APPA 2006 Engineering & Operations Technical Conference Sacramento, California

Reduction of Rainwater Intrusion Into Deerhaven Unit 2 Coal Pile Reclaim System John B. (Jack) Miller – Black & Veatch Ali McDaniel – Gainesville Regional Utilities April 9-12, 2006

Overview Gainesville Regional Utilities (GRU) Recently Installed a Rain Shield Over the Coal Reclaim for Their Deerhaven Unit 2. This Presentation Will:

Describe the Process That Lead to the Decision to Install the Cover Review the Design Development Design Features Construction Process Examine the Initial Measurements of Its Effectiveness JBM(8) - 2 04/09/2006

About the Authors Ali McDaniel

Material Science Engineer – GRU’s Project and Construction Manager for This Project

Jack Miller

Mechanical Engineer – Black & Veatch’s Project Manager for the Feasibility Study and Detailed Design JBM(8) - 3 04/09/2006

About GRU

GRU Is a Municipally-Owned Utility Serving the City of Gainesville, Florida for 100 Years Gainesville Is Located in North Central Florida GRU Serves 87,000 Retail and Wholesale Customers Owns and Operates Two Power Plants, John R. Kelly and Deerhaven Generating Stations Installed Capacity of 611 MW to Serve a Peak Demand of 450 MW JBM(8) - 4 04/09/2006

About Deerhaven Unit 2

Deerhaven Unit 2 Is a 235 MW Pulverized Coal-Fired Steam-Electric Generating Unit Commissioned in 1982 Burns Low Sulfur East Kentucky Compliance Coal JBM(8) - 5 04/09/2006

Aerial View of Deerhaven Generating Station Looking North Northeast

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Problem Definition

Rain!!

Annually 58 inches max.

48 inches avg.

34 inches min.

Wet Coal O&M Impacts Plugging in the Reclaim, Conveying Storage and Milling Systems Negative Impact to Thermal Efficiency Can Cause Significant Unit Derates and Relatively Expensive Replacement Power In 2003, Wet Coal Effects Directly Resulted in the Need for 12,879 MWh of Replacement Energy JBM(8) - 7 04/09/2006

Overview of Coal Handling System

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Highlights of Coal Handling Operations

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Highlights of Coal Handling Operations

Coal Is Delivered by Unit Trains Carrying About 11,000 Tons Unloaded From Track Hopper at 3,000 TPH Conveyed to Dual Discharge Fixed Boom Stacker Can Build 1,800 Ton Conical Coal Pile on North and South Sides JBM(8) - 10 04/09/2006

View of Stockout Tower Looking West

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Highlights of Coal Handling Operations

Reclaim System Operates at 500 TPH (2" x 0" Coal at 15% Moisture) Four Below-Grade Hoppers: Three on the South (Active Reclaim) One on the North (Emergency Reclaim) Hoppers Feed a Common 30-Inch Belt Conveyor Conveys Coal to the Six Storage Bunkers Via a Crusher Tower Bunkers Hold 18 Hours of Fuel at Typical Burn Rate Coal Is Fed to Burners Through B&W MPS 75N, DVS Rotating Classifier Pulverizers JBM(8) - 12 04/09/2006

Graphic Display – Stockout and Reclaim System

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Coal Pile Management Equipment

Excess Coal Is Moved From Stockout Pile to Long-Term Storage Using Dozers and Front-End Loaders Takes Three Machines Three Days to Move and Spread 11,000 Tons JBM(8) - 14 04/09/2006

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Analysis and Development of Solution

04/09/2006

Analysis and Development of Solution

Wet Coal Effects Had Been Manageable Until Coal Fines Content Increased In Late '90s, Began Using Lower Sulfur East Kentucky Coal Sizing Changed From Nominal 2" x 0" to ¾" x 0" Fines Increased Considerably More Conducive to Plugging When Wet More Conducive to Excessive Ratholing Above the Reclaim Hopper JBM(8) - 16 04/09/2006

