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Technical Report

EPRI-GTC Overhead Electric Transmission Line Siting Methodology

EPRI Project Manager J. Goodrich-Mahoney

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1395 • PO Box 10412, Palo Alto, California 94303-0813 • USA

800.313.3774 • 650.855.2121 • [email protected] • www.epri.com

EPRI-GTC Overhead Electric Transmission Line Siting Methodology

1013080

Final Report, February 2006

Cosponsor Georgia Transmission Corporation 2100 East Exchange Place Tucker, GA 30084

Project Managers G. Houston C. Johnson

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES

THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM:

(A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER, EXPRESS OR IMPLIED, (I) WITH RESPECT TO THE USE OF ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT, INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS, INCLUDING ANY PARTY'S INTELLECTUAL PROPERTY, OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USER'S CIRCUMSTANCE; OR

(B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES, EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT.

ORGANIZATION(S) THAT PREPARED THIS DOCUMENT

Georgia Transmission Corporation

NOTE

For further information about EPRI, call the EPRI Customer Assistance Center at 800.313.3774 or e-mail [email protected].

Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc.

Copyright © 2006 Electric Power Research Institute, Inc. All rights reserved.

CITATIONS

This report was prepared by

Georgia Transmission Corporation 2100 East Exchange Place Tucker, GA 30084

Principal Investigators G. Houston C. Johnson

This report describes research sponsored by the Electric Power Research Institute (EPRI), and Georgia Transmission Corporation.

The report is a corporate document that should be cited in the literature in the following manner:

EPRI-GTC Overhead Electric Transmission Line Siting Methodology. EPRI, Palo Alto, CA, and Georgia Transmission Corporation, Tucker, GA: 2006. 1013080.

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REPORT SUMMARY

This report explains and documents a standardized process that utilities could use to improve the way transmission line routes are evaluated and selected.

Background Starting in 2002, EPRI and Georgia Transmission Corporation (GTC) joined forces to study transmission line siting and to find ways to make siting decisions more quantifiable, consistent, and defensible. Using GTC’s existing siting process, the project team incorporated geographic information system (GIS) technology, statistical evaluation methods, and stakeholder collaboration to produce a new siting methodology. The tools, techniques, and procedures developed by the team were demonstrated through practical application on sample projects.

Objectives • To review and improve GTC’s overhead transmission line siting practice.

• To develop a new GIS siting model and new siting processes that produce site-selection decisions that are more objective, quantifiable, and consistent.

• To obtain internal and external stakeholders’ critical reviews and achieve consensus on ranking GIS database features and weighting of data layers.

• To ensure the process conforms to federal and state environmental regulations.

• To apply the corridor and route selection process to actual transmission line siting projects and evaluate the results.

Approach The project team presents the EPRI-GTC overhead electric transmission line siting methodology by defining the phases used in the new process and taking sample electric transmission siting projects from initial planning to preferred route selection. To begin, the team performed landscape analysis at different scales, from large regional areas called macro corridors, to alternative corridors, to constructible alternative routes, and to a preferred route. Analysis was performed at each phase, using off-the-shelf geographical databases and other datasets. A new GIS siting model was developed and used to manage data, produce macro and alternative corridors, generate statistics on alternative routes, and create graphic depictions. The model used a common land suitability technique that combines data layers into a comprehensive surface to identify areas of opportunity and constraint. The model employed GIS, global positioning system (GPS), and visual simulation technologies. Database features were ranked and data layers were weighted through collaboration with more than 400 internal and external stakeholders at five workshops. Consensus was achieved by using two research techniques: the Delphi and the

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analytical hierarchy processes. The new methodology was tested on a group of GTC’s construction projects.

Results All study objectives were achieved. The project developed better decision-making procedures and an analytical tool that successfully integrated GIS technology and statistical evaluation methods to generate corridors and routes. Stakeholder consensus was achieved on the ranking of GIS database features, such as geographic, environmental, and engineering elements, and the weighting of various data layers. The methodology was tested on existing transmission line siting projects. In addition, study parameters and decisions built into the process were studied and made consistent with applicable environmental regulations.

The new methodology succeeded in producing more quantifiable, objective, and consistent siting decisions than the procedures GTC used prior to the study. As a result, GTC benefits from having a siting practice that is backed by a standard, scientifically rigorous, and peer-reviewed methodology. In addition to improvements in planning productivity achieved through automated data analysis, an unexpected result was a reduction in data collection and analysis costs. Savings result from the EPRI-GTC process reducing study area boundaries for each transmission line siting project, thus reducing data acquisition costs and analytical time. GTC’s legal, public relations, and environmental efforts also benefit from decisions being well documented and reproducible.

EPRI Perspective Electric utilities continue to face challenges in siting new transmission lines. In a prior EPRI report (1009291), Survey of Electric and Gas Rights-of-Way Practitioners: Current Practices and Views of Future Transmission Line Siting Issues, eighty-eight percent of electric utility respondents said their company encountered opposition from the public and from landowners, and sixty-five percent cited environmental obstacles as barriers. Clearly, there was a need for a methodology to capture and address public opinion and other factors in siting new transmission lines. While this methodology does not attempt to ameliorate publicly controversial aspects of transmission line construction, utilities and the public can realize significant benefits from its use. To the extent that this methodology involves the public and explains and documents decisions that are more objective, quantitative, and consistent, sound public policy goals have been substantially advanced.

Keywords Electric transmission lines Siting Power lines GIS

CONTENTS

1 INTRODUCTION ....................................................................................................................1-1 Overview of the Siting Methodology......................................................................................1-2

2 SITING METHODOLOGY PHASES.......................................................................................2-1 Phase 1: Macro Corridor Generation ....................................................................................2-2

Macro Corridor Model Testing ..........................................................................................2-2 Macro Corridor Data Layers .............................................................................................2-3 Macro Corridor Avoidance Areas .....................................................................................2-5 Macro Corridor Scenarios and Weights............................................................................2-6 Description of Suitability Values .......................................................................................2-6 Macro Corridor Composite Suitability Surface..................................................................2-7 Numeric Analysis and “Least Cost Path” Areas ...............................................................2-9 Generating Macro Corridors from the Composite Suitability Surface...............................2-9 Macro Corridor Composite .............................................................................................2-13

Phase 2: Alternative Corridor Generation ...........................................................................2-13 Alternative Corridor Data Collection ...............................................................................2-14 Alternative Corridor Database ........................................................................................2-14 Avoidance Areas ............................................................................................................2-16 Tier 1 – Feature Value Calibration..................................................................................2-17 Tier 2 – Data Layer Weighting........................................................................................2-17 Tier 3 – Perspectives......................................................................................................2-17 Built Environment Perspective........................................................................................2-21 Natural Environment Perspective ...................................................................................2-23 Engineering Requirements Perspective .........................................................................2-26 Least Cost Path Algorithm..............................................................................................2-30 Generating Alternative Corridors from the Composite Suitability Surface......................2-33 Alternative Corridor Weighting and Simple Average Corridor ........................................2-38

Phase 3: Alternative Route Analysis and Evaluation ..........................................................2-39

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Alternative Route Generation .........................................................................................2-39 Right-of-Way Considerations..........................................................................................2-39 Map Overlay Analysis.....................................................................................................2-40 Qualitative Expert Judgment ..........................................................................................2-43 Selecting the Preferred Route ........................................................................................2-45

3 SITING CASE STUDIES ........................................................................................................3-1 Macro Corridors.....................................................................................................................3-1 Alternative Corridors..............................................................................................................3-2 Engineering Requirements Alternative Corridor Perspective ................................................3-4 Alternative Routes.................................................................................................................3-5 Alternative Route Analysis ....................................................................................................3-9 Selection of Preferred Route ...............................................................................................3-11 Validation of Results............................................................................................................3-12

4 PROJECT MILESTONES.......................................................................................................4-1 Team Formation – 2002........................................................................................................4-1 Project Meetings – January 2003..........................................................................................4-1 External Stakeholder Workshop – June 2003.......................................................................4-1 Georgia Integrated Transmission System Stakeholder Workshop – August 2003 ..............4-2 Stakeholder/ITS Update Workshop – November 2003 .........................................................4-2 Electric Utility Workshop – January 2004..............................................................................4-2 External Stakeholder Workshop – March 2004.....................................................................4-3 EPRI-GTC Report – 2005 .....................................................................................................4-3

5 CONCLUSIONS .....................................................................................................................5-1 Accomplishments ..................................................................................................................5-1

Integrating GIS Technology With a New Methodology.....................................................5-2 Obtaining Stakeholder Involvement..................................................................................5-2 Data Collection Cost Savings ...........................................................................................5-2 Documentation for Supporting GTC’s Environmental Reporting ......................................5-2

Improvements .......................................................................................................................5-3 Incorporating Rights-of-Way Access ................................................................................5-3 Incorporating Visual Impacts ............................................................................................5-4 GIS Siting Model Refinements .........................................................................................5-6

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Future Testing and Evaluation..........................................................................................5-7 Appendices ...........................................................................................................................5-8

6 POST FACE ...........................................................................................................................6-1

A EPRI-GTC OVERHEAD ELECTRIC TRANSMISSION LINE SITING METHODOLOGY PROJECT TEAM ........................................................................................ A-1

Dr. Joseph K. Berry .............................................................................................................. A-1 Dr. Steven P. French............................................................................................................ A-1 Jesse Glasgow..................................................................................................................... A-2 John W. Goodrich-Mahoney................................................................................................. A-3 Gayle Houston ..................................................................................................................... A-3 Christy Johnson ................................................................................................................... A-4 Dr. Elizabeth A. Kramer........................................................................................................ A-4 Steven Richardson............................................................................................................... A-4 Chris Smith........................................................................................................................... A-5 Dr. Paul D. Zwick.................................................................................................................. A-5 Contributors.......................................................................................................................... A-6

B LIST OF ACRONYMS AND GLOSSARY OF TECHNICAL TERMS ................................... B-1 List of Acronyms................................................................................................................... B-1 Glossary of Terms................................................................................................................ B-2

C GEOGRAPHIC INFORMATION SYSTEMS METADATA .................................................... C-1 Engineering .......................................................................................................................... C-1

Linear Infrastructure ........................................................................................................ C-1 Rebuild Existing Transmission Lines .......................................................................... C-1 Parallel Existing Transmission Lines .......................................................................... C-1

Parallel Gas Pipelines ..................................................................................................... C-2 Parallel Roads ................................................................................................................. C-2 Parallel Interstates ROW ................................................................................................. C-3 Parallel Railway ROW ..................................................................................................... C-3 Road ROW ...................................................................................................................... C-4 Future GDOT Plans......................................................................................................... C-4 Scenic Highways ............................................................................................................. C-4

Slope .................................................................................................................................... C-5

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Slope 0% – 15%; 15% - 30%; and > 30% ....................................................................... C-5 Intensive Agriculture............................................................................................................. C-5

Center Pivot Irrigation...................................................................................................... C-5 Pecan Orchards............................................................................................................... C-6 Fruit Orchards.................................................................................................................. C-6

Public Lands......................................................................................................................... C-7 USFS............................................................................................................................... C-7 WMA – State Owned ....................................................................................................... C-7 WMA – Non-State Owned ............................................................................................... C-8 Other Conservation Land ................................................................................................ C-8

Streams/Wetlands................................................................................................................ C-8 Trout Streams (100’ Buffer) ............................................................................................. C-8 Streams <5cfs Regulatory Buffer..................................................................................... C-8 Rivers/Streams >5cfs Regulatory Buffer ......................................................................... C-9 Forested Wetlands and 30’ Buffer ................................................................................... C-9 Non-Forested Wetlands and 30’ Buffer ......................................................................... C-10 Non-Forested Costal Wetlands and 30’ Buffer .............................................................. C-10

Floodplain........................................................................................................................... C-10 Land Cover......................................................................................................................... C-11

Hardwood and Mixed Forests........................................................................................ C-11 Undeveloped Land (Pastures, Scrub/Shrub, Clear Cut, and Abandoned Fields).......... C-11 Row Crops and Horticulture .......................................................................................... C-11 Managed Pines.............................................................................................................. C-11 Developed Land ............................................................................................................ C-12

Wildlife Habitat ................................................................................................................... C-12 Species of Concern ....................................................................................................... C-12 Natural Areas................................................................................................................. C-12

Eligible NRHP Structures ................................................................................................... C-12 Building Density.................................................................................................................. C-13 Proximity to Buildings......................................................................................................... C-13 Spannable Lakes and Ponds ............................................................................................. C-14 Proposed Development...................................................................................................... C-14 General Land Divisions ...................................................................................................... C-15

Edge of Fields................................................................................................................ C-15

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Land Lots....................................................................................................................... C-15 Land Use............................................................................................................................ C-16

Undeveloped ................................................................................................................. C-16 Non-Residential ............................................................................................................. C-16 Residential..................................................................................................................... C-16 NRHP Listed Archeology Districts and Sites ................................................................. C-17 NRHP Listed Districts and Structures............................................................................ C-17 Eligible NRHP Districts .................................................................................................. C-18 Building + Buffers .......................................................................................................... C-18 Airports .......................................................................................................................... C-19 EPA Superfund Sites..................................................................................................... C-19 Non-Spannable Water Bodies ....................................................................................... C-19 State and National Parks............................................................................................... C-20 Military Facilities ............................................................................................................ C-20 Mines and Quarries ....................................................................................................... C-21 City and County Parks................................................................................................... C-21 Day Care Parcel ............................................................................................................ C-22 Cemetery Parcel............................................................................................................ C-22 School Parcel (K-12) ..................................................................................................... C-22 USFS Wilderness Area.................................................................................................. C-22 Church Parcel................................................................................................................ C-22 USFS Wilderness Area.................................................................................................. C-23 Wild/Scenic Rivers......................................................................................................... C-23 Ritual Importance .......................................................................................................... C-23 Wildlife Refuge .............................................................................................................. C-23

D APPENDIX D ........................................................................................................................ D-1 Least Cost Path Algorithm for Identifying Optimal Routes and Corridors ............................ D-1

Routing Procedure........................................................................................................... D-1 Identifying Corridors ........................................................................................................ D-2 Using the Delphi Process for Calibrating Map Criteria .................................................... D-3 Using the Analytical Hierarchy Process (AHP) for Weighting Map Criteria ..................... D-5 EPRI-GTC Overhead Electric Transmission Line Siting Experience............................... D-6

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E PHASE 2: ALTERNATIVE CORRIDOR MODEL – DELPHI FEATURE CALIBRATIONS....................................................................................................................... E-1

Built Environment Delphi Results ......................................................................................... E-2 Natural Environment Delphi Results .................................................................................... E-3 Engineering Environment Delphi Results............................................................................. E-4

F PHASE 2: ALTERNATIVE CORRIDOR MODEL – AHP PERCENTAGES BY DATA LAYER.......................................................................................................................................F-1

Analytical Hierarchy Process Layer Percentages .................................................................F-2

G PHASE 2: ALTERNATIVE CORRIDORS WEIGHTING – AHP PAIRWISE COMPARISON QUESTIONS ...................................................................................................G-1

Pairwise Comparison Question Weights ..............................................................................G-1 Engineering Layer Pairwise Comparison Questions ............................................................G-1 Natural Environment Pairwise Comparison Questions ........................................................G-2 Built Environment Pairwise Comparison Questions .............................................................G-3

H PHASE 3: PREFERRED ROUTE WEIGHTING – AHP PAIRWISE COMPARISON QUESTIONS............................................................................................................................. H-1

Preferred Route Layer Calculations – Engineering .............................................................. H-2 Preferred Route Layer Calculations – Natural Environment ................................................ H-3 Preferred Route Layer Calculations – Built Environment ..................................................... H-4

I ENVIRONMENTAL JUSTICE GUIDELINES ...........................................................................I-1

J STAKEHOLDER MEETING INVITEES..................................................................................J-1

K SUMMARY OF SURVEY RESPONSES FROM THE ELECTRIC UTILITY STAKEHOLDER WORKSHOP ................................................................................................ K-1

Electric Utility Workshop Participants* ................................................................................. K-1 Questionnaire Responses.................................................................................................... K-3

L LOCATIONS OF ONLINE REFERENCE MATERIALS.........................................................L-1 References to Related Online Materials................................................................................L-1

M APPENDIX M........................................................................................................................M-1 Articles, Presentations and Conferences Items Related to the EPRI-GTC Siting Methodology.........................................................................................................................M-1

GeoTech..........................................................................................................................M-1

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GeoWorld Article .............................................................................................................M-1 Transmission & Distribution World Article .......................................................................M-1 GTC News Releases .......................................................................................................M-2 California Energy Commission Presentation ...................................................................M-2 Environmental Concerns on Rights-of-Way Management Symposium...........................M-2 Conference Presentations ...............................................................................................M-2

A Consensus Method Finds Preferred Routing....................................................................M-2 The GTC/EPRI Project .........................................................................................................M-3 GIS Needed .........................................................................................................................M-3 Approach Overview..............................................................................................................M-4 Adding Data .........................................................................................................................M-5 Engineering Considerations .................................................................................................M-7 Natural Environment.............................................................................................................M-7 Built Environment .................................................................................................................M-8 Lessons Learned..................................................................................................................M-8 Georgia Transmission News Release ..................................................................................M-9

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LIST OF FIGURES

Figure 2-1 Phase 1: Macro Corridor Generation – Raw Landsat Imagery.................................2-4 Figure 2-2 Phase 1: Macro Corridor Generation – Anderson Level II Landsat Imagery

Classification ......................................................................................................................2-4 Figure 2-3 Phase 1: Macro Corridor Generation – Land Use/Land Cover Dataset ...................2-5 Figure 2-4 Phase 1: Macro Corridor Generation – Composite Suitability Surface.....................2-8 Figure 2-5 Phase 1: Macro Corridor Generation – Least Cost Path Calculation Diagram.........2-9 Figure 2-6 Phase 1: Macro Corridor Generation – Existing Transmission Line Macro

Corridor ............................................................................................................................2-10 Figure 2-7 Phase 1: Macro Corridor Generation – Existing Transmission Line Macro

Corridor Histogram...........................................................................................................2-10 Figure 2-8 Phase 1: Macro Corridor Generation – Roadside Macro Corridor..........................2-11 Figure 2-9 Phase 1: Macro Corridor Generation – Roadside Macro Corridor Histogram ........2-11 Figure 2-10 Phase 1: Macro Corridor Generation – Cross-Country Macro Corridor................2-12 Figure 2-11 Phase 1: Macro Corridor Generation – Cross-Country Macro Corridor

Histogram.........................................................................................................................2-12 Figure 2-12 Phase 1: Macro Corridor Generation – Final Macro Corridor Composite

Suitability Surface Combined Parallel Existing Transmission Lines Macro Corridor, Parallel Roadside Macro Corridor and Cross-Country Macro Corridor ............................2-13

Figure 2-13 Phase 2 Alternative Corridor Generation – GIS Siting Model Data Tiers .............2-15 Figure 2-14 Delphi Calibrations and Analytical Hierarchy Weightings.....................................2-19 Figure 2-15 Phase 2: Alternative Corridor Generation – GIS Siting Mode...............................2-20 Figure 2-16 Phase 2: Alternative Corridor Generation – Built Environment Perspective.........2-22 Figure 2-17 Phase 2: Alternative Corridor Generation – Natural Environment Perspective ....2-25 Figure 2-18 Phase 2: Alternative Corridor Generation – Engineering Requirements

Perspective ......................................................................................................................2-28 Figure 2-19 Phase 2: Alternative Corridor GIS Data Layers Least Cost Path Algorithm .........2-29 Figure 2-20 Phase 2: Alternative Corridor Generation – Data Layer Features are

Calibrated and Weighted to Derive a Map of the Relative Preference for Locating the Alternative Corridors ..................................................................................................2-31

Figure 2-21 Phase 2: Alternative Corridor Generation – The Optimal Path from Anywhere in a Project Area is Identified by the Steepest Downhill Path Over the Accumulated Cost Surface...............................................................................................2-32

Figure 2-22 Phase 2: Alternative Corridor Generation – The Sum of Accumulated Surfaces is used to Identify Corridors as Low Points on the Total Accumulated Surface.............................................................................................................................2-32

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Figure 2-23 Phase 2: Alternative Corridor Generation – Built Environment Alternative Corridor ............................................................................................................................2-34

Figure 2-24 Phase 2: Alternative Corridor Generation – Built Environment Alternative Corridor Histogram...........................................................................................................2-34

Figure 2-25 Phase 2: Alternative Corridor Generation – Natural Environment Alternative Corridor ............................................................................................................................2-35

Figure 2-26 Phase 2: Alternative Corridor Generation – Natural Environment Alternative Corridor Histogram...........................................................................................................2-35

Figure 2-27 Phase 2: Alternative Corridor Generation – Engineering Requirement Alternative Corridor ..........................................................................................................2-36

Figure 2-28 Phase 2: Alternative Corridor Generation – Engineering Requirement Alternative Corridor Histogram.........................................................................................2-36

Figure 2-29 Phase 2: Alternative Corridor Generation – Simple Average Alternative Corridor ............................................................................................................................2-37

Figure 2-30 Phase 2: Alternative Corridor Generation – Simple Average Alternative Histogram.........................................................................................................................2-37

Figure 2-31 Phase 2: Alternative Corridor Generation Diagram – A Conceptual Diagram Showing how Alternative Corridors are Generated by Systematically Emphasizing Different Perspectives ......................................................................................................2-38

Figure 2-32 Phase 3: Alternative Route Generation – Alternative Routes within Alternative Corridors ........................................................................................................2-39

Figure 2-33 Phase 3: Alternative Route Generation – Map Overlay Analysis is Used to Summarize the Relative Siting Preference along an Alternative Route ...........................2-41

Figure 3-1 Siting Case Studies – Macro Corridor Composite ....................................................3-2 Figure 3-2 Siting Case Studies – Built Environment Alternative Corridor Perspective ..............3-3 Figure 3-3 Siting Case Studies – Natural Environment Alternative Corridor Perspective..........3-3 Figure 3-4 Siting Case Studies – Engineering Requirements Alternative Corridor

Perspective ........................................................................................................................3-4 Figure 3-5 Siting Case Studies – Simple Average Alternative Corridor Perspective .................3-5 Figure 3-6 Siting Case Studies – Route A .................................................................................3-6 Figure 3-7 Siting Case Studies – Route B .................................................................................3-6 Figure 3-8 Siting Case Studies – Route C .................................................................................3-7 Figure 3-9 Siting Case Studies – Route D .................................................................................3-7 Figure 3-10 Siting Case Studies – Route E ...............................................................................3-8 Figure 3-11 Siting Case Studies – Route F ...............................................................................3-8 Figure 3-12 Siting Case Studies – Alternative Routes...............................................................3-9 Figure 3-13 Siting Case Study – Preferred Route ...................................................................3-12 Figure 5-1 Future Initiatives: Effective Distance Map – Calculating an Effective Distance

Map that Shows the Relative Access from Roads to All Locations in a Project Area ........5-4 Figure 5-2 Future Initiatives: Viewshed Map – Calculating a “Viewshed” Map that

Identifies all Locations in a Project Area that can be seen from a Given Location.............5-5

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Figure 5-3 Future Initiatives: Visual Exposure Map – Calculating a “Visual Exposure” Map that Identifies the Relative Exposure for All Locations from an Extended Feature, Such as a Road Network ....................................................................................5-6

Figure D-1 GIS-Based Routing Uses Three Steps to Establish a Discrete Map of the Relative Preference for Siting at Each Location, Generate an Accumulated Preference Surface from a Starting Location(S) and Derive the Optimal Route from an End Point as the Path of Least Resistance Guided by the Surface ............................. D-2

Figure D-2 The Sum of Accumulated Surfaces is Used to Identify Siting Corridors as Low Points on the Total Accumulated Surface ................................................................. D-3

Figure D-3 The Delphi Process Uses Structured Group Interaction to Establish a Consistent Rating for Each Map Layer ............................................................................. D-4

Figure D-4 The Analytical Hierarchy Process Uses Pairwise Comparison of Map Layers to Derive their Relative Importance................................................................................... D-5

Figure D-5 Alternate Routes are Generated by Evaluating the Model Using Weights Derived from Different Group Perspectives....................................................................... D-6

Figure M-1 The Route-Selection Process can be Conceptualized as a Funnel that Successively Refines Potential Locations for Siting a Transmission Line.........................M-4

Figure M-2 Alternate Routes are Generated by Evaluating the Siting Model Using Weights Derived from Different Group Perspectives.........................................................M-5

Figure M-3 Within the Alternate Corridors, Additional Data are Gathered Such as Exact Building Locations from Aerial Photography .....................................................................M-6

Figure M-4 A GIS-Generated Preferred Route is Adjusted as Necessary Based on Detailed Field Information and Site-Specific Construction Requirements.........................M-6

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LIST OF TABLES

Table 2-1 Phase 1: Macro Corridor Generation – Macro Corridor GIS Database Values .........2-7 Table 2-2 Phase 2: Alternative Corridor Generation – Avoidance Areas.................................2-16 Table 2-3 Phase 2: Alternative Corridor Generation – Built Environment Perspective

Data Layer Weights..........................................................................................................2-23 Table 2-4 Phase 2: Alternative Corridor Generation – Natural Environment Perspective

Data Layer Weights..........................................................................................................2-24 Table 2-5 Phase 2: Alternative Corridor Generation – Engineering Requirements

Perspective Data Layer Weights.....................................................................................2-26 Table 2-6 Phase 3: Alternative Route Generation – Spreadsheet Statistics Summarizing

Evaluation Criteria for Alternative Routes ........................................................................2-42 Table 2-7 Phase 3: Alternative Route Generation – Expert Judgment is Applied to the

Top Three Routes to Identify their Relative Rankings......................................................2-44 Table 3-1 Siting Case Study – Evaluating Alternative Routes .................................................3-10 Table 3-2 Siting Case Study – Qualitative Expert Judgment ...................................................3-11

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1 INTRODUCTION

In fast-growing states like Georgia, demand for electricity is outpacing rapid population growth, placing pressure on electric utilities to build more electric transmission power lines. In 2004, for instance, Georgia’s utilities built more than 100 new miles of transmission lines and Georgia Transmission Corporation is currently investing more than $100 million annually in construction. With more construction comes more public scrutiny on a range of issues, including the decisions made when determining locations for new electric transmission lines.

In 2002, a team sponsored by the Electric Power Research Institute (EPRI), Palo Alto, CA, and Georgia Transmission Corp. (GTC), Tucker, GA, began analyzing existing transmission line siting procedures to find ways to make decisions more quantifiable, consistent and defensible. The team set out to develop a standard siting methodology that other utilities could adopt. The project team included GIS consultants from academia and the private sector, NEPA compliance and legal experts and environmental, engineering and land acquisition staff members from GTC and other utilities (Appendix A: EPRI-GTC Overhead Electric Transmission Line Siting Methodology Project Team).

The study examined GTC’s existing siting practice, including data collection, analysis, project study area identification and selection of Preferred Routes. Preferred Routes are the areas deemed most suitable for building power lines. This report describes new siting processes and standard decision-making procedures developed by the team. Current Geographic Information System (GIS) technology, statistical evaluation methods and stakeholder collaboration were employed to produce this new siting methodology. The tools, techniques and procedures developed by the team were tested with GTC’s existing siting projects.

This EPRI-GTC Overhead Electric Transmission Line Siting Methodology report defines the new siting methodology and new GIS Siting Model. The report then illustrates how the methodology and GIS Siting Model are integrated by following a sample transmission line project from start to finish. Conclusions and potential improvements are then described. The study accomplished the following objectives:

1. Developed a new methodology and GIS Siting Model for producing more objective, quantifiable and consistent siting decisions,

2. Obtained more than 400 stakeholders’ critical reviews and achieved consensus on the ranking of geographic, land use, environmental, engineering and other GIS database Features, as well as the weighting of Data Layers,

3. Ensured the process conforms to environmental regulations, and

4. Improved Georgia Transmission’s transmission line siting practice.

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Introduction

Overview of the Siting Methodology

The EPRI-GTC Overhead Electric Transmission Line Siting Methodology consists of three phases:

1. Generation of a Macro Corridor, a large geographic swath that defines the project boundaries;

2. Generation of Alternative Corridors, linear areas within a Macro Corridor that are deemed most suitable when the Natural Environment, Built (manmade) Environment and Engineering Requirements Perspectives, and a Combined Perspective, are considered; and

3. Analysis of Alternative Routes, constructible areas within the Alternative Corridors, and selection of the Preferred Route.

Once Alternative Routes are scrutinized using detailed geographical data, a Preferred Route, the most suitable location for a power line, is determined through professional collaboration guided by study results. At each phase, satellite land cover data, aerial photography or statewide and local digital data are used to reach decisions.

A number of factors influence the suitability of power line locations, such as housing density, wetlands and land cover. The project team developed a list of database Features that were evaluated, modified and weighted with the help of more than 400 stakeholders. One group of shareholders included representatives of neighborhood groups, regulatory agencies and natural resources and land conservation organizations. A second group was made up of utility professionals from Georgia Transmission Corporation, Georgia Power Company (GPC) and Municipal Electric Authority of Georgia (MEAG) Power. Features were ranked using the Delphi Process, a research decision-making technique, and Data Layers were weighted using the Analytical Hierarchy Process (Appendix D: Least Cost Path, Delphi Process and Analytical Hierarchy Process Techniques).

The EPRI-GTC Overhead Electric Transmission Line Siting Methodology is based on land suitability analysis techniques developed in the 1970s by Ian McHarg.1 These techniques combine Data Layers into a comprehensive surface that identifies areas of opportunity and constraint. McHarg’s process is commonly used for siting shopping centers, subdivisions, linear utility corridors and other facilities. The EPRI-GTC effort automated much of this data processing and analysis with the use of the GIS Siting Model. The model combines contemporary GIS, visual simulation and Global Positioning Systems (GPS) applications. GIS technology provides the modeling environment, and other applications manage data, produce corridors and routes, create graphic depictions and generate reports.

Chapter 2 of this report describes how different database Features and Data Layers were selected, ranked and weighted, and it illustrates how the GIS Siting Model generates corridors and routes. Chapter 3 demonstrates each phase of the siting methodology by following a case study from the beginning, the identification of two endpoints, through selection of a Preferred

1 McHarg, Ian L. Design with Nature (1969) Natural History Press, New York, NY.

1-2

Introduction

Route. Chapter 4 describes the main research actions and timeframes. Chapter 5 presents conclusions and potential improvements that could be made to the methodology and GIS Siting Model.

