Design Criteria Manual

PREPARED FOR:

Ketchikan Public Utilities Ketchikan, Alaska

DESIGN CRITERIA MANUAL

WHITMAN LAKE HYDROELECTRIC PROJECT

Rev. 0 October 11, 2010 H332729 Prepared by Hatch, Seattle, WA

Prepared for

Ketchikan Public Utilities Ketchikan, Alaska

DESIGN CRITERIA MANUAL (REV. 0) Whitman Lake Hydroelectric Project

Approver’s Signature and Date 0

October 11, 2010

Rev

Rev Date

C. Mannheim Revision Details

Author of Revision

Approved

Approved Date

Ketchikan Public Utilities

WHITMAN LAKE HYDROELECTRIC PROJECT Design Criteria Manual (Rev. 0)

Table of Contents 1 Intro Int rodu duct ctio ion n ..................... ................................ ...................... ..................... ..................... ...................... ...................... ..................... ..................... ................... ................ ........1 1 1.1 Project Purpose Purpos e ........................................ ................... ......................................... ......................................... .......................................... .......................1 ..1 1.2 Existing Features.......................................................................................................1 1.2.1 Whitman Dam Spillway Rating Curve ................. ......................... ................. .................. ................. ................1 ........1 1.3 Project Features........................................................................................................2 1.4 Water Rights ............................................................................................................3 1.5 References, Codes and Standards ................ ......................... ................. ................. ................. ................ ................. ................. ..........3 ..3 1.5.1 General ........................................ ................... ......................................... ......................................... ......................................... ........................3 ....3 1.5.2 Civil ......................................... .................... .......................................... .......................................... .......................................... ...........................3 ......3 1.5.3 Mechanical ...................................................................................................4 1.5.4 Electrical .......................................................................................................5 1.6 Whitman Dam Analysis............................................................................................5 2 General Projec Pro jectt Criter Cri teria................. ia............................ ...................... ..................... ..................... ...................... ...................... ...................... ..................... ............ 1 2.1 Units of Measure......................................................................................................1 2.2 Project Access ....................................... .................. ......................................... ......................................... .......................................... ..........................1 .....1 2.3 Dams and Diversion Structures ................ ......................... ................. ................. ................. ................. ................. ................. .............1 ....1 2.4 The New Penstocks and Intakes ................. .......................... ................. ................. ................. ................. .................. ................. ..........1 ..1 2.5 Powerhouse Powerho use ......................................... ..................... ......................................... ......................................... ......................................... ...........................2 ......2 2.6 Turbine and Generator Units....................................................................................2 2.7 Scope of Construction Work ....................................................................................3 2.8 Modifications to the SSRAA Hatchery Water Supply ...................... ............................... .................. .................4 ........4 2.9 Vertical and Horizontal Datum ................................................................................4 3 General Design Desig n Criter Cri teria ia.......... ..................... ...................... ...................... ..................... ..................... ...................... ...................... ..................... ..................5 ........5 3.1 Material Properties Proper ties ........................................ .................... ........................................ ........................................ ....................................... ...................5 5 3.1.1 Concrete .......................................................................................................5 3.1.2 Reinforcement...............................................................................................5 3.1.3 Embedded Steel Plates and Shapes ................. ......................... ................. ................. ................. ................. .............5 .....5 3.1.4 Embedded Anchor Bolts........ Bolts ................ ................. ................. ................. ................. ................ ................. ................. .............5 .....5 3.1.5 Shear Stud Anchors ................. .......................... ................. ................. ................. ................ ................. ................. ................. ...........6 ..6 3.1.6 Expansion Anchors........................................................................................6 3.1.7 Waterstops ................ ......................... ................. ................. ................. ................. ................. ................. ................. ................. ................6 .......6 3.1.8 Structural Steel ................. ......................... ................. ................. ................. ................. ................. .................. ................. .................6 .........6 3.1.9 Welding ......................................... ..................... ......................................... ......................................... ......................................... ......................6 .6 3.1.10 Concrete Masonry Units................................................................................6 3.1.11 Mortar ........................................ ................... ......................................... ......................................... ......................................... ..........................6 ......6 3.1.12 Grout (Masonry) (Masonry ) ......................................... ..................... ......................................... ......................................... ..............................7 ..........7 3.1.13 Coefficients of Thermal Expansion.................................................................7 3.1.14 Unit Weights.................................................................................................7 3.2 Loads and Forces......................................................................................................7 3.2.1 Summary of Loads Considered ................. .......................... .................. ................. ................. ................. ................. ..........7 .7 3.2.2 Dead Loads – Unit Weights ..........................................................................8 3.2.3 Live Loads ....................................... .................. ........................................... ........................................... ........................................ ...................8 8 3.2.4 Water Pressure ................. .......................... ................. ................. .................. ................. ................. ................. ................. .................9 ........9

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3.2.5 Active Pressure..............................................................................................9 3.2.6 At Rest Pressure.............................................................................................9 3.2.7 Passive Pressure ............................................................................................9 3.2.8 Earthquake ....................................................................................................9 3.2.9 Thermal Loads.............................................................................................10 3.2.10 Wind Load ..................................................................................................10 3.2.11 Snow Loads.................................................................................................10 3.2.12 Frost Depth .................................................................................................10 3.2.13 Ice Load ......................................................................................................10 3.2.14 Construction and Moving Surface Loads......................................................10 3.3 Structural Design....................................................................................................10 3.3.1 General Requirements.................................................................................11 3.3.2 Reinforced Concrete Design........................................................................11 3.3.3 Watertightness.............................................................................................11 3.3.4 Minimum Reinforcement and Cover ...........................................................12 3.3.5 Allowable Stresses.......................................................................................12 3.4 Seismic Analysis.....................................................................................................13 3.4.1 Objective ....................................................................................................13 3.4.2 References...................................................................................................13 3.4.3 Seismic Site Class ........................................................................................13 4 Powerhouse and Tailrace ..................................................................................................14 4.1 Foundation.............................................................................................................14 4.2 Structural Design - Stability Analysis ......................................................................15 4.2.1 Description .................................................................................................15 4.2.2 Powerhouse Loading Combinations ............................................................15 4.2.3 Powerhouse Factors of Safety ......................................................................15 4.2.4 Powerhouse Flotation..................................................................................15 4.2.5 Sliding Analysis ...........................................................................................16 4.3 Structural Design - Seismic Analysis .......................................................................16 4.3.1 Powerhouse Structures Earthquake Structural Analysis ................................17 4.3.2 Powerhouse Substructure and Base Slab......................................................17 4.3.3 Powerhouse Superstructure .........................................................................17 4.4 Architectural Design...............................................................................................17 4.4.1 General .......................................................................................................17 4.4.2 Exterior Treatments......................................................................................17 4.4.3 Interior Treatments ......................................................................................18 4.5 Powerhouse Mechanical Services...........................................................................18 4.5.1 Cooling Water.............................................................................................18 4.5.2 Domestic Water and Service Water.............................................................18 4.5.3 Restroom.....................................................................................................19 4.5.4 Compressed Air...........................................................................................19 4.5.5 Drainage System .........................................................................................19 4.5.6 Turbine Unwatering ....................................................................................19 4.5.7 Sanitary Drainage........................................................................................19 4.5.8 Fire Protection.............................................................................................19

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4.5.9 Heating and Ventilating System...................................................................20 4.6 Powerhouse Crane .................................................................................................20 4.6.1 General .......................................................................................................20 4.6.2 Design Codes..............................................................................................20 4.6.3 Design Parameters.......................................................................................20 4.6.4 Design Loads...............................................................................................21 4.7 Turbine and Generator Equipment .........................................................................21 4.7.1 General .......................................................................................................21 4.7.2 Design Parameters – to be confirmed during Detailed Design .....................21 4.7.3 Operating Conditions..................................................................................23 4.7.4 Performance Guarantees .............................................................................23 4.7.5 Other Guarantees........................................................................................23 4.7.6 Design Codes..............................................................................................23 4.7.7 Design Stresses and Loadings ......................................................................23 4.8 Tailrace with Fish Exclusion Barrier........................................................................24 4.8.1 Description .................................................................................................24 4.8.2 Design Parameters.......................................................................................24 4.8.3 Foundation Conditions................................................................................24 4.8.4 Tailrace Channel .........................................................................................24 4.8.5 Fish Exclusion Barrier – Pickets ...................................................................25 4.9 Powerhouse Electrical and Transmission Design Criteria........................................27 4.9.1 Site Conditions............................................................................................27 4.9.2 Protection and Control System ....................................................................27 4.9.3 Switchyard and Interconnection to Existing Distribution System..................29 4.9.4 AC Station Services .....................................................................................29 4.9.5 DC Services.................................................................................................29 4.9.6 Lighting.......................................................................................................29 4.9.7 Single Line Diagrams...................................................................................30 5 Conduits and Pipelines ......................................................................................................31 5.1 Codes and Standards..............................................................................................31 5.2 Description ............................................................................................................31 5.2.1 Intent...........................................................................................................31 5.2.2 Penstock Design..........................................................................................32 5.2.3 Inlet Valves .................................................................................................32 5.2.4 Anchor Blocks.............................................................................................32 5.2.5 Intermediate Support Foundations...............................................................32 5.3 Design Factors........................................................................................................32 5.3.1 Alignment Control.......................................................................................32 5.3.2 Stations and Elevations ................................................................................32 5.3.3 Unit Weights...............................................................................................32 5.3.4 Earth/Rock Parameters.................................................................................32 5.3.5 Coefficients of Thermal Expansion...............................................................32 5.3.6 Corrosion Allowance...................................................................................32 5.4 Design Loads .........................................................................................................33 5.4.1 Dead Load ..................................................................................................33

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5.4.2 Live Load ....................................................................................................33 5.4.3 Lateral Earth Pressure ..................................................................................33 5.4.4 Hydraulic Loads ..........................................................................................33 5.4.5 Earthquake Load..........................................................................................33 5.4.6 Thermal Load ..............................................................................................33 5.4.7 Snow Load ..................................................................................................34 5.5 Materials ................................................................................................................34 5.5.1 Concrete .....................................................................................................34 5.5.2 Reinforcement.............................................................................................34 5.5.3 Penstock Steel .............................................................................................34 5.5.4 Embedded Anchor Bolts..............................................................................34 5.5.5 Expansion Anchors......................................................................................34 5.5.6 Expansion/Contraction Joints .......................................................................34 5.5.7 Joints ...........................................................................................................34 5.5.8 Structural Steel ............................................................................................34 5.5.9 Welding ......................................................................................................34 5.5.10 Protective Coating .......................................................................................35 5.6 Analysis and Design...............................................................................................35 5.6.1 Loading Conditions – Penstock ...................................................................35 5.6.2 Penstock Analysis........................................................................................35 5.6.3 Loading Conditions – Anchor Blocks ..........................................................38 5.6.4 Stability Analysis .........................................................................................38 5.6.5 Minimum Reinforcement and Cover ...........................................................39 5.6.6 Allowable Concrete Stress Increase for Combined Loading .........................39 5.6.7 Wye Branch Design ....................................................................................40 5.7 Valves ....................................................................................................................40 5.8 Hydraulic Design ...................................................................................................40 5.8.1 Head Losses ................................................................................................40 5.8.2 Transient Analysis Load Cases .....................................................................41 5.9 Appurtenances .......................................................................................................41 5.9.1 Air Inlet Valves............................................................................................41 5.9.2 Access Hatches ...........................................................................................41 5.9.3 Walkway and Stairs.....................................................................................41 5.9.4 Wildlife Crossings .......................................................................................42 5.9.5 Drain Valves ...............................................................................................42 5.9.6 Filling Lines.................................................................................................42 6 Intakes and Dam Valvehouse............................................................................................43 6.1 Intakes....................................................................................................................43 6.1.1 Description .................................................................................................43 6.1.2 Design Flows...............................................................................................43 6.1.3 Fish Screening Criteria.................................................................................43 6.2 Unit 1 Intake ..........................................................................................................43 6.2.1 Description .................................................................................................43 6.2.2 Hydraulic Design ........................................................................................43 6.2.3 Structural Design.........................................................................................43

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6.3

Unit 2 Variable Elevation Intake.............................................................................44 6.3.1 Description .................................................................................................44 6.3.2 Hydraulic Design ........................................................................................44 6.3.3 Structural Design.........................................................................................44 6.4 Unit 2 Deep Intake.................................................................................................44 6.4.1 Description .................................................................................................44 6.4.2 Hydraulic Design ........................................................................................44 6.4.3 Structural Design.........................................................................................44 6.5 Whitman Dam Valve House ..................................................................................44 7 Achilles Diversion and Pipeli ne ........................................................................................45 7.1 Description ............................................................................................................45 7.2 General Design Parameters ....................................................................................45 7.3 Foundation.............................................................................................................45 7.4 Trashracks and Intake Screen .................................................................................46 7.4.1 Arrangement ...............................................................................................46 7.4.2 Fish Screening Criteria.................................................................................46 7.4.3 Design Parameters.......................................................................................46 7.5 Analysis and Design...............................................................................................46 7.5.1 Stability Analysis .........................................................................................46 7.6 Vertical Lift Gates...................................................................................................48 7.6.1 Vertical Lift Gate Design Parameters ...........................................................48 7.7 Diversion Pipeline..................................................................................................48 7.7.1 Material.......................................................................................................48 7.7.2 Supports ......................................................................................................48 8 Construction Roads ...........................................................................................................49 8.1 Description ............................................................................................................49 8.2 Design Criteria .......................................................................................................49 8.2.1 Whitman Creek Bridge Crossing..................................................................49 9 Hatchery Head Tank and Valve House.............................................................................51 9.1 Hatchery Head Tank ..............................................................................................51 9.2 Valve House ..........................................................................................................51

Appendix A - Figures

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List of Tables Table 3-1 Uniform Live Loads ..............................................................................................................................8 Table 4-1 Earth and Rock Design Parameters ..................................................................................................14 Table 4-2 Powerhouse Crane Design Parameters.............................................................................................20 Table 4-3 Turbine and Generator Equipment Design Parameters (To be confirmed) ..............................22 Table 8-2 Access Road Design Criteria ..............................................................................................................49

