY VENDORS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 8 c2. The storage silo will be sized for approximately seven days (7) of storage capacity with the silo diameter limited to a maximum of fourteen (14) feet. Larger storage capacities, per sorbent injection system vendors, would require additional silos due to shop fabrication and equipment shipping limitations.
d. ID Fans d1. NGS utilizes four (4) ID fans per unit arranged in parallel. d2. Capacity: 4 x 25% per Unit – Original MCR rating of 675,000 acfm at 33.8 inwg. In 1996 Howden was contracted to complete a performance test to establish an As Tested Condition for the ID fans. Table 3 of the report, “Scrubber Converted Condition @ 300 F”, shows the operating point of the ID fans to be at 895,103 acfm and 31.41 inwg. d3. Type: Centrifugal, Inlet vane control – Westinghouse-Sturtevant, size 4132 D, DWDI Airfold, arrangement 3. d4. Motor: Constant Speed – Originally 5,500 HP and upgraded to 8,000 HP for scrubber conversion. According to Howden performance test (Table 3) the current operating point is 6143 horsepower. d5. Evaluation of the existing ID fans to support the new SCR installation is based on the following inputs and assumptions:

Input Value Source Coal Analysis %C-59.16 %Moist-13.33 SGS Coal Analysis

Higher Heating Valve 10,418 btu/lb SGS Coal Analysis Gross Output 812 MW Questionnaire Heat Input to Boiler 7,350 * 10^6 btu/hr Questionnaire Excess Air 18% Draft System Data Sheet ESP Leakage 3% Standard Value SCR Leakage 0% No SCR bypass damper assumed Air Heater Leakage 22% Back calculated from stack O 2 Site Elevation 4365 ft ID fan data sheet Static Pressure at Furnace 0 inwc Gas Profile Pressure Loss through SCR dp 10 inwc Estimate, w/ ductwork

Pressure Loss through AH dp 7.2 inwc Gas Profile Wet FGD Pressure Loss dp 10 inwc Estimate w/ ductworkS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 9 Pressure Loss from FGD through Stack 3.9 inwc, at Test Block Assumed

Air Heater Outlet Temp 251 deg F Gas Profile d6. Based on preliminary calculations the existing ID Fans will require modifications to support installation of new SCRs. d6.1 Existing rotating element will be replaced with a new rotor assembly (impeller, shaft and bearings) with maximum tipped blades in order to support the new SCR System. d6.2 Tipping a centrifugal ID fan of the existing size and arrangement will typically result in an increase of up to 7.5% flow, 15% pressure, and 27.5% brake horsepower. d6.3 Pressure Rise: Tipping the ID fans will increase the maximum pressure rise by 15% from 41.5 inches water column to 47.7 inches water column at the calculated MCR flow of 890,000 acfm. The required pressure rise for the ID fans with a SCR addition is 42.3 inches water column. ID fans that were tipped would have a 12.8% pressure margin of the maximum capability of the fan above the required fan pressure rise. This pressure margin is less than the 15% margin that S&L typically uses in design work. With additional plant data from actual flow and pressure testing, the acceptable margin may be reduced to 12.8% because system duct losses will be better defined thereby allow less margin to be accepted. d6.4 Flow Increase: The addition of an SCR to the flue gas path at Navajo will increase the volumetric flow by approximately 4.5% due to the injection of dilution air with the ammonia. This increased flow will not affect fan performance. Motor HP: From the 1996 performance test report issued by Howden, the ID fan motor is providing 6,143 brake horsepower at the current full load operating point. With the ID fans tipped, the brake horsepower requirement of the fan would be approximately 27.5% larger in value, resulting in an estimated 7,832 brake horsepower. This larger horsepower requirement is acceptable for the existing fan motor because the ID fan motors are rated at 8,000 horsepower output. e. Compressed Air e1. The compressed air demand of the SCR sy stems will be provided by the existing service / instrument air systems.