Ratholing at the Center Reclaim Hopper

JBM(8) - 17 Ratholing Provides Direct Path for Rainfall and Runoff to Enter the Reclaim Hopper and Flow Directly Onto Reclaim Belt  Primary Source of Entrained Water in the Coal and Attendant Problems 04/09/2006

GRU Study

Correlation Between Rainfall and Need for Replacement Energy Due to Unit Derates Short-Term Rain Events of Greater Than 2 Inches Cause Derates on a Proportional Basis  More Rain, More Replacement Energy Needed Results for 2003

Months in Which Derates Occurred in 2003

February March May June July

Totals 20-Year Average Rainfall Recorded at Deerhaven (Inches)

3.1

4.5

2.5

6.9

6.1

23.1

Actual Rainfall Recorded at Deerhaven in 2003 (Inches)

7.2

10.9

1.9

10.1

4.0

34.1

Duration of Derate (hrs)

29 74 43 55 5

207 Replacement Energy Necessitated by Derate (MWh)

1,366 4,592 2,365 4,132 425

12,879

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B&V Study Potential Solutions

Improve Pile Management Practices  Reduce Fines Stratification Modify Reclaim Equipment  Water Collecting Gates Install Alternate Reclaim  Above Grade, Dewatering Dozer Trap Install Cover Over Active Reclaim  Intercept Rainfall – GRU’s Preferred Alternative – Estimated Cost $1.5 Million JBM(8) - 19 04/09/2006

GRU Economic Analysis

Focused on Cost of Replacement Energy Resulting From Unit Derates Recognized That 2003 Experience (12,879 MWh) Was Based on Above Average Rainfall Conservatively Assumed Average Annual Derate of 40 MW for 120 Hours Correlates to 4,800 MWh of Replacement Energy Based on Fuel Forecast (Natural Gas and Coal) – Avoidance of Replacement Energy Yielded and IRR of 13.4%  Satisfied GRU Threshold JBM(8) - 20 04/09/2006

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Design

04/09/2006

Functional Design Criteria

Sized to Prevent Rainfall From Impinging on Active Reclaim Area High Enough to Accommodate 1,800 Ton Conical Pile Maximize Area of Coverage Within Space Between Stockout Tower and Perimeter Drainage Swale Support System Cannot Impede Movement of Coal by Mobile Pile Management Equipment Support Structure Should Be Resistant to Contact by Mobile Equipment Must Accommodate Night Time Pile Management Operations JBM(8) - 22 04/09/2006

Other Design Criteria Design Life:

30 Years

Environment:

Winters Subtropical Climate  Hot Summers; Mild

Temperature and Humidity:

70 F and 90% – Design 115 F and 100% – Extreme Max 10 F – Extreme Min

Rainfall:

10-Year Return Period, 24-Hour Event  Per Hour, 7.2 Inches Total 0.30 Inches

Wind Speed:

Per the Florida Building Code (FBC)

Seismic:

Aa = .05; Av = .05, Soil Profile S-3

Grade:

189 msl

Lighting:

5 Footcandles of Illumination, Ability to Control Lighting Level JBM(8) - 23 04/09/2006

Design

Foundation System 16 – 48 Inch x 55 Foot Drilled Piers Reinforced Concrete Pier Cap  Two Piers Per Cap 2' x 3' Reinforced Concrete Grade Beams Cover Support Structure Concrete Columns Precast Concrete Beams Top of Support Is 25 Feet Above Grade JBM(8) - 24 04/09/2006

Cover Support Structure – Concrete Columns and Beams

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Cover and Its Structural Framework

Initial Concept Was a Geodesic Dome Finally Selected a Rectangular Plan Arrangement to Maximize Coverage Within Allotted Area Arched North to South  Feet Clear Span of 175 160 in Length East to West and 91 Feet Above Grade at High Point of Arch JBM(8) - 26 04/09/2006

Cover and Its Structural Framework Trusses:

Fully Triangulated Space Truss Truss Depth Is 8 Feet 7 Trusses With 25 Foot Spacing Fabricated From 8 Inch Wide Flange Aluminum Struts Lateral Stability Provided by 4 Inch Aluminum Tubing Framework Is Bolted Together