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1 Introduction 1.1 Project Purpos e

Ketchikan Public Utilities (KPU) is the utility division of the City of Ketchikan, Alaska. KPU buys, generates, and resells most of the electricity consumed in the City of Ketchikan and Ketchikan Gateway Bureau. KPU has historically been an isolated electrical network with no interconnection to any other utility or transmission system outside their service territory, except for the Southeast Alaska Power Agency’s (SEAPA) Swan Lake Hydroelectric Project (FERC No. 2911). With the recent completion of the Tyee-Swan Lake Intertie, Ketchikan is now connected to other members of the SEAPA, making available some capacity of the Tyee Lake Hydroelectric Project to KPU. However, the intertie also will use some capacity of the SEAPA Swan Lake Project at times when Tyee project is not fully available due to maintenance activities. Therefore, KPU could use the power generated by the 4,600-kW Whitman Lake Hydroelectri c Project (Project) to help meet both its own power needs and to reduce the power it uses from Swan Lake, and to displace diesel-fueled electric power generation. The Project will also increase the total generation capacity available to the newly interconnected SEAPA system. 1.2 Exist ing Features

Whitman Lake was a naturally formed lake prior to impoundment. However, construction of the concrete arch dam in 1927 increased the reservoir in total area to 0.23 square miles (148 acres) in size. The concrete dam is shown on Figure 1-1 and includes intakes which supply the existing fish hatchery via penstocks. The Whitman Lake watershed is 4.11 square miles, providing an average annual inflow of 75 cfs into the lake. Whitman Lake tapers from its widest point of 2,200 ft in the west to its narrowest point of 100 ft wide at Whitman Dam in the east. The Whitman Lake storage characteristics are provided on Figure 1-2. The drainage areas affecting the flow to Whitman Lake are the Whitman Lake and the Achilles diversion drainage areas (refer to Figure 1-3). Whitman Creek exits Whitman Lake at the dam and continues for 4,000 ft until its mouth at George inlet. Whitman Lake has several small, unnamed tributaries, with only one si gnificant tributary, Deer Creek. Deer Creek is 2.3 miles long and enter Whitman Lake from the northwest. Achilles Creek originates northeast of Whitman Lake and enters Whitman Creek approximately 900 ft downstream from Whitman Dam. The 0.92 square mile Achilles Creek watershed provides an average annual flow of 17 cfs. The fish hatchery is located on the north shore of Herring Cove, southeast of Whi tman Lake, and is operated by Southern Southeast Aquaculture Association (SSRAA). The hatchery will remain in operation during the construction of Project features. Currently, no hydroelectric generation exists at Whitman Lake, and the existing infrastructure serves only to supply water to the hatchery. Water is conveyed from Whitman Lake via two pipelines (24-inch and 12-inch diameters, reducing to 18inch and 10-inch, respectively) for the purpose of supplying up to approximately 30 cubic ft per second (cfs) to the hatchery. 1.2.1

Whitman Dam Spillw ay Rating Curve

The Whitman Dam spillway is a 50-ft wide overflow spillway with crest elevation 379.8 ft. Refer to Figure 1-1 for spillway details. Figure 1-4 presents the theoretical Whitman Dam rating curve and points are from the original rating curve by CH2M-Hill (CH2M 1978).

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1.3 Project Features

The Whitman Lake Hydroelectric Project will be located on the southeast end of Revillagigedo Island in Southeastern Alaska, approximately 4 miles east of the City of Ketchikan, Alaska. Figure 1-5 shows an overview of the proposed Project. The powerhouse will be located southeast of Whitman Lake and adjacent to the fish hatchery. The Project Project will generate power from the hatchery supply flow and from additional flow when lake supply is sufficient. Project features that will be included in the design are:

 Construction roads – Provide access to Whitman Dam and the Achilles Diversion and partial access to associated penstocks during construction. There will be one low-water crossing of Whitman Creek and one road crossing of the existing pipelines. The access roads will be 12-foot wide gravel roads and incorporate turnouts, laydown areas, and drainage features as necessary.

 Whitman Dam deep water intake – Provides chilled water to the hatchery. The deep water intake flow can be mixed with the warm water from the variable elevation intake to achieve the appropriate temperature for the raceways. A portion of the deep water intake flow (up to approximately 4 cfs) will bypass the powerhouse for cold water supply to the incubation room. The existing deep water intake will be replaced.

 Whitman Dam variable elevation intake – provides warm surface water to the hatchery. The warm surface water flow can be mixed with the cold water from the deep water intake to achieve the appropriate temperature for the raceways. The existing variable elevation intake will be replaced.

 Whitman Dam Unit 1 intake – New supply intake that will utilize an unused existing penetration in Whitman Dam.

 Penstocks and hatchery water supply conduits – Will be located in the clearing for the access roads to the extent possible to limit disturbing the forest.

 Achilles diversion structure and pipeline – A portion of Achilles Creek flows will be diverted to Whitman Lake to increase water available to the new powerhouse for generation.

 Powerhouse and tailrace with fish exclusion – The powerhouse will house two new hydro turbines, and its tailrace will include a fish exclusion structure to prevent fish from migrating upstream into the turbines.

 Hatchery interconnection – A 25-feet high constant head water tank with a water surface elevation of 45 feet will serve as a pressurized tailrace to Unit 2 to ensure adequate hatchery pressure from the Unit 2 diversion. Detailed descriptions of the Project features are discussed in the Project Definition Report (PDR) and will not be repeated herein. It is understood that the PDR provides the basis for the designs that will be executed utilizing this Criteria Manual. The PDR contains preliminary design values for Project features that are subject to change during the detail design that will be executed in accordance with this Criteria Manual.

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1.4 Water Rights

An existing small concrete diversion structure on lower Whitman Creek, appr oximately 2,800 ft downstream of Whitman Dam, diverts 0.15 cfs for the Ketchikan Gateway Borough (KGB). This diversion is 100 ft downstream of KPU’s stream gage. The KGB has a water right for up to 100,000 gallons per day (0.15 cfs) from lower Whitman Creek for a domestic water supply that is used to serve area homes. This 0.15 cfs is a minimum bypass flow requirement and is not available for generation. SSRAA holds a water right for 39 cfs from Whitman Lake to be used at the Whitman hatchery. Therefore, although maximum average monthly hatchery water demand is only 30 cfs, Unit 2 intake and penstock and the incubation line should have a combined hydraulic capacity of 39 cfs to be able to provide the full water right flow. A 1978 agreement signed by SSRAA and KPU requires SSRAA to subordinate its interests in the water right in favor of KPU for the purpose of KPU constructing and operating a hydroelectric power generating facility at Herring Cove (FERC 2007). Refer to the PDR for additional hydrology and hydraulic design criteria including hatchery requirements in PDR Section 2.5. 1.5 References, Codes and Standards

These design criteria will be supplemented as appropri ate by the latest issue of the following publications.

1.5.1

General

 Hatch Acres. 2009. Project Definition Report, Whitman Lake Hydroelectric Project. March 2009.

 Hatch Acres. 2006. Whitman Lake Dam Condition Assessment, Whitman Lake Hydroelectric Project. September 2006. 1.5.2

Civil

The following codes and standards will be referenced for the design of the civil structur es:

 International Building Code, 2006.  Proposed Building Code Adoptions per Title 19 of the Ketchikan Municipal Code” Ketchikan Municipal Code (KMC).

 American Concrete Institute, “Building Code Requirements for Structural Concrete”, (ACI 318-08 and 318-99, Appendix A).

 American Concrete Institute, “Building Code Requirements for Masonry Structures”, (ACI 530-05/ASCE 5-05).

 American Concrete Institute, “Specification for Masonry Structures”, (ACI 530.105/ASCE 6-05).

 American Institute of Steel Construction, “Steel Construction Manual – Allo wable Stress Design”, 9th Edition (AISC).

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 American Society of Civil Engineers, “Minimum Design Loads for Buildings and Other Structures”, (ASCE/SEI 7-05).

 American Society for Testing and Materials Standards (ASTM).  American Welding Society, “Structural Welding Code – Steel” (AWS D1.1:2006), 20th Edition.

 Occupational Safety and Health Administration Standards (OSHA).  United States of America Department of the Army, “Planning and Design of Hydroelectric Power Plant Structures”, April 30, 1995 (CORPS-EM 1110-2-3001).

 United States of America Federal Energy Regulatory Commission, “Engineering Guidelines for the Evaluation of Hydropower Projects” (FERC 0119-2).

 National Electrical Manufacturers Association, “Power Switching Equipment”, NEMA Publication SG-6.

 United States Department of the Army, “Retaining and Flood Walls”, September 29, 1989 (CORPS EM 1110-2-2502).

1.5.2.1

Ketchikan Municipal Code Proposed Building Code Adoptions Section 19.04.020

Climatic and Geographic Design Criteria. PROPOSED CHANGED SECTION. Seismic Design Category B; SS=0.261 (0.2 sec), S1=0.167 (1.0 sec): Ground Snow Load=55 psf; Roof Design Snow Load=40 psf: Wind load; 110 mps, 3 sec gusts, exposure C, or D above 150 ft sea level (MHW) (buffering determines C or D by Senior City Project Engineer). 120 mph, 3 sec gusts below 150 ft to sea level, Exposure C or D (buffering determines C or D by Senior City Engineer): Frost line is 32 inches for frost susceptible materials with 12 inches minimum bury over the top of base footings where percolation drainage materials are provided. (Meets structural foundation bury code): NEW SECTIONS. Weathering-moderate; Termite-none; Decay-severe; Winter Design Temperature-14 degrees; Ice Shield-not required; Flood Hazard (FEMA)-April 16, 1990 Firm; Air Freezing Index550; Mean Annual Temp-45 degrees. These determinations are based on the most recent NOAA and USGS mapping indexes and known local historical data. 1.5.3

Mechanical

The following codes and standards will be referenced for the design of the mechanical systems:

 Uniform Mechanical Code, 1997 edition;  International Building Code (IBC) 2000;  American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE);

 American National Standards Institute (ANSI);  Occupational Safety and Health Act (OSHA);  Sheet Metal and Air Conditioning Contractor’s National Association (SMACNA);  National Fire Protection Association (NFPA);

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 Underwriters Laboratories, Inc. (UL); and  Ketchikan Building Regulations Chapter 19.24 Mechanical Code. 1.5.3.1

KPU Building Regulations General Comments

 Weathering – moderate.  Termite – none.  Delay – severe.  Ice Shielding – not required. 1.5.4

Electrical

The following codes and standards will be referenced for the design of the electrical systems as applicable:

 American National Standards Institute (ANSI);  International Electrical and Electronic Engineers (IEEE);  International Society for Automation (ISA):  Insulated Cable Engineers Association (ICEA);  National Electrical Code, (NEC), ANSI/NFPA 70 latest edition;  National Electrical Manufacturers Association (NEMA);  National Electrical Safety Code, (NESC) ANSI C2 latest edition;  National Fire Protection Association (NFPA);  Occupational Safety and Health Act (OSHA);  Underwriters Laboratories Inc (UL) – for items required by NEC or local Code; and  Ketchikan Building Regulations Chapter 19.12 Electrical Code. 1.6 Whitm an Dam Analysis

A finite element analysis of Whitman Dam was performed as part of 2006 Condition Assessment (Hatch Acres “Whitman Lake Dam – Condition Assessment”, Document no. H-016923, prepared for Ketchikan Public Utilities, September 2006.) The study was completed with the purpose of evaluating the suitability of the dam for power production under a FERC license. FERC licensing requirements for the existing arch dams are discussed in FERC 0119 Engineering Guidelines (FERC Guidelines) Chapter 11 – Arch Dams. The 2006 Condition Assessment included a site inspection as recommended in FERC Guidelines 11-1.4. Site inspection found the arch dam structurally sound and in good repair. FERC Guidelines 11-1.4.2 prefer three dimensional finite element for the static and dynamic analysis of arch dams. The tensile strengths for safety factor comparison were calculated in accordance with section 11-7.3.2. The analyzed load combinations, expected existing concrete strengths, calculated principal stresses, resulting provided safety factors and FERC required safety levels are presented in the Table 1-1 below. The provided safety factors exceed requirements. The conclusion of the study is that the dam is capable of being a long-term feature for the proposed hydropower development at Whitman Lake. No major upgrades to

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Whitman Lake Dam should be expected in order to meet the requirements for dam safety of the FERC. Table 1-1 Whitman Lake Dam Stress Safety Factors

Load

Concrete Strength (psi)

Finite Element Calculated Stress (psi)

Safety Factor

FERC Required SF

Load Combination

Type

Stress Type

Unusual (Normal Operating)

Static

Compressive

3,800

-280

13.6

2.0

Tensile

560

+170

3.3

1.0

Unusual (Flood Condition)

Static

Compressive

3,800

-380

10.0

1.5

Tensile

560

+280

2.0

1.0

Extreme (Normal + Eq)

Dynamic Compressive

3,800

-450

8.4

1.1

827

+360

2.3

1.0

Tensile

Note: Principal tensile and compressive stresses are reported above and are the maximum stresses which occur on the plane having zero shear.

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2 General Project Criteria 2.1 Units of Measure

Units of measure for the project shall be U.S. Customary, per the standards of the National Institute of Standards and Technology (NIST). Engineered equipment furnished by non-U.S. manufacturers, if using SI units, shall indicate dimensions in both the International System of Units (SI), and U.S. Customary. 2.2 Project Access

Project access will be designed considering the following:

 Project will be accessed through the SSRAA hatchery at Herring Cove.  Permanent maintenance access to Whitman Dam and Achilles diversion from the powerhouse.

 Designed for wheeled vehicles, such as pickup trucks and tractor-trailers, to complete construction and perform routing maintenance.