GTC’s routing and siting practice was standardized in accordance with the EPRI-GTC siting methodology. This standardization fosters sound siting decisions by ensuring that selection criteria and choices are based on more objective and uniform information. In addition, the process provides consistency in data acquisition and use. The structured nature of the methodology helps ensure its consistent application across projects, locations and siting teams. In addition, information and assumptions used in choosing one route over a less suitable alternative are well documented and reproducible (Appendix C: Geographic Information Systems Metadata).

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2 SITING METHODOLOGY PHASES

The project team examined Georgia Transmission Corporation’s current transmission line siting methodology to identify areas that could be standardized and otherwise improved. Several major issues were identified, including potential adverse impacts to existing and proposed development, cultural resources and sensitive biotic resources. To address the issues, the project team established three important phases in the EPRI-GTC Overhead Electric Transmission Line Siting Methodology.

The three phases are as follows:

• Phase 1 – Macro Corridor Generation

During Phase 1, land cover data derived from satellite imagery, consisting of 30-meter grid cells, and existing statewide databases, e.g., roads, slope and existing overhead electric transmission lines, are used to generate Macro Corridors between two endpoints determined by Georgia Transmission’s Electric System Planning department. Because Macro Corridors parallel or collocate along existing linear facilities or cross largely undeveloped areas, they are expected to include the most suitable areas for locating overhead electric transmission lines. The outside limits of the Macro Corridors become the boundaries of a project study area.

• Phase 2 – Alternative Corridor Generation

In Phase 2, Alternative Corridors are developed within the Macro Corridors. During this phase, one-foot aerial photography is acquired and digital orthophotography is produced. More detailed digital data are collected for wetlands, floodplains, land use/land cover and other Features and entered into the GIS database. This more detailed data is used to identify four distinct types of Alternative Corridors. Input from stakeholders was used to define the four types of Alternative Corridors.

• Phase 3 – Alternative Route Analysis and Evaluation

In Phase 3, the siting team identifies a set of Alternative Routes within the Alternative Corridors. Each route is then scored using a standard set of evaluation criteria and compared. The preferred route is selected on the basis of this comparison.

As the project progresses from Macro Corridor generation to Alternative Route analysis and evaluation, the methodology uses more detailed data to refine the route selection. This chapter describes in greater depth the actions that take place during each of the three phases.

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Siting Methodology Phases

Phase 1: Macro Corridor Generation

After reviewing GTC’s existing study area delineation practices, the project team developed a new technique for determining project boundaries. This technique, termed Macro Corridor Generation, departs from a more traditional siting process where boundaries of the project study area are determined by four major criteria:

1. Distance between termini, such as generator to substation,

2. Natural and manmade physical barriers, including major rivers and interstates,

3. Administrative barriers, such as military bases and wilderness areas, and

4. Budgets and schedules for data collection.

Macro Corridor Generation was chosen to replace this method of study area delineation because of cost and time concerns and the need for more detailed analysis of feasible routes. By using inexpensive and free off-the-shelf digital data and sophisticated GIS modeling, a costly and time-consuming data collection and data processing step was eliminated.

Development of Macro Corridors is based on land cover products derived from satellite imagery and other off-the-shelf digital data. The GIS Siting Model identifies corridors that minimize adverse impacts to built and natural environments. In many cases, paralleling existing transmission lines or paralleling existing road rights-of-way can minimize adverse impacts to these environments. The GIS Siting Model eliminates from consideration those areas where there is no viable option for building a transmission line. Macro Corridors define the area where orthophotography and other detailed data collection and analysis will occur in Phase 2.

Macro Corridor Model Testing

The Macro Corridor Phase of the GIS Siting Model was calibrated by testing it on GTC’s completed overhead transmission line projects. Twelve projects were selected for the test because they were representative of various landscape characteristics within Georgia. In addition, the projects were chosen because they were sited on schedule, within budget, and with minimal adverse impacts to the built and natural environments.

Using satellite imagery and other off-the-shelf data, suitability grids were generated for each completed project. The suitability grid generated for these tests covered 100 percent of the study area on each project. The boundaries of the Macro Corridors were determined by identifying the percentage of the suitability grid that consistently included all alternative routes that had been generated during the route selection process on the completed projects.

Superimposing the alternative routes from the test projects on the new suitability grid showed that all alternative routes fell within the first five percent of the numeric values of the suitability grid. In future uses, the suitability grids on new projects will be reviewed in order to validate the numeric value essential to generating consistent Macro Corridor boundaries.

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Macro Corridor Data Layers

Macro Corridor Generation uses available digital Data Layers, allowing for quick identification of a project area. These datasets include land cover derived from Landsat satellite imagery, a Digital Elevation Model (DEM), existing roads from Geographic Data Technologies (GDT) and overhead electric transmission lines from the Georgia Integrated Transmission System (ITS). The suitability of these Features is ranked for cross-country, road parallel and existing transmission line rebuild/parallel routes.

The source layer for the Macro Corridor GIS dataset is Landsat satellite imagery that was developed by NASA and is maintained by the U.S. Geological Survey (USGS). The USGS collects current imagery through a satellite system that scans electromagnetic energy reflected from the surface. The satellite repeats its data collection every 16 days. These data have a minimum ground resolution of 30 meters and a single image covers approximately 180km2. A scanner collects data from seven different bands of the electromagnetic spectrum, including visible light, infrared and thermal infrared reflectance (Figure 2-1: Raw Landsat Imagery). These raw data typically are classified into 15 to 30 land cover classes based on the Anderson Land Use/Land Cover Classification Level II (Figure 2-2: Anderson Level II Landsat Imagery Classification). Although these land cover data are much coarser in resolution than aerial photographs, it is fairly inexpensive to obtain and can be updated regularly at a relatively low cost. A number of national land cover datasets are widely available at no charge. It is important to note, however, that there is a lag time between availability of national land cover products and the dates of the original imagery. It is important to assess whether the land cover data are timely. For Georgia, the available datasets include a 1988 land cover map developed by the Georgia Department of Natural Resources, 1992 National Land Cover Dataset (NLCD) developed by the USGS, and a 1998 land cover map developed by USGS GAP Analysis Program. A 2001 NLCD is under development.

In addition, each state is being mapped as part of the National Gap Analysis Program (GAP). According to the GAP mission statement, the USGS provides regional, state and national assessments of the conservation status of native vertebrate species and natural land cover types of the United States. A number of states are beginning to generate their own versions of land use/land cover datasets for planning and monitoring. In Georgia, the land use/land cover dataset was developed by the Georgia GAP Program from 1998 Landsat imagery and the Georgia Land Use Trends Project (GLUT). GLUT tracks and analyzes changes in Georgia’s land use over the past 25 years. It uses an Anderson Land Use/Land Cover Level II Classification that includes 18 classes. These data are available for a minimal cost from the Georgia GIS Clearinghouse (Figure 2-3: Land Use/Land Cover Dataset).

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Figure 2-1 Phase 1: Macro Corridor Generation – Raw Landsat Imagery

Figure 2-2 Phase 1: Macro Corridor Generation – Anderson Level II Landsat Imagery Classification

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Figure 2-3 Phase 1: Macro Corridor Generation – Land Use/Land Cover Dataset

The team also identified areas that are significant barriers to constructing an overhead electric transmission line and should be avoided. These “Avoidance Areas” include locations where routes are prohibited either by physical barriers and administrative regulations, and locations where significant permitting delays would be expected. These areas include National Register of Historic Places (NRHP), historic or archeological districts, airports, EPA Superfund sites, military bases, national and state parks, non-spannable water bodies, U.S. Forest Service (USFS) wilderness areas, national wildlife refuges (NWR), mines and quarries, wild and scenic rivers and sites of ritual importance. Data for most of these Avoidance Areas are available currently in GIS format.

Macro Corridor Avoidance Areas

The first step in the Macro Corridor development process is to remove all Avoidance Areas from the Macro Corridor database. Eliminating these Avoidance Areas prohibits the proposed Macro Corridor from crossing places that internal and external stakeholders identified as requiring maximum protection.1

1 As noted above, some “Avoidance Areas” may be reconsidered later in the decision-making and route selection

processes when justified by specific, consistent, quantitative and defensible site-specific information.

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Macro Corridor Scenarios and Weights

To locate Macro Corridors in the most suitable areas, the project team identified three Macro Corridor GIS Siting Model scenarios:

1. Rebuilding or paralleling existing transmission lines,

2. Paralleling existing road rights-of-way, and

3. Crossing undeveloped land (cross-country).

Next, a weighting system was designed to identify areas where transmission line development is most or least suitable. A suitability value is assigned to each Feature in the Macro Corridor GIS database. Assigned values range from 1 to 9, reflecting the suitability of each grid cell. A value of 1 identifies an area of greatest suitability, and 9 identifies an area of least suitability. A Feature is suitable if a transmission corridor through it is feasible with little adverse impact, such as undeveloped land. A Feature is considered unsuitable if a transmission line going through it would have some adverse consequences, such as steep terrain or densely populated areas. Numbers between 1 and 9 are used to represent intermediate degrees of suitability.

Description of Suitability Values

Areas of High Suitability for an overhead electric transmission line (1, 2, 3): These areas do not contain known sensitive resources or physical constraints, and therefore should be considered as suitable areas for the development of Macro Corridors. Examples include undeveloped land, pasture and rebuilding an existing transmission line.

Moderate Suitability for a transmission line (4, 5, 6): These areas contain resources or land uses that are moderately sensitive to disturbance or present a moderate physical constraint to line construction and operation. Resource conflicts or physical constraints in these areas generally can be reduced or avoided using standard mitigation measures. An example is a primary road crossings.

Low Suitability for a transmission line (7, 8, 9): These areas contain resources or land uses that present a potential for significant adverse impacts that cannot be readily mitigated. Locating a transmission line in these areas would require careful siting or special design measures. Examples include wetlands and densely populated urban areas. These areas can be used, but it is not desirable to do so if other alternatives are available.

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Table 2-1 Phase 1: Macro Corridor Generation – Macro Corridor GIS Database Values

Land Cover Classification Source X-Country Roads T/Ls

Open Water LANDSAT 7 7 7

Secondary Roads LANDSAT 5 1 5

Other Utility Corridors LANDSAT 5 5 5

Urban LANDSAT 9 9 9

Open Land LANDSAT 1 2 2

Surface Mining/ Rock Outcrop LANDSAT 9 9 9

Forest LANDSAT 1 2 2

Agriculture LANDSAT 1 2 2

Wetland LANDSAT 9 9 9

Transmission Corridors ITS* 5 5 1

Primary Roads GDT** 5 1 5

Interstate GDT 9 9 9

Slopes > 30 degrees USGS 9 9 9

Avoidance Features

Airports GDT

Military Facilities GDT

NRHP Listed Historic Structures NPS

NRHP Listed Historic Districts NPS

NRHP Listed Archaeology Sites NPS

NRHP Listed Archaeology District NPS

State and National Park Interiors NPS

Non-spannable Water Bodies USGS

Wildlife Refuges GA DNR

USFS Wilderness Areas GA DNR

EPA Superfund Site EPA

Mines and Quarries LANDSAT

* Georgia Integrated Transmission System (ITS) ** Geographic Integrated Data Technologies (GDT)

Macro Corridor Composite Suitability Surface

Once all data for the project area are collected, entered into the Macro Corridor GIS database, and numeric values assigned to each feature, a composite suitability surface is created for the entire study area. The composite suitability surface provides an overview of the study area. Each grid cell in the composite suitability surface is assigned a ranking associated with its underlying land cover type (Figure 2-4: Composite Suitability Surface).

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A separate suitability surface is developed for each of the three types of routes:

1. Rebuilding or paralleling existing transmission lines,

2. Paralleling existing road rights-of-way, and

3. Crossing undeveloped land (cross-country).

Figure 2-4 Phase 1: Macro Corridor Generation – Composite Suitability Surface

The Macro Corridor GIS Siting Model uses a “Least Cost Path” (LCP) algorithm to work its way across each of the three composite suitability surfaces. Figure 2-5, the Least Cost Path Calculation Diagram, illustrates the operation of the LCP algorithm. If a transmission line must go from Point A to Point B, the LCP algorithm will find the path across the accumulated surface (represented by suitability values in the grid cells) that minimizes the sum of the values along that route. Any other path will result in a larger suitability sum and therefore be less optimal. For example, the “optimal” route indicated in green has a suitability sum of 21 (3+1+6+1+7+3), compared to a sum of 35 (3+8+20+1+3) for the most direct route. The lower sum indicates higher overall suitability of the green route (Appendix D: GIS Siting Model Techniques).

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The sum of the LCP calculation is a function of the number of cells crossed (distance) and the values in the individual cells. The path will turn to avoid less preferred areas or Avoidance Areas (high “cost” cells), but still follow the most direct path possible. If cells have the same score, the resulting path between the two points would be a straight line.

4

5

7

6

3

14

20

10

1

2

8

4

20

6

9

6

8

1

12

10

3

7

8

2

4

Start Point A

End Point B

Figure 2-5 Phase 1: Macro Corridor Generation – Least Cost Path Calculation Diagram

Numeric Analysis and “Least Cost Path” Areas

Numeric analysis assigns a suitability value from 1 to 9 to each Feature in the Macro Corridor GIS database. These values are assigned to each of three composite suitability surfaces based on subsets of the criteria layers: rebuilding or paralleling existing transmission lines, paralleling existing road rights-of-way and crossing undeveloped lands. Then, GTC’s GIS siting software, Corridor Analyst™, uses standard routing algorithms to identify the areas of “avoidance and opportunities” on each of the three composite suitability surfaces. The software begins at the designated starting point and adds one grid cell at a time by adding an adjacent cell with the lowest suitability score until it reaches the endpoint.

Generating Macro Corridors from the Composite Suitability Surface

After the three Composite Suitability Surfaces are generated, a histogram is developed for each surface. The histogram shows the cumulative value of each of the grid cells within the project study area. It is used to identify the most suitable areas for each of the three Macro Corridors scenarios: rebuilding or paralleling existing transmission lines, paralleling existing road rights-of-way and crossing undeveloped lands (cross-country) (Figure 2-6: Existing Transmission Line Macro Corridor; Figure 2-8: Roadside Macro Corridor; and Figure 2-10: Cross Country Macro Corridor). In each scenario, the Macro Corridor boundary is determined by the first statistical break in its histogram. A statistical break occurs when the grid cell value, as shown on the X-axis of the histogram, abruptly decreases.

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Figure 2-6 Phase 1: Macro Corridor Generation – Existing Transmission Line Macro Corridor

Figure 2-7 Phase 1: Macro Corridor Generation – Existing Transmission Line Macro Corridor Histogram

To validate this method, Macro Corridor boundaries were tested on 12 projects and the statistical break occurred within the first 1 and 5 percent of the grid cell value. In Figure 2-7: Existing Transmission Line Macro Corridor Histogram, Figure 2-9: Roadside Macro Corridor Histogram,

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and Figure 2-11: Cross Country Macro Corridor Histogram, the X-axis represents “grid cell values” and the Y-axis represents the “number of grid cells.” These figures show that a statistical break occurs after two percent on the X-axis, the grid cells values. This two percent area is the area of greatest suitability for Macro Corridor Generation. The variable-width Macro Corridors may have a width of as much as a mile or greater for segments that have substantial length through areas of high suitability, while still allowing enough width in the low suitability areas for the right-of-way requirements of the project.

Figure 2-8 Phase 1: Macro Corridor Generation – Roadside Macro Corridor

Figure 2-9 Phase 1: Macro Corridor Generation – Roadside Macro Corridor Histogram

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Figure 2-10 Phase 1: Macro Corridor Generation – Cross-Country Macro Corridor

Figure 2-11 Phase 1: Macro Corridor Generation – Cross-Country Macro Corridor Histogram

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Macro Corridor Composite

After the most suitable area of each Macro Corridor is identified, the three corridors are merged into a final Macro Corridor Composite Suitability Surface (Figure 2-12 – Final Macro Corridor Composite Suitability Surface).

Figure 2-12 Phase 1: Macro Corridor Generation – Final Macro Corridor Composite Suitability Surface Combined Parallel Existing Transmission Lines Macro Corridor, Parallel Roadside Macro Corridor and Cross-Country Macro Corridor

Phase 2: Alternative Corridor Generation

In Phase 1, the outer limits of the Macro Corridors Composite Suitability Surface were used to define the project study boundaries and to generate a final Macro Corridor Composite Surface. During Phase 2, four Alternative Corridors were generated within the Macro Corridor boundaries. With input from stakeholders, the project team decided to standardize the alternatives for transmission line corridor selection by the following:

• Protecting people places and cultural resources (Built Environment Perspective),

• Protecting water resources, plants and animals (Natural Environment Perspective),

• Minimizing costs and schedule delays (Engineering Requirements Perspective) and

• A composite of the Built, Natural and Engineering alternatives (Simple Combined Perspective).

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ting Methodology Phases

Alternative Corridor Data Collection

Following Macro Corridor Generation, additional data are collected to produce Alternative Corridors within the Macro Corridors. Data are collected or derived from several sources. Some Data Layers are gathered from existing off-the-self data warehouses, while others are created specifically for each project based on aerial photo interpretation. For example, data on roads, interstates and railways are purchased from a data provider that updates these Features every year. Some datasets are created and maintained by GTC and Integrated Transmission System (ITS) companies. However, just as in the Macro Corridor Phase of the EPRI-GTC methodology, some of the data for Alternative Corridor Generation must be derived. For example, USGS Digital Elevation Models (DEMs) are acquired as off-the-self data, but slope must be derived from the DEMs to be included in the model.

The Land Use/Land Cover Map used in the Macro Corridor Phase is not detailed or accurate enough to define Alternative Corridors. Instead, more detailed datasets are developed for Land Use/Land Cover and Intensive Agriculture from digital orthophotography. This orthophotography is used to “derive” data for the building dataset. Although buildings are identified in the orthophotography, the buildings themselves are not used in Alternative Corridor Phase of the GIS Siting Model. Instead, building density, building proximity and building buffers are derived from the building dataset using standard functionality commonly available in GIS software. Then, the derived datasets are inserted into the GIS Siting Model.

Alternative Corridor Database

The GIS database for the Alternative Corridor Phase can be thought of on three levels (Figure 2-13: GIS Siting Model Data Tiers). At the lowest level is Tier 1, which consists of Features that are important in siting a transmission line, e.g., slope, building density and wetlands. The Tier 1 Features contain grid cells that are assigned a value ranging from 1 to 9 and cover the entire study area. Tier 1 Features include distinct categories, such as overhead electric transmission lines, roads and railroads. They also include numerical ranges for Features like building density.

In the second level (Tier 2), similar Features are grouped into Data Layers, e.g., land cover that contains managed pine forests, row crops, undeveloped land and developed land. At the highest level, Tier 3, Data Layers are grouped into three Perspectives: Built Environment, Natural Environment and Engineering Requirements. Each perspective reflects distinct stakeholder viewpoints on critical siting issues.


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Legend Avoidance Areas Built Environment Natural Environment Engineering Requirements

NRHP Listed Archaeology Sites Proximity to Buildings Floodplain Linear Infrastructure Avoidance Areas NRHP Listed Archaeology Districts Background Background Rebuild Existing Transmission Lines Tier 3 - Perspectives NRHP Listed Historic Districts 900-1200 100 Year Floodplain Parallel Existing Transmission Lines Tier 2 - Data Layers NRHP Listed Historic Structures 600-900 Streams/Wetlands Parallel Roads ROW Tier 1 – Features NRHP Eligible Historic Districts 300-600 Background Parallel Gas Pipelines

EPA Superfund Sites 0-300 Streams < 5cfs Parallel Railway ROW

Airports Eligible NRHP Historic Non-forested Non-Coastal Background Military Facilities Background Rivers/Streams > 5cfs Future GDOT Plans

Mines & Quarries 900 – 1200 Non-forested Coastal Wetlands Parallel Interstates ROW

Buildings + Buffers 600 – 900 Trout Streams (50' Buffer) Road ROW

School Parcels (K – 12) 300 – 600 Forested Wetlands + 30' Buffer Scenic Highways ROW

Day Care Parcels 0 – 300 Public Lands Slope Church Parcels Building Density Background Slope 0-15% Cemetery Parcels 0 - 0.05 Buildings/Acre WMA - Non-State Owned Slope 15-30%

Non-Spannable Water Bodies 0.05 - 0.2 Buildings/Acre Other Conservation Land Slope >30%

Wild & Scenic Rivers 0.2 - 1 Buildings/Acre USFS Intensive Agriculture Wildlife Refuge 1 - 4 Buildings/Acre WMA - State Owned Background

USFS Wilderness Areas 4 - 25 Buildings/Acre Land Cover Fruit Orchards National & State Parks Proposed Development Open Land, Pastures, Pecan Orchards

County & City Parks Background Managed Pine Plantations Center Pivot Agriculture

Sites of Ritual Importance Proposed Development Row Crops and Horticulture

Spannable Lakes and Ponds Developed Land Background Hardwood/Natural Coniferous

Spannable Lakes and Ponds Wildlife Habitat

Land Divisions Background Edge of field Species of Concern Habitat

Land lots Natural Areas

Background

Land Use Undeveloped

Non-Residential

Residential

Figure 2-13 Phase 2 Alternative Corridor Generation – GIS Siting Model Data Tiers


Avoidance Areas

The first step in Alternative Corridor Generation is to remove all Avoidance Areas from the Alternative Corridor database. Removing these sensitive areas from consideration means they will not be used in the Alternative Corridor selection process.

As stated in the Macro Corridor Phase, Avoidance Areas are not suitable for locating overhead electric transmission lines. The GIS Siting Model will avoid these areas except in specific situations.2 An exception, for example, is where a road right-of-way is adjacent to a military base. The existence of the road “trumps” the military base as an Avoidance Area by weighting the roadside edge grid cells as suitable for a transmission line corridor. Internal and external stakeholder groups identified Avoidance Areas as shown in Table 2-2.

Table 2-2 Phase 2: Alternative Corridor Generation – Avoidance Areas

Avoidance Areas

NRHP Archaeology Districts NRHP Archaeology Sites NRHP Historic Districts NRHP Structures Eligible NRHP Districts EPA Superfund Sites Airports Military Facilities Mines and Quarries Building and Buffers School Parcels Day Care Parcels Church Parcels Cemetery Parcels Non-Spannable Water Bodies Wild and Scenic Rivers Wildlife Refuges USFS Wilderness Areas National and State Parks County and City Parks Sites of Ritual Importance

2 “Avoidance Areas,” which are identified at an early stage of the transmission line siting process to assure that

“community preferences” or to avoid significant permitting delay factors, may be reconsidered when justified by specific, consistent, quantitative and defensible site-specific information.

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Tier 1 – Feature Value Calibration

The project team decided to normalize the Tier 1 Features within each Data Layer. Stakeholders were asked to calibrate the Features in a Delphi Process. This collaborative process involves iterative discussion and structured input designed to assist each stakeholder group in reaching consensus as they calibrated the Feature maps.

The suitability of each Feature was calibrated on a scale of 1 (most suitable) to 9 (least suitable). Putting Features into a common 1-9 scale allows Data Layers to be mathematically combined without being distorted by differences in measurement scale. For example, if one foot is measured as 30.48 centimeters rather than 12 inches, the larger number would give it more weight in any mathematical operations even though the physical length is the same. Putting all data on the same scale allows data to be combined into Data Layers and compared. These Feature Calibrations were developed through stakeholder input (Appendix D: GIS Siting Model Techniques and Appendix E: Phase 2-Alternative Corridor Model Delphi Feature Calibrations).

For example, a new transmission line right-of-way that parallels an existing transmission line was considered more suitable than one that parallels a scenic highway. Therefore, areas adjacent to the existing transmission line received a 1. Those adjacent to the scenic highway received a 9. Characterizing suitability for slope for a transmission line is another example. Stakeholders assigned 1 (most suitable) to slopes between 0 and 15 percent, 5.5 (fairly neutral) to slopes between 15 and 30 percent and a 9 (least suitable) to slopes greater than 30 percent.

Tier 2 – Data Layer Weighting

In the second tier, Data Layers were weighted as to their relative importance using the Analytical Hierarchy Process (AHP). This collaborative procedure involves pairwise comparison among the set of Feature maps to determine the relative importance of each map layer. The result is the derivation of an importance weight assigned to each map layer (Appendix F: Phase 2-Alternative Corridor Model AHP Percentages by Data Layer). Once weighted, the Data Layers are combined to form a group perspective. The stakeholders and the project team developed Data Layer weights, reflecting the importance of each Data Layer in the transmission line siting methodology.

Tier 3 – Perspectives

In Tier 3, individual Data Layers were combined to form three distinct Perspectives: the Built Environment, Natural Environment and Engineering Requirements. The Built Environment Perspective recognized that the most significant opposition to overhead electric transmission lines comes from residential neighborhoods and over special places of value to the community (such as proximity to existing and proposed buildings or historic sites). The Natural Environment Perspective sought to minimize the disturbance to ecological resources and natural habitat. The Engineering Requirements Perspective focused on minimizing the cost of construction by seeking the shortest path, while avoiding areas that pose significant construction obstacles. The Simple Combination Perspective placed an equal weighting on the Built Environment, Natural Environment and Engineering Requirements Perspectives to form a composite perspective.

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Within each perspective, the Data Layers in that group are emphasized. However, Data Layers from other perspectives must be included so the model does not completely ignore those factors. For example, the model must account for the location of houses even when emphasizing the Natural Environment Perspective.

These four different perspectives produce a set of distinct Alternative Corridors that are evaluated and compared prior to developing Alternative Routes. The weighted Data Layers are combined to create a perspective that reflects the “Optimal Path” for each Alternative Corridor. This “Optimal Path” is the most suitable route because it receives the lowest score, representing the route with the least impact considering that perspective. Figure 2-14, Delphi Calibrations and Analytical Hierarchy Weightings, illustrates the 1 to 9 calibration of the Feature Values established by the Delphi Process. The Layer Weights that were developed using the Analytical Hierarchy Process are shown as percentages beside each Feature and Data Layer (Figure 2-14: Delphi Calibrations and Analytical Hierarchy Weightings).


Avoidance Areas Built Environment Engineering Natural Environment NRHP-Listed Archaeology Sites Proximity to Buildings 11.5% Linear Infrastructure 48.3% Floodplain 6.2%

NRHP-Listed Archaeology Districts Background 1 Rebuild Existing Transmission Lines

1 Background 1

NRHP-Listed Historic Districts 900-1200 1.8 Parallel Existing Transmission Lines

1.4 100-Year Floodplain 9

NRHP-Listed Historic Structures 600-900 2.6 Parallel Roads ROW 3.6 Streams/Wetlands 20.9%NRHP-Eligible Historic Districts 300-600 4.2 Parallel Gas Pipelines 4.5 Background 1 EPA Superfund Sites 0-300 9 Parallel Railway ROW 5 Streams < 5cfs+ Regulatory Buffer 5.1

Airports Eligible NRHP Historic Structures 13.9% Background 5.5 Non-forested Non-Coastal Wetlands 6.1

Military Facilities Background 1 Future GDOT Plans 7.5 Rivers/Streams > 5cfs+ Regulatory Buffer

7.4

Mines & Quarries 900 – 1200 2.8 Parallel Interstates ROW 8.1 Non-forested Coastal Wetlands 8.4 Buildings + Buffers 600 – 900 3.6 Road ROW 8.4 Trout Streams (50' Buffer) 8.5 School Parcels (K – 12) 300 – 600 5.2 Scenic Highways ROW 9 Forested Wetlands + 30' Buffer 9 Day Care Parcels 0 – 300 9 Slope 9.1% Public Lands 16.0%

Church Parcels Building Density 37.4% Slope 0-15% 1 Background 1

Cemetery Parcels 0 - 0.5 Buildings/Acre 1 Slope 15-30% 5.5 WMA - Non-State-Owned 4.8

Non-Spannable Water Bodies 0.5 - 0.2 Buildings/Acre 3 Slope >30% 9 Other Conservation Land 8.3

Wild & Scenic Rivers 0.2 - 1 Buildings/Acre 5 Intensive Agriculture 42.6% USFS 8

Wildlife Refuge 1 - 4 Buildings/Acre 7 Background 1 WMA – State-Owned 9

USFS Wilderness Areas 4 - 25 Buildings/Acre 9 Fruit Orchards 5 Land Cover 20.9%

National & State Parks Proposed Development 6.3% Pecan Orchards 9 Open Land, Pastures, Scrub/Shrub, etc.

1

County & City Parks Background 1 Center Pivot Agriculture 9 Managed Pine Plantations 2.2

Sites of Ritual Importance Proposed Development 9 Row Crops and Horticulture 2.2

Spannable Lakes and Ponds

3.8% Developed Land 6.5

Background 1 Hardwood/Natural Coniferous Forests 9

Spannable Lakes and Ponds 9 Wildlife Habitat 36.0% Land Divisions 8.0% Background 1

Edge of Field 1 Species of Concern Habitat 3

Land Lots 7.9 Natural Areas 9

Background 9

Land Use 19.1% Undeveloped 1 Nonresidential 3

DELPHI RANKS

SITING MODEL

AVOIDANCE AREAS

PERSPECTIVES

LAYERS

AHP PERCENTAGES

FEATURES

Residential 9

Figure 2-14 Delphi Calibrations and Analytical Hierarchy Weightings

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Avoidance Areas

Phase 2 Alternative Corridor

GIS Siting Model

Natural Environment

Streams and Wetlands

Floodplain

Land Cover

Public Lands

Wildlife Habitat

Engineering

Intensive Agriculture

Slope

Linear Infrastructure

Built Environment

Land Divisions (Edge of Field)

Land Use


Proposed Development

Proximity to Buildings

Building Density

Eligible NRHP Structures

Si

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Figure 2-15 Phase 2: Alternative Corridor Generation – GIS Siting Mode



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Built Environment Perspective

Public controversy over the siting of new transmission power lines can cause significant delays to a construction project. The purpose of the Built Environment Perspective is to select routes that avoid or minimize impacts to communities.

As shown in Figure 2-16, Built Environment Perspective, building locations are a critical component of this perspective. All buildings are buffered and treated as Avoidance Areas.3 In the Built Environment Layer Group, additional protection is provided to building avoidance areas by adding 300-foot proximity zones. As one approaches a building Avoidance Area, each 300-foot proximity zone becomes increasingly less suitable.