Skin:

0.050 Inch Thick Aluminum Skin Is Bolted to Frame

Lighting: Interior:

24 HPS Fixtures Attached to Inside of Cover Framework

Exterior:

8 HPS Fixtures Attached to Support Structure Each Switch Controls Six Fixtures  Provides Adjustability JBM(8) - 27 04/09/2006

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Construction

04/09/2006

Construction

JBM(8) - 29 Contracting Approach Engineering – Black & Veatch (Owner’s Engineer) Cover Supply (Detailed Design, Furnish and Erect) – Conservatek General Construction – Yates Construction Construction Management – GRU Overall Schedule Design, Fabrication and Delivery of Cover – 60 days Erection of Cover – 60 days General Construction Original Schedule Was 4 Months Actual Schedule Was 8 Months 04/09/2006

Construction

Site Preparation For Foundation and Support Structure Construction – Removed 50% of Coal From Active Pile For Erection of Cover Framework and Skin – Rebuild Minimum Coal Base of 12 Feet to Function as Construction Platform Coal Base Filled the 175' x 160' Covered Area Plus 30 to 50 Foot Margin on the East West and South Sides Foundations and Concrete Support Structures Six Week Delay in Mobilizing Drilled Pier Contractor Encountered Unforeseen Subsurface Obstructions Causing Damage to Caisson Installed 16-48 Inch Diameter Drilled Piers Tied Pairs of Piers Together With Reinforced Concrete Pier Cap Tied Outboard Pier Caps Together With 2 Foot by 3 Foot Grade Beams JBM(8) - 30 04/09/2006

Drilled Pier Caisson

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Drilled Pier Installation Equipment

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Damaged Drilled Pier Caisson

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Pier Cap Form Work

Foundations and Concrete Support Structures Poured in Place Concrete Columns Were Constructed on the Pier Caps Precast Support Beams Were Placed on Top of the Columns 04/09/2006 JBM(8) - 34

Concrete Support Structure – Lifting of Precast Beam

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Concrete Support Structure – Positioning of Precast Beam

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Concrete Support Structure – Setting of Precast Beam

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Completed Concrete Support Structure

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Erection of Cover and Supporting Structural Framework

Unique Design of Cover Necessitated Custom Designed Lifting Towers Framed Two Bays at a Time  Lift  and Proceed. Once Peak Was Reached, Sheeting to the Mid-Point of the Cover Was Accomplished The Process Was Conducted Two Bays at a Time in That Manner Until Complete JBM(8) - 39 04/09/2006

Erection Towers and Partially Completed Trusses

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Positioning Erection Towers – Partially Completed Trusses

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North Side of Trusses Resting on Concrete Support – Skin Partially Installed

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Skin Installation About 2/3 Complete – Repositioning South Towers

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Skin About 2/3 Complete – Opening for Stockout Chute Almost Complete

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View of Erection Towers on South Side and Underside of Trusses

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Close-Up View of Erection Towers on South Side

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South Side of Cover Being Raised Onto Concrete Supports

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Completing Setting of Cover on Concrete Supports

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Completed Cover Looking Northwest

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Completed Cover Looking Northeast

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Completed Cover Looking North From Tripper Gallery

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Cost of Cover

Preliminary Estimate Was $1,500,000 – Plus or Minus 30% As Bid Costs Totaled $1,718,543 Final Cost Was $1,890,573 Subsurface Difficulties Additional Dewatering Requirements for Foundation Work Extended Schedule JBM(8) - 52 04/09/2006

Initial Measurement of Results

Rainfall During First 5 Months of Operation Was 60% Above Average

No Wet Coal-Related Derates or Replacement Energy Requirements During That Time!

Estimated Savings Potentially Accruing From Avoided Replacement Energy Could Have Been $660,000

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APPA 2006 Engineering & Operations Technical Conference Sacramento, California

Questions?

April 9-12, 2006