 Provision of erosion and drainage structures.  Apply U.S. Forest Service (USFS) road design guidelines or similar. 2.3 Dams and Diversio n Structur es

Dams and diversion structures will be designed considering the following:

 Designed to meet FERC 0119-2, Water Retaining Structures Criteria.  Include bypasses to maintain minimum required instream flows.  Reinforced concrete utilized for new diversion structure.  Refer to PDR Table 1-1 for preliminary dam design parameters. 2.4 The New Penst ocks and Intakes

The new penstocks and intakes will be designed considering the following:

 Utilization of materials withstanding erosion and corrosion.  Means of isolation ties into automatic safe shutdown.  Venting / Surging.  Thermal expansion.  Manhole access for future inspections.  Instrumentation ports.  Means of draining.  Refer to PDR Table 1-1 for preliminary conduit design parameters.

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2.5


Powerhouse

The new powerhouse will be designed considering the following:

 Expected 50 year design life.  Economic / aesthetically pleasing exterior.  Parking area and access.  Normally not unoccupied; attended only occasionally  Remote operation  Automatic safe shutdowns.  Remote alarm capabilities.  Systems will tie into the existing KPU SCADA and hatchery control systems.  Electrical transmission system.  New transformer switchgear connecting into the existing KPU grid.  Fire protection systems.  Adequate ventilation and heating to maintain interior temperatures between 50° to 90°.  Adequate lighting (natural and artificial) to maintain the proper lighting range interior and exterior, in accordance with IES recommendations.

 Noise levels shall be maintained below 90 dB (A).  Exterior and interior security.  Powerhouse separate from dam.  Design/stability in accordance with Corps of Engineers’ EM 1110-2-3001.  Intake isolation valve tied to the automatic safe shutdown.  Sump.  Access hatches.  OSHA compliant safety systems.  Tailrace fish exclusion structure.  Refer to PDR Table 1-1 for preliminary powerhouse design parameters. 2.6 Turbine and Generator Units

The new turbine and generator units shall be designed with the following:

 Unit 1 rated capacity approximately 3.9 MW.  Unit 2 rated capacity approximately 0.7 MW.  Expected operation of 25 years before requiring major overhaul.

2



 Annual one week outage, per unit, for maintenance work.  Unattended, continuous operation.  Horizontal-axis Francis units.  Unit 1 is expected to be normally operated at peak efficiency point.  Unit 2 is expected to be operated over a range of flows.  Turbine rated flow to be confirmed during detailed design.  Refer to PDR Table 9-1 for preliminary generating units design parameters. 2.7

Scope of Constructi on Work

The Whitman Lake Hydroelectric Project will be constructed under two construction contr acts executed in successive years. The first contract will be for site layout, clearing and construction of access roads which would be completed in 2010. The second construction contract would be executed at site in 2011 and include construction of dams, intakes, penstocks, fishery supply structures and the powerhouse and tailrace. A separate turbine/generator equipment supply contract would commence in 2010 and provide delivery of equipment to site for installation in the powerhouse in 2011.

 The dam and diversion structures will be of reinforced concrete constr uction.  The intakes will be a mix of steel screen structures combined with low-press ure HDPE pipe.

 The new high-pressure portion of the penstocks will be steel while the low-pressure portions will be HDPE.

 Each turbine unit will have a butterfly valve for operational shutdown and routine overhaul or maintenance.

 The new powerhouse will be located to the west of the existing SSRAA hatchery at Herring Bay.

 The powerhouse substructure will be of reinforced concr ete construction. The superstructure will be structural steel with likely precast concrete wall panels and standing seam steel roof.

 The Unit 1 draft tube will discharge into a new tailrace channel that includes a fish exclusion structure. The Unit 2 draft tube will normally discharge into the hatchery head tank, but any head tank overflow will be routed to the tailrace channel.

 Powerhouse mechanical services will include drainage and dewatering systems, cooling water system, compressed air system and heating and ventilating.

 Powerhouse electrical services will include protection and control systems, AC station services, DC services, lighting and welding and convenience outlets distributed around the powerhouse.

3



2.8 Modif icati ons to the SSRAA Hatch ery Water Supply

The water supply to the fish hatchery will be re-routed through the new Unit 2 turbine that will discharge to a head tank with overflow protection. The tank will provide a constant head pressure at elevation 45 ft, which is assumed required to operate the various equipment of the fish hatchery (oxygenation and degassing systems) and to ensure adequate flow capacity to all raceways. The hatchery supply valve system will control flow directly from Whitman Dam (high pressure) and from the new head tank. 2.9 Verti cal and Horizont al Datum

The Whitman Lake Hydroelectric Project will use Mean Lower Low Water (MLLW) Ketchikan vertical datum that is established at the hatchery. This vertical datum has been used for all survey data produced for the work. The Project horizontal datum will be Alaska State Plane Coordinate System Zone 1 (NAD 83).

4



3 General Design Criteria 3.1 Material Properties 3.1.1

Concrete

Three different classes of concrete, based on minimum 28-day compressive strengths (for new concrete), are assumed for the various structures: Class Designation NEW Structural Structural (for areas subject to abrasion from high velocity flows transporting sediment) Fill EXISTING Whitman Dam upstream face Whitman Dam downstream face 3.1.2

Min 4,000 psi at 28 days Min 5,000 psi at 28 days Min 3,000 psi at 90 days Average 3,000 psi Average 4,000 psi

Reinforcement

Reinforcing Bars Welded Wire Fabric

3.1.3

Compressive Strength

Class Designation ASTM A615, Grade 60, deformed ASTM A185, Grade 40

Yield Strength 60 ksi

40 ksi

Embedd ed Steel Plates and Shapes

Embedded steel plates and shapes

Class Designation ASTM A36


Embedded steel pipe

ASTM A53, Grade B

35 ksi

Galvanizing, where warranted

3.1.4

ASTM A123 and A143

Embedded Anch or Bolt s

Anchor bolts - standard

Class Designation ASTM F1554, Grade 36


Anchor bolts - high strength

ASTM F1554, Grade 105

105 ksi

5



Galvanizing

ASTM A153 and A153 3.1.5

Shear Stud Anch ors

Class Designation

Stud anchors:

Tensile/Yield Strength

ASTM A108, Grades 10101020

Minimum Tensile Strength

60 ksi

Minimum Yield Strength

50 ksi

3.1.6

Expansion Anch ors

Expansion anchors are assumed to conform to the specifications for stud-type (KwikBolt Anchoring System), carbon or stainless steel, as manufactured by H ilti, Inc. 3.1.7

Waterstops

Waterstops are assumed to conform to CRD-C-572, “Corps of Engineers Specification for Polyvinylchloride Waterstops”. 3.1.8

Stru ct ural Steel

Structural steel W shapes


65 ksi


50 ksi

Other structural steel shapes

ASTM A36


58 ksi


36 ksi

Structural plates and bars

3.1.9

ASTM A992

ASTM A36


58 ksi


36 ksi

Welding

All welding will be assumed to be in accordance with the American Welding So ciety ANSI/AWS D1.1 as modified by the AISC. 3.1.10 Concrete Masonr y Units

Normal Weight Block: ..............................ASTM C90, Type 1, Grade N Compressive Strength (f1m): ....................................................... 1,500 psi 3.1.11 Mortar

Engineered Masonry Mortar:.................................. ASTM C270, Type S

6



3.1.12 Grout (Masonry)

Compressive Strength (f1c).......................................3,000 psi @ 28 days 3.1.13 Coefficient s of Thermal Expansion

Steel.........................................................................6.5 x 10--6 in/in per ºF Concrete.................................................................. 5.5 x 10-6 in/in per ºF Aluminum ............................................................. 13.4 x 10-6 in/in per ºF Masonry................................................................... 3.5 x 10-6 in/in per ºF HDPE ..................................................................... 4.0 x 10-4 in/in per ºF 3.1.14 Unit Weights

Steel.................................................................................................. 490 PCF Water .............................................................................................. 62.4 PCF HDPE ............................................................................................... 60 PCF Concrete: Structural Concrete ......................................................... 150 PCF Mass Concrete .................................................................. 145 PCF Excavated Rockfill: Dry ..................................................................................... 130 PCF Saturated............................................................................ 140 PCF Submerged .......................................................................... 78 PCF Structural and Granular Backfills: Dry ..................................................................................... 120 PCF Saturated............................................................................ 130 PCF Submerged .......................................................................... 68 PCF Bedrock.............................................................................. 165 PCF Compacted sands and clays.......................................................... 130 PCF Loose sands and clays ..................................................................... 85 PCF 3.2 Loads and Forces 3.2.1

Summary of Loads Consid ered

The following loads will be considered for design of structures. Loads used for specific structures are included in the relevant sections referring to those structures:

 Dead loads  Live loads  Water pressure

7



 Active pressure  At rest pressure  Passive pressure  Earthquake  In situ stresses  Thermal  Wind  Snow  Ice  Construction and moving surface loads 3.2.2

Dead Loads – Unit Weights

The dead load will be taken as the weight of the structure and all permanently installed equipm ent and machinery. 3.2.3

Liv e Loads

Live loads will include all loads imposed upon the structures, with the exception of dead load, wind load, snow load, hydrostatic/earth load and earthquake load. Applicable equivalent uniform and concentrated live loads are given presented in the following sections: 3.2.3.1

Uniform Live Loadings

Table 3-1 Uniform Live Loads Uniform Live Load Loaded Areas

Stairways

(lb/sq ft)

100

Floors: Offices, Corridors, Reception Rooms

100

Equipment and Storage Areas

250

Control Room

200

Mezzanine Floor

250

Shop and Turbine Floor

1,000

Mechanical/Electrical Floor

1,000

In general, floors are to be designed for an assumed uniform load per square foot of floor area. However, the floors should be investigated for the effects of any concentrated load, minus the uniform load over the area occupied. Equipment loads should take into account installation, erection, and maintenance conditions as well as impact and vibration after installation.

8



Designated uniform live loads are minimum loadings for design of slabs, beams, girders, and columns in the areas indicated. These loads may be modified, if necessary, to suit more severe specific conditions. They may be reduced 20 percent for the design of a girder, truss, column, or footing supporting more than 300 sq ft of slab, except that for the erection floor, this reduction will be allowed only where the member under consideration supports more than 500 sq ft of slab. Moving live loads are discussed in Section 2.3.13. 3.2.3.2

Concentrated Live Loads

Applicable concentrated live loads for the powerhouse due to turbine, generator and r elated equipment subassemblies and assemblies will be taken from the turbine/generator supplier submittals. 3.2.4

Water Pressu re

The magnitude of the water pressure shall be determined according to the principl es of hydrostatics, except for earthquake loading, where the effect of dynamic water pressure will be considered. The basic formula for water pressure is: P

=  w H

P

= water pressure in psf

 w

= 62.4 pcf

H

= height (or depth) in feet

3.2.5

Acti ve Pressure

Where:

Static active pressure against vertical or nearly vertical structural surfaces will be calculated using Rankine’s or Coulomb’s theory, as appropriate. The minimum horizontal pressure condition, or active earth pressure, develops when a wall rotates about its base and away from the backfill on the order of 0.002H, where H is the wall height (applies to dense cohesionless soils). 3.2.6

At Rest Pressu re

If no wall movement occurs (movement less than limit for active pressure), the lateral earth pressure condition is termed the at-rest earth pressure. 3.2.7

Passiv e Pressu re

Passive soil pressure against vertical, or nearly vertical, structural surfaces will be calculated using Rankine’s or Coulomb’s theory, as appropriate. Development of the maximum possible horizontal stress, or passive earth pressure, requires much larger wall rotation than for the active case. For dense cohesionless soils, a top deflection of 0.02H, where H is the wall height, is required to mobilize full passive pressure. 3.2.8

Earthquake

Earthquake design is discussed in Section 3.4 in detail. Lateral dynamic earth pressures will be determined in accordance with the procedures outlined in “Retaining and Flood Walls”, EM 1110-2-2502. Earthquake loads are assumed to have no effect on the water pressures considered for uplift.

9


3.2.9


Thermal Loads

Thermal loads due to expansion and contraction of materials will be calculated based on the following outside temperatures: Minimum temperature on record (winter): Maximum temperature on record (summer):

-1 F 89 F

Average winter low temperature (January) Average summer high temperature (July):

34 F 58 F

3.2.10 Wind Load

Vertical and lateral loads caused by wind will be determined in accord ance with ASCE 7-05 and the International Building Code, 2006. Wind load will be 110 mph, 3 sec gusts, Exposure C or D, above EL. 150 ft to sea level. Wind load will be 120 mph, 3 sec gusts, Exposure C or D, below EL.150 ft to sea level. 3.2.11 Snow Loads

The allowance for ground snow load will be taken as 55 psf. The roof design snow load will be 40 psf. It is not to be applied in combination with vertical hydrostatic loading and/or truck loadings. 3.2.12 Frost Depth

Frost line is 32 inches for frost susceptible materials with 12 inches minimum bury over the top of base footings where percolation drainage materials are provided. 3.2.13 Ice Load

Ice pressure of 10 kips/linear ft 1 during normal pool elevations, acting radially over the entire dam length which corresponds to an ice thickness of 3 ft. 3.2.14 Cons truc tio n and Moving Surface Loads

Construction and moving surface loads will be based on actual equipment used for construction on similar jobs. 3.3 Structur al Desig n

The design of the reinforced concrete is in accordance with the Alternate Design Method, Appendix A of ACI 318. The design of structural steel was in accordance with the AISC Steel Constr uction Manual, Allowable Stress Design. Analysis of concrete structures will begin with the overall structural stabil ity. The water retaining structures (dams) are assumed to act as rigid bodies. FERC “Engineering Guidelines for the Evaluation of Hydropower Projects” (FERC 0119-2), applies to stability of water retaining structures. FERC Engineering Guidelines provide prudent designs that are acceptable to regulatory agencies. The powerhouse is separate from the dam and analysis will begin with o verall stability in accordance with Corps’ EM 1110-2-3001 “Planning and Design of Hydroelectric Power Plant Structures”. 1

To be confirmed by analysis of climatological data

10


3.3.1


General Requir ements

The following general requirements for the design of structural elements will be met in the design. a) Beams – Fixity of beam ends depends on the relative stiffness of the beam and the beam support. Beams are designed for the requirements of shear, flexure and torsion where applicable. Beams subjected to axial load are designed taking axial load into account. No longitudinal loads are considered to be transmitted across contraction joints. b) Columns – Moment magnification is accounted for in the design of the columns. Loads are assumed to be resisted by frame action resulting from beam and column stiffness. c) Slabs – Where span/width ratios were greater than 2.0, slabs are designed as one-way members. Slab thickness will be proportioned such that no shear reinforcing is required. d) Walls – Wall thickness will be designed to have adequate shear capacity without shear reinforcement. Loads are assumed to be resisted by frame action resulting from slab and wall stiffness. 3.3.2

Reinfo rced Concrete Design

The design of the reinforced concrete will be in accordance with the Alternate Design Method, Appendix A, of ACI 318-99. In addition to the turbine/generator foundation of the powerhouse, the following elements apply to the reinforced concrete design of the powerhouse and transformer gallery. 3.3.2.1

Equipment Floors

The generator and turbine floors will be designed to sustain the following loads:

 Dead load;  Uniform load; and  Concentrated equipment loads in excess of the uniform load during equipment installation. 3.3.3

Watertightness

Control of cracking in concrete will be per the requirements specified in ACI 318. Waterstops will be provided on construction joints within the structures. The installation of polyvinylchloride (PVC) waterstops in joints in hydrau lic structures is based on principles and requirements to prevent infiltration of high-water pressures into the joint system and to prevent seepage into the dry interior spaces. To accomplish these objectives, the PVC waterstops will be used in:

 All contraction joints subject to water pressure; Vertical and horizontal construction joints daylighting to surfaces exposed to high-water pressure; Vertical and horizontal construction joints subject to water pressu re and daylighting to dry interior spaces; and  Vertical construction joints in the draft tubes. 