The Built Environment Perspective also considers clusters of buildings, such as subdivisions or urban neighborhoods by assigning a higher weight that makes the area less preferable for a transmission line. Therefore, it is difficult for the line to go through a densely populated urban area, even if it skirts individual, isolated buildings. Listed National Landmark sites, National Register sites, traditional cultural sites and eligible historic districts and their properties are treated as “Avoidance Areas,” providing maximum protection. In Georgia, a 1,500-foot Adverse Potential Effect (APE) buffer is created around listed and eligible NRHP structures.

Stakeholders requested that land use be emphasized in the procedure. The project team created three land use categories in the Land Use Layer: residential, non-residential developed and undeveloped. Residential land is the least preferred, and undeveloped land is the most preferred. A Proposed Development Layer anticipates future development, including subdivisions, commercial developments, public facilities and other projects that have been permitted by a local government, but not constructed.

One of the most suitable areas for a transmission line is along a property line of an undeveloped parcel. Land lot lines, comparable to section lines in the West, and edges of fields identified on aerial imagery are included in a Land Division Layer. These locations are preferable because they are associated with property boundaries. Spannable Lakes and Ponds are included in the Built Environment Perspective because they are considered amenity features that are less preferred than other areas. Table 2-3 shows the weights associated with each layer.

Taken together, these layers capture the salient features of the Built Environment Perspective. Alternative Corridors for the Built Environment Perspective will avoid developed areas whenever possible. Table 2-3 identifies the relative importance applied to the seven map layers forming the Built Environment Perspective. Building density has the most influence (37.4%) and is nearly twice as important as land use considerations. As previously discussed, the AHP process involving group collaboration with stakeholders determined the weights (AHP process is described in Appendix D: GIS Siting Model Techniques).

3 “Avoidance Areas,” which are identified at an early stage of the transmission line siting process to assure that “community preferences” or to avoid significant permitting delay factors, may be reconsidered when justified by specific, consistent, quantitative and defensible site-specific information.

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BUILT ENVIRONMENT PERSPECTIVE

Back-ground

Lakes & Ponds

Spannable Waters

Back-ground

Edge of Field

Land Lots

Land Divisions

Back-ground

Eligible Archaeology Sites

Eligible Historic Structure

NRHP-Eligible

Back-ground

Proposed Develop-

ment


Undeve-loped

Non-Residenti

-al

Resident-ial

Land Use

Back-ground

900’-1,200’

600’-900’

300’-600’

0-300’

Building Proximity

>25 Buildings

/AC

4-25 Buildings

/AC

1-4 Buildings

/AC

0.02-1 Buildings

/AC

0.05-0.02 Buildings

/AC

0-0.05 Buildings

/AC

Building Density

Figure 2-16 Phase 2: Alternative Corridor Generation – Built Environment Perspective



Table 2-3 Phase 2: Alternative Corridor Generation – Built Environment Perspective Data Layer Weights

Data Layer Layer-Weights

Proximity to Buildings 11.5 %

Eligible NRHP Structures 13.9 %

Building Density 37.4 %

Proposed Development 6.3 %

Spannable Lakes and Ponds 3.8 %

Land Divisions 8.0 %

Land Use 19.1 %

Natural Environment Perspective

The Natural Environment Perspective seeks to minimize the effects of construction and maintenance of overhead electric transmission lines on sensitive natural resources. Federal and state environmental regulations require the identification and protection of environmentally sensitive areas. At the federal level, environmental regulations cover wetland protection under the Clean Water Act and protection of endangered animal and plant species under the Endangered Species Act. State regulations protect riparian buffer through the state of Georgia’s Erosion and Sedimentation Control Act and the Metropolitan River Protection Act. In addition, the Georgia Department of Natural Resources monitors a number of listed endangered plant and animal species. This list includes state candidate species that require additional concern beyond those listed under federal law. Environmental permits are required from many federal, state and local government agencies.

Because of their span length and the small footprint for structure placement, overhead electric transmission line construction and maintenance activities generally have minor impacts on the natural environment. There are two areas of concern, however, that must be accounted for during data collection: habitat fragmentation and encroachment on environmentally sensitive areas. These concerns can be avoided by minimizing the amount of the transmission line rights-of-way located in environmentally sensitive, undeveloped areas.

This perspective includes five Data Layers: public lands, streams and wetlands, floodplains, land cover and wildlife habitat. Although some public lands, such as state and national parks, city and county parks, wild and scenic rivers, U.S. Forest Service (USFS) wilderness areas and wildlife refuges were included as Avoidance Areas, the remainder have been included as part of the Natural Environment Perspective (See Table 2-4: Natural Environment Perspective Data Layer Weights). Inclusion in this perspective ensures that impacts to these areas would be considered in the routing process.

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Table 2-4 Phase 2: Alternative Corridor Generation – Natural Environment Perspective Data Layer Weights


Public Lands 16.0 %

Streams/ Wetlands 20.9 %

Floodplain 6.2 %

Land Cover 20.9 %

Wildlife Habitat 36.0 %

Many agencies have developed Data Layers that can be used in the planning of transmission line routes. The commonly available datasets include: U.S. Fish and Wildlife’s National Wetland Inventory (NWI), Federal Emergency Management Agency’s (FEMA) floodplain maps and U.S. Geological Survey’s (USGS) National Hydrological Dataset. State Heritage programs often provide some level of information on the distribution of threatened and endangered species within a state. However, this information is limited because few comprehensive surveys have been completed for these plants and animals. It is important to note that although these datasets have been developed with high standards, they were produced at a scale much larger than the width of a transmission line and also may not be updated frequently enough to capture changes in the landscape. Therefore, it is always necessary to check the proposed route to be certain nothing was inadvertently overlooked (Figure 2-17: Natural Environment Perspective).

To minimize adverse impacts of transmission line construction and maintenance on streams and wetlands, it is critical to collect accurate data about their location and characteristics during the routing step. In the Streams and Wetlands Data Layer, information is collected on streams, forested wetlands and non-forested coastal wetlands. Streams with flows greater than 5 cubic feet per second create construction and maintenance access problems. In Georgia, trout streams are protected with a 100-foot vegetative buffer (50 feet either side of the stream). Clearing for an overhead transmission line right-of-way in forested wetlands causes adverse impacts to the wetlands by removing the tree canopy. The absence of tree canopy increases water temperatures in the wetland and may contribute to sedimentation. Non-forested coastal wetlands were included in this category because of construction and maintenance access problems.

FEMA Q3 Flood information is used for the floodplain delineation, because NEPA regulations prohibit steel tower structures from being located in a floodplain because they can trap debris and obstruct the flow.


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NATURAL ENVIRONMENT PERSPECTIVE

Back-ground

Floodplain

Floodplain

Back-ground

Conservation Lands

Private WMA

State WMA

USFS

Public Lands

Back-ground

Non-Forested Coastal

Wetlands

Non-Forested Wetlands

Forested Wetlands

Rivers/Stream> 5 cfs

Streams < 5 cfs

Trout Streams

Streams/Wetlands

Developed Land

Open Land

Row Crops Horticulture

Forests

Managed Pine

Land Cover

Undeveloped Land

Natural Areas

T & E Habitat

Wildlife Habitat

Figure 2-17 Phase 2: Alternative Corridor Generation – Natural Environment Perspective


Land cover data are digitized from orthophotography and includes the following land cover types: managed pine, row crops and horticulture, hardwood mixed and natural forests, undeveloped land and developed lands. Other categories in the Land Cover Data Layer include land use information, such as transportation, utility rights-of-way, low intensity urban, high intensity urban, clear cut/sparse vegetation, quarries/strip mines, rock outcrops, deciduous forest, mixed forest, evergreen forest, golf courses, pastures, row crops, forested wetlands, coastal marshes and non-forested wetlands.

In Georgia, it was difficult to locate timely and accurate data on threatened and endangered species. For this project, the Wildlife Data Layer includes terrestrial endangered species and Natural Area data used as a surrogate for listed plant species. These data, from the Georgia GAP analysis program, contain potential distribution of terrestrial vertebrates and a map of natural vegetation.

Engineering Requirements Perspective

The criteria in this perspective focused on the engineering requirements for routing, constructing and maintaining overhead transmission lines. External stakeholders who took part in the study included engineers and scientists from utilities and state agencies involved in site selection for linear facilities. The group was selected to provide specific knowledge regarding the co-location of power lines with other linear features, including pipelines, roadways and other power lines. There are three Data Layers within this perspective: linear infrastructure, slope and intensive agriculture (Table 2-5: Engineering Requirements Perspective Data Layer Weights).

Table 2-5 Phase 2: Alternative Corridor Generation – Engineering Requirements Perspective Data Layer Weights


Linear Infrastructure 48.3 %

Slope 9.10 %

Intensive Agriculture 42.6 %

If the Data Layers were equally suitable, the engineering solution would be a straight line connecting the two endpoints. Since this rarely occurs, the Engineering Requirements Perspective utilizes the Data Layer suitability information to represent actual conditions. Categories in the Linear Infrastructure Data Layer include rebuilding existing transmission lines or paralleling (co-locating) with other linear infrastructure.

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The most cost-effective solution with the least adverse impact to the natural and cultural resources is rebuilding an existing transmission line in its existing right-of-way. In the Linear Infrastructure Data Layer, the stakeholders ranked the rebuild alternative as the most suitable alternative.

Paralleling (co-locating) other linear facilities is ranked as “the second most suitable place,” mainly due to lower construction and maintenance access costs. Use of an existing transmission line or road right-of-way decreases the acreage needed for a new right-of-way, significantly reducing land acquisition costs. Access for construction and maintenance is improved, since there are existing transmission line rights-of-way access roads. Paralleling existing linear features places new transmission lines in areas where natural resources already have been disturbed. Paralleling also reduces the amount of land clearing needed for a new transmission line corridor.

Another engineering consideration is slope. Slopes less than 15 percent are most suitable for the construction and maintenance of an overhead transmission line. Slopes of 16 to 30 percent pose a moderate constraint by increasing construction costs and having a greater chance of erosion. Slopes greater than 30 percent should be avoided, if possible, because of the high costs of construction and maintenance. Construction costs in these areas are significantly greater due to soil stabilization requirements, equipment constraints and environmental permits. In addition, heavily sloped terrain can limit access to areas and result in construction and maintenance work being performed from the air.

Three types of agriculture that pose significant engineering constraints are included in the Intensive Agriculture Data Layer: center pivot irrigation, pecan orchards and fruit orchards. Avoiding these areas provides an opportunity to minimize the cost of affecting expensive orchards and agricultural irrigation facilities (Figure 2-18: Engineering Requirements Perspective).


Background

ENGINEERING REQUIREMENTS PERSPECTIVE

Background

Parallel Railroad

ROW

Parallel Gas Pipeline

Parallel Existing TL

Future DOT Plans

Road ROW

Scenic Highway

Parallel Road ROW

Rebuild Existing TL

Parallel Interstate

ROW


Slope 16% - 30%

Slope 16% - 30%

Slope 0% – 15%

Slope

Fruit Orchards

PecanOrchards

Center PivotIrrigation


Figure 2-18 Phase 2: Alternative Corridor Generation – Engineering Requirements Perspective

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Phase 2: Alternative Corridors Avoidance Areas Siting Criteria: Engineering Natural Built Overall Preference Surface

Wt. Average Natural

Discrete Preference

Surface

CombinedAvoided

Areas

Can’t go there…

Avoid if possible…

Wt. AverageCRITERIA

Wt. Average Built

GroupPerspective Layers

Wt. Average Engineering

Floodplain (6%)Streams/Wetlands (21%) Public Lands (16%) Land Cover (21%) Wildlife Habitat (36%)

Buildings + BufferSpecial Places Sensitive Areas Physical Barriers

Proximity Buildings (12%)NRHP Historic (14%) Building Density (37%) Proposed Development (6%) Spannable Water bodies (4%) Land Divisions (8%) Land Use (19%)

Linear Infrastructure (48%)Slope (9%) Intensive Ag (43%)

Natural Environment Perspective - Data Layers

Avoidance Areas – Data Layers

Built Environment Perspective - Data Layers

Engineering Requirements Perspective - Data Layers

TIER 2

TIER 2

TIER 2

Figure 2-19 Phase 2: Alternative Corridor GIS Data Layers Least Cost Path Algorithm

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Least Cost Path Algorithm

As in the Macro Corridor Generation phase, the least cost path (LCP) procedure is used to identify the most suitable corridor for each of the three perspectives. As discussed in Appendix D, the LCP approach involves the following three basic steps:

1. Deriving a discrete preference surface,

2. Calculating an accumulated preference surface, and

3. Determining the “Optimal Path,” respecting the spatial distribution of the relative preferences for locating an overhead electric transmission line.

By far, the most critical step is the first one. This step identifies the relative preference for locating a transmission line at any location within a perspective. A series of Features are calibrated on a scale of 1 (most suitable) through 9 (least suitable). The Calibrated Features are combined to form Data Layers. Data Layers are weight-averaged to reflect the relative importance of the different perspectives.

In practice, three tiers of weights are applied: Tier 1 for the Feature Calibration, Tier 2 for the Data Layer Weighting within each group perspective (Built, Natural, Engineering) and Tier 3 for reflecting the relative importance among the group perspectives. A map of areas to absolutely avoid is combined with the weighted criteria map to characterize the relative “goodness” of routing an overhead electric transmission line at every location in the project area, as depicted by the discrete preference surface (See the right side of Figure 2-20: EPRI-GTC Routing Model Criteria and Weights).

The second step in the LCP procedure uses this information to calculate the most suitable corridor for each perspective. The result is an accumulation preference surface that simulates routing of a transmission line from a starting location to all other locations in a project area. The final step identifies the “path of least of resistance” along the accumulated cost surface that minimizes the less preferred areas that are crossed along a route connecting the starting and ending locations. This route identifies the “Optimal Path,” as any other path incurring more “less preferred crossing” (sub-optimal). This route is derived by identifying the steepest down hill path from the end point to the bottom of the accumulated cost surface (Figure 2-21: Optimal Path). The least cost procedure for determining surfaces and the Optimal Path is defined in Appendix D.

A corridor of optimality can be generated by identifying the next best route, then the next best and so on. In practice, however, a more efficient procedure is to add the accumulation surfaces from both the starting and endpoints as shown in Figure 2-22: Sum of Accumulated Surfaces. The result is a surface that identifies the total cost of forcing an Optimal Path through every location in the project area.


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EPRI-GTC Routing Model Avoided Areas Routing Criteria: Engineering Natural Built Overall Preference Surface

Floodplain (6%)Streams/Wetlands (21%) Public Lands (16%) Land Cover (21%) Wildlife Habitat (36%)

Buildings + BufferSpecial Places Sensitive Areas Physical Barriers

Proximity Buildings (12%)NRHP Historic (14%) Building Density (37%) Proposed Development (6%) Spannable Water bodies (4%) Land Divisions (8%) Land Use (19%)

Linear Infrastructure (48%)Slope (9%) Intensive Ag (43%)

Natural Environment

Avoided Areas

Built Environment

Engineering

Wt. AverageNatural

Discrete Preference

Surface

CombinedAvoided

Areas

Can’t go there…

Relativepreferences…

Wt. AverageCRITERIA

Wt. AverageBuilt

Group Layers

Wt. AverageEngineering

(1)

(1)

(1)

Figure 2-20 Phase 2: Alternative Corridor Generation – Data Layer Features are Calibrated and Weighted to Derive a Map of the Relative Preference for Locating the Alternative Corridors


Figure 2-21 Phase 2: Alternative Corridor Generation – The Optimal Path from Anywhere in a Project Area is Identified by the Steepest Downhill Path Over the Accumulated Cost Surface

Figure 2-22 Phase 2: Alternative Corridor Generation – The Sum of Accumulated Surfaces is used to Identify Corridors as Low Points on the Total Accumulated Surface

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The series of lowest values on the total accumulation surface (valley bottom) identifies the best route. The valley walls depict increasingly less optimal areas. The red areas in Figure 2-22 identify all locations that are within 5 percent of the “Optimal Path.” The green areas indicate 10 percent sub-optimality.

The corridors are useful in delineating boundaries for detailed data collection, such as high-resolution aerial photography and parcel ownership records. The detailed data within the Alternative Corridor is helpful in making slight adjustments in identifying Alternative Routes within each of the perspectives.

Generating Alternative Corridors from the Composite Suitability Surface

As in the Macro Corridor Phase, a histogram is generated and interpreted. In the case of Alternative Corridor Generation, it is run on surfaces for each of the Built Environment, Natural Environment and Engineering Requirements Perspectives. The histogram is used to choose the corridors for each of the three perspectives. The boundaries of these corridors are chosen by the first statistical break in the histogram. Typically, the statistical break occurs between 1 and 5 percent. Alternative Corridors are shown in:

• Figure 2-23: Built Environment Alternative Corridor,

• Figure 2-25: Natural Environment Alternative Corridor,

• Figure 2-27: Engineering Requirement Alternative Corridor, and

• Figure 2-29: Simple Average Alternative Corridor.

The histograms below each of these figures illustrate that the breaks occur between one and five percent in:

• Figure 2-24: Built Environment Alternative Corridor Histogram,

• Figure 2-26: Natural Environment Alternative Corridor Histogram,

• Figure 2-28: Engineering Requirement Alternative Corridor Histogram, and

• Figure 2-30: Simple Average Alternative Corridor Histogram.

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Figure 2-23 Phase 2: Alternative Corridor Generation – Built Environment Alternative Corridor

Figure 2-24 Phase 2: Alternative Corridor Generation – Built Environment Alternative Corridor Histogram

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Figure 2-25 Phase 2: Alternative Corridor Generation – Natural Environment Alternative Corridor

Figure 2-26 Phase 2: Alternative Corridor Generation – Natural Environment Alternative Corridor Histogram

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Figure 2-27 Phase 2: Alternative Corridor Generation – Engineering Requirement Alternative Corridor

Figure 2-28 Phase 2: Alternative Corridor Generation – Engineering Requirement Alternative Corridor Histogram

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Figure 2-29 Phase 2: Alternative Corridor Generation – Simple Average Alternative Corridor

Figure 2-30 Phase 2: Alternative Corridor Generation – Simple Average Alternative Histogram

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Alternative Corridor Weighting and Simple Average Corridor

Alternative Corridors are generated by emphasizing the different perspectives (Figure 2-31 – Alternative Corridor Generation Diagram). Emphasis is achieved by combining the three preference surfaces with a weighted average in which one of the perspectives is considered five times more important than the other two. Testing of weight averaging on various projects demonstrated that the weighting of five times was most effective in emphasizing one perspective over the others while still retaining some influence from the other two perspectives.

The result is three different corridors as shown in Figure 2-31. In this figure, the Built Environment corridor was generated by weighting the Built Perspective Data Layers five times more than the Natural and Engineering Perspectives. In a similar manner, Engineering and Natural emphasized alternatives are over-weighted to identify distinct solutions for those Perspectives.

In addition to the corridors generated for each perspective, a simple average preference surface is used to establish a consistent base line for all three perspectives. Alternative Corridors are combined to identify the optimal “decision space” for locating an overhead electric transmission line, considering the different siting perspectives. A proposed route venturing outside the combined Alternative Corridors is sub-optimal from all three perspectives and would need to be justified by extenuating factors not included in the model’s set of map criteria.

Figure 2-31 Phase 2: Alternative Corridor Generation Diagram – A Conceptual Diagram Showing how Alternative Corridors are Generated by Systematically Emphasizing Different Perspectives

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Phase 3: Alternative Route Analysis and Evaluation

Alternative Route Generation

In Phase 2, the Least Cost Path (LCP) algorithm was run to generate Alternative Corridors for the Built, Natural, and Engineering Perspectives and an overall Simple Combination Corridor for all three. This algorithm generates a 15-foot wide “Optimal Path” the size of one grid cell in each Corridor (Figure 2-32 Alternative Routes within Alternative Corridors). As with the other two phases, additional detailed data are collected for areas within the Alternative Corridors. Property lines are identified and building centroids that were digitized during the Phase 2 Alternative Corridor are classified by types: occupied house, commercial building or industrial building. These additional data are entered into the GIS Siting Model. These data aid the project team in refining the “Optimal Path” within each Alternative Corridor. Waiting until these Alternative Corridors have been identified before collecting this very detailed data, the total time and cost to the project are greatly reduced.

Figure 2-32 Phase 3: Alternative Route Generation – Alternative Routes within Alternative Corridors

Right-of-Way Considerations

Because the width of the “Optimal Path” is 15 feet, it is too narrow for meaningful analysis of the Alternative Routes by the current GIS Siting Model. To increase the “Optimal Path” from 15 feet (width of one grid cell) to the right-of-way width for the voltage of the project, additional grid cells must be added to each side of the “Optimal Path.” This refinement creates an “Optimal Route.” For example, an “Optimal Route” for a 500-kilovolt transmission line would require a width of 12 grid cells to form a 180-foot right-of-way.

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Map Overlay Analysis

The route evaluation process is designed as a productivity tool for siting professionals. Staff members from engineering, land acquisition, environmental and other areas can easily evaluate the advantages and disadvantages of the Alternative Routes and selection of the Preferred Route. They can evaluate siting criteria and summaries of Data Layers (preferences layers) using map overlay analysis, spreadsheet processing, interactive geo-queries and other quantitative and qualitative metrics. Variations among the Built Environment Perspective, Natural Environment Perspective and Engineering Requirements Perspective (preference surface alternatives) can be illustrated graphically, using Map Overlap Analysis (Figure 2-33: Map Overlay Analysis).

In analyzing a composite Alternative Route, the GIS Siting Model isolates the evaluation criteria for all Data Layers. The results can be reported in a variety of formats: map display, inspection of “drill-down data,” graphic illustrations and summary statistics. For example, the hypothetical route in Figure 2-33 shows that only a small stretch at the top of the route crosses a “least preferred” area (red), while the majority of the route crosses “moderate” to “most preferred” areas (green).

In a similar manner, a siting team member can “click” at any location along the route and pop-up a table listing preference conditions on any of the other active map layers. This interactive geo-query feature facilitates rapid retrieval of information to support siting team discussions. In addition to graphical display, interactive geo-query can produce spreadsheet tables for evaluation criteria, metrics summarizing individual segments and Alternative Routes.

Table 2-6, Tabular Summary of Alternative Routes, shows an example spreadsheet of summary information (rows) for several Alternative Routes (columns). Corridor Analyst™ software is used to summarize the evaluation metrics in terms of counts for the siting team discussion of relative lengths and acres of easement.

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Figure 2-33 Phase 3: Alternative Route Generation – Map Overlay Analysis is Used to Summarize the Relative Siting Preference along an Alternative Route

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Table 2-6 Phase 3: Alternative Route Generation – Spreadsheet Statistics Summarizing Evaluation Criteria for Alternative Routes

Tabular Summary of Alternate Routes Data for All Routes

Built Route

A Route

B Route

C Route

D Route

E Route

F Feature Unit Unit Unit Unit Unit Unit

Relocated Residences (within 75' Corridor) 0.0 0.0 1.0 0.0 1.0 0.0

Normalized 0.0 0.0 1.0 0.0 1.0 0.0 Proximity to Residences (300') 5.0 37.0 13.0 9.0 14.0 10.0 Normalized 0.0 1.0 0.3 0.1 0.3 0.2 Proposed Developments 2.0 0.0 1.0 0.0 0.0 0.0 Normalized 1.0 0.0 0.5 0.0 0.0 0.0 Proximity to Commercial Buildings (300') 3.0 4.0 1.0 1.0 1.0 5.0

Normalized 0.5 0.8 0.0 0.0 0.0 1.0 Proximity to Industrial Buildings (300') 1.0 0.0 0.0 0.0 3.0 3.0

Normalized 0.3 0.0 0.0 0.0 1.0 1.0 School, DayCare, Church, Cemetery, Park Parcels (#) 8.0 2.0 2.0 1.0 1.0 1.0

Normalized 1.0 0.1 0.1 0.0 0.0 0.0

NRHP Listed/Eligible Strucs./ Districts (1500' from edge of R/W) 2.0 1.0 0.0 0.0 0.0 0.0

Normalized 1.0 0.5 0.0 0.0 0.0 0.0 Natural Natural Forests (Acres) 1.2 6.4 5.8 7.0 9.6 10.7 Normalized 0.0 0.5 0.5 0.6 0.9 1.0 Stream/River Crossings 4.0 5.0 4.0 4.0 6.0 6.0 Normalized 0.0 0.5 0.0 0.0 1.0 1.0 Wetland Areas (Acres) 2.0 1.9 5.4 5.9 6.9 7.5 Normalized 0.0 0.0 0.6 0.7 0.9 1.0 Floodplain Areas (Acres) 4.3 2.6 8.3 7.4 6.4 4.3 Normalized 0.3 0.0 1.0 0.9 0.7 0.3 Engineering Length (Miles) 12.5 11.2 15.3 17.2 11.4 16.3 Normalized 0.2 0.0 0.7 1.0 0.0 0.8 Miles of Rebuild with Existing T/L* 5.2 4.7 5.1 4.6 4.8 4.8 Normalized 1.0 0.2 0.8 0.0 0.4 0.3 Inverted 0.0 0.8 0.2 1.0 0.6 0.7 Miles of Co-location with Existing T/L* 2.58 1.25 8.5 2.36 3.69 9.5

Normalized 0.2 0.0 0.9 0.1 0.3 1.0 Inverted 0.8 1.0 0.1 0.9 0.7 0.0 Miles of Co-location with Roads* 0.0 0.1 0.0 0.1 0.8 0.8 Normalized 0.0 0.2 0.0 0.2 1.0 1.0 Inverted 1.0 0.8 1.0 0.8 0.0 0.0 Number of Parcels 4.05 1.04 3.63 0.62 0.43 0.23 Normalized 1.0 0.2 0.9 0.1 0.1 0.0 Total Project Costs 45 34 48 37 34 34 Normalized 0.8 0.0 1.0 0.2 0.0 0.0

Evaluation Metrics

Relocated Residences

Proximity of Residences

Proposed Developments

Proximity to Commercial Buildings

Proximity to Industrial Buildings

School, Daycare, Church, Cemetery, Park Parcels

NRHP Listed/Eligible Structures/ Districts

Natural Forests

Stream/River Crossings

Wetland Areas

Floodplain Areas

Total Length

Miles of Rebuild

Miles of Co-location

Number of Parcels

Total Project Costs

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Metrics, such as the number of relocated residences or length of the route passing through natural forests, are used to guide discussions comparing the advantages and disadvantages of the Alternative Routes. These discussions help organize and focus the siting team’s review, as well as provide ample opportunity for free exchange of expert experience and opinion.

Qualitative Expert Judgment

The project team uses evaluation metrics that are normalized and assigned weights developed using AHP to derive a relative score for each Alternative Route (Appendix G: Phase 2-Alternative Corridor Weighting: AHP Pairwise Comparison Questions). The scores are combined for the three Perspectives (Built Environment, Natural Environment and Engineering Requirements) and then totaled for an overall score. The numerical score provides an objective reference for comparing Alternative Routes and stimulates discussion of their relative merits.

The left side of Table 2-7, Evaluating Alternative Routes, shows the translation of the “raw” evaluation metrics to a normalized and weighted score. In this example, the sub-criteria for each perspective are assigned relative weights. For example, the Built Environment Perspective’s consideration of relocated residences is much more important (40 percent) than close Proximity to Industrial Buildings (2 percent). The three perspectives are weighted equally (33 percent) in this example, but these weights could be changed to make a routing solution more sensitive to the Built Environment Perspective, Natural Environment Perspective or the Engineering Requirement Perspective.

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Table 2-7 Phase 3: Alternative Route Generation – Expert Judgment is Applied to the Top Three Routes to Identify their Relative Rankings

Evaluating Alternative Routes

Built 33% Route A

Route B

Route C

Route D

Route E

Route F

Feature Unit Unit Unit Unit Unit Unit Relocated Residences (within 75' Corridor)

44.3% 0.00 0.00 1.00 0.00 1.00 0.00

Weighted 0.00 0.00 0.44 0.00 0.44 0.00

Proximity to Residences (300') 13.1% 0.00 1.00 0.25 0.13 0.28 0.16

Weighted 0.00 0.13 0.03 0.02 0.04 0.02

Proposed Residential Developments 5.4% 1.00 0.00 0.50 0.00 0.00 0.00

Weighted 0.05 0.00 0.03 0.00 0.00 0.00

Proximity to Commercial Buildings (300') 3.6% 0.50 0.75 0.00 0.00 0.00 1.00

Weighted 0.02 0.03 0.00 0.00 0.00 0.04

Proximity to Industrial Buildings (300') 1.8% 0.33 0.00 0.00 0.00 1.00 1.00

Weighted 0.01 0.00 0.00 0.00 0.02 0.02

School, DayCare, Church, Cemetery, Park Parcels (#)

16.3% 1.00 0.14 0.14 0.00 0.00 0.00

Weighted 0.16 0.02 0.02 0.00 0.00 0.00

NRHP Listed/Eligible Strucs./Districts (1500' from edge of R/W)

15.5% 1.00 0.50 0.00 0.00 0.00 0.00

0.16 0.08 0.00 0.00 0.00 0.00

TOTAL 100.0% 0.40 0.26 0.53 0.02 0.50 0.07

WEIGHTED TOTAL 0.13 0.09 0.17 0.01 0.16 0.02

Natural 33%

Natural Forests (Acres) 9.3% 0.00 0.54 0.49 0.61 0.88 1.00

Weighted 0.00 0.05 0.05 0.06 0.08 0.09

Stream/River Crossings 38.0% 0.00 0.50 0.00 0.00 1.00 1.00

Weighted 0.00 0.19 0.00 0.00 0.38 0.38

Wetland Areas (Acres) 40.3% 0.02 0.00 0.62 0.72 0.90 1.00

Weighted 0.01 0.00 0.25 0.29 0.36 0.40

Floodplain Areas (Acres) 12.4% 0.29 0.00 1.00 0.85 0.67 0.29

Weighted 0.04 0.00 0.12 0.11 0.08 0.04

TOTAL 100.0% 0.04 0.24 0.42 0.45 0.91 0.91

WEIGHTED TOTAL 0.01 0.08 0.14 0.15 0.30 0.30

Engineering 33%

Miles of Rebuild with Existing T/L* 65.6% 1.00 0.16 0.84 0.00 0.43 0.32

Weighted 0.66 0.11 0.55 0.00 0.28 0.21

Miles of Co-location with Existing T/L* 19.2% 2.58 1.25 8.50 2.36 3.69 9.50

Weighted 0.50 0.24 1.63 0.45 0.71 1.82

Miles of Co-location with Roads* 7.8% 0.84 1.00 0.12 0.87 0.70 0.00

Weighted 0.07 0.08 0.01 0.07 0.05 0.00

Total Project Costs 7.4% 4.05 1.04 3.63 0.62 0.43 0.23

Weighted 0.30 0.08 0.27 0.05 0.03 0.02

TOTAL 100.0% 1.52 0.50 2.46 0.57 1.08 2.05

WEIGHTED TOTAL 0.50 0.17 0.81 0.19 0.36 0.68

SUM OF WEIGHTED TOTALS 0.65 0.33 1.12 0.34 0.82 1.00

FOR TOP 3-5 ROUTES (INTERNAL)

EXPERT JUDGEMENT Sample Weights

Per

Project Route

A Route

B Route

D

Visual Issues 5% 1 5 1

Weighted 0.05 0.25 0.05

Community Issues 25% 1 5 3

Weighted 0.25 1.25 0.75

Schedule Delay Risk 30% 2 5 1

Weighted 0.60 1.50 0.30

Special Permit Issues 30% 4 5 1

Weighted 1.20 1.50 0.30 Construction/ Maintenance Accessibility 10% 5 1 2

Weighted 0.50 0.10 0.20

TOTAL

100% 2.6 4.6 1.6

Expert Judgment

Visual Concerns (5%) Community Concerns (25%) Schedule Delay Risk (30%) Special Permit Issues (30%) Construction/Maintenance

Accessibility (10%)

…the evaluation metric are normalized and assigned weights to derive a relative score for the alternative routes. The siting team applies expert judgment to rank the top three routes (routes A, B and D).