2.2 SCR AND BAGHOUSE OPTION
a. SCR: Refer to Section 2.1.a. b. Reagent Unloading and Storage: Refer to Section 2.1.b. c. Sorbent Injection System (Trona): Refer to Section 2.1.c.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 10 d. ID Fans d1. Refer to Section 2.1.d for configuration and performance data for existing ID Fans. d2. Evaluation of the existing ID Fans to support a new SCR and Baghouse is based on the inputs and assumptions defined in Section 2.1.d including the following:

Input Value Source System Balance Point at existing ID fan discharge (-1 inwc at baghouse inlet) Industry standard for Baghouse to be under negative pressure Baghouse Pressure Loss dp 10 inwc Estimate w/ ductwork Booster Fan Pressure Margin 15% S&L standard Booster Fan Flow Margin 5% S&L standard

d3. Based on preliminary calculations, new ID Booster Fans will be required to support installation of a new SCR and Baghouse. The cost estimate shall be based on the following ID Booster Fan configuration: d3.1 The 4 x 25% existing ID fans (per Unit) will be utilized. Two new 100% axial ID Booster fans (per Unit) will be added in-between the Baghouse outlet and Wet Scrubber inlet to account for the remaining system pressure loss. The following table identifies the calculated fan sizing parameters:

PRELIMINARY DATA FOR EXISTING ID FAN FOR REVISED CONFIGURATION Test Block MCR

Volumetric Inlet Flow, each existing ID fan acfm 945,000 890,000

Fan Total Press in. wg 32.3 28.1

Density at Fan Inlet lb/cuft 0.0431 0.0437

Number of ID Fans 4 4

Temperature at Fan Inlet deg F 251 251

Fan Inlet Static Pressure in. wg -33.1 -28.8

Fan Inlet Area sq ft 240 240

Fan Outlet Static Pressure in. wg -1.2 -1.0

Fan Outlet Area sq ft 182 182S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 11 Motor Horsepower BHP 5,384 4,821

PRELIMINARY DATA FOR NEW BOOSTER FANS Test Block MCR (Full Load, no margins)

Volumetric Inlet Flow, each ID fan acfm 1,890,000 1,785,000

Fan Total Press Rise in. wg 31.3 26.5

Density at Fan Inlet lb/cuft 0.0443 0.0446

Number of ID Fans 2 2

Temperature at Fan Inlet deg F 274 272

Fan Inlet Static Pressure in. wg -13.8 -12.0

Fan Inlet Area sq ft 240 240

Fan Outlet Static Pressure in. wg 16.0 13.1

Fan Outlet Area sq ft 182 182

Motor Horsepower BHP 9,968 8,714 e. Baghouse (Pulse-Jet Fabric Filter) e1. A Pulse-Jet Fabric Filter (PJFF), if required, will be designed per the following basis: e2. A new Pulse-Jet Fabric Filter will collect the solid byproduct generated by the reaction between airborne SO 3 and injected sorbent. The fabric filter will be designed with a gross air to cloth ratio of 6:1.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 12 e3. The fabric filter consists of the following equipment and components per Unit:

Equipment Qty/Redundancy Casing(s) 2 Flue Gas Flow Configuration Flue Gas Inlet & Outlet on the Same Side Compartments 8 Compartments; 4 per side per baghouse casing (pending vendor design) Bag Type PPS fabric bags Pulse Air Compressor 2 x 100% Pulse Air Dryer 2 x 100% Pulse Air Receiver 2 x 100%; 1 wet receiver, 1 dry receiver Pre-Filters 2 x 100% After-Filters 2 x 100% Hopper Vibrators 2 x 100% per hopper e3.1 Compressor Type: Oil Free Centrifugal Compressor, e3.2 The compressor is sized for the Pulse Jet cleaning cycle of the baghouse delivering 125 psi instrument quality air. The compressed air system will also provide compressed air to new intermittent users (valves, instruments, tools, etc.). e3.3 Dryer Type: Heated blower purge type regenerative desiccant dryer (-40 deg F dew point). e4. Fabric Filter Waste Collection and Disposal e4.1 Waste collection and disposal will be designed per the following basis: e4.2 Reacted & unused sorbent collected in the baghouse hoppers will be transferred via a pneumatic system to waste storage silo. The waste storage silo will be sized for a 7-day storage capacity.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 13 e4.3 The waste collection and disposal system consists of the following equipment and components:

Equipment Qty/Redundancy Fabric Filter Waste Collection Silo 1 x 100% (per Unit) Fabric Filter Waste Collection Blowers 3 x 50% (per Unit, Units 2 & 3) 2 x 100% (per PJFF, Unit 1) e5. Waste will be disposed to existing plant land fill via truck. f. Compressed Air System f1. Compressed instrument and service air for new users will be provided by the PJFF pulse air compressors.