11



Waterstops to prevent infiltration of water into the joint system are installed as close to the source of water pressure as practicable. 3.3.4

Minimum Reinf orcement and Cover

Temperature and shrinkage reinforcement will generally be in accordance with ACI 318-99, except that those requirements will be modified for thick members where reinforcement will be designed according to the cracking theory. Shrinkage stresses will be reduced as much as practicably by careful selection of the location of joints and the order of concrete placements. Minimum reinforcement shall be as follows:

 Thickness less than 48 inches:

Per ACI 318-99

 Thickness greater than 48 inches:

#8’s @ 12 inches

The minimum concrete cover for reinforcement will generally be in accordance with ACI 318-08, except as follows: Minimum Cover (inches)

Concrete in water passages

4

Concrete placed against rock or ground or in contact with still water

3

3.3.5

Allo wable Stresses

3.3.5.1

Structural

The AISC Specification will be used as a basis for the design. For normal loading conditions, the allowable stresses will not exceed those permitted by AISC. For extreme loading conditions, the stresses may be increased by 33 percent, provided they do not exceed 80 percent of the elastic limit of the material. 3.3.5.2

Welded Connections

Basic allowable stresses in welded connections will not be greater than 90 percent of the values permitted by AWS Standard D1.1. For extreme conditions, the stresses will not exceed 133 percent of the values permitted by AWS Standards D1.1, provided they do not exceed 80 percent of the elastic limit of the material. Welded field connections on major structural components will not be permitted. 3.3.5.3

Bolted Field Connections

All field connections for structural steel will be designed using high-strength bolts in slip critical type connections, in accordance with AISC Standards. 3.3.5.4

Mechanical Components

For normal loading conditions, the allowable stresses will not exceed 33 percent of the yield strength or 20 percent of the ultimate strength of the material. Stresses may be increased 33 percent for bearing stresses in pin connections. Stresses in welded connections will not exceed 50 percent of the values permitted by AWS Standard D1.1.

12



For normal loading conditions, a safety factor of not less than 5, based on ultimate strength, shall be used for the design of wire rope, lifting lugs and connections. For extreme loading conditions, this safety factor may be reduced to 2.5. 3.4

Seismi c Analysis 3.4.1

Objective

The purpose of this section is to provide general guidance and direction for the seismic design for the concrete structures of the Whitman Lake Hydroelectric Project. Specific requirements for individual structures are presented under the corresponding section. Procedures for selecting design earthquakes and associated specific motions are available (Ref. 1, 2, 3 and Ref. 4) for use in assessing the resistance of structures to earthquakes. 3.4.2

References

1. International Building Code, 2006. 2. ASCE “Minimum Design Loads for Buildings and Other Str uctures”, (ASCE/SEI 7-05). 3. ER 1110-2-1806, Earthquake Design and Analysis for Corps of Engineers Dams. 4. Engineering Guidelines for the Evaluation of Hydropower Projects, FERC 0119-2. 5. Chopra, A. K., Earthquake Response Analysis of Concrete Dams: Advanced Dam Engineering for design, construction, and rehabilitation, Edited by R. B. Jansen, pub. Van Nostrand, 1988. 3.4.3

Seismi c Site Class

For seismic analysis, the structures at the site will be designed using the following seismic characteristics, based on the 2007 KMC proposed Building Code Adoptions:

 Seismic Design Category (Site Class)=B  Mapped Spectral Acceleration (0.2 sec) SS=0.261  Mapped Spectral Acceleration (1.0 sec) S1=0.167. The above spectral accelerations correspond with the Maximum Considered Earthquake (MCE) ground motions (5% of critical damping).

13



4 Powerhouse and Tailr ace This section presents the description and the structural, ar chitectural, and general mechanical and electrical equipment design criteria applicable to the powerhouse. A general description of the powerhouse is presented in the PDR. The powerhouse foundation will be reinforced concrete construction and designed for the turbine and generator foundation loads that are provided by the turbine/generator supplier, for the various mechanical and electrical services system loads, and for the superstructure with overhead crane loads. The primary design considerations for the superstructure are:

 Structural support for the building envelope loads (primarily dead load plus live 

loads due to wind, snow and equipment) and support for the powerhouse crane including the lateral and axial loads; Seismic loads (primarily due to building weight and overhead crane operation);

 Exterior suitable for the environmental setting (seaside & relatively cold);  Owner’s architectural requirements;  Compatibility with the roof and ventilation requirements; and  Efficient and economic to erect. A structural steel framing system is recommended to accommodate the overhead crane and crane runway and provide support to the anticipated exterior wall and roof systems. 4.1

Foundation

Earth/rock parameters will be based on the subsurface investigations performed by KPU in June 2007, under the supervision of Hatch Acres senior geotechnical staff. Preliminary bearing capacity of the bedrock at the base of the power house excavation will be 120 tons per square ft (tsf) based on an unconfined compressive strength of 10,000 psi or more. Table 4-1 Earth and Rock Design Parameters Unit weight (lbs/ft 3):

Compacted sands and clays

130

Loose sands and clays

85

Angle of Internal Friction:

Compacted (SM, SP, GW) sands and gravels

35°

Loose (SM, SP, GW) sands and gravels

28°

Clay soils

0°

Cohesion (psf):

Sands and gravel

0

14


Medium clay and sandy clay


600

A friction angle of 45 degrees can be used for evaluating sliding of mass concrete on clean (water pressure washed) sound rock with cohesion equal to 0. 4.2

Structural Design - Stabili ty Analysis 4.2.1

Description

The stability analysis and design will show the ability of the structure to r esist overturning and sliding, and that allowable foundation bearing values were not exceeded. The analysis will show, for the various load cases the indi vidual external loads, the assumed area of the base, the magnitude and distribution of the normal and shearing forces at the foundation level, and the location and direction of the resultant. If necessary to satisfy sliding stability criteria, side wall friction will be applied in accordance with the geotechnical design criteria. Side friction, however, is not considered when evaluating bearing pressures. If cracking is found to occur in the extreme condition, the other conditions will be reanalyzed assuming a cracked base and compared against a reduced factor of safety. The applicable stability requirements depend on the type of structure. The proposed Achilles diversion dam will be analyzed to meet gravity dam requirements. The powerhouse is located separate from the dams (from water retaining structures) and will be analyzed accordingly. 4.2.2

Powerhous e Loading Combin ations

Applicable when powerhouse is separated from dam per USACE EM 1110-2-3001. (a) Case S-1: Head gates open, headwater at top of flood-control pool, hydraulic thrusts, minimum tailwater, spiral case full, draft tube full, uplift, and wind or earthquake. (b) Case S-2: Head gates open, tailwater at powerhouse flooding level, spiral case full, draft tube full, uplift, and wind or earthquake. (c) Case S-3: Head gates closed, tailwater at draft tube flooding level, spiral case empty, draft tube empty, uplift, and wind or earthquake. (d)

Case S-4 (Construction): No tailwater, and no uplift.

4.2.3

Powerhous e Facto rs of Safety

The required sliding factors of safety for major concrete structures are 2.0 for normal static loadings and 1.3 for seismic loading conditions. 4.2.4

Powerhous e Flotation

The structure should be adequately stable with respect to buo yant forces. The flotation safety factor, SFf , is defined as: SFf



W c S U  W g

Ws

15



Where: W s = Weight of the structure, including weights of fixed equipment and soil above the top surface of the structure. W c = Weight of the water contained within the structure that is controlled by a mechanical operator (i.e., a gate, valve, or pump). S=

Any surcharge loads (such as take-off towers or other structures).

U=

Uplift forces acting on the base of the structure.

W g = Weight of surcharge water above top surface of the structure that is totally controlled by gravity flow. Vertical resistance mobilized by friction along the exterior faces of the structure should be generally neglected. The weight of generating machinery should be included in W s, unless there is reason to believe that it will be removed and that it makes a significant contribution to the weight of the structure. Estimates of the weight of the embedded and rotating part of the generating machinery could be obtained from the equipment manufacturers for the unit ratings and specific data. 4.2.5

Sliding Analysi s

Sliding along a horizontal or nearly horizontal plane is resisted by friction. The factor of safety against sliding is the ratio of this total resisting force to the force tending to cause sliding from the net unbalanced loads. The sliding factor of safety was determined by the formula: FS 

W  U  tan  H

Where: W = total vertical force caused by weight of concrete substructure, including water, anchorage, and seismic forces, as appropriate U=

total vertical uplift force acting over 100 percent of base area

=

angle of friction along plane

H = total horizontal thrust of headwater, tailwater, silt, or earthquake load and anchorage, as appropriate. 4.3

Structural Design - Seismi c Analysis

The powerhouse’s intended use is to shelter the turbine/generator equipment and as such it is considered a building structure based on definitions provided in ASCE 7-05, Section 11.2. Powerhouse structural design will proceed in accordance with Section 3.3 augmented by seismic analysis in this section. Powerhouse stability will be first checked for post earthquake conditions assuming a fully cracked base and no cohesion to determine if the extreme post earthquake condition meets required safety factors. If this extreme condition does not achieve adequate safety factors, then a detailed earthquake analysis will be performed. Detailed earthquake analysis would be by the seismic pseudo

16



dynamic (Chopra) method. Corps of Engineers’ safety factor criteria will apply (since powerhouse is separate from dam). 4.3.1

Powerhous e Struct ures Earthquake Struct ural Analysi s

This section presents the seismic structural criteria for the powerho use. The seismic analysis and design procedures to be used in the design of powerhouse structures shall be in accordance with Section 3.4.2, References 1 and 2. The design ground motion can occur in any horizontal direction. Seismic performance category shall be selected for all the structure components based on design ground motion and importance category of the structures following Table 1.1 and Table 11.5-1 of ASCE 7-05. The design seismic forces, and their distribution over the height, shall be determined using a linearly elastic model following linear equivalent procedure. Individual members shall be sized for the shears, axial forces, and moments determined in accordance with the appropriate provisions, and connections shall develop the strength of the connected members or the forces indicated previously. The following two sections present the structural design criteria for the different components of the powerhouse structures: 4.3.2

Powerhous e Substr uctu re and Base Slab

The powerhouse substructure and base slabs are in close contact with surrounding rock mass and will be subjected to ground motions only. Structural analysis shall be made for these structures in accordance with the requirements of Chapter 12 of ASCE 7-05. 4.3.3

Powerhous e Superstru ctu re

IBC and ASCE 7-05, Chapter 12, shall be used to perform structural analysis for the seismic loading. The powerhouse superstructures includes following structural components:

 powerhouse/transformer columns, floors, etc. above the base slab  stairs, landings, ladders, etc.  structure above the turbine floor 4.4

Archi tectural Design 4.4.1

General

The powerhouse will provide features designed to facilitate intermittent occupancy by operators and maintenance workers. All equipment and control room will be installed on the same level. The external form of the building will be a simple shed with positive roof drainage. 4.4.2

Exterior Treatments

4.4.2.1

Walls

TO BE DETERMINED. 4.4.2.2

Roof

A steel framed superstructure is recommended as a cost effective framing system suited to accept the exterior wall panels. A standing seam insulated metal roof will provide a durable and cost effective roof system and would also readily accept roof ventilator curb details. The metal roof

17



panels would receive factory applied paint systems to assure long term durability while providing KPU a wide range of color possibilities. 4.4.2.3

Doors

The exterior man-doors will be thermally insulated holl ow core steel doors. The doors will have a mineral core suited to obtain the required fire rating as required to meet KPU underwriter’s requirements. The exterior doors will have security reinforce windows and glazing. The doors will have steel frames that are similarly fire rated as required. Door hardware will be selected to provide smooth operation and the security required at an unoccupied facility. The roll up truck door will be an overhead coiling steel door with operating hardware and electric operation. The door details and hardware will be selected to provide smooth operation and the security required at an unoccupied facility. 4.4.3

Interior Treatments

4.4.3.1

Floors

Concrete floors will be given a trowel finish and sealed to prevent dusting. 4.4.3.2

Walls

Interior surfaces of powerhouse concrete walls will have a smooth surface devoid of spalls or honeycomb. These surfaces will be sealed and painted. The wall panels discussed in 4.4.2.1 will be specified with a smooth interior face to allow the painted interior finish. 4.4.3.3

Doors

In general, all interior doors will be hollow metal, flush panel design, glazed or unglazed as required with pressed steel frames. Doors to areas containing combustible materi als will be unglazed steel doors with a minimum 3 hours fire rating. 4.5 Powerhou se Mechanical Servi ces

Attachments and equipment supports for all the complex equipment such as valves and valve operators, turbines and generators shall be designed to resist the minimum lateral forces specified in Section 13.6. of ASCE 7-05. For more specific information see Sections 4 and 5 of this document. 4.5.1

Cool ing Water

The powerhouse will have a cooling water system for the generator bearings and for the turbi ne seals. Flow rates and filtering requirements will be determined by the turbine supplier. The system will draw water from the penstock, with pressure reducing valves used as r equired. Filters and strainers will be automatic backwash type. There will be 100 % redundancy in pressure reducing valves, filters and strainers. The design maximum raw water temperature will be 65ºF. 4.5.2

Domest ic Water and Servic e Water

The Whitman Lake powerhouse will be an unmanned facility and will not have potable water supply. The powerhouse will have a service sink with service water supplied from a tap in the penstock. The battery area eyewash will have a self-contained water supply.