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Selecting the Preferred Route

The final step in the evaluation process applies expert judgment for ranking the top Alternative Routes (Appendix H: Phase 3: Preferred Route Weighting AHP Pairwise Comparison Questions). Each siting team member ranks the top scoring routes based on several important considerations: visual concerns, community concerns, schedule delay risk, special permit issues and construction and maintenance accessibility. These considerations are assigned weights (5, 25, 30, 30, and 10 percent respectively), and individual responses are combined for an overall team ranking.

It is important to note that the specific evaluation criteria can be expanded or contracted as the unique aspects of routing situations vary. However, the general process of deriving and evaluating explicit metrics remains the same. The process is designed to encourage thorough discussion of clearly defined evaluation criteria that explicitly captures the thought process of the siting team in evaluating and selecting a final route. The process is objective, consistent and comprehensive, while directly focusing and capturing siting team deliberations.

Environmental justice is evaluated as a part of GTC’s risk analysis work and is not part of the route selection process. Thus, environmental justice is included in the methodology and siting model to indicate the point where environmental justice reviews would be typically performed. GTC plans to perform them when alternative routes have been established (Appendix I: Environmental Justice).

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3 SITING CASE STUDIES

Macro Corridors

The project team tested the Macro Corridor Model on 17 of Georgia Transmission Corporation’s (GTC) existing transmission line projects. Alternative Corridors, Alternative Routes, Alternative Route analysis and selection of the Preferred Route were tested on seven of the company’s existing transmission line projects. The tests represented projects from different regions of Georgia, including rural projects in the Coastal Plains and Piedmont areas to urban and suburban projects around Atlanta. The methodology will be tested further, and possibly refined, as GTC uses it on new transmission line projects.

For the purposes of this report, one transmission line project was selected as a case study to illustrate the EPRI-GTC Overhead Electric Transmission Line Methodology and GIS Siting Model. This project is located in southern Georgia, in a predominantly rural area with pockets of residential development. Sensitive project area resources include wetlands, agriculture fields with center pivot irrigation, pecan orchards and a church and cemetery listed on the NRHP.

In Phase 1, Macro Corridor generation, the Least Cost Path (LCP) algorithm was used to identify the boundaries of the project study area by generating three well-defined Macro Corridors. As expected, the test resulted in one corridor paralleling an existing transmission line, another paralleling a road and the third running cross-country. The combination of the three Macro Corridors defines the boundaries of the project area by creating boundaries that capture all possible co-location opportunities as well as sufficient areas for cross-country corridors to be generated. Repeated testing on other projects established that the Macro Corridor Phase of the Siting Methodology would consistently produce successful project area boundaries (Figure 3-1: Macro Corridor Composite).

3-1

Siting Case Studies

Figure 3-1 Siting Case Studies – Macro Corridor Composite

Alternative Corridors

Running the Composite Suitability Surfaces for each of the three perspectives produced four primary corridors: Built Environment, Natural Environment, Engineering Requirements and the Simple Combined. Two corridors, the Built Environment and the Simple Combined, had cross-country sections and co-locations sections. The other two models co-located with an existing transmission line or a road.

The Built Environment Corridor minimizes adverse impacts to roadside residences by running cross-country behind them. Although the road appears to be a direct route between the endpoints, it has scattered residences, as well as several churches. One church and cemetery lot is listed on the NRHP. This NRHP Avoidance Area causes the Built Environment Corridor to go cross-country west of the road until it is north of the constraints. The Built Environment Corridor crosses environmentally sensitive areas, however, it manages to maneuver around large wetlands (Figure 3-2: Built Environment Alternative Corridor Perspective).

3-2

Siting Case Studies

Figure 3-2 Siting Case Studies – Built Environment Alternative Corridor Perspective

The Natural Environment Corridor co-locates with an existing road that appears to be a direct route between the endpoints of the project. Scattered along the roadside route are residences and churches. The Natural Environment Corridor passes in front of a NRHP listed church and cemetery. By co-locating with the road, this corridor avoids environmentally sensitive areas, such as wetlands, and adverse impacts to intensive agriculture, such as row crops with center pivot irrigation (Figure 3-3: Natural Environment Alternative Corridor Perspective).

Figure 3-3 Siting Case Studies – Natural Environment Alternative Corridor Perspective

3-3

Siting Case Studies

The Engineering Requirements Corridor co-locates with an existing transmission line between the two project endpoints. It co-locates with the existing transmission line even though there are row crops with center pivot irrigation adjacent to the right-of-way. The irrigation system and its infrastructure preclude the proposed transmission line from paralleling the existing line without relocating or removing the irrigation system. The existing transmission line cuts through a subdivision near the northern end of the route (Figure 3-4: Engineering Requirements Alternative Corridor Perspective).

Figure 3-4 Siting Case Studies – Engineering Requirements Alternative Corridor Perspective

Engineering Requirements Alternative Corridor Perspective

The Simple Average Corridor begins by avoiding row crops with center pivot irrigation. It utilizes edge-of-field opportunities along the center pivot fields and pecan orchards. This corridor intersects with the existing transmission line about halfway and then co-locates with the transmission line through the residential area to the north endpoint. It also contains similar paths as the Built and Natural Environment models.

In each case, the Built, Natural Environment and Engineering Requirements Corridors minimized adverse impacts to sensitive features (Figure 3-5: Simple Average Alternative Corridor Perspective).

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Siting Case Studies

Figure 3-5 Siting Case Studies – Simple Average Alternative Corridor Perspective

Alternative Routes

Once the Alternative Corridors are generated, data on property lines and building classifications are collected and entered into the GIS Siting Model. These data are used to refine the “Optimal Paths” into six routes for further evaluation.

Route A – Built Route: This route was developed within the Built Environment Corridor, which is primarily cross-country, until joining the road at the northern end. The cross-county section avoided wetlands, residences, the NRHP listed church and cemetery and pecan orchards. It utilized pine plantations when appropriate (Figure 3-6: Route A).

Route B – Natural Route: This route parallels the road that connects the two project endpoints. The route was developed to minimize adverse impacts to ecological resources although it impacts residences that are located along the road and a listed NRHP church and cemetery on the opposite side of the road (Figure 3-7: Route B).

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Siting Case Studies

Figure 3-6 Siting Case Studies – Route A

Figure 3-7 Siting Case Studies – Route B

Route C – Simple Average Route: This route was developed within the Simple Combination Corridor. It is adjacent to the edge of fields and land lot features throughout the southern half of the route. This alignment minimized adverse impact to center pivot irrigation in the project area. About midway, the route turns and parallels an existing transmission line. However, paralleling the existing transmission line would require relocating a residence (Figure 3-8: Route C).

3-6

Siting Case Studies

Route D – Simple Average Route (avoids relocation): This is the second route developed within the Simple Combination Corridor. To avoid relocating a residence, the proposed route must go cross-country for a short distance before returning to the parallel alignment (Figure 3-9: Route D).

Figure 3-8 Siting Case Studies – Route C

Figure 3-9 Siting Case Studies – Route D

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Siting Case Studies

Route E – Engineering Requirements Route: This route was developed within the Engineering Corridor. It parallels the existing transmission line between both project endpoints. However, like Route C, it would be necessary to relocate a residence (Figure 3-10: Route E)

Route F – Engineering Requirements Route (avoids relocation): This is the second route developed within the Engineering Corridor. To avoid relocating a residence, the proposed route must go cross-country for a short distance before returning to the parallel alignment (Figure 3-11: Route F).

Figure 3-10 Siting Case Studies – Route E

Figure 3-11 Siting Case Studies – Route F

3-8

Siting Case Studies

Alternative Route Analysis

Statistics were generated for each route and tabulated into an Excel spreadsheet. They are normalized and weighted by importance of the statistic, and the resulting scores were calculated (Figure 3-12: Alternative Routes).

Figure 3-12 Siting Case Studies – Alternative Routes

Routes A, B and D were chosen for further study. These routes had the best score based on the weighted Alternative Route Analysis. Routes C and E scored higher, or worse, in the Built Environment Category because of the relocation of a residence. Routes E and F scored higher, or worse, because of high adverse impacts to Features in the Natural Environment Category. No significant differences were obvious among the routes in the Engineering Category (Table 3-1: Evaluating Alternative Routes).

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Siting Case Studies

Table 3-1 Siting Case Study – Evaluating Alternative Routes

Built 33% Route A Route B Route C Route D Route E Route F

Feature Unit Unit Unit Unit Unit Unit

Relocated Residences (within 75’ Corridor) 44.3% 0.00 0.00 1.00 0.00 1.00 0.00

Weighted 0.00 0.00 0.44 0.00 0.44 0.00

Proximity to Residences (300’) 13.1% 0.00 1.00 0.25 0.13 0.28 0.16

Weighted 0.00 0.13 0.03 0.02 0.04 0.02

Proposed Residential Developments 5.4% 0.00 0.00 0.00 0.00 0.00 0.00

Weighted 0.00 0.00 0.00 0.00 0.00 0.00

Proximity to Commercial Buildings (300’) 3.6% 1.00 1.00 1.00 1.00 1.00 1.00

Weighted 0.04 0.04 0.04 0.04 0.04 0.04

Proximity to Industrial Buildings (300’) 1.8% 0.33 0.00 0.00 0.00 1.00 1.00

Weighted 0.01 0.00 0.00 0.00 0.02 0.02

School, Daycare, Church, Cemetery, Park Parcels (#) 16.3% 1.00 1.00 1.00 1.00 1.00 1.00

Weighted 0.16 0.16 0.16 0.16 0.16 0.16

NRHP Listed/Eligible Structures/Districts (1500’ from edge of R/W)

15.5% 1.00 0.50 0.00 0.00 0.00 0.00

0.16 0.08 0.00 0.00 0.00 0.00

Total 100.0% 0.36 0.41 0.67 0.22 0.70 0.24

Weighted Total 0.12 0.13 0.22 0.07 0.23 0.08

Natural 33%

Natural Forests (Acres) 9.3% 0.00 0.54 0.49 0.61 0.88 1.00

Weighted 0.00 0.05 0.05 0.06 0.08 0.09

Stream/River Crossings 38.0% 0.00 0.50 0.00 0.00 1.00 1.00

Weighted 0.00 0.19 0.00 0.00 0.38 0.38

Wetland Areas (Acres) 40.3% 0.02 0.00 0.62 0.72 0.90 1.00

Weighted 0.01 0.00 0.25 0.29 0.36 0.40

Floodplain Areas (Acres) 12.4% 0.00 0.00 0.00 0.00 0.00 0.00

Weighted 0.00 0.00 0.00 0.00 0.00 0.00

Total 100.0% 0.01 0.24 0.29 0.35 0.82 0.88

Weighted Total 0.00 0.08 0.10 0.11 0.27 0.29

Engineering 33%

Miles of Rebuild with Existing T/L 65.6% 0.00 0.00 0.00 0.00 0.00 0.00

Weighted 0.00 0.00 0.00 0.00 0.00 0.00

Miles of Co-location with Existing T/L 19.2% 0.96 1.00 0.51 0.66 0.00 0.15

Weighted 0.18 0.19 0.10 0.13 0.00 0.03

Miles of Co-location with Roads 7.8% 0.49 0.00 0.86 0.77 0.97 1.00

Weighted 0.04 0.00 0.07 0.06 0.08 0.08

Total Project Costs 7.4% 0.00 0.17 0.50 0.64 0.83 1.00

Weighted 0.00 0.01 0.04 0.05 0.06 0.07

Total 100.0% 0.22 0.20 0.20 0.23 0.14 0.18

Weighted Total 0.07 0.07 0.07 0.08 0.05 0.06

Sum of Weighted Totals 0.19 0.28 0.39 0.26 0.55 0.43

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Siting Case Studies

Selection of Preferred Route

Once the Preferred Route(s) were ranked by the weighted Alternative Route Analysis, the routes were analyzed further by applying qualitative expert judgment. The project team ranked expert judgment criteria. as 1 = low impact, 2 = medium impact, and 3 = high impact (Table 3-2: Qualitative Expert Judgment).

Table 3-2 Siting Case Study – Qualitative Expert Judgment

Expert Judgement Weights Per Project

Route A

Route B

Route D

Visual Issues 10% 1 3 1

Weighted 0.1 0.3 0.1

Community Issues 20% 1 3 2


Schedule Delay Risk 0% 0 0 0

Weighted 0 0 0

Special Permit Issues 40% 1 3 1


Construction/ Maintenance Accessibility 30% 3 1 2


Environmental Justice 0% 0 0 0

Weighted 0 0 0

Total

100% 1.6 2.4 1.5

The weights were applied to the rankings and summed. In Table 3-1, Evaluating Alternative Routes, Route D scored the best and Route B scored the worst out of the top three routes. This was due primarily to the close proximity of the listed NRHP church to Route B. In Table 3-2: Qualitative Expert Judgment Process, the two best routes, Route D and A, are close but Route D scored slightly better due to construction and maintenance accessibility. Therefore, Route D was selected as the Preferred Route. (Figure 3-13: Preferred Route)

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Siting Case Studies

Figure 3-13 Siting Case Study – Preferred Route

Validation of Results

Georgia Transmission Corporation is actively routing many new transmission lines. There are also a number of new projects that will soon be released for routing to begin. To further test and validate this new siting process, GTC will use the EPRI-GTC Overhead Electric Transmission Line Siting Methodology and GIS Siting Model on its new transmission line projects. An internal GTC team will analyze the results of the methodology for each new transmission line project during the next year. If areas of weakness are discovered in the siting methodology, GIS Siting Model, Feature Calibration or Data Layer Weighting, sensitivity testing will be performed to determine the causes and solutions.

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4 PROJECT MILESTONES

Team Formation – 2002

An EPRI-GTC study team was formed in 2002. Team members were Dr. Joseph K. Berry, Dr. Steven P. French, Jesse Glasgow, Dr. Elizabeth A. Kramer, Steven Richardson, Chris Smith and Dr. Paul D. Zwick. Project managers were Georgia Transmission Corporation’s (GTC) Gayle Houston and Christy Johnson and EPRI’s J.W. Goodrich-Mahoney. GTC staff members assisted the team and Photo Science Inc. developed the siting software used in the GIS Siting Model (Appendix A: EPRI-GTC Overhead Electric Transmission Line Siting Methodology Project Team).

Project Meetings – January 2003

From January 2003 to August 2004, the project team focused their efforts on creating a methodological framework for overhead electric transmission line siting that was scientific, comprehensive and defensible and that integrated advanced GIS technology.

The team developed goals and objectives of the project, determined the project agenda and timeline and discussed responsibilities of individual team members. The project was divided into three major phases: Macro Corridor Generation, Alternative Corridor Generation and Alternative Route Analysis and Evaluation.

During the initial meeting, the strengths and weaknesses of the current transmission line siting methodology were evaluated. The team concluded that inconsistent use of data from project to project was a flaw in the existing process. Subsequent team meetings focused on determining data features and layers for each of the three phases. After this, a series of five workshops was held with external and internal stakeholders to calibrate and weight the data.

External Stakeholder Workshop – June 2003

Based on recommendations from the academic consultants, GTC included external stakeholders as early in the process as practical. GTC held the first workshop after the Macro Corridor selection process was identified. Prior to the workshop, the EPRI-GTC team analyzed information from the GIS database and determined the resource categories needed for the siting model to identify Alternative Corridors within the Macro Corridors. Participants included federal and state officials, community and economic groups’ representatives and other professionals (Appendix J: Stakeholder Meeting Invitees).

4-1

Project Milestones

During the workshop, participants assigned ranks using the Delphi process to categories of resources. They then used the AHP process to weight the three major corridor types: the Built Environment, Natural Environment and Engineering Requirements Perspectives. Participants completed several iterations of both ranks and weights to reach consensus and to demonstrate how changes in Delphi ranks and AHP weights affected corridor and route locations (Appendix E: Phase 2 – Alternative Corridor Model: Delphi Feature Calibration; Appendix F: Phase 2 – Alternative Corridor Model: AHP Percentages by Data Layer; and Appendix G: Phase 2 – Alternative Corridor: AHP Pairwise Comparison Questions).

Georgia Integrated Transmission System Stakeholder Workshop – August 2003

A goal of this project was to provide a comprehensive, consistent and defensible process for overhead transmission line siting in Georgia. Attendees at this workshop were employees of Georgia Transmission Corp., Georgia Power Company and MEAG Power. These companies are part of the Georgia’s Integrated Transmission System (ITS), a statewide electric transmission planning and operations group. The agenda for the ITS workshop was the similar to the one used for the external stakeholder workshop.

The EPRI-GTC project team thought that extensive electric transmission line siting experience would provide members of this group a different perspective on the ranks and weights than external stakeholders who had little or no siting experience.

GIS consultants and members of Photo Science Inc. and Georgia Transmission Corp. ran models using the Delphi rankings and AHP weights developed in two workshops. These rankings and weights were tested on several existing power line siting projects. The academicians and project team members analyzed the model results and adjusted model calibrates and weights where tests indicated obvious inconsistencies and/or missing criteria.

Stakeholder/ITS Update Workshop – November 2003

The external stakeholders (from the June workshop) and ITS attendees (from the August workshop) were invited to attend an update meeting to see a presentation of the results of the workshops they attended. The comments during the discussion session indicated that the participants thought the model was working well at that stage of development. Several participants thought that GTC should hold more meetings to obtain input from additional stakeholders.

Electric Utility Workshop – January 2004

Representatives from electric utility companies attended a meeting to see a presentation of the EPRI-GTC Overhead Electric Transmission Line Siting Methodology Project. The presentation explained the siting tasks. The attendees participated in a discussion and filled out comment forms (Appendix K: Electric Utility Stakeholder Workshop Summary of Questionnaire Responses).

4-2

Project Milestones

External Stakeholder Workshop – March 2004

A second External Stakeholder Meeting was held to provide another opportunity for new stakeholders and stakeholders who could not attend the June meeting. The agenda was the similar to the Electric Utility Meeting in January 2004.

EPRI-GTC Report – 2005

In the third quarter of 2004 and in 2005, the project team documented the study and results and prepared this EPRI-GTC Overhead Electric Transmission Line Siting Methodology Report.

4-3

5 CONCLUSIONS

The research team from the Electric Power Research Institute (EPRI) and Georgia Transmission Corporation (GTC) achieved its primary objective of developing a new electric transmission line siting methodology that produces more quantifiable, consistent and defensible siting decisions.

To do this, the team accomplished the following:

1. Developed a new siting methodology and integrated it with a new data analysis tool called the GIS Siting Model,

2. Obtained internal and external stakeholders’ critical reviews and achieved consensus on the ranking of GIS database features and weighting of data layers,

3. Ensured the process conforms to federal and state environmental regulations, and

4. Applied the corridor and route selection processes to actual transmission line siting projects and evaluated the results.

Georgia Transmission Corporation has revised its transmission line siting practice to conform with the new methodology. As a result, the company’s siting practice is now more consistent and scientifically rigorous, and officials are in a better position to explain, justify and defend their siting decisions.

The team’s project managers reported that the two most successful aspects of the effort were integrating GIS technology with a new methodology, and obtaining stakeholder involvement in the study’s outcome. Additional improvements came in the areas of unexpected cost savings in data collection and the GIS Siting Model producing reports that support GTC’s environmental reporting. In addition, a group of electric utility professionals from companies throughout the Southeast reviewed the EPRI-GTC methodology and siting model and offered their opinions. Their viewpoints are documented in survey results contained in Appendix K.

The project team listed four potential improvements: incorporating rights-of-way access in the methodology, incorporating visual impacts, GIS Siting Model refinements and future testing. Accomplishments and improvements are defined in next few pages.

Accomplishments

As envisioned by EPRI and GTC, the project team and stakeholders developed a GIS Siting Model and incorporated stakeholder input into the siting methodology utilizing the AHP and the Delphi Process. In addition, the team assessed the objectivity and predictability of results when applying the criteria to corridor and route selection, and ensured that the Siting Methodology complied with the National Environmental Protection Act (NEPA) and other environmental regulations.

5-1

Conclusions

Integrating GIS Technology With a New Methodology

GTC integrated a proprietary transmission line siting software, Corridor Analyst™, with off-the-shelf digital data to automate the siting methodology. This GIS approach ensures a comprehensive, objective and consistent methodology for siting transmission lines that can be implemented by other electric industry companies nationwide. GTC is actively working with other members of the Georgia ITS to use this methodology when siting new overhead electric transmission lines in Georgia.

Obtaining Stakeholder Involvement

Siting experts from the electric industry, federal and state agencies and external stakeholders participated in the EPRI-GTC Overhead Electric Transmission Line Siting Methodology development and provided feedback on its strengths and weaknesses. As confirmed by stakeholders’ comments, calibration of Features using the Delphi Process and weighting of Data Layers using the Analytical Hierarchical Process provided a scientifically rigorous methodology.

Another achievement of the project was getting stakeholders’ input during five multi-day workshops. Transmission line siting professionals indicated that the involvement of external stakeholders throughout the development of the siting methodology was an uncommon approach. This approach is a significant departure from most other transmission line siting methodologies because it integrated stakeholders’ input into the methodology and standardized the calibrating and weighting that will be applied to subsequent projects.

Data Collection Cost Savings

An important benefit of standardizing the siting methodology is a savings in data collection costs. Savings result from the GIS Siting Model and off-the-shelf digital data reducing the study area boundaries of the Macro Corridors, Alternative Corridors and Alternative Routes. Reducing study area boundaries eliminates the need for extensive data collection and verification that is both costly and time-consuming. This methodology shortens the time required for the siting portion of the transmission line construction project.

Documentation for Supporting GTC’s Environmental Reporting

As a side benefit, the EPRI-GTC Siting Model will help Georgia Transmission Corporation complete its environmental reports. Among the benefits of the land suitability analysis underlying this approach is the improved consistency and objectivity of information that describes, explains, analyzes and discloses the direct, indirect, and cumulative environmental impacts that would result from proposed actions and alternatives. Along with developing an advanced land suitability analytic modeling capability, GTC has adopted a standardized template for its environmental documents.

As envisioned by EPRI and GTC, the successful Overhead Electric Transmission Line Siting Methodology should encompass several critical tasks, including compliance with the NEPA and other environmental regulations.

5-2

Conclusions

Most important, this process created new transmission line siting tools, techniques and procedures that produce siting decisions that are more objective, quantitative, predictable, consistent and defensible. As such, the team has compiled an effective new mechanism for documenting relevant data, selection of a preferred alternative and the rational connection between the facts found and choices made.

Improvements

Potential improvements are presented in four categories: incorporating rights-of-way access into the methodology, incorporating visual impacts, possible refinements to the GIS Siting Model and additional testing and evaluation on real-world siting programs.

Incorporating Rights-of-Way Access

A potential improvement to the GIS Siting Model would be including access for construction and maintenance in routing an overhead electric transmission line. For example, an area considered suitable for a transmission line right-of-way should be downgraded if it is found to be an isolated parcel that is difficult to access without considerable adverse impact to the environment and local property owners. Currently the routing model does not consider relative access. GIS has been used for years to solve complex off-road construction and maintenance access questions, particularly by the forest industry in valuing timber parcels and by wildfire response units interested in travel-time maps to remote locations.1

The procedure to derive an effective distance map from a road network is shown in Figure 5-1, Identifying Alternative Route Access. In this instance, the gray areas are environmentally sensitive areas that act as absolute barriers to access from the roads. The movement off the roads has to go around the barrier locations like the ripples in a pond have to go around islands. The result is the construction and maintenance access map in the upper right portion of the figure with yellow/red tones indicating relatively remote locations. The bottom set of figures identifies a procedure for identifying the relative access along a proposed overhead electric transmission line route.

Like other criteria maps in the routing model, the effective distance map can be “calibrated” on a preference scale of 1 to 9 and “weighted” with other maps depending on its perceived relative importance. The ability to incorporate relative construction and maintenance accessibility at the onset of analysis is an important extension to the EPRI-GTC routing model for regions with pockets of sensitive terrain conditions and ownerships.

1 For more information on effective distance see http://www.innovativegis.com/basis/MapAnalysis/Default.html,

Topic 14, Deriving and Using Travel-Time Maps, online Map Analysis book by Joseph K. Berry

5-3

http://www.innovativegis.com/basis/MapAnalysis/Default.html

Conclusions

Figure 5-1 Future Initiatives: Effective Distance Map – Calculating an Effective Distance Map that Shows the Relative Access from Roads to All Locations in a Project Area

Incorporating Visual Impacts

Visual impacts are a top community concern with many transmission line construction projects. With the EPRI-GTC methodology, these visual impacts are considered when professional judgment is used to compare Alternative Routes and identify the most suitable site.

If desired, GIS technology could be used to identify the relative visual exposure from “sensitive viewer” locations, such as roads and houses, to all locations throughout a project area. This capability has been part of the GIS toolbox for decades and generates useful information for electric transmission line routing. Relative importance of certain features, such as steep slopes, land cover and building density, could be established.

Figure 5-2, Establishing Visual Connectivity, depicts how visual exposure is calculated. The algorithm uses simple trigonometry relationships to identify whether a location is seen from a given location. The schematic in the top portion of the figure shows how the “rise to run” relationship (tangent) is used in calculating line-of-sight connectivity. The ratio of the elevation difference (rise indicated as striped boxes) to the distance away (run indicated as the dotted line) is used to determine visual connectivity. Whenever the ratio exceeds the previous ratio, the location is marked as seen (red); when it fails, it is marked as not seen (gray).

5-4

Conclusions

Figure 5-2 Future Initiatives: Viewshed Map – Calculating a “Viewshed” Map that Identifies all Locations in a Project Area that can be seen from a Given Location

The lower portion of the figure characterizes the conceptual result. Imagine a searchlight illuminating portions of a landscape. As the searchlight revolves about a viewer location, the lighted areas identify visually connected locations. Shadowed areas identify locations that cannot be seen from the viewer (nor can the viewer be seen). The result is a Viewshed map over the elevation surface. Additional considerations, such as tree canopy, viewer height and view angle/distance, provide a more complete rendering of visual connectivity.

If the procedure is repeated for multiple viewer locations, the relative visual exposure can be calculated for all locations in a project area. A Visual Exposure map (Figure 5-3: Visual Exposure from Extended Features) is generated by noting the number of times each location is seen from a set of viewer locations. Figure 5-3 shows the result, considering an entire road network as a set of viewer locations. In the example, the exposure values range from zero times seen (light gray) to one location that is seen from 270 times from the set of all road locations …highly exposed to roads.

5-5

Conclusions

Figure 5-3 Future Initiatives: Visual Exposure Map – Calculating a “Visual Exposure” Map that Identifies the Relative Exposure for All Locations from an Extended Feature, Such as a Road Network

Other locations, such as individual houses, subdivisions and parks, can be included in the “sensitive viewers” layer to generate a comprehensive Visual Exposure map.2 In addition, the different types of viewers (houses vs. roads) can be considered to identify a relative visual exposure map that reacts to both the number of times seen and the importance of the locations that are visually connected.

GIS Siting Model Refinements

Some enhancements to the GIS Siting Model itself could increase capabilities and automate several key tasks. Four of the most important enhancements are: “Optimal Path” right-of-way development; interactive tools for querying information and refining portions of the computer generated routes; software development for identifying right-of-way road access for construction and maintenance; and computer generated identification of visual resources.

2 For more information on effective distance, see http://www.innovativegis.com/basis/MapAnalysis/Default.html,

Topic 15, Deriving and Using Visual Exposure Maps, online Map Analysis book by Joseph K. Berry

5-6


Conclusions

As currently applied, the “Optimal Path” is limited to the width of a single grid cell. Future enhancements to Corridor Analyst™ could include designing a least cost path (LCP) algorithm that can vary the required width of rights-of-way. Thus, the LCP would be several cells wide instead of the current single cell width.

In addition to map analysis tools, new technologies are available for interacting with model results. One such technology is the Interactive Mapping Methodology (IMM)3 developed by the Colorado Division of Wildlife that uses a real-time, stand-up digitizing environment. The process integrates ArcGIS software and a SMART Board interactive whiteboard system that uses a pen/marker as a mouse. The procedure enables GIS and field personnel to work together as a project team to query, edit and capture spatial data. Field personnel edit and enter map features directly into the GIS database by drawing on base maps projected onto the interactive whiteboard. Supporting map layers can be panned, zoomed and queried to assist the managers as they draw habitat boundaries on the whiteboard.

Another enhancement would be the incorporation of Georgia Power Corporation’s Smart/PowerTrack system for evaluating Alternative Routes. With such a system, siting teams can quickly retrieve pertinent information, identify questionable routing segments, digitize alternative routing around an area using the pen/marker, evaluate the possible re-routing options and select the best option.

As part of this research project, the EPRI-GTC team has used an extensive number of GIS resources, many of them online. The list of sources is included in Appendix L: Location of Online Reference Materials.