3. ELECTRICAL/I&C

3.1 SCR OPTION a. SCR Electrical System a1. The existing 8000 HP ID fan motors are rated at 13,200 volts, 1.15 SF and 330 FLA. During the initial field walkdown, it was noted that with the units operating at close to full capacity, the ID fan motors were operating at an average of 230 amps. This confirms that although, fan modifications are required to overcome additional pressure drop due to the SCRs, the existing motors will have enough capacity to drive the modified fans. a2. Based on review of existing plant drawings, it was determined that new 480 V electrical distribution equipment will be required to handle the additional SCR and Sorbent Injection System loads. Two (2) new 4.16 KV – 480 V unit substation transformers (USTs) will be added to each unit. The power supply for those transformers will originate from the ex isting FGD 4.16 KV switchgear located in each FGD Pump House. The transformers will in turn supply power to a new 480 V switchgear, which will distribute that power to new 480 V MCCs. a3. For each unit, the new USTs will be located to the east of the Pump House, and the 480 V switchgear will be located within the FGD Pump House. For Units 1 and 3, the new SCR MCCs will be located in new PDCs near the SCRs. Due to space constraints by Unit 2, the MCCs will be located in the Unit 2 FGD Pump House a4. The Ammonia Delivery System associated with the installation of the SCRs for each of the three units will be located at the south end of the power plant. The Ammonia Delivery System will require new 480 V MCCs. The MCCs will beS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 14 powered from the existing switchgears LSPA and LSPB located in the Limestone Prep Enclosure. a5. Miscellaneous equipment, such as UPS, UPS batteries, lighting transformers, distribution panels, etc, will also be include in the overall SCR electrical system design. b. SCR Distributed Controls System b1. The SCR system will be controlled by new DCS equipment that will be tied into the existing plant Foxboro DCS system. New DCS equipment for Unit 1 and Unit 3 will be located in their respective EE buildings near the SCR. New DCS equipment for Unit 2 will be located in the existing Unit 2 FGD Pump House. The common DCS equipment for the anhydrous ammonia equipment will be located in the Anhydrous Ammonia Unloading and Storage Area. All new DCS equipment will tie into the existing network in the Environmental and Chemical Lab Control Room. The new Unit 1 and Unit 2 DCS equipment will tie into the existing cabinet 0-DCS-CABQ. The new Unit 3 and common DCS equipment will tie into the existing cabinet 0-DCS-CABR. Each Unit DCS will require 500 I/O points and the common DCS will require 100 I/O points. c. SCR Continuous Emissions Monitoring System c1. Each Unit’s SCR has two reactors. Each reactor will require an In-Situ NOx and O2 measurement on both the inlet and outlet side for a total of 4 measurements per Unit. In additions to these measurements, a common meteorological station will also be added.
d. SCR Instrumentation d1. Each Unit will require approximately 100 balance of plant instruments. These instruments include various transmitters, switches, thermocouples, etc. for the various SCR reactor measurements interface. The common DCS will require approximately 10 balance of plant instruments. These instruments include various transmitters, switches, thermocouples, etc. for the anhydrous ammonia unloading tanks and transfer pumps.