18


4.5.3


Restroom

The powerhouse will have a small unisex restroom with a sink and toil et. The toilet will discharge to the septic tank. The septic tank will be sized to accommodate expected restroom use per the following: Maximum number of daily flushes: 5 per day Low-flow toilet: 1.5 gallons per flush Total discharge per day: 15 gallons, including use of sink for hand washing 4.5.4

Compressed Air

Service air will be provided by a single tank-mounted compressor, with aftercoolers, air dryer, and service air distribution piping around the powerhouse. Hose connections will be provided at each generating unit and in the unloading bay area. The compressor will have a capacity of at least 25 cfm and will be rated for 125 psi operation. 4.5.5

Drainage Syst em

All floor and equipment drains will discharge into a drainage sump after first passing through an oil separator or filter. The drainage system will have a submersible pump or pu mps that discharge the water to the tailrace. 4.5.6

Turbine Unwatering

As the turbines are above tailwater level, normal unwatering can to be done with a valve that directs the water to tailwater. A separate line will be provided to drain the low point in the turbine spiral case and the penstock to the tailrace, which would be located in the tailrace pit. The powerhouse main floor will be located at approximately El 22.0 and above maximum tide El 21.3 to prevent powerhouse flooding in the event of high tailwater level. Turbine filling will be with a valved bypass line around the turbin e inlet valve. 4.5.7

Sanitary Drainage

The drainage from the service sink and restroom will discharge into a septic s ystem with a holding tank and drain field, unless sewer connection to hatchery sewer is possible. The septic system will be sized to accommodate a maximum flow of 100 gpd 4.5.8

Fire Protectio n

Fire protection will be provided by portable fire extinguishers. The fire protection system will meet the requirements of KPU’s insur ance underwriter. Fire protection water, if required, will be taken from the penstock, with pressure reducing valve to reduce the pressure to approximately 60 psi. Fire projection distribution piping, if required, will be provided in the powerhouse with a fire hose station on the turbine floor and in the unloading bay area. Portable fire extinguishers will generally be type ABC and will be strategically located around the powerhouse. The Whitman Dam intake valve house will have a single portable fire extinguisher.

19


4.5.9 4.5.9


Heating Heating and Ventilating System

4.5.9.1

Temperatures

See Section 3.2.9. 4.5.9.2

System Description

The primary source of powerhouse heating will be waste heat from the generators. Supplementary electric will be provided for freeze protection and comfort in the event that the powerhouse is not operating. The heating system will be sized to provide a minimum of 40F powerhouse temperature with no heat from the generators. Powerhouse cooling will be accomplished by roof-mounted ventilation fans that discharge hot air outside the powerhouse. Air intake will be via wall-mounted louvers and with motorized dampers. The louvers will have insert screens and will be sized for an air velocity of no more than 400 fpm, to preclude water (rain) from entering the powerhouse. The intake valve house will have a small electric unit heater for freeze protection in winter. 4.6 Powerhou se Crane 4.6.1

General

The powerhouse crane shall be of the electric motor driven travelling bridge type overhead crane with a main hoist. The crane shall be used for the installation and servicing of turbines, generators , and other powerhouse equipment. 4.6.2 4.6.2

Design Codes

 CMAA Specification No. 70 – Specifications for Top Runner Bridge and Gantry Type Multiple Girder Electric Overhead Travelling Cranes; and

 OSHA Standards. 4.6.3 4.6.3

Design Parameters

Table 4-2 Powerhouse Crane Design Parameters Electric bridge crane Type Rated capacity

Main hook

See Notes 1 and 2

Span

See Note 3 High Speed Minimum

Low Speed Maximum

Bridge

60 ft/min

6 ft/min

Trolley

60 ft/min

6 ft/min

Hoist

8 ft/min (Note 2)

0.8 ft/min

Speed

Lift

20


Main hook


See Note 3

Motion Tolerances

bridge

0.375 in

trolley

0.25 in

main hook

0.06 in

Crane classification

A1

Notes 1) At least 105% of heaviest lift for turbine and generator installation and any subsequent maintenance dismantling. 2) Hoist shall have capability of operating at higher speed with reduced capacity. The height of hook lift above the crane rail shall be based on the required lifting clearance for the turbine/generator components. 3) Crane dimensions to be determined.

4.6.4 4.6.4

Design Loads

The powerhouse crane will be designed in accordance with CMAA Specification No. 70. 4.7 Turbi ne and Generator Generator Equipm ent 4.7.1

General

The Whitman Lake powerhouse will have two generating units with horizontal Francis turbi nes and synchronous generators. The turbine runner will be connected directly to the end of the generator shaft, allowing a simple two guide bearing system for the units. Each turbine will be controlled by a digital governor through a high pressure oil system. A butterfly type turbine inlet valve (TIV) will be located at the entrance to the turbine spiral case. The generator will have an external flywheel flywheel if necessary to obtain satisfactory rotating inertia. The exciter will be brushless type. The turbine and generator equipment will be supplied under u nder a single contract that will include:

 turbines  governors and hydraulic power units (Unit 1)  gate positioner (Unit 2)  generators  exciters  controls 4.7.2 4.7.2

Design Design Parameters Parameters – to be conf irm ed duri ng Detailed Detailed Design

21



Table 4-3 Turbine and Generator Equipment Design Parameters (To be confirmed) confirmed) Number of units

2

Hydraulic Conditions

Unit 1

Unit 2

Maximum (spillway EL)

El 379.8

El 379.8

Average

El 375

El 375

Minimum

El 367.5

El 347

El 23.5

El 45.0 (head tank)

Type

Francis

Francis

Configuration

Horizontal shaft

Horizontal shaft

Maximum

TBD

TBD

Rated

340 ft

325 ft

Minimum

TBD

TBD

To be determined from transient analysis

To be determined from transient analysis

Maximum (full gate)

150 cfs

35 cfs

Peak efficiency

130 cfs

30 cfs

Speed

720 rpm (tentative)

1,200 rpm (tentative)

Runner centerline

El 28.5 (tentative)

El 27.0 (tentative)

Reservoir (lake) levels

Tailwater level Turbine

Net head

Maximum transient (for runaway speed design) Discharge per unit at rated head

Turbine Inlet Valve

Type

Butterfly

Butterfly

Diameter

42 inches (tentative)

24 inches (tentative)

Operator

Electric or hydraulic

Electric

Type

Digital with HPU

Gate positioner

Maximum operating pressure

2,000 psi

2,000 psi

Governor

22



Generator

Type

Synchronous

Synchronous

Configuration

Horizontal

Horizontal

Rated output

4.333 MVA

1.0 MVA

Power factor

0.9

0.9

Voltage

4,160 V

4,160 V

Insulation

Class F

Class F

Temperature rise

80ºC

80ºC

Cooling

Air

Air

Inertia (WR2)

To be determined by transient analysis

Exciter

Type

4.7.3

Static

Static

Operating Condit ions

Unit 1 will be designed to operate at flows ranging from 60% to 100% of full gate flow over the range of head conditions given in Section 4.2.2. Unit 2 will be designed to operate at flows ranging from 30% to 100% of full gate flow over the range of head conditions given in Section 4.7.2. Operation will be without objectionable surges in power output, detrimental vibration or objectionable noises. The unit shall have good efficiency over a wide range of flows and heads. 4.7.4

Perfor manc e Guarantees

The turbine and generator equipment contractor will be requ ired to guarantee weighed efficiency as well as maximum output. The specific formula for the weighted efficiency will be part of the turbine and generator specification. The turbine and generator contract will have liquidated damages to cover shortfalls in performance. 4.7.5

Other Guarant ees

Other guarantees will include:

 Turbine cavitation damage  Generator temperature rise The specific requirements will be included in the turbine and generator equipment specification. 4.7.6

Design Codes

Design codes will be given in the turbine and generator equipment specification. 4.7.7

Design Stresses and Loading s

The design stresses and loading will be given in the turbine and generator equ ipment specification.

23


4.8


Tailrace with Fish Exclusion Barrier 4.8.1

Description

The tailrace will be designed for 185 cfs and will handle primarily the discharge from Unit 1 (up to 150 cfs), although it must also handle any overflow from the hatchery headtank (up to 35 cfs). The tailrace will be a rectangular reinforced concrete channel with a width of approximately 10 feet and a wall height of approximately 8.5 feet. The exclusion barrier will be designed to minimize the attraction and stop the migration of upstream migrating fish into the tailrace. The exclusion barrier will also be designed to minimize the potential for injury of fish that are attracted to the tailrace. A picket fence installed in the tailrace is the preferred exclusion barrier as it will maximize the energy generation by allowing a lower tailrace water level than a velocity barrier. The tailrace fish exclusion steel pickets will be designed similar to trashracks. 4.8.2

Design Parameters

The fish exclusion structure will be subject to NOAA’s fish exclusion criteria in “Anadromous Salmonid Passage Facility Design”. Durable screen media should be used. Stainless steel screens are expected. Design flow = 185 cfs Maximum picket bar spacing = 1 inch Maximum average picket through velocity = 1.0 fps Tailrace channel freeboard = 1 ft Maximum tide elevation = 21.3 feet 10% exceedance tide elevation = 19.5 feet 4.8.3

Foundation Conditi ons

The depth to bedrock is too great for the tailrace channel to be economically founded on bedrock. Based on testpits dug in June 2007, the foundation material is primarily manmade fill and riprap (broken phyllite, sand and gravel, boulders up to 7 feet in diameter) to a depth of about 6 feet, and silt and clay with very high moisture content at greater depths. 4.8.4

Tailrace Channel

The tailrace channel will be designed according to the criteria for concrete lined flood control channels in USACE EM 1110-2-2007. The channel will likely be constructed as a U-frame section with continuously reinforced concrete paving. 4.8.4.1 Load Conditions

The primary loadings on the U-frame structure are weights of the structure and contained water and the geohydraulic pressures resulting from the restraint provided by the structure. The following loading conditions will be considered: Case 1 – Construction condition (unusual condition): Structure complete with backfill in place; at-rest earth pressure; channel empty; compaction effects and construction surcharge loadings.

24



Case 2 – Design loading (usual condition): Water in channel at maximum design water level; atrest earth pressure; backfill saturated to the normal ground water level adjusted to reflect the effectiveness of any drainage system. Case 3 – Drawdown loading (usual condition): Construction complete; water in channel to normal level; active earth pressures; backfill saturated to normal ground water level adjusted to reflect the effectiveness of any drainage system. Case 4 – Earthquake loading (unusual condition): Construction complete; water in channel to normal level; active earth pressures; backfill saturated to normal ground water level adjusted to reflect the design effectiveness of any drainage system; seismic loadings. Case 5 – Other special load cases: Modify the above load cases to include other special loads applied to the U-frame structure. Examples are maintenance vehicles and bridges or other permanent structures which are supported by the U-frame. 4.8.4.2 Stability

The tailrace structure will be designed to resist sli ding, overturning, bearing failure according to the criteria in USACE’s EM 1110-2-2502. Flotation stability will be verified based on the criteria in USACE’s ETL 1110-2-307. 4.8.4.3 Reinforced Concrete Design

The design of the reinforced concrete will be in accordance with the Alternate Design Method, Appendix A, of ACI 318-99. 4.8.5

Fish Exclus ion Barrier – Pickets

4.8.5.1 General

The fish exclusion picket assembly will be designed to satisfy the von Mises-Hencky criteria for ductile fracture, with biaxial stresses in accordance with: F y 2 2 2 = f x + f y - f x f y + 3 xy n

where: F y

= minimum specified yield strength of the material

n

= factor of safety > 1.33

f x

= normal stress in x-direction

f y

= normal stress in y-direction

τ

xy

= shear stress

The lateral stability of the picket bars will be determined according to: F f =

 t 2 E 1 - 0.63 t/d L d

2.6

where: F f

= failure stress

F y

= minimum specified yield strength of the bar material

25



E

= Youngs modulus

L

= laterally unsupported length of bars

d

= depth of bar

t

= thickness of bar

The allowable stress shall be 0.6F f or 0.5F y , whichever is lower. The slenderness ratio, L/r , of the bars shall not exceed 300 with the radius of gyration, r = t / 12 4.8.5.2 Vibration

The picket bars and screens shall be designed to be safe against flow induced vibration. The n atural frequency of the bars and screens will be at least three times the forcing frequency. The natural frequency of bar vibration, f n , will be calculated as follows: f n =



E I g

2 

W L3

where: I

= moment of inertia of bar

g

= acceleration due to gravity



=

d t 3/12

= end fixity coefficient : =

17

=



=

4  2 / 3 for fixed ends

2

for welded ends for simply supported ends

W

= virtual weight (total weight of bar + weight of vibrating fluid) = V(  + f b/t)

V

= volume of bar between supports



= specific weight of bar material

 f

= specific weight of fluid

b

= effective clear spacing of bars ( < 0.55d )

=

d t L

Forcing frequencies shall be calculated as follows: Vortex shedding frequency, f 1 =

v S t

where: v = average net velocity of flow past the picket bars S = Strouhal number = 0.12 + 0.012 d / t If d/t < 4, S will be determined from Fig. 3 in the article “Production of flow-induced forces and vibrations” by Penneno (February 1981).