Future Testing and Evaluation

During the development of this methodology, tests were run on a series of case study sites. This testing was extremely helpful in identifying the strengths and limitations of the approach. This testing identified significant omissions and oversights and uncovered several unanticipated interactions among the data layers. However, the use of the methodology on actual siting projects will inevitably reveal additional strengths and weaknesses.

After this methodology has been used on a significant number of projects, its performance and results should be rigorously evaluated. A representative set of projects could be analyzed to see how well the methodology has performed. Also a structured evaluation could compare the projects done using the methodology with a set of controls that were sited using traditional methodologies. The analysis could identify differences between the two groups with respect to project duration, project cost, percent of Preferred Routes within each perspective, data layers not relevant to the project study area, additional data layers needed, number and kind of regulatory permits required and major delays encountered.

3 More information on IMM see http://www.geoplace.com/gw/2003/0303/0303nrs.asp, online article in GeoWorld,

March 2003, by Michelle Cowardin and Michelle Flenner

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http://www.geoplace.com/gw/2003/0303/0303nrs.asp

Conclusions

The analysis also could test whether there are significant differences in these measures by physiographic region, by transmission line length or between metropolitan and rural locations. This analysis could determine whether one model can address all regions of the state or if regional variations are needed. In addition, the evaluation should explore further the interactions among the data layers. For example, the relative weighting of the layers changes significantly when a data layer is not present for a particular study area. The behavior of the model under these conditions needs to be more fully understood.

Appendices

The appendices of this report include biographies of the team members; a glossary; GIS metadata used in the study; explanation of Least Cost Path, Delphi and Analytical Hierarchy Process techniques; a list of stakeholders invited to workshops; online reference materials; and a list of articles and conferences where the methodology was presented.

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6 POST FACE

Legal statement about the relationship of the EPRI-GTC methodology and eminent domain and National Environmental Policy Act regulations

Building overhead electric transmission lines requires companies like Georgia Transmission Corporation (GTC) to acquire the rights to use and occupy land. Acquisitions are accomplished through voluntary transactions and through the use of eminent domain.

Eminent domain is an attribute of sovereignty. The U.S. and State Constitutions and laws require that this authority be used sparingly and have restricted its use. Article III of the Georgia Constitution “grants to the General Assembly the power to make all laws... consistent with [its] Constitution, and … the Constitution of the United States, which it shall deem necessary and proper for the welfare of the state and, among other things, to provide by law for... instrumentalities of the state ... to condemn property.”

In fact, eminent domain law in Georgia requires a state-authorized entity, including GTC and other electric utility companies, to justify the public purpose for which the property is taken, and provides the owner with the right to just compensation as guaranteed by the U.S. and Georgia constitutions. Condemnation proceedings are judicial proceedings that require the exercise of judicial power and are subject to judicial review. Procedural safeguards in such matters allow the owner to interpose objections to the claim of a public purpose of the taking and to litigate the fair value of the property taken.

A standardized siting methodology for overhead transmission lines implemented using GIS is not a substitute for evidence, witnesses, judicial proceedings, judicial review or procedural safeguards that allow property owners to interpose objections to a claim of public purpose or to litigate the fair value of the property taken. In fact, to be successful and defensible, the siting tools, techniques and procedures developed here must be complimentary to the processes of law and produce results that are objective, quantitative, predictable and consistent. To this end, the methodology must explain and document decisions so that all information and assumptions used in choosing a Preferred Route and avoiding other less suitable alternatives are available to the courts and the public. In other words, any decision based on GIS technology must be well documented and reproducible.

The National Environmental Policy Act is the basic national charter for protection of the environment. NEPA is intended to ensure that environmental information is available to federal agencies and the public before decisions are made and before actions requiring federal involvement are taken. It helps assure that federal agencies make decisions that are based on understanding of environmental consequences. NEPA establishes policy, sets goals (Section 101), and provides means (Section 102) for carrying out the policy. Section 102(2) contains certain “action-forcing” provisions to ensure that federal agencies act according to the letter and spirit of the Act.

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Post Face

GTC prepares environmental documents in compliance with NEPA, and other relevant federal and state regulations. Among other reasons, GTC does so to be eligible for federal actions on its projects by the U.S. Department of Agriculture’s (USDA) Rural Utilities Service (RUS). RUS actions may, for example, involve providing a loan commitments or approval necessary for GTC to construct a project. GTC’s NEPA documentation and actions must be in compliance with 7 CFR Part 1794 (RUS Environmental Policies and Procedures) and 40 CFR Part 1500 (the President’s Council on Environmental Quality (CEQ) regulations for implementing NEPA), 42 USCA §§4321-4347.

In the end, NEPA imposes procedural, not substantive, requirements on federal agencies such as RUS. “NEPA does not work by mandating that agencies achieve particular substantive environmental results.” Instead, “NEPA ‘works’ by requiring that the environmental consequences of an action be studied before the proposed action is taken.” It is well settled law that a court’s “only role [under NEPA]” is to ensure that the agency has taken a ‘hard look’ at the environmental consequences of the proposed action.” An agency has satisfied its “hard look” requirement if it has “examine [d] the relevant data and articulate [d] a satisfactory explanation for its action including a rational connection between the facts found and the choice made.”

As envisioned by Electric Power Research Institute (EPRI) and GTC, the successful Overhead Electric Transmission Line Siting Methodology should encompass several critical tasks, including compliance with the NEPA and other environmental regulations. To the extent that this process develops new transmission line siting tools, techniques and procedures that are objective, quantitative, predictable, consistent, and defensible, GTC has compiled an effective new mechanism to describe the relevant data and articulate a satisfactory explanation for selection of a preferred alternative and established a rational connection between the facts found and the choice made.

While this new methodology does not attempt to ameliorate publicly controversial aspects of transmission line construction, utilities and the public can realize significant benefits from such innovations. To the extent the innovations prepare, explain and document decisions that are more objective, quantitative and consistent, sound public policy goals have been substantially advanced.

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A EPRI-GTC OVERHEAD ELECTRIC TRANSMISSION LINE SITING METHODOLOGY PROJECT TEAM

Dr. Joseph K. Berry

Dr. Joseph K. Berry is the principal of Berry and Associates // Spatial Information Systems (BASIS), consultants and software developers in Geographic Information Systems (GIS) technology. He is a contributing editor and author of the Beyond Mapping column for GeoWorld magazine since 1989. He has written over two hundred papers on the analytic capabilities of GIS technology, and is the author of the popular books Beyond Mapping (Wiley, 1993), Spatial Reasoning (Wiley 1995) and Map Analysis (in preparation, online). Since 1977, he has presented workshops on GIS technology and map analysis concepts to thousands of professionals. Dr. Berry taught graduate level courses and performed basic research in GIS for twelve years as an associate professor and the associate dean at Yale University’s School of Forestry and Environmental Studies, and is currently a special faculty member at Colorado State University and the W.M. Keck Scholar at the University of Denver. He is the author of the original Academic Map Analysis Package and the current MapCalc Learner-Academic educational materials used in research and instruction by universities worldwide and by thousands of individuals for self-instruction in map analysis principles. Dr. Berry’s research and consulting has been broad. Such studies have involved the spatial characterization of timber supply, outdoor recreation opportunity, comprehensive land use plans, wildlife habitat, marine ecosystem populations, haul road networks, surface and ground water hydrology, island resources planning, retail market analysis, in-store movement analysis, hazardous waste siting, air pollution modeling, precision agriculture and site-specific management. Of particular concern have been applications that fully incorporate map analysis into the decision-making process through spatial consideration of social and economic factors, as well as physical descriptors.

Dr. Steven P. French

Steven French, an urban planner, completed his PhD at the University of North Carolina at Chapel Hill in 1980. He is also a member of the American Institute of Certified Planners, Urban and Regional Information Systems Association and Earthquake Engineering Research Institute. Dr. French, is the director of the City Planning Program at the Georgia Institute of Technology in Atlanta. His teaching, research and consulting activities are primarily in the areas of computer applications in city and regional planning and in analysis of the risk posed to urban development by earthquakes and other natural hazards.

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http://www.innovativegis.com/basis/basis/b&a.html

http://www.geoplace.com/gw/

http://www.innovativegis.com/basis/basis/bm_des.html

http://www.innovativegis.com/basis/basis/spatial.htm

http://www.innovativegis.com/basis/basis/spatial.htm


http://www.innovativegis.com/basis/basis/pmap.htm

http://www.redhensystems.com/mapcalc/index.htm

EPRI-GTC Overhead Electric Transmission Line Siting Methodology Project Team

Dr. French has had a long involvement in teaching and research on the application of database management techniques and geographic information systems to urban systems. He has prepared several parcel level land use databases for local communities on the central coast of California. As a consultant to the county of San Luis Obispo he recently conducted a user needs assessment to determine the feasibility and requirements of an automated mapping system to serve the planning, engineering and assessor departments. His primary teaching areas are in computer applications in city and regional planning, including quantitative methods, database management and geographic information systems. Dr. French has participated in a number of National Science Foundation projects dealing with flood and earthquake hazards. With colleagues at Stanford University he is currently developing an expert system for conducting building inventories based on secondary data sources. He recently developed a risk analysis method that uses a GIS to model damage to urban infrastructure as a part of a National Science Foundation research project. He has also had NSF support to analyze damage to urban infrastructure caused by the Whittier Narrows and Loma Prieta earthquakes. As a part of a previous NSF project, he demonstrated the application of a raster-based geographic information system to earthquake damage modeling for land use planning. This work entailed the development of a structural inventory in a case study community and damage modeling based on structure type, ground motion and site conditions over a large area. An earlier NSF project supported Dr. French’s dissertation and a subsequent book on flood plain land use management.

Prior to his doctoral work at North Carolina, Mr. French was a professional planner in Colorado in both public and private practice. He served as the land use administrator for Garfield County, Colorado, and worked in two civil engineering firms involved with land use and oil shale development. He was a major contributor to the 1975 report “Evaluation of Selected Community Needs,” which detailed the infrastructure and fiscal capabilities of fifteen communities in Western Colorado subject to energy related growth.

Jesse Glasgow

Jesse Glasgow is the GTC operations manager for Photo Science, Inc. Since December 1998, Jesse has been responsible for managing the Georgia Transmission Corporation (GTC) Contract for Photo Science, Inc. GTC out sources its GIS, photogrammetry and surveying services to Photo Science. In this position, he coordinates with GTC associates to assess needs, prepare project plans and ensure that projects are completed to the clients’ satisfaction. Jesse has led the development of a geographic information system/process used for siting, permitting, surveying, designing and constructing new facilities. He also manages GIS software development projects and coordinates survey activities. Prior to joining Photo Science, Jesse was a planner at the Northwest Alabama Council of Local Governments. In this position he worked on several local government initiatives. He also participated in transportation planning for the Metropolitan Planning Organization. Jesse holds a Bachelor of Science in Professional Geography from the University of North Alabama, with a Certificate in GIS.

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John W. Goodrich-Mahoney

John Goodrich-Mahoney is a technical leader and program manager with the Electric Power Research Institute and project manager for the EPRI-GTC Overhead Electric Transmission Line Siting Methodology. He manages the Mercury, Metals and Organics in Aquatic Environments and the Rights-of-Way Environmental Issues in Siting, Development and Management research programs within the Water and Waste Management Business Area. He develops, with input from staff and members, the research portfolios for these two research programs and manages research budgets. Research subjects include: water quality criteria (e.g., mercury and selenium); development of site-specific criteria; bioaccumulation of metals; integrated risk assessments; vegetation management (e.g. use of herbicides); endangered species; bank and trade; avian interaction; and remote sensing. For seven years, he served as a project manager in the Land and Water Quality Studies Program, where he was responsible for research projects for assessing the effects on ground-water quality from the land disposal and land application of utility solid wastes. He developed and continues to manage an innovative research program on the use of constructed wetlands and other passive technologies for the treatment of wastewater. The program includes a plant genetic research component to improve plants for phytoremediation. John earned a Bachelors of Science in Geology from St. Lawrence University, Canton, N.Y., and a Master of Science in Geochemistry from Brown University, Providence, R.I.

Gayle Houston

Gayle Houston is an environmental and regulatory coordinator for Georgia Transmission Corporation and project manager for the EPRI-GTC Overhead Electric Transmission Line Siting Methodology. Ms. Houston is a landscape architect and planner with significant experience in site and route evaluations and selections, environmental studies, regulatory compliance, land management and natural resource planning. Gayle has many years of experience managing complex transmission, substation and power generation siting projects in the southeastern United States. She is a technical expert in the analysis and development of creative solutions for specific project needs. She is experienced in process-oriented strategic planning and utilizes the latest technologies, such as geographic information systems, image processing of satellite and aerial photography, and viewshed analysis, including visual simulations, to enhance the decision making process.

Prior to joining Georgia Transmission Corporation, she served as a senior environmental project manager for Burns and McDonnell; senior project manager, environmental studio manager and GIS manager for EDAW, a landscape architecture and planning company; application analyst, configuring hardware and software systems on multiple platforms, for ERDAS, Inc., an industry leader in image processing and GIS; and consultant to NASA’s Institute for Technology Development Space Remote Sensing Center at the Stennis Space Center in Mississippi where she designed Real Estate Geographic Information System (REGIS) for the Multiple Listing Service industry. Ms. Houston has a Bachelor of Business of Administration from Tulane University and a Master of Landscape Architecture from Louisiana State University. She managed Burns & McDonnell’s Transmission Siting Seminar in Atlanta in 2000; the Edison Electric Institute’s Land Management and Transmission Line Siting Workshop for over 100 electric utility managers in Atlanta in 1993; and was a team leader for the Edison Electric Institute’s Land Management Planning Workshop in Portland, Oregon in 1990.

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Christy Johnson

Christy Johnson is an environmental and regulatory compliance coordinator for Georgia Transmission Corporation and project manager for the EPRI-GTC Overhead Electric Transmission Line Siting Methodology study. Ms. Johnson has served as a coordinator in GTC’s Electric System Maintenance since 1996. Christy is responsible for environmental compliance at electric facilities in GTC’s transmission and distribution system. She monitors construction sites for compliance with federal and state environmental regulations, providing designs and implementation plans for remedial site stabilization projects. Christy provides technical assistance to internal planning, legal and maintenance staffs and has been called upon to provide expert testimony to state environmental regulatory agencies. Her previous work with Soil Systems Incorporated involved archaeological investigations of historic and prehistoric sites. Christy was responsible for the coordination of several cultural resource surveys and mitigation projects in Maryland, South Carolina and Delaware. Christy holds a Bachelor of Arts in Anthropology and a Master of Landscape Architecture from the University of Georgia in Athens.

Dr. Elizabeth A. Kramer

Dr. Liz Kramer received her B.S. in Forest Resources from Michigan State University, her Masters in Forest Science from the Yale School of Forestry and Environmental Studies, and her PhD in Ecology from the University of Georgia. She is currently a public service assistant and the director of the Natural Resource Spatial Analysis Laboratory (NARSAL) at the Institute of Ecology, College of Environment and Design. The mission of NARSAL is to conduct research, training and public service and outreach in the application of geospatial technology to natural resource management and planning. A primary goal is to conduct work in an interdisciplinary fashion to bring ecological science to the environmental policy arena.

Some projects that the lab is involved with include: GIS and remote sensing analysis for a multi-disciplinary study of stream structure and function in the Chattahoochee watershed; the integration of landscape, geomorphic and biological indicators for understanding water quality in Piedmont streams in the Etowah Watershed; Georgia GAP and the SE Regional GAP, a biodiversity mapping program; the development of a GIS enabled Greenspace Planning tool; Georgia Land Use Trends Project (GLUT), an analysis of 25 years of land use change for the State of Georgia; the development of a Regional Greenspace Plan with local governments in the Upper Etowah River Watershed; and the development of a multi-species aquatic Habitat Conservation Plan for the Upper Etowah Watershed.

Steven Richardson

Steven Richardson’s practice focuses on representing companies, Tribes and individuals on land and water issues before the U.S. Departments of the Interior, Agriculture and Energy; other federal agencies; the U.S. Congress; and state and federal courts. He specializes in providing strategic, legal and legislative counseling for clients seeking project approvals for the use and occupation of federal, state, Tribal and private lands. Mr. Richardson has three decades of public and private experience in using sound science, innovative strategies and cutting-edge technology to design, develop and expedite the approvals that get projects built on time and at lower cost, using state of the art environmental documentation techniques and innovative project management solutions.

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Prior to joining Van Ness Feldman, Mr. Richardson served for five years as the chief of staff for the Bureau of Reclamation, where he oversaw the daily operation of the largest wholesaler of water in the country, serving more than 31 million people and providing water for farmland that produces sixty percent of the nation’s vegetables and twenty-five percent of its fruits and nuts, and producer of more than 40 billion kilowatt hours of electricity each year. During his tenure at the Department of the Interior, Mr. Richardson served for seven years as a principal policy advisor to Secretary of the Interior Bruce Babbitt. In that role, he directed the environmental compliance, habitat conservation planning and mitigation activities for two federal agencies in daily contact and consultation with the U.S. Fish and Wildlife Service.

Mr. Richardson also served as the deputy director of the Bureau of Land Management and was responsible for the management and use of 264 million acres of land, about one-eighth of the land of the United States. Additional positions held by Mr. Richardson include: professional staff member and counsel to Congressman Mike Synar (D-OK), Chairman of the Environment, Energy and Natural Resources Subcommittee of the Government Operations Committee; senior counsel for The Wilderness Society; staff director and chief counsel to the House Oversight and Investigations Subcommittee of the Interior and Insular Affairs Committee (now the Resources Committee); and legislative counsel to Representative Edward Markey (D-MA). In addition, Mr. Richardson served as counsel on the U.S. Senate Judiciary Subcommittee on the Constitution, which was chaired by then-Senator Birch E. Bayh, Jr. (D-IN). Mr. Richardson is admitted to practice in the District of Columbia and the State of Indiana.

Chris Smith

Christopher D. Smith is a GIS analyst for Photo Science, Inc. Mr. Smith has more than seven years experience in Geographic Information Systems and Cartography. He has experience with ARC/INFO software, ArcView software, ArcIMS software, ArcSDE and Trimble GPS equipment and software. His experience with GIS includes cartographic design (including publishing a map in ESRI’s annual ESRI map book), database design and development and creating, maintaining, and editing spatial data. He has performed geographic analysis on a wide variety of projects using GIS and other methods as tools. He also has experience with developing and designing geographic related web sites, as well as developing GIS custom applications. Mr. Smith has worked on site at Georgia Transmission Corporation for Photo Science, Inc. for five years. Previously, he worked with the Montgomery Water Works and Sanitary Sewer Board in Montgomery, Ala., as a GIS co-op through the University of North Alabama. He also worked for the International Fertilizer Development Center as a GIS intern. Chris holds a Bachelor of Science in Professional Geography from the University of North Alabama, with a Certificate in GIS.

Dr. Paul D. Zwick

Dr. Paul D. Zwick holds a Doctor of Philosophy in Environmental Engineering Science and a Master of Arts in Urban and Regional Planning. He is an associate professor and chair of the Urban and Regional Planning Department at the University of Florida. Dr. Zwick is also the director of the Geo-Facilities Planning and Information Research Center (GeoPlan), which was established in 1984 in the Department of Urban and Regional Planning at the University of Florida’s College of Design, Construction and Planning. The center was developed in response

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to the need for a teaching and research environment in Geographic Information Systems (GIS). His research emphasis has been directed at the design, development and analysis of paradigms used for computer applications in urban and environmental planning, and engineering. Specifically, Dr. Zwick’s research efforts have been directed at the analysis and design of dynamic models and the use of spatial analysis systems, commonly referred to as geographic information systems. For the past four years, he has been the principal investigator for the development of an environmental geographic information system for the Florida Department of Transportation and for the Florida Geographic Data Library. The FGDL is a data library for the dissemination of GIS data to the citizens of Florida, including middle schools and high schools, libraries, planning agencies, private corporations and businesses, and citizens. Dr. Zwick recently completed a five year project, as co-principal investigator, with a team of multidisciplinary researchers to identify and locate statewide greenway corridors and recreational trails. Dr. Zwick is continuing his greenways work as co-principal investigator for a grant with the U.S. Department of Environmental Protection, locating greenway opportunities in the Southeastern United States. This work has been in progress for the past two years and is expected to become an ongoing funded project with the EPA.

Contributors

Also contributing significantly to the EPRI-GTC research effort were Georgia Transmission’s Herschel Arant, Bob Fox, R. Vince Howard and John Lasseter.

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B LIST OF ACRONYMS AND GLOSSARY OF TECHNICAL TERMS

List of Acronyms

AHP Analytical Hierarchy Process

CEQ Council on Environmental Quality

DEM Digital Elevation Model

EPRI Electric Power Research Institute

FEMA Federal Emergency Management Agency

GAP National GAP Analysis Program

GDT Geographic Data Technologies

GeoPlan Geo-Facilities Planning and Information Research Center

GIS Geographic Information System

GLUT Georgia Land Use Trends

GPC Georgia Power Company

GTC Georgia Transmission Corporation.

IMM Interactive Mapping Methodology

ITS Integrated Transmission System

LCP Least Cost Path

MEAG Municipal Electric Authority of Georgia

NARSAL Natural Resource Spatial Analysis Laboratory

NEPA National Environmental Protection Act

NLCD National Land Cover Dataset

NPHP National Register of Historic Places

NWI National Wetland Inventory

NWR National Wildlife Refuge

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List of Acronyms and Glossary of Technical Terms

PSI Photo Science Inc.

RUS Rural Utility Service

USDA United States Department of Agriculture

USFS United States Forest Service

USFW United States Fish and Wildlife

USGS United States Geological Survey

Glossary of Terms

Access Roads – Existing or new corridors that provide vehicular access to transmission line rights-of-way for construction and maintenance activities.

Accumulated Cost Surface – A grid-based map indicating the total “cost” of routing a linear feature from a starting location to all other locations in a project area by the optimal (least cost) path.

Analytic Hierarchy Process (AHP) – A decision-making process designed to help groups set priorities and make the best decision possible when both qualitative and quantitative aspects of a problem need to be considered. By reducing complex issues to a series of pairwise comparisons and then synthesizing the results, AHP not only helps decision-makers arrive at the best solution, but also provides a clear rationale for the decision reached. (From Expert Systems documentation)

Built Environment – An area of existing or proposed development found within the landscape, typically dominated by commercial, industrial, residential, and cultural structures.

Composite Suitability Surface – See Discrete Cost Surface.

Calibration – A set of graduations to indicate values or positions.

Criteria – A standard on which a judgment or decision may be based.

Derived Data – The result of applying analytical procedures to existing data to generate new information, as opposed to Source Data that is field-collected or obtained from a reputable data warehouse.

Delphi Process – A traditional method developed to obtain the most reliable consensus among a group of experts by a series of questionnaires interspersed with controlled feedback; the process offers a structured method of consultation that may reduce bias and allow groups of individuals as a whole to resolve a complex problem.

Discrete Cost Surface – A grid-based map indicating the relative “goodness” for locating a route at any location within a project area considering a multiple set of criteria map layers. Most often the surface’s range of values are from 1=most preferred through 9=least preferred. Excluded areas are assigned a value of null or no-data. Also termed a Composite Suitability Surface.

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Electric Power Research Institute (EPRI) – A non-profit research-based organization presently serving over 1000 energy organizations worldwide, founded in 1973 to provide technology-based and environmental solutions for the energy industry and society by managing a comprehensive program of scientific research, technology development, and product implementation.

Exclusion – A feature completely eliminated or removed from the analytical process; past research and committee debate has deemed these features to be unsuitable for siting of transmission facilities; justified need will allow for rare exceptions to be included within the model on a case by case basis (i.e., military bases).

Expert Choice – A software application developed in 1983 to assist the group decision making process; based on AHP principles, this application provides a medium whereby through the prioritization of multiple variables and assessment, decision makers can attain solutions to critical organizational issues.

Feature – In the EPRI research project, these are represented within the Siting Model conceptual diagram as yellow boxes. These features will serve as the base for the grids used to generate suitability surfaces.

Geographic Information Systems (GIS) – An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.

Georgia Transmission Corporation (GTC) – A statewide non-profit electric utility cooperative providing transmission services to rural energy customers since 1993. Prior to then, GTC was a part of Oglethorpe Power Corporation a generation and transmission cooperative formed in 1974. GTC is member-owned by 39 regional Electric Membership Cooperatives (EMCs) throughout Georgia that serve more than 3 million residential, commercial, and industrial customers.

Impedance – The amount of resistance (or cost) required to traverse a line from its origin to its destination node or to make a turn (i.e. move from one arc thru a node to another arc). Resistance may be a measure of travel distance, time, speed, or travel times the length, etc. Higher impedance indicates more resistance to movement, with 0 indicating no cost. Often, a negative impedance value or null value indicates an absolute barrier that cannot be transversed. (From ArcInfo Glossary)

Layer – In the EPRI research project, these are represented within the Siting Model conceptual diagram as green boxes. These layers are grids representing various aspects of suitability, such as slope, building density, proximity to cultural resources, etc.

Layer Weights – A percentage assigned to a specific layer of data based on its preference or importance as relative to the remaining variables in a given comparison of features or perspectives.


Least Cost Path – The path, among possibly many, between two points that has the lowest traversal “cost.” In this definition, “cost” is a function of time, distance, or other factors defined by the user. See also impedance. (From ArcInfo Glossary)

Least Preferred Path – A route that is modeled or created by a mathematical algorithm, which analyzes suitability scores determined by features in a given study area. The path in theory connects point A to point B or points in between by recognizing the least suitable areas between the source points.

Linear Infrastructure – An existing network or system in a given area composed of transportation or utility based facilities (i.e. roads, highways, railways, pipelines, and transmission lines).

Macro Corridors – Large, uninterrupted, and irregular paths which are developed by multiple models to in order to define a study area for more detailed analyses.

Methodology – A set of methods and procedures used to solve a problem.

Metadata – A document referencing the critical details of a spatial dataset; this information provides important aspects of the dataset, such as its source, author, date of creation, scale and appropriate uses.

Model – A representation of reality used to simulate a process, understand a situation, predict an outcome, or analyze a problem. A model is structured as a set of rules and procedures, including spatial modeling tools available in a geographical information system (GIS). (From ArcInfo Glossary)

Most Preferred Path – A route that is modeled or created by a mathematical algorithm, and analyzes suitability scores determined by features in a study area. The path connects point A to point B or points in between by utilizing the most suitable areas, which are contiguous betweens the source points.

Natural Environment – Naturally occurring physical features of the landscape. These features are represented by the hydrography, flora, fauna, and topography of a given area.

Optimal Route – The most desirable or suitable location for a transmission line route.

Orthophotography – Aerial photography that has been rectified such that it is equivalent to a map of the same scale. It is a photographic map that can be used to measure true distances, an accurate representation of the earth’s surface.

Pair-Wise Comparison – A structured comparison of two variables to determine preferences.

Perspective – In the Siting Methodology, alternatives for corridors selection have been standardized to represent community values (Built Environment), protection of biotic resources (Natural Environment), and engineering considerations (Engineering Requirements). They are represented within the Siting Model conceptual diagram as blue boxes.

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Sensitive Areas – Areas on a map that are susceptible to degradation from proposed construction or maintenance activities.

Siting Model – A multi-tiered conceptual framework developed to calculate and assess alternatives in siting transmission facilities.

Source Data – Base data that is field-collected or obtained from a reputable data warehouse, as opposed to Derived Data that is the result of applying analytical procedures to existing data to generate new information. For example, a building centroid dataset is source data that is not used directly in the model. However, Building Density and Building Proximity are derived from the source data.

Stakeholders – External individuals with vested interest in an issue or problem, such as the more than 400 officials from government, utilities, academia and community groups that took part in the EPRI-GTC study.

Study Area – An area delineated to encompass the necessary extent for analysis of a routing or siting problem. Data consisting of aerial photography, land ownership, environmental constraints, and cultural features is collected and later analyzed within this study area to determine a preferred path and a composite of alternatives for a transmission facility.

Transmission Line – A power line that typically serves as a means of transporting electric energy from generation facilities to users.

Visual Exposure (VE) – A grid-based map value indicating the number of times a location is seen from a set of “viewer” locations, such as a group of houses (points), a network of roads (lines) or set of identified suburban subdivisions (polygons).