3.2 SCR AND BAGHOUSE OPTION a. SCR Electrical System: Refer to Section 3.1 above. b. Baghouse Electrical System b1. After reviewing existing plant drawings and the available auxiliary power study, it was determined that the new ID booster fans (estimated at 2 X 10,000 HP per unit) cannot be supported from the existing UATs. It is therefore necessary to add one (1) new UAT and two (2) 13.8KV switchgears for each unit to supply power to the booster fans. The additional 480V system loads will be handled by spare capacity from the new USTs and 480 V switchgear added for the SCRS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 15 System. The 480 V switchgear will distribute power to new 480 V Baghouse MCCs. The new MCCs will be located in the existing FGD Pump Enclosure. b2. 13.8 kV distributions will be required to distribute startup and shutdown power for the new booster fans. The new common 13.8KV switchgears will be powered from the existing Station Service 13.8KV buses SSA and SSB. It is assumed that the RSS and MSS can handle the additional startup loads. b3. Each unit will be provided with a new 3-winding UAT. The UAT will be located in the vacant space adjacent to the existing UAT. The new UAT will tap into the existing isolated phase bus duct on the high side of the existing UAT and step down the voltage from 26 KV to 13.8 KV. b4. Two (2) new 13.8 KV switchgears will be provided for each unit. The 13.8 KV switchgears will be located in new PDC enclosures. The new 13.8 KV switchgears will have cable bus connections to the new UAT. b5. Common switchgears will be added for unit startup and shutdown. The two (2) additional common 13.8KV switchgears will be located in a common PDC enclosure. b6. To the extent possible each unit will have 480V MCCs located in their respective FGD Pump House, utilizing the available space that exists there. b7. Miscellaneous equipment, such as UPS, UPS batteries, lighting transformers, distribution panels, etc, will also be include in the overall baghouse electrical system design. c. SCR & Baghouse Distributed Controls System c1. The SCR and baghouse system will be controlled by new DCS equipment that will be tied into the existing plant Foxbor o DCS system. New DCS equipment for Unit 1 and Unit 3 will be located in their respective EE buildings near the SCR, their respective PDC buildings, and thei r respective FGD Pump Houses. New DCS equipment for Unit 2 will be located in the existing Unit 2 FGD Pump House and the new Unit 2 PDC building. The common DCS equipment for the anhydrous ammonia equipment will be lo cated in the Anhydrous Ammonia Unloading and Storage Area and the common PDC building. All new DCS equipment will tie into the existing network in the Environmental and Chemical Lab Control Room. The new Unit 1 and Unit 2 DCS equipment will tie into the existing cabinet 0-DCS-CABQ. The new Unit 3 and common DCS equipment will tie into the existing cabinet 0-DCS-CABR. Each Unit DCS will require 1000 I/O points and the common DCS will require 200 I/O points. d. SCR & Baghouse Continuous Emissions Monitoring System
d1. Refer to Section 3.1.c above e. SCR & Baghouse InstrumentationS ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 16 e1. Each Unit will require approximately 150 balance of plant instruments. These instruments include various transmitters, switches, thermocouples, etc. for the various SCR reactor measurements, the new ID booster fans, and the new Baghouse equipment. The common DCS will require approximately 10 balance of plant instruments. These instruments include various transmitters, switches, thermocouples, etc. for the anhydrous ammonia unloading tanks and transfer pumps.

4. CIVIL/STRUCTURAL/ARCHITECTURAL/GEOTECHNICAL

4.1 GEOTECHNICAL DESIGN BASIS a. Existing Soil Conditions a1. Previous geotechnical reports compiled in support of the original construction at the site circa 1970 and of the FGD addition in the mid-1990s provide soil borings and other pertinent soil information. Refer to Bechtel Corporation’s “Report – Foundation Investigation, Proposed Navajo Steam Plant, Near Page, Arizona, for Salt River Project” dated October 15,1969 and Stone & Webster’s “Geotechnical Report – Navajo Scrubber Project” dated April 1993. These reports form the technical basis for the design of the foundations. b. Foundation Types b1. Heavily loaded structures will be support ed by caissons founded on rock. Lightly loaded structures will be founded on shallow foundation mats or footings.