26


If R =

bar spacing bar thickness


< 5 , then S will be multiplied by S fac

with S fac = - 0.1022 R3 + 1.181 R 2 - 4.525 R + 6.881 4.8.5.3 Embedded Parts

The bearing stresses on the concrete shall not exceed those allowed for 3,000 psi concrete in ACI 318. The embedded anchor bolts for the picket structure shall be installed in p rimary concrete. Anchors shall be headed with end plates as required and will not be of the L- or J-type construction. 4.9

Powerhouse Electri cal and Transmi ssion Design Criteria 4.9.1

Site Conditi ons

 Altitude is less than 1,000 m (3,280 ft)  See 3.2.9 for ambient temperature criteria (outdoors)  See 3.2.10 for wind loading criteria (outdoors)  See 3.2.11 for snow loading criteria (outdoors)  See 3.4 for seismic design criteria  Ice loading 0.25 inch at wind 50 mph, based on NESC (outdoors) 4.9.2

Protectio n and Contro l System

The control system will be designed to provide three modes of control: 1. Remote Automatic, the unit will be started, stopped, and loaded through the SCADA control system. 2. Local Automatic, the unit will be started, stopped, and loaded through the local control system independent of the SCADA system, but the start/stop and control sequence will be controlled by a local PLC. 3. Local Manual, the unit sequence will be manually initiated, this mode is primarily intended to facilitate unit testing and commissioning. The control system will be designed to allow various modes of operation depending upon the number of units available, water available and the hydraulic conditions. The operator will be able to select the mode of operation and the range of the operating parameters:

 Reservoir water level control.  Constant power output.  Best efficiency point (for periods of low water). Each turbine/generator unit control system will be provided with an independent power supply such that any unit can be removed from service without affecting others.

27



The turbine/generator unit control system will interface with the existing KPU SCADA system control and monitoring equipment using ModbusRTU® protocol. NovaTech Orion protocol converters shall be used as needed for converting DNP3 relay protocol to ModbusRTU protocol. Generator and other protection will be provided by the use of multi-functional utility grade relays. The relays will be provided with event recording and oscillographic capabili ties (fault capture). The relays will be able to communicate with the SCADA system using RS-232 or RS-485 interface, DNP 3.0 protocol, as well as being locally interrogated. The generator protection will include the following IEEE functions using Basler generator protection relays:

 24 volts/hertz (over fluxing protection);  27/59 under/over voltage;  32 reverse power*;  46 negative sequence over current;  47 negative sequence over voltage;  50/51 phase over current protection;  50/51N neutral over current protection;  50/62 BF breaker fail protection;  60 voltage imbalance or voltage transformer fuse failure;  81 O/U over/under frequency;  87 G generator differential; and  Protective relay fail (waterdog timer and voltage fail).  For the reverse power function, two set points will be required, one for the operation in active generation mode, and one for operation in the synchronous condenser operation mode with the turbine dewatered. Step-up transformer protection shall use Schweitzer Engineering Laboratories relays that include:

 50/51 phase over current protection;  50/51N neutral over current protection;  50/62 BF breaker fail protection;  87 T transformer differential; and  Protective relay fail (watchdog timer and voltage fail). 34.5 kV line protection shall use Schweitzer Engineering Laboratories relays that include:

 21 three-zone timed distance impedance;  67/67N directional over current protection; and  Protective relay fail (watchdog timer and voltage fail). In addition, various mechanical protections for the turbine and generator will be provided:

28



 generator winding temperature monitoring  stator core temperature  cooling air temperature  cooling water low flow  cooling water high temperature  guide bearings high temperature  thrust bearing high temperature  vibration monitoring  unit over speed  unit creep The mechanical protection may be provided by separate devices or incorporated into the protective relay scheme as applicable. 4.9.3

Switchyard and Interconnection to Existing Distributi on System

The generation will be at the nominal 4,160 volt level. Generator circuit breakers shall be vacuuminterrupter, draw-out type housed in metalclad, arc-resistant switchgear. To connect to the existing 34.5 kV system, one new transformer will be required. The transformer will step up voltage from 4,160 volts to 34.5 kV and shall be sized such that it can carry the maximum output of both units. The switchyard is expected to be located just northeast of the powerhouse. 4.9.4

AC Station Servic es

480/277 volt and 120/208 volt station services will be provided to distribution panels through draw out breakers in metal clad switchgear. AC station services will include maintenance welding outlets, grounding system and lower voltage convenience outlets distributed throughout the powerhouse. Each unit auxiliary services will be supplied through an independent breaker. The 480 volt switchgear will also provide backup power to the hatchery. 4.9.5

DC Servic es

DC services will provided from a new battery bank. The bank will be sized during detailed design. Two (redundant) chargers will be provided. The battery bank will provide 125-V DC power to the protective devices and to the SCADA/PLC equipment through appropriately sized DC/AC inverters. 4.9.6

Lighting

Powerhouse lighting will be by means of switched high bay fixtures. Lighting in the control room and offices will be by means of high efficiency, non glare fluorescent fixtures. Lighting in the substation shall be provided with switched HID lighting. Emergency lighting will be by means of self contained “battery pack” type fixtures sized in accordance with the building occupancy requirements.

29


4.9.7


Singl e Lin e Diagrams

The KPU system one-line diagram is shown on Figure 4-1 and was last updated in 2008. The KPU one-line includes a place holder for the future Whitman Lake substation. The conceptual level Whitman Lake substation one-line diagram is shown on Figure 4-2.

30



5 Conduit s and Pipelines 5.1 Codes and Standards

The following codes and standards will govern the design of the penstocks, anchor blocks, and supports:

 American Society of Civil Engineers (ASCE) “Steel Penstocks” – Manual No. 79.  American Concrete Institute, “Building Code Requirements for Reinforced Concrete” (ACI 318).

 American Institute of Steel Construction, “Steel Construction Manual, Al lowable Stress Design,” 9th Edition (AISC).

 American Society of Civil Engineers, “Minimum Design Loads for Buildin gs and Other Structures,” ASCE 7.

 American Society of Mechanical Engineers (ASME), “ASME Boiler Vessel Code, Section VIII Pressure Vessels, Division 1.”

 American Society of Mechanical Engineers (ASME), “ASME Boiler Vessel Code, Section VIII

Pressure Vessels, Division 2 Alternate Rules.”

 American Society for Testing and Materials Standards (ASTM).  American Welding Society, D1.1 “Structural Welding Code” (AWS D1.1).  Federal Energy Regulatory Commission (FERC), “Engineering Guidelines for the Evaluation of Hydropower Projects”.

 International Building Code, 2006.  United States Department of the Interior, Bureau of Reclamation, “Welded Steel Penstocks,” Engineering Monograph No. 3, 1977.

 American Iron & Steel Institute (AlSl) “Steel Penstocks and Tunnel Liners” Steel Plate Engineering Data – Volumes 3 & 4.

 United States Department of the Interior, Bureau of Reclamation, “Stress Analysis of Wye Branches,” Engineering Monograph No. 32, 1964. 5.2

Description 5.2.1

Intent

The penstock general design parameters were discussed in Section 1.4.3. The Project Definition Report suggested a mix of steel penstock for high-pressure locations and HDPE pipe in lowpressure locations. Detailed design will confirm or alter the mix of penstock materials. The existing Whitman Dam intakes will be modified for the increased flow and used to route water from Whitman Lake through the new penstocks, down the slope to a new powerhouse. The routing of the penstocks will generally follow the route of the penstock access roads to the extent possible.

31


5.2.2


Pensto ck Design

The new steel portion of penstock will be of welded steel construction and will be designed in accordance with this section. The high-density polyethylene (HDPE) portion of the penstock will be sized from vendor information to meet the criteria of this section, and detail design will be by the HDPE vendor. 5.2.3

Inlet Valves

Penstock inlet valves are discussed in Section 5.7. 5.2.4

Anch or Bloc ks

The anchor blocks will be founded on rock at the major changes in horizontal and vertical ali gnment as required. Thrust rings will be provided on the new steel penstock to transfer load to the anchor block concrete. The anchor blocks will be designed to be stable under all anticipated lateral and longitudinal loadings. 5.2.5

Intermediate Support Foundatio ns

Intermediate ring girder or saddle type supports are anticipated. It is intended that the penstock span between supports and anchor blocks. 5.3 Desig n Facto rs 5.3.1

Alig nment Contro l

The alignment of the proposed penstocks are shown on the project drawings. The Contractor will be responsible for all site survey during construction to establish all construction sight lines and temporary benchmarks. 5.3.2

Stations and Elevations

Stations and elevations will be determined based upon existing hatchery reference drawings and the project drawings. Surge head will be assumed to be 30% above the static head at the powerhouse. The headwater elevation at Whitman Lake will be taken as 379.8 ft (spillway crest) for design purposes. 5.3.3

Unit Weight s

Refer to Section 3.1.14. 5.3.4

Earth/Roc k Parameters

Refer to Section 4.1. 5.3.5

Coefficient s of Thermal Expansion

Refer to Section 3.1.13. 5.3.6

Corrosi on Allo wance

The new penstock will have a protective coating system applied to both internal and external surfaces. Associated plates and stiffeners will be painted on all surfaces and/or sealed against moisture. Accordingly a corrosion allowance is not required per ASCE Manual 79, Section 1.9.

32



5.4 Desig n Loads 5.4.1

Dead Load

 Penstock: Weight of steel or HDPE only  Anchor Blocks and Ring Girder Foundations: Weight of steel or HDPE and concr ete 5.4.2

Liv e Load

 Stairs and Platforms =

100 lbs/ft2

The live load for the penstock and supporting concrete foundations will include the weight of water. The penstock will be investigated for the following as needed:

 Penstock half-full  Penstock full, unpressurized  Penstock full, normal operating pressure  Penstock full, maximum surge pressure 5.4.3

Lateral Earth Pressu re

The anchor blocks and ring girder foundations are earth-retaining str uctures. The stabilizing effects from lateral earth pressures will be included using active, at rest, and passive loads as appropriate. 5.4.4

Hydraulic Loads

Water pressure will be assumed to act in accordance with the prin ciples of hydrostatics except for the condition of earthquake loading when it will be calculated in accordance with Section 2.3.5. Internal water pressures for the surge condition will be increased according to the assumed pressure rise of 30% of maximum static head at the powerhouse and decreasing linearly to El 482.6 at the intake. The actual maximum hydraulic pressure will be verified based on shutdown time for the respective generating units in the powerhouse. 5.4.5

Earthq uake Load

Refer to Section 3.4. 5.4.6

Thermal Load

Differential thermal expansion and contraction will be considered in the design of the various components of the replacement penstock. The range of penstock temperatures at the site is as follows: Installation Temperature =

45°F

Maximum Penstock Temperature =

88°F

Minimum Penstock Temperature =

0°F

33


5.4.7


Snow Load

The snow load for the project will be based on ASCE 7. 5.5

Materials 5.5.1

Concrete

See Section 3.1.1. 5.5.2

Reinforcement

Existing reinforcement will be assumed to have a yield strength of 33 ksi, in accordance with “Mechanical Engineers’ Handbook”, edited by Lionel S. Marks, First Edition, Ninth printing, 1916. New reinforcement will conform to ASTM A615, “Specification for Deformed and Plain Billet Steel Bars for Concrete Reinforcement,” Grade 60. 5.5.3

Pensto ck Steel

ASTM A516 Grade 70 will be used for rolled and welded steel plates in the fabrication of the penstocks. Spiral weld pipe will not be used. 5.5.4

Embedded Anch or Bolt s

Anchor bolts shall be galvanized and will conform to ASTM A307 or equivalent. For design, all anchor bolts will be assumed to be ASTM A307. Anchor bolt galvanizing shall conform to ASTM A153. 5.5.5

Expansion Anch ors

Expansion anchors will conform to the specifications for Phillips Red Head Anchors (Series WS, S, J, or RM) as manufactured by ITT Phillips Drill Division. 5.5.6

Expansion/Cont ractio n Join ts

Expansion/contraction joints will be used as required. 5.5.7

Joints

HDPE to HDPE: ductile iron clamps or equivalent, or field weld. HDPE to steel: Design steel flange to match HDPE stub end flange and use of cast iron clamping rings or equivalent. Steel to steel: Field weld with full penetration welds. 5.5.8

Stru ct ural Steel

Structural steel shapes and plates other than those used in the penstock fabrication will conform to ASTM A36, Grade C. 5.5.9

Welding

All welding of the penstock and ring girders will be in accordance with the ASME codes. All welding of structural steel will be in accordance with AWS D1.1 as modified by the AISC. For design, normal shield metal arc welding (SMAW) with E70XX electrodes will be assumed.