C GEOGRAPHIC INFORMATION SYSTEMS METADATA

Engineering


Rebuild Existing Transmission Lines

GIS Layer(s): GTC Transmission Lines; ITS Transmission Lines

Methodology: Existing transmission lines are buffered depending on the width of the transmission line right of way

Source: Georgia Transmission Corporation

Note: This data set was created from GPS points acquired from helicopter reconnaissance in 1997; Transmission lines since that time have been added from X,Y coordinates of structures supplied by GTC Transmission line designers

Scale/Accuracy: Sub-Meter

Source: Georgia Power Company

Note: This data set was created from GPS points acquired from helicopter reconnaissance in 1997

Methodology of updating facilities is unknown at this time


Parallel Existing Transmission Lines

GIS Layer(s): GTC Transmission Lines; Other ITS Transmission Lines

Methodology: Existing transmission lines are buffered depending on the width of the transmission line right of way the derived data is a buffer from the previous buffer, which represents the area needed for an additional transmission line adjacent to the existing utility corridor

Source: Georgia Transmission Corporation

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Geographic Information Systems Metadata

Note: This data set was created from GPS points acquired from helicopter reconnaissance in 1997 Transmission lines since that time have been added from X,Y coordinates of structures supplied by GTC Transmission line designers


Source: Georgia Power Company

Note: This data set was created from GPS points acquired from helicopter reconnaissance in 1997

Methodology of updating facilities is unknown at this time


Parallel Gas Pipelines

GIS Layer: Pipelines

Methodology: The existing pipeline is buffered depending on the width of the pipeline ROW plus the area needed for an additional transmission line ROW

Source: Georgia Department of Transportation

Note: This dataset contains utility pipelines and transmission lines Features were captured from the Georgia Department of Transportation’s General Highway Base Map This data set does not include all utility pipelines and transmission lines Distributed by: Georgia GIS Data Clearinghouse

All pipelines are selected from the dataset The utility map was clipped and reprojected from UTM 83 Zone 16 The dataset is also enhanced by digitizing pipelines from the Georgia ITS (Integrated Transmission System) book and Aerial Photography

Scale/Accuracy: 1:31,680

Parallel Roads

GIS Layer(s): Streets; Tax Parcel Map

Methodology: The road ROW is buffered to represent the area needed for a transmission line along the secondary paved roads

Source: Geographic Data Technology – Dynamap/1000 v 110

Note: This dataset contains public roads including interstates, state highways, county roads, and city streets, which are classified by FCC code The layers where provided for each individual county These layers where merged together

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Scale/Accuracy: 1: 12,000 (+/-33’)

Source: Various Counties Tax Assessor Offices

Note: Tax Assessor Maps are acquired from County Tax Assessor Offices to digitize Transportation Right of Ways and Special Parcels (see Special Parcel Metadata) or acquired in a digital coverage if available

Scale/Accuracy: Per County

Parallel Interstates ROW

GIS Layer(s): Streets; Tax Parcel Map

Methodology: The Interstate ROW is buffered to represent the area needed for a transmission line along the interstates


Note: This dataset contains public roads including interstates, state highways, county roads, and city streets, which are classified by FCC code The layers where provided for each individual county These layers where merged together

Scale/Accuracy: 1: 12,000 (+/-33’)




Parallel Railway ROW

GIS Layer(s): Railroads; Tax Parcel Map

Methodology: The railway ROW is buffered to represent the area needed for a transmission line along the railway


Scale/Accuracy: 1:12,000 (+/- 33’)


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Road ROW

GIS Layer(s): Tax Parcel Map

Methodology: Transportation Row’s are digitized from Tax Parcel Map using aerial photography as reference




Future GDOT Plans

GIS Layer(s): Future DOT Plans

Methodology: Not Applicable

Sources: GDOT Plans – digital or hard copy Aerial Photography, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1’

Note: Plans that are received as digital CAD drawings are converted to ArcView GIS shapefiles and modified appropriately to generate a polygon coverage of the extent that will be effected by the Future Road

If the plans are received as hard copy drawings, these are digitized on screen using ArcView GIS and using Aerial Photography as reference

Scale/Accuracy: 1:12,000 (+/- 33’)

Scenic Highways

GIS Layer(s): Parkways and Scenic Rivers; Tax Parcel Map

Methodology: The scenic highway ROW is buffered to represent the area to avoid along a scenic highway

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Source: U.S. Geological Survey, Digital Line Graph Data – (Linear Federal Land Features of the United States – USGS)

Note: This file was originally digitized by the National Mapping Division based on the sectional maps contained in ‘The National Atlas of the United States of America’ published by the USGS in 1970; The sectional maps were updated during 1978-1981 and digitized in the early 1980s; The data were updated in 1995 using 1:1,000,000-scale and 1:2,000,000 scale Bureau of Land Management State base maps; These data were published on CD-ROM in 1995; Using Arc/INFO software, the DLG optional format files were converted to Arc/INFO coverage’s using the DLGARC command Only linear federal land features and attribute information were extracted for inclusion ;The individual State coverages were then merged together using the Arc/INFO command APPEND

Scale/Accuracy: 1:2,000,000




Slope

Slope 0% – 15%; 15% - 30%; and > 30%

GIS Layer(s): Slope

Methodology: Reclassification: Reclassify to 0-15%; 16% - 30%; > 30%

Source: USGS 75 Min Digital Elevation Model

Note: The DEMs (Digital Elevation Models) for the study area were merged together in a seamless surface Using ESRI’s slope algorithm, a slope surface was created

Scale/Accuracy: 1:24,000 (+/-40’)


Center Pivot Irrigation

GIS Layer(s): Center Pivot Irrigation Agriculture Fields

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Source: Aerial Photography

Note: The center pivot points were “heads-up” digitized as a point file using ArcView 32; The center of the irrigation pivot was used as its location Aerial photography taken is used as a geo-referenced image for center pivot location

The center pivots where buffer by a distance measured from the aerial photography; The buffer was edited depending of the rotation of the center pivot fields

Scale/Accuracy: 1:12,000 (+/-33’)

Pecan Orchards

GIS Layer(s): Land Use/Land Cover


Source: Aerial Photography, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1’

Note: The polygons were digitized on screen from imagery derived from aerial photographs taken on per project basis Data was collected through identification of land cover areas using ArcGIS Land Cover is compared to field gathered data to insure accuracy

Classifications: Natural Forests, Undeveloped land, Row Crops and Horticulture, Managed Pine Plantations, Pecan Orchard, Fruit Orchards, Mines and Quarries, Commercial/Industrial, Institutional, Recreational, Utility Right of Way, Transportation, Hydrology

Scale/Accuracy: 1:12,000 (+/-3333’)

Fruit Orchards





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Scale/Accuracy: 1:12,000 (+/-3333’)

Natural Environment

Public Lands

USFS

GIS Layer(s): Public Lands and Forests


Source: Georgia Department of Natural Resources, Georgia Department of Transportation County Maps

Note: This dataset provides 1:100,000-scale data depicting the locations of public lands within the State of Georgia It includes polygon representations of National, State and county parks; National and State historic sites; National Wildlife Refuges; National Wilderness Areas; Wildlife Management Areas; Wild and Scenic Areas; archaeological sites; off-road vehicle areas; U.S. Department of Agriculture land; and other areas The data were collected and located by the Georgia Department of Natural Resources (GADNR) and the U.S. Geological Survey (USGS) The locations were mapped onto existing 1:100,000-scale maps and also digitized from existing mylar maps Data was previously collected in 1986-87 by GADNR and USGS from existing 1:63,360- and 1:126,720-scale Georgia Department of Transportation County Maps which included State owned lands as well as existing county parks Much of this data was not updated in 1993

Scale/Accuracy: 1:100,000 (+/- 166’)

WMA – State Owned

GIS Layer(s): DNR Managed Lands


Source: Georgia Department of Natural Resources

Note: This dataset provides 1:24,000-scale data depicting boundaries of land parcels making up the public lands managed by the Georgia Department of Natural Resources (GDNR) It includes polygon representations of State Parks, State Historic Parks, State Conservation Parks, State Historic Sites, Wildlife Management Areas, Public Fishing Areas, Fish Hatcheries, Natural

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Areas and other specially designated areas The data were collected and located by the Georgia Department of Natural Resources Boundaries were digitized from survey plats, lines on U.S. Geological Survey 1:24,000-scale topographic maps that were added from land survey plat or other information, or already existed on the maps

Scale/Accuracy: 1:24,000 (+/- 40’)

WMA – Non-State Owned



Source: See WMA – State Owned

Other Conservation Land



Source: See WMA – State Owned

Streams/Wetlands

Trout Streams (100’ Buffer)

GIS Layer(s): Trout Streams

Methodology: Buffer trout streams by 100’

Source: Georgia Natural Heritage Program (GNHP), USGS 75 min Quadrangle

Note: USGS blue lines are selected that are identified by GNHP and converted to an individual layer

Scale/Accuracy: 1:24000 (+/-40’)

Streams <5cfs Regulatory Buffer

GIS Layer(s): Streams greater or less than 5 cfs

Methodology: Buffer streams < 5 cfs by regulatory distance

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Source: U.S. Army Corp of Engineers, USGS 75 Min Quadrangles

Note: This layer represents the streams or portions of streams that yield a stream flow greater than or equal to 5 cfs The basis for this theme is the USGS blue line layer A runoff coefficient of 16 cfs/mi2 for streams in this basin was used to determine the land area of a basin that will be drained before the water reaches a flow of 5 cfs It was determined that the land area required to generate such a flow in this basin is approximately 313 mi2 Drainage basins were delineated to find those with total land areas at these limits Streams below the lower boundary of each basin and subsequent downstream reaches were selected as those with flows of greater than 5 cfs

Accuracy/Scale: 1:24,000 (+/-40)

Rivers/Streams >5cfs Regulatory Buffer

GIS Layer(s): Streams greater or less than 5 cfs

Methodology: Buffer rivers/streams > 5 cfs by regulatory distance

Source: See Streams <5cfs Regulatory Buffer

Forested Wetlands and 30’ Buffer

GIS Layer(s): Land Cover/Land Cover; Hydric Soils; National Wetlands Inventory

Methodology: Intersect National Wetlands Inventory with Hydric Soils (if available) Land Cover All wetlands that fall within Hardwood and Mix Forests and Managed Pine Plantations are considered NWI forested wetlands Buffer the intersected wetlands by a 30’ distance




Scale/Accuracy: 1:12,000 (+/-3333’)

Source: Soil Survey of Georgia Counties, United States Department of Agriculture, Soil Conservation Service

Scale/Accuracy: 1:24,000 (+/- 40’)

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Source: U.S. Fish and Wildlife Service National Wetlands Inventory

Note: All NWI maps for the state of Georgia were reprojected from UTM NAD 83 Zone 16 & Zone 17 meters to Geographic NAD83 Decimal Degrees and merged into one layer

Scale/Accuracy: 1:24,000 (+/-40’)

Non-Forested Wetlands and 30’ Buffer


Methodology: Intersect National Wetlands Inventory and Hydric soils (if available) with Land Cover All wetlands that fall outside Hardwood and Mix Forests and Managed Pine Plantations are considered NWI non-forested wetlands Buffer the intersected wetlands by a 30’ distance

Source: See Forested Wetlands and 30’ Buffer

Non-Forested Costal Wetlands and 30’ Buffer


Methodology: Intersect/Buffer: Intersect National Wetlands Inventory and Hydric Soils (if available) with Land Cover All wetlands that fall outside Hardwood and Mix Forests and Managed Pine Plantations are considered NWI non-forested wetlands Buffer the intersected wetlands by a 30’ distance

Source: See Forested Wetlands and 30’ Buffer

Floodplain

GIS Layer(s): 100 year floodplain


Source: Flood Insurance Rate Maps, USGS 75 min Quadrangle

Note: The Q3 FEMA FLOODPLAIN DATA are downloaded from the Georgia GIS Clearinghouse The layer is checked for spatial integrity by comparing the flood coverage a USGS 75 min quadrangle If the Flood zones do not align with the topology and blue lines on the USGS 75 min Quadrangles, the polygons were “heads-up” digitized using ArcGIS Digital USGS Topographic maps were used as a guide Flood Insurance Rate Maps were used as a source

Scale/Accuracy: 1:24,000 (+/- 40’)

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Land Cover

Hardwood and Mixed Forests




Note: The polygons were digitized on screen from imagery derived from aerial photographs taken on per project basis Data was collected through identification of land cover areas using ArcGIS Land Cover is compared to field gathered data to insure accuracy Classifications: Natural Forests, Undeveloped land, Row Crops and Horticulture, Managed Pine Plantations, Pecan Orchard, Fruit Orchards, Mines and Quarries, Commercial/Industrial, Institutional, Recreational, Utility Right of Way, Transportation, Hydrology

Scale/Accuracy: 1:12,000 (+/-3333’)

Undeveloped Land (Pastures, Scrub/Shrub, Clear Cut, and Abandoned Fields)



Source: See Hardwood and Mixed Forests

Row Crops and Horticulture




Managed Pines




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Developed Land


Methodology: Merge all Urban Land Use/Land Cover Categories


Wildlife Habitat

Species of Concern

GIS Layer(s): Species of Concern Habitat


Source: University of Georgia

Scale/Accuracy: 1: 24,000 (+/-40’)

Natural Areas

GIS Layer(s): Natural Areas


Source: University of Georgia

Scale/Accuracy: 1: 24,000 (+/-40’)

Built Environment

Eligible NRHP Structures

GIS Layer(s): Historic Structures

Methodology: Buffer Eligible NRHP Buildings 1500’

Source: Architectural Historic Consultant, USGS 75 Minute Quadrangles Aerial Photography, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1’

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Note: Structures are field surveyed and determined NRHP (National Register of Historic Places) listed, eligible, possibly eligible, not eligible by an Architectural Historian All structures that are listed, eligible, or possibly eligible are mapped by placing a centroid at the approximate center of the structure using USGS 75 Minute Quadrangles and best available photography

Scale/Accuracy: 1:24,000 (+/-40’)

Building Density

GIS Layer(s): Buildings Centroids

Methodology: A density surface is created from building centroids within the study area and is classified by six defined: 0-005 bldg/ac, 005-02 bldg/ac, 02-1 bldg/ac, 1-4 bldg/ac, 4-25 bldg/ac, and 25+ bldg/ac

Source: Aerial Photography taken per project basis, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1’

Note: The building centroids were digitized on screen using ArcGIS software Aerial photography is used as a geo-referenced image for building location identification

Building for all projects are stored in an Oracle table named RTE_BUILDINGS as SDE layers Buildings are collected on a per project basis

Scale/Accuracy: 1:12,000 (+/- 3333’)

Proximity to Buildings

GIS Layer(s): Buildings Centroids; Building Footprints

Methodology: All buildings not represented in building footprints are given a 40’ buffer to represent the extent of the smaller structures A proximity surface is created from the Building buffers and the Building Footprints, and is classified into four defined categories: (0-300’, 300-600’, 600-900’, 900-1200’)


Note: The building footprints were digitized on screen using ArcGIS software Only buildings of certain size have their footprints digitized For example buildings that appear to be commercial buildings, industrial buildings, hospitals, government buildings, agricultural buildings, special structures such as water towers are utility type structures (water stream plants, power plants, etc…) and Apartment/Condo Buildings Aerial photography is used as a geo-referenced image for building footprint delineation

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Scale/Accuracy: 1:12,000 (+/-3333’)




Scale/Accuracy: 1:12,000 (+/- 3333’)


GIS Layer(s): Lakes and Ponds

Methodology: Proximity: A proximity surface is created from Day Care Parcel, School Parcel (K-12), and Church Parcel is classified by nine defined categories: (0-100’, 100-200’, 200-300’, 300-400’, 400-500’, 500-750’, 750-1000’, 1000-1500’, 1500’+)


Note: This dataset contains polygonal hydrologic features, including lakes, ponds, reservoirs, swamps, and islands Data were captured from Mylar separates containing the “blue-layer” from the U.S. Geologic Survey’s 1:24,000-scale quadrangle maps Individual quadrangles were combined and edge matched using Arc/Info GIS software, and then clipped into individual county tiles using boundary data from the Georgia Department of Transportation’s 1:31,680-scale County General Highway Maps



GIS Layer(s): Proposed Developments Plans accepted by local government.


Sources: Aerial Photography, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1’

County Planning and Development Departments

Note: Proposed Developments are digitized on screen using orthophotography and the Development Plans as sources

Scale/Accuracy: 1:24,000 (+/- 40’)

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General Land Divisions

Edge of Fields


Methodology: The perimeters of areas classified as Agriculture are buffered by the width of the proposed transmission line easement Next the perimeter of areas classified as Planted Pine and Hardwood forests are buffered by the width of the proposed transmission line easement These two buffers are then intersected. Stream buffers are removed and visual interpretation of the resulting layer is performed to ensure only areas of opportunity are present




Scale/Accuracy: 1:12,000 (+/-3333’)

Land Lots

GIS Layer(s): Tax Parcel Maps

Methodology: Land lots are digitized using tax parcel maps and orthophotography The perimeters of land lots are buffered by the width of the proposed transmission line easement




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Land Use

Undeveloped


Methodology: Merge all Land Use/Land Cover categories that are not Urban




Scale/Accuracy: 1:12,000 (+/-3333’)

Non-Residential


Methodology: Merge: Merge all Land Use/Land Cover categories that are Urban with the exception of Residential

Source: See Residential Land Use

Residential



Source: See Residential Land Use

Excluded Areas – The Linear Infrastructure features are not included in the excluded areas. If existing corridors reside in these areas, it is acceptable to cross in existing corridors or parallel to existing corridors

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NRHP Listed Archeology Districts and Sites

GIS Layer(s): Archeology Sites

Methodology: Only listed sites are selected from database An Area of Potential Effect (APE) buffer may need to be created The APE buffer distance is a regulatory distance

Source: Georgia Archaeological Site Files (UGA, Athens)

Note: This layer represents as point data the archaeological sites within the study area as provided to GTC by consultants. The site files at the Georgia Archaeological Site Files (UGA, Athens) were researched to obtain information about previously identified archaeological sites Site centroids are based on UTM coordinates as recorded on State of Georgia Archaeological Site Forms through September 6, 2001 and were projected by Brockington from Easting and Northing coordinates in UTM NAD 27, Zone 16 into the coordinate system described below

Scale: Varies due to source

NRHP Listed Districts and Structures

GIS Layer(s): Historic Districts; Historic Structures

Methodology: An APE buffer will be created for Historic structures using 1,500 feet

Source: Architectural Historic Consultant, USGS 75 Minute Quadrangles

Aerial Photography, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1’

Note: Districts are field surveyed and determined NRHP (National Register of Historic Places) listed or eligible by an Architectural Historian All districts are mapped by placing a polygon of the approximate area of the district using USGS 75 Minute Quadrangles and best available photography

Scale/Accuracy: 1:24,000 (+/-40’)



Note: Structures are field surveyed and determined NRHP (National Register of Historic Places) listed, eligible, possibly eligible, not eligible by an Architectural Historian All structures that are listed, eligible, or possibly eligible are mapped by placing a centroid at the approximate center of the structure using USGS 75 Minute Quadrangles and best available photography

Scale/Accuracy: 1:24,000 (+/-40’)

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Eligible NRHP Districts

GIS Layer(s): Historic Districts




Note: Districts are field surveyed and determined NRHP (National Register of Historic Places) listed or eligible by an Architectural Historian All districts are mapped by placing a polygon of the approximate area of the district using USGS 75 Minute Quadrangles and best available photography

Scale/Accuracy: 1:24,000 (+/-40’)

Building + Buffers

GIS Layer(s): Footprints; Buildings Centroids

Methodology: Buffer Building Centroids by 40’ and half the proposed transmission line easement width Buffer Building Footprints by half the proposed transmission line easement width


Note: The building footprints were digitized on screen using ArcGIS software Only buildings of certain size have their footprints digitized For example buildings that appear to be commercial buildings, industrial buildings, hospitals, government buildings, agricultural buildings, special structures such as water towers are utility type structures (water stream plants, power plants, etc…) and Apartment/Condo Buildings Aerial photography is used as a geo-referenced image for building footprint delineation

Scale/Accuracy: 1:12,000 (+/-3333’)




Scale/Accuracy: 1:12,000 (+/- 3333’)

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Airports

GIS Layer(s): Airports

Methodology: Airports boundary adjusted to include glide path Glide paths are determined by the closest tree line or existing overhead utilities on either end of the airport runways


Note: This dataset contains all international and regional airports

The layers where provided for each individual county These layers where merged together

Scale/Accuracy: 1: 12,000 (+/-33’)

EPA Superfund Sites

GIS Layer(s): EPA Superfund Sites


Source: U.S. EPA Comprehensive Environmental Response, Compensation, and Liability Information System (CERCLIS) database

Note: This database can be accessed through the EnviroFacts Data Warehouse web site This site allows general users to access most EPA source databases regarding waste, water, toxics, air, radiation, and land The data can be accessed through the online Superfund Query Form found within the EPA’s main web site Queries are made on a County basis, and the addresses of the individual sites will be used to geocode each of the sites The point file that is created will be overlain on aerial photography for the project study area The physical boundary of the sites will be delineated through visual interpretation of the photos

Scale/Accuracy: 1: 12,000 (+/-33’)

Non-Spannable Water Bodies

GIS Layer(s): Lakes/Ponds

Methodology: Create an internal buffer of half the maximum span distance Next, union the Buffer with Lakes and Ponds Areas inside the Lakes/Ponds, but outside Buffer are Non-Spannable


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Note: This dataset contains polygonal hydrologic features, including lakes, ponds, reservoirs, swamps, and islands Data were captured from Mylar separates containing the “blue-layer” from the U.S. Geologic Survey’s 1:24,000-scale quadrangle maps Individual quadrangles were combined and edge matched using Arc/Info GIS software, and then clipped into individual county tiles using boundary data from the Georgia Department of Transportation’s 1:31,680-scale County General Highway Maps


State and National Parks

GIS Layer(s): DNR Managed Lands; Public Lands and Forests


Source: Georgia Department of Natural Resources

Note: This dataset provides 1:24,000-scale data depicting boundaries of land parcels making up the public lands managed by the Georgia Department of Natural Resources (GDNR) It includes polygon representations of State Parks, State Historic Parks, State Conservation Parks, State Historic Sites, Wildlife Management Areas, Public Fishing Areas, Fish Hatcheries, Natural Areas and other specially designated areas The data were collected and located by the Georgia Department of Natural Resources Boundaries were digitized from survey plats, lines on U.S. Geological Survey 1:24,000-scale topographic maps that were added from land survey plat or other information, or already existed on the maps

Scale/Accuracy: 1:24,000 (+/- 40’)

Military Facilities

GIS Layer(s): Military Facilities



Note: This dataset was extracted from the Landmarks data layer, which is classified by FCC code The D10 FCC classification was selected out and converted to a shape file to represent military facilities

Scale/Accuracy: 1: 12,000 (+/-33’)

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Mines and Quarries






Scale/Accuracy: 1:12,000 (+/-3333’)

City and County Parks

GIS Layer(s): Special Parcels


Sources: Aerial Photography, Control: Survey Grade GPS, Photo Scale: 1”=800’, Pixel Resolution: 1

County Tax Assessor

Note: Special Parcel boundaries are on screen digitized using aerial photography as a base map Tax Assessor Maps are used to determine boundary lengths and azimuths The record in the counties Tax Digest are linked to there corresponding parcel by the PIN (Parcel Identification Number), which is entered as an attribute at the time the parcel boundary is delineated

Scale/Accuracy: 1:24,000 (+/- 40’)

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Day Care Parcel



Source: See City and County Parks

Cemetery Parcel




School Parcel (K-12)




USFS Wilderness Area



Church Parcel




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USFS Wilderness Area



Wild/Scenic Rivers

GIS Layer(s): Parkways and Scenic Rivers

Methodology: A regulatory buffer is created for both sides of the Wild/Scenic River

Source: U.S. Geological Survey, Digital Line Graph Data – (Linear Federal Land Features of the United States – USGS)

Note: This file was originally digitized by the National Mapping Division based on the sectional maps contained in ‘The National Atlas of the United States of America’ published by the USGS in 1970 The sectional maps were updated during 1978-1981 and digitized in the early 1980s The data were updated in 1995 using 1:1,000,000-scale and 1:2,000,000 scale Bureau of Land Management State base maps These data were published on CD-ROM in 1995 Using Arc/INFO software, the DLG optional format files were converted to Arc/INFO coverages using the DLGARC command Only linear federal land features and attribute information were extracted for inclusion The individual State coverages were then merged together using the Arc/INFO command APPEND

Scale/Accuracy: 1:2,000,000

Ritual Importance

GIS Layer(s): Source currently unknown


Wildlife Refuge



Source: Georgia Department of Natural Resources, Georgia Department of Transportation County Maps

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Note: This dataset provides 1:100,000-scale data depicting the locations of public lands within the State of Georgia It includes polygon representations of National, State and county parks; National and State historic sites; National Wildlife Refuges; National Wilderness Areas; Wildlife Management Areas; Wild and Scenic Areas; archaeological sites; off-road vehicle areas; U.S. Department of Agriculture land; and other areas The data were collected and located by the Georgia Department of Natural Resources (GADNR) and the U.S. Geological Survey (USGS) The locations were mapped onto existing 1:100,000-scale maps and also digitized from existing mylar maps Data was previously collected in 1986-87 by GADNR and USGS from existing 1:63,360- and 1:126,720-scale Georgia Department of Transportation County Maps which included State owned lands as well as existing county parks Much of this data was not updated in 1993

Scale/Accuracy: 1:100,000 (+/- 166’)

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D APPENDIX D

GIS Siting Model Techniques:

• Least Cost Path,

• Delphi Process and

• Analytical Hierarchy Process

Least Cost Path Algorithm for Identifying Optimal Routes and Corridors

Determining the best route through an area is one of the oldest spatial problems. Meandering animal tracks evolved into a wagon trail that became a small road and ultimately a super highway. While this empirical metamorphosis has historical precedent, contemporary routing problems involve resolving complex interactions of engineering, environmental and social concerns.

In the past, overhead electric transmission lines and other siting applications required thousands of hours huddling around paper maps, sketching hundreds of possible paths, and then assessing their feasibility to “eyeball” the best routes using a straight edge and professional experience. While the manual approach capitalizes on expert interpretation and judgment, often it is criticized as a closed process that lacks a defendable, documented procedure and fails to fully engage alternative perspectives of what constitutes a preferred route.

Routing Procedure

The use of the Least Cost Path (LCP) procedure for identifying an optimal route based on user-defined criteria has been used extensively in GIS applications for siting linear features and corridors. Whether applications involve movement of elk herds, herds of shoppers, or locating highways, pipelines or overhead electric transmission lines, the procedure is fundamentally the same — 1) develop a discrete cost surface that indicates the relative preference for routing at every location in a project area, 2) generate an accumulated cost surface characterizing the optimal connectivity from a starting location (point, line or area) to all other locations based on the intervening relative preferences, and 3) identify the path of least resistance (steepest downhill path) from a desired end location along the accumulated surface. See Author’s Note 1 for more information on applying LCP to routing applications.

D-1

Appendix D

Figure D-1 schematically shows a flowchart of the GIS-based routing procedure for a hypothetical example if siting an overhead electric transmission line that avoids areas that have high housing density, far from roads, near or within sensitive areas and have high visual exposure to houses.

Figure D-1 GIS-Based Routing Uses Three Steps to Establish a Discrete Map of the Relative Preference for Siting at Each Location, Generate an Accumulated Preference Surface from a Starting Location(S) and Derive the Optimal Route from an End Point as the Path of Least Resistance Guided by the Surface

These four criteria are shown as rows in the left portion of the figure. The Base Maps are field collected data such as elevation, sensitive areas, roads and houses. Derived Maps use computer processing to calculate information that is too difficult or even impossible to collect, such as visual exposure, proximity and density. The discrete Preference Maps translate this information into decision criteria. The calibration forms maps that are scaled from 1 (most preferred—favor siting, gray areas) to 9 (least preferred—avoid siting, red areas) for each of the decision criteria.

The individual cost maps are combined into a single map by averaging the individual layers. For example, if a grid location is rated 1 in each of the four cost maps, its average is 1 indicating an area strongly preferred for siting. As the average increases for other locations it increasingly encourages routing away from them. If there are areas that are impossible or illegal to cross these locations are identified with a “null value” that instructs the computer to never traverse these locations under any circumstances.

Identifying Corridors

The technique generates accumulation surfaces from both the Start and End locations of the proposed power line. For any given location in the project area one surface identifies the best route to the start and the other surface identifies the best route to the end. Adding the two surfaces together identifies the total cost of forcing a route through every location in the project area.

D-2

Appendix D

The series of lowest values on the total accumulation surface (valley bottom) identifies the best route. The valley walls depict increasingly less optimal routes. The red areas in Figure D-2 identify all of locations that within five percent of the optimal path. The green areas indicate ten percent sub-optimality.

Figure D-2 The Sum of Accumulated Surfaces is Used to Identify Siting Corridors as Low Points on the Total Accumulated Surface

The corridors are useful in delineating boundaries for detailed data collection, such as high-resolution aerial photography and ownership records. The detailed data within the macro-corridor is helpful in making slight adjustments in centerline design.

Using the Delphi Process for Calibrating Map Criteria

Implementation of the LCP routing procedure provides able room for interpretation and relative preferences. For example, one of the criteria in the routing model seeks to avoid locations having high visual exposure to houses. But what constitutes “high” …5 or 50 houses visually impacted? Are there various levels of increasing “high” that correspond to decreasing preference? Is “avoiding high visual exposure” more or less important than “avoiding locations near sensitive areas.” How much more (or less) important?

The answers to these questions are what tailor a model to the specific circumstances of its application and the understanding and values of the decision participants. The tailoring involves two related categories of parameterization—calibration and weighting.

D-3

Appendix D

Calibration refers to establishing a consistent scale from 1 (most preferred) to 9 (least preferred) for rating each map layer used in the solution. Figure D-3 shows the result for the four decision criteria used in the routing example.

Figure D-3 The Delphi Process Uses Structured Group Interaction to Establish a Consistent Rating for Each Map Layer

The Delphi Process, developed in the 1950s by the Rand Corporation, is designed to achieve consensus among a group of experts. It involves directed group interaction consisting of at least three rounds. The first round is completely unstructured, asking participants to express any opinions they have on calibrating the map layers in question. In the next round the participants complete a questionnaire designed to rank the criteria from 1 to 9. In the third round participants re-rank the criteria based on a statistical summary of the questionnaires. “Outlier” opinions are discussed and consensus sought.

The development and summary of the questionnaire is critical to Delphi. In the case of continuous maps, participants are asked to indicate cut-off values for the nine rating steps. For example, a cutoff of 4 (implying 0-4 houses) might be recorded by a respondent for Housing Density preference level 1 (most preferred); a cut-off of 12 (implying 4-12) for preference level 2; and so forth. For discrete maps, responses from 1 to 9 are assigned to each category value. The same preference value can be assigned to more than one category, however there has to be at least one condition rated 1 and another rated 9. In both continuous and discrete map calibration, the median, mean, standard deviation and coefficient of variation for group responses are computed for each question and used to assess group consensus and guide follow-up discussion. See Author’s Note 2 for more information on applying Delphi to routing applications.

D-4

Appendix D

Using the Analytical Hierarchy Process (AHP) for Weighting Map Criteria

Weighting of the map layers is achieved using a portion of the Analytical Hierarchy Process (AHP) developed in the early 1980s as a systematic method for comparing decision criteria. The procedure involves mathematically summarizing paired comparisons of the relative importance of the map layers. The result is a set map layer weights that serves as input to a GIS model.

In the routing example, there are four map layers that define the six direct comparison statements identified in Figure D-3 (#pairs = (N * (N – 1) / 2) = 4 * 3 / 2 = 6 statements) as shown in Figure D-4. Members of the group independently order the statements so they are true, then record the relative level of importance implied in each statement. The importance scale is from 1 (equally important) to 9 (extremely more important).

Figure D-4 The Analytical Hierarchy Process Uses Pairwise Comparison of Map Layers to Derive their Relative Importance

This information is entered into the importance table a row at a time. For example, the first statement in the figure views avoiding locations of high Visual Exposure (VE) as extremely more important (importance level = 9) than avoiding locations close to Sensitive Areas (SA). The response is entered into table position row 2, column 3 as shown. The reciprocal of the statement is entered into its mirrored position at row 3, column 2. Note that the last weighting statement is reversed so its importance value is recorded at row 5, column 4 and its reciprocal recorded at row 4, column 5.