4.2 CIVIL DESIGN BASIS a. Civil and Sitework Design Requirements a1. The site development work is closely linked with buried utility and foundation work and will require the following activities in support of the installation of the proposed air quality equipment. a1.1 Providing temporary erosion control during all construction phases. a1.2 Demolition of existing roads, concrete paving, and structures, and disposal of waste. a1.3 Grading and earthwork to shape the existing grade for new work. a1.4 Construction of temporary construction roads and access ways, if necessary. a1.5 Construction of temporary and permanent drainage facilities, and providing permanent erosion and sediment control devices as required. a1.6 Installation of temporary and permanent fencing and gates for plant security. a1.7 Restoration of construction areas following project completion.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 17 a1.8 Final grading, surfacing and permanent plant road construction. a1.9 Verification of the locations of existing underground utilities by subsurface investigation using ground-penetrating radar or similar means. a1.10 Surveying of the site areas impacted by the new work. b. Site Area, Location And Elevation b1. The overall property, including the existing station and other facilities covers approximately 50 acres. The cost estimate considers that the new work associated with the added SCRs and baghouses falls within the developed areas of the site. b2. New work will generally match existing grades and top of concrete elevations.
c. Plant Site And Grid Datum c1. Coordinates for all points will be based on the existing Navajo Generation Station plant grid system. c2. Similarly, the vertical control shall be based on existing plant monuments. These permanent monuments have been established by SRP at various locations throughout the site, and each monument is tied to the plant grid system and referenced vertical datum. d. Drainage
d1. General d1.1 The estimate considers that new equipment and building areas will be provided with appropriate drainage systems as listed below. The new drainage provisions added locally for new structures will be connected into the existing sewer systems to the greatest possible. The following items have been included in the cost estimate. d1.1.1 Storm water sewer system. d1.1.2 Oily water sewer system. d1.1.3 Process wastewater sewer system. d1.1.4 Sanitary sewer system. d2. Storm Water Sewer System d2.1 Generally all clean storm water runoff from developed site areas is collected by the existing storm sewer system. No new plant areas will be disturbed by the new work. New or relocated storm water runoff facilities will connect to the existing system and maintain similar erosion control methods and drainage patterns. d2.2 The existing storm water runoff system consists primarily of drainage trenches and storm sewers within the main power block and equipment areas.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 18 d3. Oily Water Sewer System d3.1 An existing oily water sewer system collects discharges from equipment areas that have a potential for oil contamination, and drains to an existing oil water separator for treatment prior to being recovered for use. d3.2 New or relocated oily water runoff facilities will connect to the existing systems where practical, or discharge to a new oil water separator where required. The cost estimate considers that two new oil water separators will be necessary to work around the added items and handle any additional flow. d4. Process Wastewater Sewer System d4.1 For existing mechanical process drain systems and planned process drain system, see the Mechanical Design Basis. d5. Sanitary Sewer System d5.1 Existing sanitary sewage systems conflic ting with new construction activities will be relocated. New sewer systems for new facilities or relocated systems will drain by gravity where practical and w ill connect to the existing sewer systems that will remain in-place. Where it is unfeasible or impossible to route sewage via gravity, a packaged lift station will be used. d6. High Water/ Flood Elevations d6.1 The existing Navajo Generating Station site is protected from storm water flooding by concrete lined swales and ditches, storm water runoff ponds, and recoverable water reservoirs. Since an adequate storm water management facility is in place, no additional flood protection measures are planned for new work within the developed areas of the site and no costs are included in the estimate for them. e. Roads and Surfacing e1. Construction laydown and material storage areas will be surfaced with a layer of crushed stone or gravel. e2. New surfacing work will be consistent with existing surfacing methods. Relocated plant roads will be surfaced in a similar manner to the original roads. f. Parking and Laydown Areas f1. Contractor parking and laydown will utilize previously developed laydown and parking areas to the greatest extent possible. g. Erosion and Sediment Control g1. Temporary facilities will be provided for control of erosion and turbid runoff during earthwork operations and from graded areas until they are provided with permanent erosion control measures.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 19 g2. Permanent erosion control facilities for ditches and slopes will follow the Arizona Department of Environmental Quality (ADEQ) procedures and guidelines.