34



5.5.10 Protectiv e Coating

Painting specifications will be developed for application on interior and exterior surfaces. Portions to be embedded in concrete will not be painted on the outside except for a small overlapping band. Circumferential joints and other penstock sections that will be field welded, will be unpainted over a width of 6 inches on each side of the weld. Cathodic protection will be used for buried sections. 5.6 Analysis and Design

Analysis of the penstock will begin with the overall structural stability. Anchor blocks will be assumed to act as rigid bodies and will be analyzed according to USBR Engineering Monograph No.3 to meet the FERC guidelines for water-retaining structures. Concrete design will be in accordance with ACI 318. Structural steel will be designed according to the AISC Steel Construction Manual. Penstock design will be in accordance with ASCE “Steel Penstocks” Manual No. 79. The penstock design will also be in accordance with AISI “Steel Plate Engineering Data Volume 4, Steel Penstocks and Tunnel Liners”, where applicable. 5.6.1

Loading Conditi ons – Penst ock

The following loading conditions will be used for the design of various compo nents of the penstock: (a)

Construction Conditions

The diameter of the penstock is such that transportation restrictions will appl y. Accordingly the penstock will be fabricated, at site, from shell pieces. A temporary jig assembly will be required to support shell pieces as they a welded longitudinally and circumferentially. Temporary support of the pipe during installation will be the responsibility of the Contractor. (b)

Normal Load Condition

The normal load condition includes dead loads, hydrostatic pressures from water at normal operating level, thermal loads and snow loads. This loading condition will also include surge loading as required by ASCE Manual No. 79. (c)

Intermittent Condition

The intermittent conditions will be taken as follows: Conditions during filling and draining of the penstock. This can include pipe half full or full and unpressurized. Normal operating pressure plus earthquake. (d)

Emergency Condition

The emergency condition includes normal operating pressur e plus maximum surge resulting from governor cushioning stroke inoperative and final part gate closure to zero position at a maximum governor rate in 2L/a seconds. 5.6.2

Pensto ck Analysi s

5.6.2.1 Stability

Structural buckling stability of the penstock will be maintained by limiting compressive stresses induced by gravity loads and axial (including thermal) loads.

35



5.6.2.2 Allowable Stresses

Allowable steel stresses are limited by factors of safety applied to yield strength, ulti mate strength and buckling strength. Different loading conditions warrant the use of varying safety factors, depending on the likelihood of occurrence and the duration of the loading. Safety factors related to the tensile strength of the material are also limited by the degree of weld inspection performed. Conversely, the degree of inspection at different locations on the pipe can be established by reviewing the required strength at those locations. Safety factors will be in accordance with Section 3 of ASCE “Steel Penstocks” Manual No. 79. Buckling stability will be checked. For that analysis, stability under compression due to bending and axial forces and shear stability will be determined. Allowable stresses are determined by the following: 1.

Tension

Stresses will be in accordance with Section 3 of ASCE “Steel Penstocks” Manual No. 79. 2.

Compression

The penstock is classified as an intermediate length tubular structure. In such cases, local buckling of the shell controls, and the allowable stress is a function of the diameter to shell thickness ratio. The following relationship2 will be used for design: 2

 L   D  Z  2     D   t 

1

  2

If

 D  2.85  Z  1.2   t 

then

E t f crit  0.33 D

where: E

2



31

  2 

=

modulus of elasticity

D

=

diameter of pipe

T

=

thickness of pipe shell



=

Poisson’s ratio

The safety factor against compression buckling is determined in a fashion similar to the approach used in the AISC ASD Manual 9th edition Chapter E., where: 

K L r 2   2 2C c     F c  K L r 3 5 3K L r    3 3 8C c 8C c  Qs Qa 1 

2

f crit

Based on Equations 14.2 and 14.4 of “Guide to Stability Design Criteria for Metal Structures” edited by Theodore V. Galambos, Fourth edition, 1988.

36


WHITMAN LAKE HYDROELECTRIC PROJECT Design Criteria Manual (Rev. 0) 1 2

C c

 2 2 E      Q Q f  s a crit 

where: Qs

=

shape factor = 1

Qa

=

effective area factor = 1

K

=

effective length factor

L

=

length of span

r

=

radius of gyration

In no case will F c be allowed to exceed allowable tension stress. 3.

Shear

Similar to compression, shear buckling can occur in the elastic range: For

10

t R



L R

3

R

f crs

t

 t   0.632   R 

5 4

R L

where: L = length of span The critical shearing stress, f crs, will be limited to the shear yield stress,

F y

3

. A safety

factor of 1.67 will be applied to f crs in calculating the allowable shear stress, F v. Allowable stress will be in accordance with Section 3 of ASCE “Steel Penstocks” Manual No. 79. 5.6.2.3 Combined Stresses

The von Mises-Hencky shear yield criterion will be used to combine biaxial tension and compression with shear at any given element: F T  f e

where: f e =

  f x2  f y2  f x f y  3 f v2 

12

equivalent stress

f x, f y = bending or axial stress in the x and y axes, respectively, (tension positive;

compression negative) f v =

shear stress

Buckling stress combinations will also be limited at any section of penstock by the following interaction equation: 2

f c F c

 f    v   1  F v 

where: f c = axial compression or bending stress 5.6.2.4 Penstock Vibration

Since the penstock will not be buried, it will be checked for vibration.

37


5.6.3


Loading Conditions – Anchor Blocks

The following loading conditions will be used for the design of components of the penstock anchor blocks. (a)

Construction Condition

There will be no significant unbalanced loads associated with construction of the anchor blocks. The case with no water in the penstock will be considered as an unusual load condition. (b)

Usual Load Conditions

The usual load condition includes: dead loads and hydrostatic pressures from water at the normal operating or surge levels, thermal loads and snow loads. (c)

Unusual Load Conditions

The unusual load condition will be taken as dead loads (withou t water). (d)

Extreme Load Condition

The extreme load condition includes the usual load condi tion combined with earthquake effects or emergency surge condition. 5.6.4

Stability Analys is

The stability analysis and design will demonstrate the ability of the stru cture to resist overturning and sliding, and that allowable foundation bearing values are not exceeded. The analysis will show, for the various load cases, the i ndividual external loadings, the assumed area of the base, the magnitude of the shearing force and the location and magnitude of the resultant. Lateral loading from earth pressure will be neglected. These lateral earth loads are relatively small compared to the other forces acting on the anchor blocks, and should have a stabilizing effect. 5.6.4.1 Factors of Safety

Factors of safety are the ratio of the resisting forces to the forces tending to cause movement. The location of the resultant and the sliding factors of safety resulting from design will meet the criteria listed below. Allowable bearing pressures will have factors of safety corresponding to that required for sliding. Load Case

Sliding Factor of Safety

Resultant Location on Base

Usual

3.0

within middle 1/3

Unusual

2.0

within middle 1/2

Extreme

1.25

within base

Construction

1.5

within middle 1/3

38



5.6.4.2 Analysis - Sliding

Sliding along a horizontal or nearly horizontal plane is resisted by friction plus any cohesion between the potential sliding surfaces. The factor of safety against sliding is the ratio of this total resisting force to the force tending to cause sliding due to the net unbalanced loads. The sliding factor of safety will be determined by the shear-friction formula: F .S . 

W  U tan   c A H

where: = appropriate W

total vertical force caused by weight of concrete substructure, including water as

= total vertical uplift force acting over 100% of base area; this is assumed to be zero in the free-draining soil around the anchor blocks U 

=

angle of friction along plane

C

=

unit cohesion along plane

A

=

uncracked base area of potential sliding plane

H

=

horizontal thrust due to static and dynamic water loads or earthquake.

5.6.5

Minimum Reinf orcement and Cover

Temperature and shrinkage reinforcement will generally be in accordance with ACI 318, except that those requirements will be modified for thick members where reinforcement will be designed according to the cracking theory. Shrinkage stresses will be reduced as much as practicable by careful selection of the location of joints and the order of concrete placements. Minimum reinforcement shall be as follows:



Thickness less than 48 inches:

per ACI 318



Thickness greater than 48 inches:

#8’s @ 12 inches

The minimum concrete cover for reinforcement will generally be in accordance with ACI 318. 5.6.6

Allo wable Concrete Stress Increase for Combi ned Loading

Concrete will be designed in accordance with ACI 318, Appendix A - Alternate Design Method. Where concrete stresses caused by earthquake, construction or other temporar y and unusual forces are combined with those caused by dead, water or normal live loads, the sum of the stresses will not exceed the allowable stresses by more than shown in the following table.

Combined Loading

Dead plus (live or earthquake or thermal) Dead plus hydrostatic and (live or earthquake or thermal)

Allowable Increase of Normal Stress 0%

0%

39


Dead plus live and snow

5.6.7


0%

Dead plus hydrostatic and water surge

33-1/3%

Dead plus thermal and earthquake

33-1/3%

Dead plus live plus hydrostatic and earthquake

33-1/3%

Wye Branch Desig n

Wye branches will be designed using manual calculation methods descr ibed in Engineering Monograph No 32 and checked using AlSl “Steel Penstocks and Tunnel Liners” – Volume 3. Alternatively, finite element methods may be used. 5.7

Valves

The penstocks will include a series of flow control and shutoff valves. The penstock shutoff valves will be located just downstream of Whitman Dam and be designed to close in an emergency in the event of a rupture or leak in the penstock upstream of the turbine inlet valves (TIV). A butterfly-type TIV will be located at the entrance to each turbine spiral case. Design parameters for the valves are given in Section 4.7.2. A pressure reducing valve (or two valves in series) will be installed on the powerhou se bypass from the Unit 2 penstock to the hatchery headtank. The valve(s) will designed to open automatically if flow through Unit 2 to the headtank is interrupted to maintain hatchery flow supply. The valve(s) will either be mechanically or DC motor operated. Isolating valves will be i nstalled on each side of the pressure reducing valve(s) to allow maintenance of the valve(s). A shutoff valve will be installed at the end of the Unit 2 draft tube in the pipe to the headtank. The valve will be used for unwatering and maintenance of the Unit 2 tailrace. A bypass with a valve from the Unit 1 penstock to the Unit 2 penstock near the Unit 2 powerhouse bypass to the headtank will allow dewatering of the Unit 2 penstock for maintenance or inspection while maintaining flow to the hatchery. A shutoff valve upstream of the Unit 2 penstock upstream of the junction will prevent back flow into Unit 2 penstock. Both these valves could be manually operated and would normally be closed (bypass valve) and open (Unit 2 penstock valve). All valves will be supplied by recognized valve manufacturers and will be designed for the maximum transient pressures. The valves will be shop fabricated and shipped to site complete with valve, operator, and gaskets. Select valves will have electric motor operators that have additional contact points to allow interface with the powerhouse and hatchery control system. 5.8 Hydrauli c Desig n 5.8.1

Head Los ses

Head losses for the Whitman Lake Hydroelectric Project will be calculated based on the proposed design layout, for the maximum and average powerhouse flow with modified friction losses through the new intake, valves and new penstocks. Head losses will be calculated according to:

40


H L


V 2

 k

2g

Where k is the loss coefficient, V is the velocity in feet per second, and g is 32.2 ft/s 2. Values of k for entrance losses, bend losses, valve losses, and contraction and expansion losses will be determined in accordance with USBR “Design of Small Dams.” Head losses for pre-manufactured intake screens will be based on the manufacturer’s data. Friction losses will be calculated according to the Darcy-Weisbach equation, in which k is defined as: k  f

L D

Where f is the friction factor from the Moody diagram, L is the length of pipe, and D is the pipe diameter. The friction factor is a function of the relative roughness of the pipe, k/D. For steel and HDPE pipe, the following surface roughness values ( k ) will be used: Commercial steel pipe:

0.000150 ft

HDPE:

0.000008 ft

5.8.2

Transient Analysi s Load Cases

The following transient load cases will be investigated: Load Rejection – full load rejection from maximum plant capacity with reservoir at maximum normal water level. Load Acceptance – Speed-no-load to maximum plant capacity with reservoir at minimum water level. 5.9

Appurtenances

Pipeline appurtenances, which include air inlet valves, blow-offs, manholes, fill lines, and cathodic protection system (if required), will be designed for maximum pressures. 5.9.1

Air Inlet Valves

Air vents and corresponding valves will be sized and located according to the requi rements of the penstock system. 5.9.2

Access Hatches

Access hatches will be provided at maximum intervals of 500 feet per ASCE Manual 79. The location of hatches will be next to adjacent to any line valves or air inlet valves. Minimum diameter is 24 inches. 5.9.3

Walkway and Stairs

Sections along the penstock that are not adjacent to the construction access road will have a walkway on top of the penstock for maintenance and inspection access to the pipe. Stairs to ground level will be provided at regular intervals.

41


5.9.4


Wildlif e Crossi ngs

Wildlife crossings will be provided to ensure migration routes are not interrupted by the pipeline. The location of crossings will be based on Connectivity Plan. The design wi ll likely be wood- or logclad steel ramps on both sides of the penstocks and designed primarily for resident black bears. 5.9.5

Drain Valves

Drain valves will be provided at the downstream end of the penstock and at any intermediate low points to dewater the line. A drain valve will also be installed just downstream of the intake shutoff valve to handle any leakage past the valve during penstock maintenance. 5.9.6

Filling Lines

Fill lines will be provided to fill the penstocks from the reservoir and place them under balanced pressure to facilitate opening of the intake valves/gates. The fill lines will be provided with suitable control valves.

42



6 Intakes and Dam Valvehouse 6.1

Intakes 6.1.1

Description

There will be three intakes at the dam: a new intake for Unit 1; a replacement of existing variable elevation intake for Unit 2; and replacement of the deep water intake. The Unit 1 intake will be a pre-manufactured drum screen assembly at a fixed elevation. The Unit 2 intake will be a replacement in kind of the existing intake. It will be a variable elevation intake with an intake screen. All intakes will have shut-off valves on the downstream side of the dam to allow dewatering of the penstocks for maintenance. 6.1.2

Design Flows

The following will be the design flows for each intake: Deep intake = 39 cfs Variable elevation intake = 35 cfs Unit 1 intake = 130 cfs 6.1.3

Fish Screening Criteria

Except for the deep intake, the intakes will be subject to NOAA’s fish screening criteria. Based on previous reports by Bates and Nordlund (2007) and FERC (2007), no fry are present in the vicinity of the proposed Whitman Dam intake location. Therefore, the NOAA screening criteria indicate a maximum screen approach velocity of 0.8 fps, measured 3 inches from the face of the screen, and a maximum width opening of ¼ inch for profile bar screen (NOAA 2004). Durable screen media should be used. Stainless steel screens are expected. 6.2

Unit 1 Intake 6.2.1

Description

The new Unit 1 intake will be a pre-manufactured tee screen type passive intake with provisions for an air-burst cleaning system. The intake will be connected to the existing 36 inch diameter penetration in the dam at approximately EL 354. 6.2.2

Hydraulic Design

The new Unit 1 intake will be designed by the manufacturer to meet the design flow and fish screening criteria. The length will be approximately 16 feet and the diameter will be approximately 8 feet. 6.2.3

Struct ural Design

The structural design of the Unit 1 intake will be in accordance with Section 5 – Conduits and Pipeline.