Once the importance table is completed, the map layer weights are calculated. The procedure first calculates the sum of the columns in the matrix, and then divides each entry by its column sum to normalize the responses. The row sum of the normalized responses derives the relative weights that, in turn, are divided by minimum weight to express them as a multiplicative scale. See Author’s Note 2 for more information on calculations and applying AHP to routing applications.

D-5

Appendix D

The relative weights for a group of participants are translated to a common scale then averaged before expressing them as a multiplicative scale. Alternate routes are generated by evaluating the model using weights derived from different group perspectives.

EPRI-GTC Overhead Electric Transmission Line Siting Experience

Figure D-5 shows the results of applying different calibration and weighting information to derive alternative routes for a routing application in central Georgia. Four routes and corridors were generated emphasizing different Perspectives—Built environment (community concerns), Natural environment (ecology and cultural concerns), Engineering (construction concerns) and the Simple un-weighted average of all three group perspectives.

Figure D-5 Alternate Routes are Generated by Evaluating the Model Using Weights Derived from Different Group Perspectives

These results are from a comprehensive model recently developed during a project funded by the Electric Power Research Institute (EPRI) and Georgia Transmission Corporation (GTC). The project team consisted of academics, siting engineers, GIS specialists and various administrators, public relations personnel, legal advisors and other industry experts. Several group sessions involving federal agencies, industry representatives and community groups were held that used Delphi and AHP to calibrate and weight more than twenty criteria. See Author’s Note 3 for more information on the EPRI-GTC Overhead Electric Transmission Line Siting Methodology.

While all four of the routes in Figure D-5 use the same criteria layers, the differences in emphasis for certain layers generate different routes/corridors that directly reflect differences in stakeholder perspective. Note the similarities and differences between the Built, Natural, Engineering and un-weighted routes. The bottom line is that the procedure identified constructible alternative routes that can be easily communicated and discussed.

D-6

Appendix D

The final route is developed by an experienced transmission line siting team who combine alternative route segments for a preferred route. Engineers make slight centerline realignments responding the detailed field surveys along the preferred, and then design the final pole placements and construction estimates for the final route.

The ability to infuse different perspectives into the routing process is critical in gaining stakeholder involvement and identifying siting sensitivity. It acts at the front end of the routing process to explicitly identify routing corridors that contain constructible routes reflecting different perspectives that guide siting engineer deliberations. Also, the explicit nature of the methodology tends to de-mystify the routing process by clearly identifying the criteria and how it is evaluated.

In addition, the participatory process 1) encourages interaction among various perspectives, 2) provides a clear and structured procedure for comparing decision elements, 3) involves quantitative summary of group interaction and dialog, 4) identifies the degree of group consensus for each decision element, 5) documents the range of interpretations, values and considerations surrounding decision criteria, and 6) generates consistent, objective and defendable parameterization of GIS models.

D-7

E PHASE 2: ALTERNATIVE CORRIDOR MODEL – DELPHI FEATURE CALIBRATIONS

E-1

Phase 2: Alternative Corridor Model – Delphi Feature Calibrations

Built Environment Delphi Results June 2003 Workshop August 2003 Workshop Current Rankings

Proximity to Buildings Value Proximity to Proposed Development Value Proximity to Buildings Value Proximity to Buildings Value 0-100' 9 0-100' 9 Background 1 Background 1 100-200' 9 100-200' 6.9 900-1200 1.8 900-1200 1.8 200-300' 8.1 200-300' 5.1 600-900 2.6 600-900 2.6 300-400' 6.5 300-400' 3.3 300-600 4.2 300-600 4.2 400-500' 5.5 400-500' 2.6 0-300 9 0-300 9 500-750' 4.8 500-750' 2 Eligible NRHP Historic Structures Eligible NRHP Historic Structures 750-1000' 2.5 750-1000' 1.7 Background 1 Background 1 1000-1500' 1.3 1000-1500' 1 900 - 1200 2.8 900 - 1200 2.8 1500'+ 1 1500'+ 1 600 - 900 3.6 600 - 900 3.6 Proximity to Eligible Historic Structures Visual Vulnerability 300 - 600 5.2 300 - 600 5.2 0-100' 9 Category 9 9 0 - 300 9 0 - 300 9 100-200' 8.9 Category 8 8.7 Building Density Building Density200-300' 8.2 Category 7 7.4 Category 1 1 0 - 0.05 Buildings/Acre 1 300-400' 5.9 Category 6 6.6 Category 2 1.6 0.05 - 0.2 Buildings/Acre 3 400-500' 5.3 Category 5 4.9 Category 3 2.7 0.2 - 1 Buildings/Acre 5 500-750' 4.6 Category 4 4.1 Category 4 3.8 1 - 4 Buildings/Acre 7 750-1000' 2.8 Category 3 2.7 Category 5 4.9 4 - 25 Buildings/Acre 9 1000-1500' 2 Category 2 1.7 Category 6 6 Proposed Development1500'+ 1 Category 1 1 Category 7 7.1 Background 1 Proximity to Eligible Archaeology Sites Proximity to Excluded Areas Category 8 8.1 Proposed Development 9 0-100' 9 0-100' 9 Category 9 9 Spannable Lakes and Ponds100-200' 8.4 100-200' 9 Proposed Development Background 1 200-300' 5 200-300' 8.9 Background 1 Spannable Lakes and Ponds 9 300-400' 3.3 300-400' 7.4 Proposed Development 9 Land Divisions400-500' 2.8 400-500' 5.9 Spannable Lakes and Ponds Edge of field 1 500-750' 2.3 500-750' 4.3 Background 1 Land lots 7.9 750-1000' 1.8 750-1000' 3.3 Spannable Lakes and Ponds 9 Background 9 1000-1500' 1 1000-1500' 2.1 Land Divisions Land Use1500'+ 1 1500'+ 1 Edge of field 1 Undeveloped 1 Building Density Proximity to Schools/Daycares/Churches Land lots 7.9 Commercial/Industrial 3 Category 9 9 0-100' 9 Background 9 Residential 9 Category 8 7.9 100-200' 9 Proximity to Schools, Daycares, and Churches Category 7 6 200-300' 8.8 Background 1 Category 6 3.8 300-400' 7.6 900-1200 1.9 Category 5 2.2 400-500' 5.8 600-900 3.5 Category 4 1 500-750' 3.2 300-600 4.9 Category 3 1.2 750-1000' 2.2 0-300 9 Category 2 1.4 1000-1500' 1.6 Category 1 2.2 1500'+ 1

E-2


Natural Environment Delphi Results

June 2003 Workshop August 2003 Workshop Current Rankings

Floodplain Values Proximity to Protected Animal Values Floodplain Values Floodplain Value100 Year Floodplain 9 0-200' 9 Background 1 Background 1 Background 1 200-400' 9 100 Year Floodplain 9 100 Year Floodplain 9 Slope 400-600' 8 Streams/Wetlands Streams/Wetlands Slope 0-3% 1 600-800' 7 Background 1 Background 1 Slope 3-10% 3 800-1000' 6 Streams < 5cfs Regulatory Buffer 5.1 Streams < 5cfs Regulatory Buffer 5.1 Slope 10-15% 5 1000-1500' 5 Non-forested Non-Coastal Wetlands 6.1 Non-forested Non-Coastal Wetlands 6.1 Slope 15-20% 7 1500-2000' 4 Rivers/Streams > 5cfs Regulatory Buffer 7.4 Rivers/Streams > 5cfs Regulatory 7.4 Slope 20-25% 8 2000-3000' 2 Non-forested Coastal Wetlands 8.4 Non-forested Coastal Wetlands 8.4 Slope >25% 9 3000'+ 1 Trout Streams (50' Buffer) 8.5 Trout Streams (50' Buffer) 8.5 Streams/Wetlands Proximity to Protected Plant Species Forested Wetlands and 30' Buffer 9 Forested Wetlands and 30' Buffer 9 Trout Streams (50' Buffer) 9 0-100' 9 Public Lands Public LandsSpannable Lakes/Ponds 5 100-200' 9 Background 1 Background 1 Streams < 5cfs Regulatory Buffer 9 200-300' 9 WMA - Non-State Owned 4.8 WMA - Non-State Owned 4.8 Rivers/Streams > 5cfs Regulatory Buffer 9 300-400' 8 Other Conservation Land 8.3 Other Conservation Land 8.3 Forested Wetlands and 30' Buffer 9 400-500' 6 WMA - State Owned 8.7 WMA - State Owned 8.7 Non-Forested Non-Coastal Wetlands and 30' 9 500-750' 4 USFS 9 USFS 9 Non-forested Coastal Wetlands 9 750-1000' 3 Upland Forested Areas Land Cover Background 1 1000-1500' 2 Background 1 Undeveloped land, Pastures, 1 Public Lands 1500'+ 1 Hardwood and Mixed Forests 9 Managed Pine Plantations 2.2 USFS 7 Proximity to Excluded Areas Agriculture/Silviculture Row Crops and Horticulture 2.2 WMA - State Owned 9 0-100' 9 Undeveloped land, Pastures, Scrub/Shrub, 1 Developed Land 6.5 WMA - Non-State Owned 3 100-200' 9 Managed Pine Plantations 2.2 Pecan Orchards 8.6 Other Conservation Land 9 200-300' 8 Row Crops and Horticulture 2.2 Hardwood/Mixed Forests 9 Background 1 300-400' 7 Urban 6.5 Land Cover 400-500' 5 Pecan Orchards 8.6 Hardwood and Mixed Forests 9 500-750' 3 Background 9 Managed Pine Plantations 1 750-1000' 1 Protected Terrestrial Animal Species Clearcut Pines 1 1000-1500' 1 Background 1 Pecan Orchards 5 1500'+ 1 1500' Buffer 9 Undeveloped land, Pastures, Scrub/Shrub, 5 Protected Plant Species Row Crops and Horticulture 1 Background 1 Center Pivot Agriculture 1 500' Buffer 9 Background 1

E-3


Engineering Environment Delphi Results

June 2003 Workshop August 2003 Workshop Current Rankings

Existing Utilities Values Linear Infrastructure Values Linear Infrastructure Values Rebuild Existing Transmission 1.9 Rebuild Existing Transmission Lines 1 Rebuild Existing Transmission Lines 1 Parallel Existing Transmission 1 Parallel Existing Transmission Lines 1.4 Parallel Existing Transmission Lines 1.4 Parallel Gas Pipelines 9 Parallel Secondary Dirt Roads ROW 2.5 Parallel Roads ROW 3.6 Background 9 Parallel Secondary Paved Roads ROW 3.2 Parallel Gas Pipelines 4.5 Transportation Parallel Gas Pipelines 4.5 Parallel Railway ROW 5 Parallel Scenic Highways ROW 9 Parallel Primary Highways ROW 5 Background 5.5 Parallel Interstates ROW 5.7 Parallel Railway ROW 5 Future GDOT Plans 7.5 Parallel Primary Highways ROW 1.9 Background 5.5 Parallel Interstates ROW 8.1 Parallel Secondary Paved Roads ROW 1.7 Future GDOT Plans 7.5 Road ROW 8.4 Parallel Secondary Dirt Roads ROW 1 Parallel Interstates ROW 8.1 Parallel Scenic Highways ROW 9 Future GDOT Plans 4.5 Road ROW 8.4 Slope Parallel Railway ROW 1.9 Parallel Scenic Highways ROW 9 Slope 0-15% 1 Road ROW 2.9 Slope Slope 15-30% 5.5 Background 3.1 Slope 0-15% 1 Slope >30% 9 Land Cover Slope 15-30% 5.5 Center Pivot Irrigation Hardwood and Mixed Forests 5.6 Slope >30% 9 Background 1 Managed Pine Plantations 4.9 Center Pivot Irrigation Center Pivot Agriculture 9 Clear-cut Pines 2 Background 1 Pecan Orchards 6.3 Center Pivot Agriculture 9 Undeveloped land, Pastures, Scrub/Shrub, Etc. 1 Row Crops and Horticulture 5.8 Center Pivot Agriculture 9 Background 5.4 Proximity to Excluded Areas 0-100' 9 100-200' 6.9 200-300' 4.5 300-400' 3.1 400-500' 2.1 500-750' 1 750-1000' 1.5 1000-1500' 1.5 1500'+ 1

E-4

F PHASE 2: ALTERNATIVE CORRIDOR MODEL – AHP PERCENTAGES BY DATA LAYER

F-1

Phase 2: Alternative Corridor Model – AHP Percentages by Data Layer

Analytical Hierarchy Process Layer Percentages

June 2003 Workshop August 2003 Workshop Current Percentages

Engineering Environment % Engineering Environment % Engineering Environment %

Existing Utilities 64.2% Linear Infrastructure 48.3% Linear Infrastructure 48%

Transportation 20.8% Slope 13.3% Slope 9%

Land Cover 10.7% Center Pivot Irrigation 42.6% Intensive Agriculture 43%

Proximity to Excluded Areas 4.3% Natural Environment % Natural Environment %

Natural Environment % Floodplain 3.6% Floodplain 6%

Floodplain 6.9% Streams/Wetlands 12.1% Streams/Wetlands 21%

Slope 5.1% Public Lands 9.3% Public Lands 16%

Streams/Wetlands 30.3% Upland Forested Areas 10.2% Land Cover 21%

Public Lands 9.6% Agriculture/Silviculture 1.9% Wildlife Habitat 36%

Land Cover 8.1% Protected Terrestrial Animal Species 30.0% Built Environment %

Proximity to Protected Animal Species 13.7% Protected Plant Species 32.9% Proximity to Buildings 12%

Proximity to Protected Plant Species 22.7% Built Environment % Eligible NRHP Historic Structures 14%

Proximity to Excluded Areas 3.5% Proximity to Buildings 9.6% Building Density 37%

Built Environment % Eligible NRHP Historic Structures 11.6% Proposed Development 6%

Proximity to Buildings 8.2% Building Density 31.3% Spannable Lakes and Ponds 4%

Proximity to Eligible Historic Structures 16.5% Proposed Development 5.3% Land Divisions 8%

Proximity to Eligible Archaeology Site 3.0% Spannable Lakes and Ponds 3.2% Land Use 19%

Building Density 8.5% Land Divisions 6.7%

Proximity to Proposed Development 2.4% Proximity to Schools, Daycares, and Churches 32.3%

Visual Vulnerability 14.7%

Proximity to Excluded Areas 21.3%

Proximity to Schools/Daycares/Churches 25.4%

F-2

G PHASE 2: ALTERNATIVE CORRIDORS WEIGHTING – AHP PAIRWISE COMPARISON QUESTIONS

Pairwise Comparison Question Weights

The stakeholders weighted each Pairwise question using the chart shown below.

If Yes, If No, circle value in circle value in this column this column

9 9 Extremely more important 8 8 Very strong to extremely 7 7 Very strongly more important

6 6 Strongly to very strongly 5 5 Strongly more important 4 4 Moderately to strongly

3 3 Moderately more important 2 2 Equally to moderately 1 1 Equally important

Engineering Layer Pairwise Comparison Questions

Are Existing Utilities more important than Transportation Corridors?

When siting a transmission line is it more preferable to co-locate (parallel) with existing utilities or with transportation corridors?

Are Existing Utilities more important than Slope?

When siting a transmission line is it more preferable to co-locate with existing utilities or to avoid steep slopes?

(What if the line must go in an area of steep slope in order to co-locate with a existing utility?)

G-1

Phase 2: Alternative Corridors Weighting – AHP Pairwise Comparison Questions

Are Existing Utilities more important than Center Pivots?

When siting a transmission line is it more preferable to co-locate with existing utilities or to avoid center pivot irrigation?

(What if the line must go through a center pivot irrigation system in order to co-locate with existing utilities?)

Are Transportation Corridors more important than Slope?

When siting a transmission line is it more preferable to co-locate (parallel) with transportation corridors or to avoid steep slopes?

(What if the line must go in an area of steep slope in order to co-locate with transportation corridors?)

Are Transportation Corridors more important than Center Pivots?

When siting a transmission line is it more preferable to co-locate (parallel) with transportation corridors or to avoid center pivot irrigation?

(What if the line must go through a center pivot irrigation system in order to co-locate with transportation corridors?)

Is Slope more important than Center Pivots?

When siting a transmission line is it more preferable to avoid steep slopes or to avoid center pivot irrigation?

Natural Environment Pairwise Comparison Questions

Are Public Lands more important than Hydrography?

When siting a transmission line is it more important to minimize impact to public lands or to streams/wetlands?

Are Public Lands more important than Floodplains?

When siting a transmission line is it more important to minimize impact to public lands or to floodplains?

Are Public Lands more important than Land Cover?

When siting a transmission line is it more important to consider public lands or land cover (i.e., forested vs. undeveloped land)?

(What if the line must go through public lands in order to locate in an agricultural field as opposed to a forested area?)

G-2


Are Hydrography more important than Floodplains?

When siting a transmission line is it more important to minimize impact to wetlands/streams or floodplains?

Is Hydrography more important than Land Cover?

When siting a transmission line is it more important to consider streams/wetlands or land cover (i.e., forested vs. undeveloped land)?

(What if the line must go through streams/wetlands in order to locate in an agricultural field as opposed to a forested area?)

Are Floodplains more important than Land Cover?

When siting a transmission line is it more important to consider floodplains or land cover (i.e., forested vs. undeveloped land)?

(What if the line must go in an area of floodplains in order to locate in an agricultural field as opposed to a forested area?)

Built Environment Pairwise Comparison Questions

Is Proximity to Cultural Resources more important than Building Density?

When siting a transmission line is it more important to stay away from NRHP eligible historic structures or to avoid areas of high building density?

Is Proximity to Cultural Resources more important than Proximity to Buildings?

When siting a transmission line is it more important to stay away from NRHP eligible historic structures or to stay away from all buildings?

Is Proximity to Cultural Resources more important than Lakes and Ponds?

When siting a transmission line is it more important to stay away from NRHP eligible historic structures or to avoid spannable lakes and ponds?

Is Proximity to Cultural Resources more important than Proximity to Proposed Developments?

When siting a transmission line is it more important to stay away from NRHP eligible historic structures or to stay away from proposed developments?

Is Proximity to Cultural Resources more important than Land lots?

When siting a transmission line is it more important to stay away from NRHP eligible historic structures or to parallel large property lines?

G-3


Is Building Density more important than Proximity to Buildings?

When siting a transmission line is it more important to avoid areas of high building density or to avoid being close to individual buildings?

Is Building Density more important than Lakes and Ponds?

When siting a transmission line is it more important to avoid areas of high building density or to avoid spannable lakes and ponds?

Is Building Density more important than Proximity to Proposed Developments?

When siting a transmission line is it more important to avoid areas of high building density or to stay away from proposed developments?

Is Building Density more important than Land lots?

When siting a transmission line is it more important to avoid areas of high building density or to parallel large property lines?

Is Proximity to Buildings more important than Lakes and Ponds?

When siting a transmission line is it more important to stay away from buildings or to avoid spannable lakes and ponds?

Is Proximity to Buildings more important than Proximity to Proposed Developments?

When siting a transmission line is it more important to stay away from existing buildings or stay away from proposed developments?

Is Proximity to Buildings more important than Land lots?

When siting a transmission line is it more important to stay away from buildings or to parallel large property lines?

Are Lakes and Ponds more important than Proximity to Proposed Developments?

When siting a transmission line is it more important to avoid spannable lakes and ponds or to stay away from proposed developments?

Are Lakes and Ponds more important than Land lots?

When siting a transmission line is it more important to avoid spannable lakes and ponds or to parallel large property lines?

Is Proximity to Proposed Developments more important than Land lots?

When siting a transmission line is it more important to stay away from proposed developments or to parallel large property lines?

G-4

H PHASE 3: PREFERRED ROUTE WEIGHTING – AHP PAIRWISE COMPARISON QUESTIONS

H-1

Phase 3: Preferred Route Weighting – AHP Pairwise Comparison Questions

Preferred Route Layer Calculations – Engineering

Score

When siting a transmission line are the miles of rebuild of an existing transmission line more important than the miles of co-location with an existing transmission line? 8

When siting a transmission line are the miles of rebuild of an existing transmission line more important than co-location with roads? Equal 7

When siting a transmission line are the miles of rebuild of an existing transmission line more important than the total project cost? Equal 4

When siting a transmission line are the miles of co-location with an existing transmission line more important than co-location with roads? 5

When siting a transmission line are the miles of co-location with an existing transmission line more important than total project cost? 3 When siting a transmission line are the miles of co-location with roads more important than total project costs? Equal 2

Importance Percentage Miles of rebuild of existing TL 65.70% Miles of co-location with existing TL 19.20% Miles of co-location with existing roads 7.80% Total project cost 7.40%

H-2


Preferred Route Layer Calculations – Natural Environment

SCORE

When siting a transmission line is it more important to minimize impact to natural forests or to streams/river crossings? -3 When siting a transmission line is it more important to minimize impact to natural forests or to wetlands? -4 When siting a transmission line is it more important to minimize impact to natural forests or to floodplains? -2 When siting a transmission line is it more important to minimize impact to stream/river crossings or to wetlands? Equal 1 When siting a transmission line is it more important to minimize impact to stream/river crossings or to floodplains? 4 When siting a transmission line is it more important to minimize impact to wetlands or to floodplains? 4

Importance Percentage Wetlands 40.30% Streams/rivers 38% Floodplains 12.40% Natural forests 9.30%

H-3


Preferred Route Layer Calculations – Built Environment

SCORE When siting a transmission line it is more important to avoid relocations or stay 300 feet away from residences? 6 When siting a transmission line it is more important to avoid relocations or stay away from proposed developments? 7

When siting a transmission line it is more important to avoid relocations or stay 300 feet away from commercial buildings? 8

When siting a transmission line it is more important to avoid relocations or stay 300 feet away from industrial buildings? 9

When siting a transmission line it is more important to avoid relocations or stay away from the road edge of school, daycare, church or cemetery parcels? 3

When siting a transmission line it is more important to avoid relocations or stay away from NRHP eligible historic structures? 6

When siting a transmission line it is more important to stay 300 feet away from residences or to stay away from proposed developments? 5

When siting a transmission line it is more important to stay 300 feet away from residences or to stay 300 feet away from commercial buildings? 6

When siting a transmission line it is more important to stay 300 feet away from residences or to stay 300 feet away from industrial buildings? 7

H-4


When siting a transmission line it is more important to stay 300 feet away from residences or stay away from the road edge of school, daycare, church or cemetery parcels? Equal 1

When siting a transmission line it is more important to stay 300 feet away from residences or to stay away from NRHP eligible historic structures? -3

When siting a transmission line it is more important to stay away from proposed developments or to stay 300 feet away from commercial buildings? 3

When siting a transmission line it is more important to stay away from proposed developments or to stay 300 feet away from industrial buildings? 5

When siting a transmission line it is more important to stay away from proposed developments or stay away from the road edge of school, daycare, church or cemetery parcels? -5

When siting a transmission line it is more important to stay away from proposed developments or to stay away from NRHP eligible historic structures? -3

When siting a transmission line it is more important to stay 300 feet away from commercial buildings or to stay 300 feet away from industrial buildings? 5

When siting a transmission line it is more important to stay 300 feet away from commercial buildings or stay away from the road edge of school, daycare, church or cemetery parcels? -7

When siting a transmission line it is more important to stay 300 feet away from commercial buildings or to stay away from NRHP eligible historic structures? -4

When siting a transmission line it is more important to stay 300 feet away from industrial; buildings or stay away from the road edge of school, daycare, church or cemetery parcels? -9

H-5


When siting a transmission line it is more important to stay 300 feet away from industrial buildings or to stay away from NRHP eligible historic structures? -7

When siting a transmission line it is more important to stay away from the road edge of school, daycare, church or cemetery parcels or to stay away from NRHP eligible historic structures? Equal 1

Importance Percentage Relocated residences 44.20% Road edge of school, daycare, church or cemetery parcels 16.30% NRHP eligible structures 15.50% Proximity to houses 13.10% Proposed development 5.40% Proximity to commercial development 3.60% Proximity to industrial development 1.80%

H-6

I ENVIRONMENTAL JUSTICE GUIDELINES

Consideration of environmental justice (EJ) is mandated by Executive Order (EO) 12898, which states that “each Federal agency shall make achieving environmental justice part of its mission by identifying and addressing, as appropriate, disproportionately high and adverse health and environmental effects of its programs, policies and activities on minority and low-income populations in the United States and its territories and possessions.”1 For any project receiving federal funding, Georgia Transmission Corporation (GTC) is required to coordinate with the Rural Utilities Service (RUS) to ensure compliance with EO 12898. The RUS guidelines require the use of U.S. Census Bureau data for determining whether minority and/or low-income populations live within a proposed transmission corridor or substation site and whether these populations could suffer adverse environmental and/or human health effects as a result of the project. The RUS guidelines also specify measures for addressing EJ issues should they occur. An EJ review is triggered by any project that requires an environmental report (ER), environmental assessment (EA) or environmental impact statement (EIS). An ER, EA or EIS is required only if the project receives federal funding. This document describes the steps to be followed by GTC and its consultants in performing environmental justice evaluations.

As soon as the alternate routes or alternate substation sites have been established, an EJ review should be performed by a consultant experienced in compliance with EO 12898. The consultant will use GTC’s Methodology for Analyzing Potential Environmental Justice Areas of Concern and will comply with the following steps:

1. GTC will submit maps of the alternate routes or substation sites to the consultant. GTC will direct the consultant to review the area for Census blocks (racial analysis) and block groups (income analysis) whose minority and/or low-income populations meet or exceed the EPA Region 4 EJ thresholds.2 The consultant will also review the area databases for possible cumulative impacts3 from pollution sources and/or other community disturbances. After the initial review, the consultant will perform a field analysis for data verification.

1 Executive Order 12898, Federal Actions to Address Environmental Justice in Minority Populations and

Low-Income Populations. February 11, 1994.

2 The minority threshold is 35.72% of the area population, and the low-income (poverty) threshold is 17.58% (EPA Region 4. “Interim Policy to Identify and Address Potential Environmental Justice Areas.” EPA-904-R-99-004, April 1999.)

3 This term is defined as “...harmful health or other effects resulting from exposure to multiple environmental stressors…” 65 Fed. Reg. 39665 (2000). Cumulative impacts may occur when a community already contains pollution sources or other factors that may be viewed as detrimental to one’s quality of life. Some examples of these factors include, but are not limited to, industrial development (with or without smokestacks), industrial or other odors, the discharge of industrial by-products to air or water, landfills, visual obstructions, or excessive noise from highways or other sources.

I-1

Environmental Justice Guidelines

2. The consultant’s review will result in one of three findings: 1) No Occurrence of Minority/Low-Income Populations; 2) An Occurrence of Minority/Low-Income Populations, but No Adverse Effect; or 3) Possible Adverse Effect to Minority/Low-Income Populations. After performing the EJ review, the consultant will provide to GTC maps and a written report documenting the results of the analysis. The report will contain a clear conclusion regarding whether the project will have a disproportionately high and adverse environmental or human health effect on a minority or low-income population. The consultant will use data gathered during the field survey to submit specific recommendations for avoidance of minority and/or low-income communities (e.g. locating the line along a specific highway, avoiding the southwestern corner of a specific area, etc.).

3. The information from the EJ review will be used as part of GTC’s Risk Analysis. It will not be used as a component of the alternate route selection process.

4. If the final route selected has potential EJ implications (a severe Adverse Effect and/or cumulative effect), GTC will notify RUS. RUS will determine the public notification process and the method of notification. Also RUS will accept GTC’s mitigation plan or will make recommendations for changes to the mitigation plan.

5. The EJ efforts, consultant’s conclusion and a summary of the mitigation plan (if any) will be documented in the ER, EA or EIS.

Environmental

Justice

Route/Site Alternatives

Route/Site Selection

Risk Analysis

Preferred Corridor

I-2

J STAKEHOLDER MEETING INVITEES

EPRI – GTC

Stakeholder Meeting Invitation List

Alabama Electric Cooperative

Alabama Power Company

Altamaha Nature Conservancy

American Electric Power

American Transmission Company

Arkansas Electric Cooperative Corp.

Arkansas Power and Light

Association County Commissioner of Georgia

Atlanta Chamber of Commerce

Atlanta Regional Commission

Carroll EMC

CenterPoint Energy

Central Electric Power Cooperative

Central Georgia EMC

Chattahoochee Hill Country

Chattahoochee River Keeper

City of Tallahassee, FL

Cleco

Cobb Chamber of Commerce

Cobb County Community Affairs

Cobb EMC

Colquitt EMC

Council For Quality Growth

Coweta County Commissioner

Dalton Utilities

DNR, Land Protection Branch

DNR, Wildlife Resources Division

DNR-Wildlife Resources Division/Natural Heritage

Duke Power Company

Dunwoody Homeowners Association

J-1

Stakeholder Meeting Invitees

EPRI – GTC


East Cobb Civic Association

East Kentucky Power Cooperative

Entergy Transmission - New Orleans

EPA Region 4, Environmental Accountability Div.

EPA, Region 4, Reg. Wetlands Coord./Permit

Flint EMC

Florida Power and Light

Framatome-anp

GA Agribusiness Council

GA Chapter American Planning Association

GA Chapter American Society of Landscape Architects

GA Department of Natural Resources

GA Department of Transportation

GA Dept. of Community Affairs - Economic Development

GA Dept. of Industry, Trade and Tourism

GA Economic Developers Association

GA Environmental Protection Division - GIS Specialist

GA Environmental Protection Division - Stream Buffers

GA Farm Bureau

GA Greenways Association

GA Natural Heritage Program

GA Realtors Association

GA School Boards Association

GA School Supt Association

GA Water & Soil Conservation Comm., Region II

GA Wildlife Federation

Georgia Conservancy

Georgia Electric Membership Corporation

Georgia Greenspace Program

Georgia Lakes Society

Georgia Municipal Association

Georgia Power Company

Georgia Transmission Corporation

GRTA Board Member

Gulf Power

Gwinnett County Homeowner

Habersham EMC

J-2


EPRI – GTC


Henry County Development Authority

Henry County for Quality Growth

Historic Preservation Division

Home Builders Association of Georgia

HOPE (Homeowners Opposing Powerline Encroachment)

Jacksonville Electric Authority

Lake Allatoona Preservation Authority

Laurens County Commissioner

MEAG

Metro Atlanta Chamber of Commerce

Minnesota Power

Mississippi Power Company

Nashville Electric Service

New Horizon Electric Cooperative Greenville, SC

North Carolina Electric Membership Corp.