4.3 STRUCTURAL DESIGN BASIS
a. Structural Cost Estimate Basis
a1. Structural work accounted for in the cost estimate includes all new reinforced concrete foundations and containment structures, structural steel utility racks, duct support structures and flue gas ductwork required by the new air quality equipment. a2. The structural portion of the cost estimate also includes an estimate of modifications to the existing flue gas ductwork and structural steel that are necessary to permit installation of new items required by the proposed air quality modifications. a3. Additionally, the structural portion of the cost estimate includes an estimate of the reinforcement needed for the existing flue gas ductwork downstream of the SCRs due to revised internal pressures in the ductwork that result from adding the new air quality equipment into the system. Quantities for required reinforcement of this ductwork’s support steel are also included. a4. The estimate does not include any costs associated with a condition assessment of any of the existing flue gas ductwork or structural steel. All estimated costs relating to modification and reinforcement of these in-place items assume that their condition has not degraded from the original installed condition in a way that affects their structural capacities. a5. The estimate does not include any costs associated with revised internal pressures in the existing flue gas ductwork upstream of added SCRs back to the boiler. The existing and new fans in the system require sufficient controls to ensure that there are no changes to internal pressures in this length of ductwork and the boiler. a6. The arrangements of the new flue gas ductwork, pipe racks and other structures and equipment will incorporate a minimum clearance above all roads of 25 feet for vehicle access wherever possible. Exceptions to this minimum value may be taken where the costs of maintaining a clearance of that height are significantly more than not doing so or where a clearance of that height would significantly impact the performance of the system because of added configuration restraints to an already congested arrangement. In no case will the clearance above a road be less than required by normal highway traffic. b. Design Codes and Standards b1. Structural design will be performed in accordance with the IBC 2006 and Sargent and Lundy standards.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 20 c. Loading: Loads will be in accordance with the International Building Code (IBC) 2006 and American Society of Civil Engineers (ASCE) 7-05. Loading combinations will be in accordance with IBC 2006 and ASCE 7-05 for steel structures and IBC 2006, ASCE 7-05, and American Concrete Institute (ACI) 318-05 for foundations.
c1. Live Loads c1.1 Grade floors, 350 psf c1.2 Elevated concrete floors, 100 psf c1.3 Galleries and grating areas 75 psf c1.4 Electrical Equipment Rooms 200 psf c1.5 Stairs 100 psf
c2. Wind Loads
A basic wind speed (3-second gust) of 90 mph, Importance Factor of 1.15, and Exposure Category C, will be used to calculate wind loads. Design wind pressure calculations will be based on IBC-2006 and ASCE 7-05.
c3. Seismic Loads
c3.1 Seismic loads will be based on IBC 2006 and ASCE 7-05 with Seismic Use Group II, Site Soil Class = C (Table 1615.1.1), and Seismic Importance Factor of 1.25. c3.2 Seismic design parameters are as follows:
c3.2.1 S s =32% Figure 1615(1)
c3.2.2 S 1 =10% Figure 1615(2)
c3.2.3 F a = 1.2 Table 1615.1.2(1)
c3.2.4 F v = 1.7 Table 1615.1.2(2) c3.2.5 Seismic Design Category “B”
c4. Snow Loads c4.1 Snow loads are based on the following parameters; c4.1.1 Ground snow load = 5 psf c4.1.2 Exposure factor = 0.9 c4.1.3 Snow importance factor = 1.1 c4.1.4 A minimum roof live load of 20 psf will be considered per the tributary area requirements of IBC.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc 21 c5. Stability Loads c5.1 Designing for wind, seismic and other lateral loads will ensure adequate rigidity of the structures. P-Delta effects will be evaluated based on the analysis results for wind and seismic load cases.
c6. Grade Slab Live Loads c6.1 All grade slabs are designed for a minimum live load of 350 psf. In addition, any grade slab subject to truck or forklift traffic will be designed for the appropriate wheel loads.

4.4 ARCHITECTURAL DESIGN BASIS
a. Architectural Features a1.1 All Power Distribution Centers (PDCs) are prefabricated buildings with metal siding, assembled whole or in parts, complete with all electrical equipment fully installed and wired. a1.2 A new Fabrication Shop will replace the existing one south of Unit 3 that will be demolished to make room for the Unit 3 SCRs. The new building will consist of masonry walls over a steel frame, matching the existing shop building. The new building will house the relocated bridge and jib cranes from the existing shop. a1.3 A new Tool Room will replace the existing one between Units 2 & 3 that will be demolished to make room for the Unit 2 baghouses. The new building will consist of metal siding over a metal frame. a1.4 New personnel elevators will be added adjacent to the baghouses for maintenance access.
b. Codes And Standards b1. Recommendations in NFPA 850, “Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations” will be followed for power plant facilities. b2. Design for life safety will conform to NFPA 101, “Life Safety Code” and to workplace safety in U.S. 29CFR Part 1910 (OSHA). c. Building Occupancy And Construction Classifications c1. Building occupancy shall be classified as F1, Moderate Hazard in accordance with IBC 2006. The general construction classification is Type II, non-combustible unprotected steel construction. c2. Buildings and structures are considered not occupied for the purpose of determining egress and fire protection requirements and so forth, with the exception of fabrication shops and other such areas of the site where plant personnel are typically present.S ALT R IVER P ROJECT Navajo Generating Station Units 1-3 Project No. 12656-001 SCR and Baghouse Capital Cost Estimate April 16, 2010 Design Basis Rev. B

Design Basis_Navajo_Rev B.doc ATTACHMENT A

DESIGN BASIS INPUT DOCUMENT LIST