43



6.3 Unit 2 Variabl e Elevation Intake 6.3.1

Description

The new variable elevation intake will have a pre-manufactured drum screen type passive intake with provisions for an air-burst cleaning system. The intake will replace the existing variable elevation intake. 6.3.2

Hydraulic Design

The new variable elevation intake screen will be designed by the manufacturer to meet the design flow and fish screening criteria. The screen length will be approximately 3 feet and the diameter will be approximately 5 feet. 6.3.3

Struct ural Design

The structural design of the Unit 2 intake will be in accordance with Section 5 – Conduits and Pipeline. 6.4

Unit 2 Deep Intake 6.4.1

Description

The new Unit 2 deep intake will have a pre-manufactured drum screen type passive intake connected to approximately 1,500 feet of 36” HDPE pipe. 6.4.2

Hydraulic Design

The new Unit 1 intake screen will be designed by the manufacturer to meet the design flow and fish screening criteria. The screen length will be approximately 16 feet and the diameter will be approximately 8 feet. 6.4.3

Struct ural Design

The HDPE pipe will be designed by the HDPE pipe supplier to the Whiteman Lake Hydroelectric Project requirements. A performance specification for HDPE pipe supply will be prepared by Hatch Acres. 6.5 Whitm an Dam Valve House

The valve house will enclose the pipe inter-connections for mixing the cold deep water intake flow and the warmer surface water intake flow. The enclosure will be an unheated steel framed structure with corrugated metal walls. There will be no windows or other ventilation. An exterior class steel door with appropriate lock and security hardware will be provided. The valves within the Whitman Dam valve house will be manually operated.

44



7 Achilles Diversion and Pipeline 7.1

Description

A new diversion dam will divert up to approximately 20 cfs from Achilles Creek to Whitman Lake through an approximately 2,000 feet long pipeline. The diversion will be an approximately 10 feet high, reinforced concrete structure anchored on bedrock with sediment sluicing ability and a selfcleaning intake screen. The diversion pipeline will be an HDPE pipe with above-ground suppor ts that allow for HDPE thermal expansion and are sized and spaced according to HDPE supplier requirements. 7.2 General Desig n Parameters

Average annual inflow =

17 cfs

Recurrence inflow: 10-year = 50-year = 100-year = Diversion design flow =

175 cfs 210 cfs 230 cfs 20 cfs

Instream flow requirement = 1.5 cfs 7.3

Foundation

Earth/rock parameters will be based on the subsurface investigations performed by KPU in June 2007, under the supervision of Hatch Acres senior geotechnical staff. Preliminary bearing capacity of the bedrock at the base of the diversion will be 120 tons per square ft (tsf) based on an unconfined compressive strength of 10,000 psi or more. Unit weight (lbs/ft3 ): Compacted sands and clays =

130

Loose sands and clays =

85

Angle of Internal Friction: Compacted (SM, SP, GW) sands and gravels =

35°

Loose (SM, SP, GW) sands and gravels =

28°

Clay soils =

0°

Cohesion (psf): Sands and gravel

0

Medium clay and sandy clay

600

A friction angle of 45 degrees can be used for evaluating sliding of mass concrete on clean (water pressure washed) sound rock with cohesion equal to 0.

45



7.4 Trashracks and Intake Screen 7.4.1

Arrangement

The intake will have a self-cleaning Coanda-type in which the intake screen and intake are combined into one screen. The screen is sloped on the downstream side of the overflow section, which flushes debris off the screen as necessary but also allows water to pass through to be diverted to Whitman Lake. Large debris and suspended loads will be allowed to pass over the intake structure. The screen will be designed and supplied by a recognized Coanda screen manufacturer and will meet the performance criteria per Section 7.4.3. 7.4.2

Fish Screening Criteria

There are no fish in Achilles Creek and there are therefore no fish screening cri teria for Achilles Diversion. 7.4.3

Design Parameters

The smallest allowable sediment size to pass through the intake screen and be transpor ted through the pipeline to Whitman Lake is 1 mm. The Coanda screen will be designed to withstand the load of up to a 1 foot diameter bould er rolling over the screen. The corresponding weight is approximately 100 lb. The screen parameters to achieve the desired diversion discharge are: screen angle, s creen bar spacing, screen bar size, screen length, screen width, acceleration height (flat sloping section immediately upstream of the screen), and screen shape (flat or concave). The detailed screen design will be based on the USBR’s design guidelines specific to Coanda type intake structures . The screen will be designed to pass the design flow with approximately 30 percent debris blockage. The screen supports will be designed per appropriate concrete and steel codes. The intake structure will be designed to completely overflow for flows greater than the 100-year flow. 7.5 Analysis and Design

Analysis of concrete structures will begin with the overall structural stabil ity. The water-retaining structures (dams) are assumed to act as rigid bodies. FERC “Engineering Guidelines for the Evaluation of Hydropower Projects” (FERC 0119-2), applies to stability of water retaining structures. FERC Engineering Guidelines provide prudent designs that are acceptable to regulatory agencies. The design will then proceed for the various components of the concrete structures. Co ncrete design will be in accordance with ACI 318-99, Appendix A, Alternate Design Method. Structural steel will be designed according to the AISC Steel Construction Manual – ASD or LRFD. 7.5.1

Stability Analys is

The stability analysis and design will show the ability of the structure to r esist overturning and sliding, and that allowable foundation bearing values were not exceeded.

46



The analysis will show, for the various load cases the indi vidual external loads, the assumed area of the base, the magnitude and distribution of the normal and shearing forces at the foundation level, and the location and direction of the resultant. If necessary to satisfy sliding stability criteria, side wall friction will be applied in accordance with the geotechnical design criteria. Side friction, however, is not considered when evaluating bearing pressures. If cracking is found to occur in the extreme condition, the other conditions will be reanalyzed assuming a cracked base and compared against a reduced factor of safety. The proposed Achilles diversion dam will be analyzed to meet gravity dam requi rements. 7.5.1.1 Load Conditions

The following loading conditions and requirements are sui table, in general, for gravity dam of moderate height, and were adapted from FERC 0119-2, Chapter 3: Gravity Dams. Loads which are not indicated, such as wave action, or any unusual loadings are considered where applicable. Power intake sections will be analyzed with emergency bulkheads closed and all water passages empty. The Achilles diversion dam is considered a low hazard structure. Additional structure-specific loading conditions are included in those s ections pertaining to the individual structures. Case I:

Usual Loading Combination – Normal Operating Condition

The reservoir elevation is at the normal pool, as governed by the crest elevation of an overflow structure and turbine rated flow passing through the powerhouse. No tailwater. Horizontal pressure resulting from accumulation of silt, boulders, etc, will be considered, where applicable. Case II:

Unusual Loading Combination – Design Flood Discharge

The water levels are taken up to the Project Design Flood (100 year flood for low hazard classification) using levels that result in reservoir and tailwater elevations that exerted the greatest head differential and uplift pressure upon the structure. However, unusual conditions such as high tailwater will be examined on a case-by-case basis, since it is possible that the worst case loading condition exists under other than extreme floods. Case IIA:

Unusual Loading Combination – Normal Plus Ice

The reservoir at normal pool at crest of dam combined with ice load. Case III:

Extreme Loading Combination – Normal Operating with Earthquake

Acceptance based on dam’s stability under post earthquake static loading considering damage likely to result from the earthquake. 7.5.1.2 Factors of Safety: Sliding

Factors of safety are the ratio of the resisting forces to the forces tending to cause movement. The sliding factors of safety resulting from design will meet the criteria listed below. Allowable bearing pressures have, as a minimum, factors of safety corresponding to that required for sliding. Recommended safety factors are from FERC 0119-2, Tables 2 and 2A. The table below lists values corresponding to a new dam for the low hazard potential classification.

47


Load Case


Sliding F.S. With Cohesion

Usual

2.0

Unusual

1.25

Post Earthquake

>1.0

Load Case

Sliding F.S. Without Cohesion

Worst Static Case

1.5

Flood if Flood is PMF

1.3

Post Earthquake

1.3

Consideration is also given to stability in a post-earthquake condition. 7.6 Vertical Lif t Gates

Gates will be a standard design with vertical stems complete with gates, guides, seals and manual mechanical operators. The lift gates will likely be selected from the gate manufacturer’s standard catalog. 7.6.1

Vertic al Lift Gate Design Parameters

 Must close under flow.  Maximum headwater elevation (equal to top of Achilles diversion abutment): El 580.0.

 Gate invert varies by location and will be confirmed during final design. Initial estimated invert: El 571.0.

 Achilles diversion gate design flow: 24 cfs (to be confirmed).  Achilles drain gate design flow: 40 cfs (to be confirmed).  Lift gates will be constructed with stainless steel to the extent possible for long life expectancy with minimum maintenance. 7.7 Diversion Pipeline 7.7.1

Material

To be determined. 7.7.2

Supports

The pipeline supports will consist of above grade, rock bolted anchorages designed accord ing to pipeline supplier support requirements. Buried sections will be designed with appropriate embedment and backfill materials.

48



8 Construction Roads 8.1

Description

A permanent construction access and maintenance road will be constructed for access to Whitman Dam and Achilles Diversion. The road will be designed for permanent all year round construction access and long-term maintenance for wheeled construction and maintenance vehicles. No public access will be permitted and a boom will be installed at the start of the road to prevent unauthorized vehicles from entering. The total length of the road is approximately 6,500 feet.

8.2

Desig n Criteria

The road design will meet the requirements of:     

Construction of the project features Maintenance access for KPU The U.S. Forest Service Alaska State Code Alaska Forest Resources and Practices – Regulations

Table 8-1 Access Road Design Criteria Location The road will be located to minimize the disturbance to the forest, streams, or wetlands. The road will attempt to avoid areas with slopes steeper than 67 percent, slide areas, and wetlands. Stream crossings will be as close as possible to a right angle to enter and exit the stream zone and adjacent riparian management area as quickly as possible. Design Vehicle AASHTO HS-20 truck with maximum axle load of 32,000 lbf Design Speed Varies; less than 20 mph Road Grade Maximum 20 % Road Prism Design Running width = 12 feet plus curve widening to allow for off-tracking along curves (see Figure 8-1) Slopes < 55 % = Balanced-Cut-and-Fill (BCF) Slopes > 55 % = Full bench construction with end-hauling Grade < 10 % = Outsloped road with no ditch Grade > 10 % = Insloped with ditch, or no ditch depending on the distance to drainage relief Minimum road cross-slope = 2 % Road Drainage Culverts: minimum diameter = 18 in. Drainage dips (road grades < 10 % only): o Do not locate within curves with radii less than 100 ft Minimum 60 ft long transitions o Relief drainage 50-100 feet above stream crossings Maximum Spacing of water drainage (culverts, water dips, water bars) per the following (11 AAC 95.295): Road Grade (%) Max Spacing (ft) 

   

  

 

49


Curve Radius Cut and Fill Slopes (ODF, 2006. Forest Road Manual)

Base Course Surface (Traction) Course

8.2.1


2-7 8-15 > 15 Minimum 50 feet Soil Compacted fill slope: 2H:1V Sidecast fill slope: 3H:1V Cut slope: 1.5H:1V Rock Cut Slope Solid - Fresh: 1H:8V Weathered – Stained 1H:4V Full bench in rock construction: BCF construction: For grades > 15 %:

1,000 800 600

8” 3-inch-minus aggregate 10” 3-inch-minus aggregate 2” well graded ¾-inch-minus aggregate

Whitman Creek Brid ge Crossi ng

The construction access road will cross Whitman Creek at about station 27+00. The crossing will be designed as a prefab steel stringer bridge.

 Vehicle live load = See design vehicle (Sec. 8.2.2)  Ground snow load = 55 psf  Span length = 50 feet (CL to CL, bearings)  Clear width = 12 feet  Running planks = treated timber  Guard rail = Weathered steel

50



9 Hatchery Head Tank and Valve House 9.1

Hatchery Head Tank

The head tank will be sized to supply the hatchery with water at a constant pressure equivalent to a water surface elevation of 45 ft. The tank will be sized for the hydraulic capacity of Unit 2 to ensure the full hatchery water right of 39 cfs can be provided while still generating power, assuming a separate nominally 12 inch diameter pipe provides 4 cfs incubation flow directly to the hatchery valve house. Possible Unit 2 transient conditions will also be considered in sizing the tank to ensure minimal interruptions to hatchery operations during extreme events such as a load rejection. Preliminary sizing of the head tank indicates that the tank is well within the capacity of commercial tank suppliers who specialize in the design and fabrication of fluid storage tanks. A performance specification for the head tank will be prepared to allow fluid storage suppliers to provide a tank designed to the Whitman Lake Hydroelectric Project requirements.

 Max instantaneous hatchery demand = 1.3 cfs/s (equivalent to turning on the entire hatchery in 30 seconds)

 Max Unit 2 and bypass valve rate of flow change = 3.9 cfs/s (equivalent to fully open/close wicket gates/valve in 10 seconds. 9.2

Valve House

The valve house will be manually operated and designed per requirements o f Sections 5 and 6. The valve house will enclose the pipe inter-connections for the warm water from the headtank and the cold water from the deep water intake. The enclosure will be an unheated steel framed structure with corrugated metal walls, similar to existing valve house. There will be no windows or other ventilation. An exterior class steel door with appropriate lock and security hardware wi ll be provided.

51



Appendix A Figures

52

-

1-2

1-3

1-4

Figure 4-1

Figure 4-2

Design Criteria Manual

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