North Carolina Electric Service

NPS, Chattahoochee River NRA

PATH

Photo Science, Inc

Progress Energy Carolinas

Progress Energy Florida

Public Service Company of New Mexico

Reliant Energy

Rural Utilities Service

Santee Cooper

Savannah Electric and Gas

Sawnee EMC

Seminole Electric Cooperative

SHPO

Sierra Club

Society of American Foresters Southeastern Society

South Carolina Electric and Gas

South Carolina Public Service Authority

South Georgia RDC

South Mississippi Electric Power Assoc.

Southeast Watershed Research Laboratory

Southern Alliance for Clean Energy

J-3


EPRI – GTC


SW Georgia RDC

Tennessee Valley Authority

The Georgia Conservancy

The Nature Conservancy

The Nature Conservancy (Georgia Chapter)

Trust for Public Lands

U.S. Army Corps of Engineers

U.S. Fish and Wildlife Service

U.S. Forest Service

United Peachtree Corners Civic Association

University of Georgia

Wisconsin Public Service Corporation

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K SUMMARY OF SURVEY RESPONSES FROM THE ELECTRIC UTILITY STAKEHOLDER WORKSHOP

Electric Utility Workshop Participants*

Alabama Power Co (APC) 600 N 18th St Birmingham, AL 35291-0782

American Transmission Company, LLC (ATC) P.O. Box 47 Waukesha, WI 53187-0047

Center Point Energy (CPE) P.O. Box 1700 Houston, TX 77251-1700

Center Point Energy (CPE) P.O. Box 1700 Houston, TX 77251-1700

Florida Power & Light Co. (FPL) P.O. Box 14000 (PDP-JB) Juno Beach, FL 33408

Framatome – ANP (FRA) 400 S. Tyron St, Suite 2100 WC22K Charlotte, NC 28285

Georgia Power Company (GPC) 241 Ralph McGill Blvd, Bin 10151 Atlanta, GA 30308-3374

MEAG Power (MEA) 1470 Riveredge Pkwy NW Atlanta, GA 30062

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Summary of Survey Responses from the Electric Utility Stakeholder Workshop

Wesley Allen Nashville Electric Service (NES) 1214 Church St Nashville, TN 37203

Nashville Electric Service (NES) 1214 Church St Nashville, TN 37203



New Horizon Electric Coop (NHE) P.O. Box 1169 Laurens, SC 29360

New Horizon Electric Coop (NHE) P.O. Box 1169 Laurens, SC 29360

Rural Utilities Service (RUS) 1400 Independence Ave. SW Stop 1571 Washington, DC 20250

SCE & G (SCE) Mail Code 030 Columbia, SC 29218

* When more than one person represented a company, there is more than one response coded to that company. If the representative did not respond to any or all questions, there is no response in this summary.

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Questionnaire Responses

What is your experience with GIS technology?

1=Low, 2=L/M, 3=Moderate, 4=M/H, 5=High

APC 2

ATC 4

CPE 1

CPE 1

FPL 3

FRA 5

GPC 5

MEA 4

NES 3

NES 1

NES 3

NES 4

NHE 4

NHE 1

RUS 1

SCE 3

How many years of GIS experience do you have?

None, 1, 2 to 5 or >5

APC 0

ATC 2-5

CPE 0

CPE 2-5

FPL 2-5

FRA >5

GPC >5

MEA >5

NES 2-5

NES 1

NES 2-5

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NES 2-5

NHE >5

NHE 0

RUS 0

SCE 2-5

Does your organization use GIS technology in route selection?

Yes or No

APC No

ATC Yes

CPE Yes

CPE Yes

FPL Yes

FRA Yes

GPC Yes

MEA Yes

NES Yes

NES Yes

NES Yes

NES Yes

NHE Yes

NHE Yes

RUS Yes

SCE Yes

If YES, what GIS system(s)is used?

ATC ARC/Info

CPE Our transmission system is placed in GIS & our consultant uses GIS to some extent in line routing.

CPE Not sure. Survey & Mapping department GIS group is responsible for in house production. Consultants are responsible for other.

FPL Varies – we use multiple consultants for line route siting studies.

FRA ERDAS, ArcMAP, SPAHS, AutoCAD MAP

MEA No formal system, but GIS info assembled & analyzed by engineers & land personnel for relevance & general use in routing & siting.

NES ESRI ARC 8.3

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NES ARCVIEW

NES ARCVIEW

NES ARCVIEW/ARCINFO

NHE The process is done through an outside source - Framatome.

NHE We use Framatome ANP, DE&S to site out lines.

RUS Just starting to use GIS. Don’t know what system RUS is training on.

SCE Work in this area is outsourced, generally to Framatome.

If YES, describe how GIS is used (e.g., base mapping, siting team reference, manual map analysis, automated routing selection, presentations etc.)?

ATC Currently base mapping, siting team reference, manual map analysis, presentation, constraints identification, alternatives comparison, permitting & licensing applications, etc. – NOT automated route (C/L) selection yet. Also used for maintenance activities. access routes, restrictions, etc.)

CPE Base mapping, presentations

CPE Base mapping, presentations to public

FRA Base mapping, route analysis, presentations

FPL Base mapping, supplementary manual mapping efforts, presentation materials.

GPC All of the above

MEA Mapping, manual map analysis

NES Base mapping, presentations, manual map analysis

NES Base mapping, siting team reference, presentations, property ownership identification, zoning info, land use

NES Land base maps, aerials & land use & other geographic info is currently available on our GIS system

RUS Base mapping as I understand

SCE Used to depict factors such as view sheds, wetlands, etc.

Based on the discussions and your experience, how would you rank the general approach used in EPRI-GTC siting methodology?


APC 2

ATC 4

CPE 4

CPE 5

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FPL 5

FRA 3

GPC 4

MEA 4

NES 3

NES 5

NES 4

NHE 4

NHE 5

RUS 5

SCE 5

How would you rank your understanding of the basic procedures used in EPRI-GTC siting methodology?


APC 4

ATC 4

CPE 4

CPE 5

FPL 5

FRA 4

GPC 4

MEA 5

NES 4

NES 5

NES 4

NES 4

NHE 5

NHE 4

RUS 4

SCE 5

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Based on your experiences, what is the likelihood that your organization would adopt the EPRI-GTC or similar GIS-based siting methodology?


APC 2

ATC 4

CPE 1

FPL 4

FRA 2

GPC 3

MEA 4

NES 2

NES 3

NES 3

NHE 2

NHE 3

RUS 1

SCE 3

In your own opinion what is the major strength(s) of the EPRI-GTC siting approach?

APC Identifying study area.

ATC Transparency to general public – helps remove the concern that routing was arbitrary or didn’t consider the issues that the affected individuals find important.

CPE It provides a kind of transparency to the line routing process.

CPE approach is :open book” and explainable to the public.

FPL Very data driven process. Very comprehensive process. Consistency in application. Eliminates arbitrary study area boundaries.

FRA Effort that has gone into establishing weights.

GPC 1) Major strength is in selecting study routes. 2) Establishes a structured method.

MEA provides objective and consistent approach to siting.

NES Mathematical model that is quantitative and is a process that could be defendable.

NES 3 corridor models.

NES We could definitely use the methodology to limit the amount of public involvement we currently incorporate. Identifying the macro corridors based on engineering/env. & other rating factors before going to the public – narrowing the study area ahead of time.

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NES An organized approach that is a very good start to creating some “Industry Standards” as it relates to line siting. Also the way the software is flexible enough to handle several approaches.

NHE It provides a platform or standard to use on all siting projects.

NHE Considers almost all issues that need to be considered in siting a line.

RUS It’s scientific, objective & provides a solid basis for decision making.

SCE The science/math behind the approach is very sound. I think factors, categories, weightings etc. will be regionally specific, if not, site specific.

In your own opinion what is the major weakness(es) of the EPRI-GTC siting approach?

APC Too many exceptions, each project is different. Un-tested in court in Alabama; how do explain the results in court?

ATC I think the general model is good, but the Model would need to be customized to reflect regional differences in values and regulatory requirements/guidelines. We also strongly believe in having much more public involvement during our route (C/L) development and through the public hearings on our projects.

CPE Cost may not be emphasized enough.

FPL Mathematics (Delphi Process) could be overwhelming to non-utility stakeholders. Subjectivity of weighting process.

FRA Exclusion of major parts of the study area, final route evaluation.

GPC 1) Unknowns about the weight factors of different aspects. 2) Public support. 3) Political support or approval. 4) How do you get the public involved. 5) Process must be supported by the courts.

MEA It doesn’t consider “politics” (but then, how would you factor politics into an objective procedure?).

NES Not enough public input as to ranking or weighting of factors/critical elements. Public input will probably be process defined by utility.

NES As it exists, it is customized for state of Georgia. Obviously, it can be tailored to other areas.

NES Don’t know a better way to do it, but obtaining and loading criteria will be a major problem. Criteria could vary from urban to rural areas or even between similar urban areas.

NHE It appears that some cost issues are not taken into account such as access roads, property values etc., but other than that the system appears to have a strong platform.

RUS I don’t see any major weakness. I think it’s a good approach to siting transmission lines.

SCE Lack of on-going public involvement. Maybe the GTC web site does a good job getting info out to the public, but I believe that providing the opportunity for on-going public involvement will prove to be necessary. (Note: Not all projects need a sting study.)

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Based on your experiences, do you think your Organization would likely support general industry/region-wide guidelines for GIS-based Transmission line siting?

Yes or No ?

APC No

ATC No, I can see a need for at least variants of the model just in the area we serve, urban (high density), rural-ag, & a suburban/semi rural areas due to differing values/restrictions in each area.

CPE Yes

CPE Yes

FPL Maybe, can’t answer for others in Florida.

FRA Yes

GPC Unknown at this time

MEA Yes

NES Not sure

NES Yes

NES No, Our board has “adopted” a citizen’s advisory committee methodology that is working very well for us; however, see my answer to #4 above.

NES Yes

NHE Yes

NHE Yes

RUS Yes

SCE Yes, it would take some selling, but possible

If YES, do you think your Organization would likely be involved in the guidelines?

Yes or No ?

ATC Yes

CPE Yes

CPE Yes

FRA No

MEA Yes

NES Yes

NHE Yes

NHE Yes

RUS No

SCE Yes

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One key objective of the overall EPRI-GTC siting methodology is to develop a good process for identifying a proposed transmission route that is comprehendible, objective, comprehensive consistent, quantitative and defendable.

Do you think we are making progress?

1=Strongly Disagree, 2=Disagree, 3=Neutral, 4=Agree, 5=Strongly agree

APC 4

ATC 4

CPE 5

CPE 5

FPL 5

FRA 5

GPC 4

MEA 4

NES 4

NES 5

NES 5

NES 4

NHE 4

NHE 5

RUS 5

SCE 1

Please comment on strengths/weaknesses of the overall procedure:

APC Good progress in defining Study Area. The program can not replace good judgment.

ATC Transparency & understandability to the affected public.

CPE The scientific approach used is more defensible than a more subjective approach. In CenterPoint & other Texas utilities, we are required to have public forums which is not emphasized in this process.

CPE I strongly agree that this methodology provides a consistent, objective approach. It is somewhat different from the process currently employed by our consultant but many of the components are the same or similar. Individual land owner input is lacking, which may be problematic in Texas because the Texas PUC has emphasized landowner education and involvement in the routing process.

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FPL Strengths – Data driven, objective & comprehensive. Weaknesses – Process created & factor weighting done by expert panels – lay people may not “buy into” such an academic/computer based process (recall discussion on gaming the process.)

FRA Strength: Impressed with work that has gone into developing criteria/weights. Weakness: Final Route assessment.

GPC The overall concept has a lot of possibilities can we get buy-in from public, politicians and courts.

MEA Appears overall to be a non-biased approach to siting. However, in the end, final results must be determined by engineers or routing team. A weakness may be that there is not enough public involvement in the process.

NES See #4

NES It may be more complex than the general public (including regulators) can understand.

NES Good documentation regarding decision making rationale.

NES As mentioned before obtaining good criteria that is properly loaded based on a well balanced and represented cross section of stakeholders.

NHE Weakness- limiting community input and feedback.

SCE Again, I think that public involvement in some format, or other, is necessary if for no other reason, to avoid a legitimate challenge, late in the process, that the property owner, or a community has been blind-sided.

A critical element of the EPRI-GTC process is Criteria Selection involving a team of transmission line siting experts and GIS specialists who identify map criteria (exclusion and preference maps) and structure the routing model to unique circumstances in various regions.

Do you think that works?


ATC 4

CPE 4

CPE 4

FPL 4

FRA 5

GPC 4

MEA 5

NES 3

NES 5

NES 4

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NHE 4

NHE 5

RUS 4

SCE 4

Is there a better alternative for establishing site selection criteria?

ATC I think that the criteria needs to be reviewed confirmed for different project settings but I think this is a good starting point.

CPE Try to get as broad a base of stakeholders input as possible.

FPL Probably not.

NES Appointed stakeholders in community affected by proposed power line.

NES No

NES No, as long as there is flexibility when project-specific issues present.

NES Not sure – no suggestions

NHE In special situations, I feel that it is necessary to get input from the general public on the criteria selection.

SCE Not sure.

Please comment on strengths/weaknesses of the Criteria Selection procedure:

APC I think the experts in the industry should route the line taking into account all aspects & impacts (environnemental, maintenance etc.) I don’t think you want the public or government routing your lines. I think if your company uses good discretion and judgment then most property owners understand. You always have a few that will challenge your judgment.

ATC The criteria may change (or their relative importance) from project area to project area. It will be more useful & defensible if/when it has been applied to a number of projects and a track record is developed that supports the model results.

FPL Some criteria are more “pertinent” on projects than others; each project probably warrants a case-by-case analysis to establish appropriate criteria.

NES To develop study area, or macro corridors would agree that criteria selected by team of siting experts; disagree that same team develop criteria for individual corridor or criteria for selecting a route.

NES It is good to have the criteria specific to each model type.

NES Have to be careful in selecting your team.

NES Criteria selection is good as long as it is understood to be used as a guideline that should be tweaked based on project location.

NHE Weakness – adjust based on individual projects

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SCE The selection of factors and categories could be up to debate. But as a methodology is used and developed over many projects, the methodology will develop an inherent strength and will eventually be viewed as a credible process.

Underlying the EPRI-GTC approach is the Delphi procedure involving iterative calibration and feedback of group participants for calibrating the preference maps used in the routing model.

Do you think that the Delphi procedure works?


ATC 4

CPE 4

CPE 4

FPL 4

GPC 4

MEA 4

NES 4

NES 4

NES 4

NES 5

NHE 5

NHE 5

RUS 4

SCE 4

Please comment on strengths/weaknesses of the Delphi procedure:

ATC The iterative nature of the scoring is important.

FPL I like its detail and thoroughness. I think it would be difficult for non-experts to understand it if used infrequently. We have used a simpler pair-wise comparison of factors.

GPC It provides a satisfactory approach.

MEA As became evident during the process, it can be swayed by one group with particularly strong opinions.

NES May depend on scope <distance> of project.

NES Absolutely good approach.

NHE Results are only as good as the knowledge of each voter on the subject area.

SCE So long as diversity of participants is evident, I think the process is defendable

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Another tool for refining the model is the AHP procedure (Analytical Hierarchy Process) involving pair-wise comparisons of routing criteria. Is it a good process for weighting the relative importance of the preference maps?

Do you think that the AHP procedure works?


ATC 4

CPE 4

CPE 4

FPL 4

GPC 3

MEA 3

NES 4

NES 4

NES 4

NHE 5

NHE 5

RUS 4

SCE 3

Please comment on strengths/weaknesses of the AHP procedure:

ATC I’d be interested in seeing how the AHP ranking scores would vary between the publics in rural vs. urban project settings just to quantify the variability.

FPL I’m a fan of a pair-wise comparison process. Routing decisions have to be made by making a balancing of factors. Sensitivity analyses are interesting to perform as well.

GPC Depends on the one doing the comparisons.

NES See 7.

NES Procedure works.

NHE It provides a fair result based on average results from groups of individuals.

SCE Have not used this – no comment/opinion.

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The EPRI-GTC methodology should develop Alternative Routes (a.k.a. Most Preferred Path; Least Cost Path) involving route optimization based on exclusion maps and calibrated/weighted preference maps, Macro study area and alternative routes?

Do you think that this is a good process for identifying the


APC 4

ATC 5

CPE 4

CPE 4

FPL 4

GPC 4

MEA 4

NES 4

NES 4

NES 4

NES 4

NHE 5

NHE 5

RUS 4

SCE 4

Please comment on strengths/weaknesses of the Alternative Routes procedure:

APC Alternate routes always should be considered. CPE Approach is very objective, but does not take individual landowner input into

consideration. I know this has more to do with selecting a preferred route. FPL Weighting/calibrating drives the alternative routes subject to sensitivity analysis.

Here is the stage where many of the mgt participants indicated that they bring in multi-disciplinary judgment from siting professionals to identify the alternate routes (and ultimately select the preferred route.)

GPC This is the strength of the process. NES I like the fact that the model can evaluate “hundreds/thousands” of route/segment

options that a human may overlook due to lack of time or mental fatigue. May identify and option that otherwise would have been overlooked.

NES This procedure could help in benefit/cost analysis. For instance can you justify the Preferred Route if it cost 50% more than the Least Cost Path.

RUS Consideration of alternative routes demonstrates that the selection of a preferred route was ultimately made by a comparison of 2 or more routes with similar values.

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Do you think The Preferred Route procedure involving route segment evaluation and siting team judgment in manually editing/connecting segments is a good process for identifying the best routes?


APC 3

ATC 4

CPE 4

CPE 4

FRA 4

GPC 4

MEA 5

NES 2

NES 4

NES 5

NES 4

NHE 5

NHE 4

RUS 3

SCE 4

Please comment on strengths/weaknesses of the Preferred Route procedure:

ATC Based on WI. Regs – our PSCW is the group that ultimately chooses the “preferred route.”

CPE It would be almost impossible to do this step by automation because of landowner issues.

FPL Strengths – at some point, professional judgment has to be applied to data. Weakness – same as of strength. Naysayers can argue that the application of professional judgement can be “arbitrary”.

MEA I think this is a necessary step in getting to a preferred route.

NES Should include community input into final route selection.

NES I think it is very important for the design team to “touch/feel” the route segments. Also, the team may be able to evaluate social & political issues that the model could not consider.

SCE I guess the weakness would be the injection of the human element into a process that is a computer method based up to that point. But I don’t know how else you arrive at a final center line.

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Does your organization have a formal procedure that utilizes public Input into the siting process?

Yes or No

APC No

ATC Yes

CPE Yes

CPE Yes

FPL Yes

FRA Yes

GPC No

MEA No

NES Yes

NES Yes

NES Yes

NES Yes

NHE Yes

NHE Yes

RUS Yes

SCE Yes

If YES, briefly describe the process and how it might fit into a GIS-based siting process.

ATC We use a variety of methods – scoping meetings, public info meetings, newsletters, individual group meetings etc., depending on the project.

CPE If 25 or more landowners are affected, we hold one or more public meetings where we discuss need, engineering/construction, environmental, ROW requirements, EMF and ask attendees to respond to a questionnaire.

CPE Public input is facilitated by at least one open house where route segments & other information is presented at stations and a questionnaire is made available. Land owners are invited by direct mailing & the public is notified by newspaper notice approx. 2 weeks prior to open house.

FPL Public input is very important for a number of reasons:

1. Provide appropriate notice for projects.

2. Obtain local specific input for projects.

3. Validate criteria of study; also maybe relative importance/weighting of criteria.

MEA Nothing formal – it depends on where the line is located (rural vs. urban), length, public official request, etc.

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NES Form community group of affected/impacted stake holders from study area. Ask them to evaluate criteria/route/weight.

NES 1) Need defined by planning 2) Management meets with local gov’t leaders 3) Local gov’t selects members of a citizens advisory committee (CAC) 4) Hold meetings with CAC to discuss engineering design, project need and identify routing factors (e.g. proximity to houses, etc.); Hold public open house; Hold follow-up CAC to weight factors for alternative routes; Run analysis to rank routes; CAC recommends a preferred route 6) N.E.S. Board considers route for approval.

NES Workshops & formation of a CAC – Citizens Advisory committee. Representatives are usually politicians, business-folks & representatives from special interest groups.

NHE Public meetings ask for input.

NHE Community meetings (1 or 2); 1st at very beginning when no corridors have been selected & 2nd after several alternate routes have been selected, prior to selecting the preferred route.

SCE We do research to depict various factors on a map or maps. We use an initial public meeting to explain the project, the need, and to gather public input. Alternative routes are identified and we hold another public meeting to present and get comment on the alternative routes.

Does your organization have a formal procedure for information dissemination and public relations involved with siting?

Yes or No

APC No

ATC Yes

CPE Yes

CPE Yes

FPL Yes

FRA Yes

GPC Yes

MEA No

NES Yes

NES Yes

NES Yes

NHE Yes

NHE Yes

RUS No

SCE Yes

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If YES, briefly describe the process and how it might fit into a GIS-based siting process.

ATC Again project specific in scope, but we try to be open and responsive & share information as it is developed, so we may use GIS maps showing constraints/opportunities/possible routes in newsletters or discussions with elected officials.

CPE The PUCT requires newspaper notices in major newspapers & letters to landowners crossed or within distance criteria (300’ for lines below 345 KV & 500’ for 345KV +)

CPE There are public notice procedures required by the state which mandate direct mail notices and newspaper notices to specific groups – landowners, city/county officials, other utilities.

FPL Mass mailings, news releases & open house meetings are our typical mechanisms. We are integrating GIS-based products into these efforts more and more. We have a long way to go and much room for improvement in this area.

GPC We develop a communication plan for each major project. The plan includes information about the project, political contacts and general information about the need and route of the project.

MEA See above

NES Develop communication plan as to target audience and message.

NES (1) Corp. communications dept. sends info to customers in study area includes invitations to open house; Also address media inquiries regarding project; (2) Corp. affairs dept. addresses political concerns – open dialogue with local gov’t leaders etc.

NES We have a Public Relations Dept.

NHE Letters are sent inviting all property owners to attend the public meeting. Newspaper articles are also issued.

NHE Community meetings (1 or 2); 1st at very beginning when no corridors have been selected & 2nd after several alternate routes have been selected, prior to selecting the preferred route.

SCE We meet with elected officials, including the PSC ahead of time. Rotary clubs, civic groups etc. might also be presented to.

Any additional comments?

APC If you use this program for one line, do you have to on all your lines (to be consistent? For legal reasons?) Different state laws dictate your approach to routing a line.

FPL This model lays a great foundation for line route siting. Customization will have to occur to account for regional differences (criteria weightings). The science is extraordinary – you are to be commended for a job well done. One other thought: the process sets a good foundation for establishing the parameters for a routing study to the public.

K-19


MEA Many thanks to the “GTC team” for undertaking this much needed effort!

NES Good meeting, I think model has good potential, may need refinement as to targeting urban vs. rural application. Urban application may need additional input.

NES To date, we have gone through 5 CAC Processes; board has approved each preferred route.

SCE I don’t think that in the near term, say next 5 – 10 years, that public involvement can be eliminated.

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L LOCATIONS OF ONLINE REFERENCE MATERIALS

References to Related Online Materials

Least Cost Path Algorithm: The online book Map Analysis, Topic 19, “Optimal Paths and Routing” by Joseph K. Berry presents a detailed discussion on the Least Cost Path procedure for GIS-based identifying optimal routes and corridors. See:

www.innovativegis.com/basis/MapAnalysis/Default.html

Calibrating and Weighting Map Criteria: Supplemental discussion and an Excel worksheet demonstrating the calculations are posted at:

www.innovativegis.com/basis/

Select “Column Supplements” for Beyond Mapping, September, 2003.

• Delphi and AHP Worksheet link contains Excel worksheet templates for applying the Delphi Process for calibrating and the Analytical Hierarchy Process (AHP) for weighting as discussed in this sub-topic (Geo World, September 2003).

• Delphi Supplemental Discussion link describes the application of the Delphi Process for calibrating map layers in GIS suitability modeling.

• AHP Supplemental Discussion link describes the application of AHP for weighting map layers in GIS suitability modeling.

EPRI-GTC Siting Model: The EPRI-GTC Overhead Electric Transmission Line Siting Methodology is discussed in detail in a Geo World feature article, April 2004, posted online in the Geo World archives at:

www.geoplace.com/gw/2004/0404/0404pwr.asp

L-1


http://www.innovativegis.com/basis/

http://www.innovativegis.com/basis/Supplements/BM_Sep_03/T39_3.xls

http://www.innovativegis.com/basis/Supplements/BM_Sep_03/T39_3_DELPHIsupplement.htm

http://www.innovativegis.com/basis/Supplements/BM_Sep_03/T39_3_AHPsupplement.htm

http://www.geoplace.com/gw/2004/0404/0404pwr.asp

M APPENDIX M

Articles, Presentations and Conferences Items Related to the EPRI-GTC Siting Methodology

Since 2001, the Environmental Sector of EPRI has made the Overhead Electric Transmission Line Siting Methodology a priority research project. By funding this project through one of their multi-year research programs, the EPRI-GTC Tailored Collaboration Project provided EPRI, GTC and other stakeholders with an opportunity to work with some of the foremost GIS experts.

Status reports were given on the project at the Fall 2003 and Winter 2004 EPRI Advisory Council meetings. In addition, Photo Science, Inc. and Dr. Joseph Berry presented the results of this research at various conferences. EPRI and GTC have made presentations at several conferences and workshops and published articles in trade and academic publications.

GeoTech

A paper on the Delphi and AHP aspects of the project were presented at GeoTech, Toronto, Ontario, Canada, March 28-31, 2004 entitled “Optimal Path Analysis and Corridor Routing: Infusing Stakeholder Perspective in Calibrating and Weighting of Model Criteria.”

[See http://www.innovativegis.com/basis/present/GeoTec04/GIS04_Routing.htm for an online copy of the paper]

GeoWorld Article

This methodology is being introduced to other forums beyond the electric industry. In April 2004 Volume 17, No. 4, of GeoWorld, a paper entitled “A Consensus Method Finds Preferred Routing,” was published, describing the geo-technology used in the EPRI-GTC Overhead Electric Transmission Line Siting Methodology.

Transmission & Distribution World Article

This EPRI-GTC study was the subject of a six-page feature story in the February 2005 issue Transmission and Distribution World Magazine. (GIS-Based Line-Siting Methodology; Georgia Transmission collaborates with EPRI to develop a standardized, defensible siting strategy. Barry Dillon.) The article is available at magazine’s archive, www.tdworld.com.

M-1

http://www.innovativegis.com/basis/present/GeoTec04/GIS04_Routing.htm

http://www.tdworld.com/

Appendix M

GTC News Releases

In 2004, information about the EPRI-GTC Overhead Electric Transmission Line Siting Methodology was sent to newspapers in Georgia and industry trade publications. Another news release will be issued when this report is made available to the public.

California Energy Commission Presentation

On April 21, 2004, EPRI was invited to present the Overhead Transmission Line Siting Methodology to staff from the California Energy Commission.

Environmental Concerns on Rights-of-Way Management Symposium

GTC’s abstracts have been accepted by the Symposium: one for a presentation and the other for an interactive workshop.

Conference Presentations

The EPRI-GTC Overhead Electric Transmission Line Siting Methodology project was presented at the 2004 Transmission and Distribution World Expo, the 2004 Geospatial Information and Technology International Conference, the 2004 GIS for the Oil and Gas Industry Conference and the 2004 Environmental Systems Research Institute International Conference.

A Consensus Method Finds Preferred Routing

By Jesse Glasgow, Steve French, Paul Zwick, Liz Kramer, Steve Richardson and Joseph K. Berry

Glasgow is Georgia Transmission Corp. operations manager, Photo Science Inc.; e-mail: [email protected] is director, Georgia Tech Center for GIS; e-mail: [email protected]. Zwick is chair, Department of Urban and Regional Planning, University of Florida; e-mail: [email protected]. Kramer is a research scientist, Institute of Ecology, University of Georgia; e-mail: [email protected]. Richardson is a member, Van Ness Feldman, Attorneys at Law; e-mail: [email protected]. Berry is the Keck Scholar in Geosciences, University of Denver; e-mail: [email protected].

Determining the best route through an area is one of the oldest spatial problems. Meandering animal tracks evolved into a wagon trail that became a small road and ultimately a superhighway. Although this empirical metamorphosis has historical precedent, contemporary routing problems involve resolving complex interactions of engineering, environmental and social concerns.

Previously, electric transmission line siting required thousands of hours around paper maps, sketching hundreds of possible paths, and then assessing feasibility by “eyeballing” the best route. The tools of the trade were a straightedge and professional experience. This manual

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Appendix M

approach capitalizes on expert interpretation and judgment, but it’s often criticized as a closed process that lacks a defendable procedure and fails to engage the perspectives of external stakeholders in what constitutes a preferred route.

Selection of preferred routes – and the prerequisite choice of broad, generalized routing called corridors – is a growing source of public controversy and regulatory scrutiny throughout the United States. The electric industry has responded with many initiatives, including a new GIS-based system that could radically change the way electric utilities evaluate and select transmission line routes.

The GTC/EPRI Project

The Electric Power Research Institute (EPRI) and Georgia Transmission Corp. (GTC) are developing a prototype GIS tool that integrates satellite imagery with layers of statewide GIS datasets. In addition, standard business process and site-selection methods are being created in the hopes of developing new industry standards. The GTC/EPRI Transmission Line Siting Methodology Research Project is an example of how geotechnology can be used to improve productivity and help address a critical industry-wide challenge.

GTC, provider of electric transmission for 39 electric cooperatives, is sponsoring the EPRI project that’s being developed with the participation of utilities, government agencies, elected officials and community stakeholders from Georgia and neighboring states. Transmission lines carry bulk power from generating facilities to local distribution systems that, in turn, carry electricity to homes and businesses. EPRI is a nonprofit energy research consortium that provides science- and technology-based solutions for the world’s energy industry.

GIS Needed

Although the exact set of factors to be considered may change in different parts of the country, most transmission line routing requires attention to environmental (e.g., wetlands and flood plains), community (e.g., existing neighborhoods and historic sites) and engineering (e.g., slope and access) factors.

GISs are explicitly designed to manage and combine large amounts of spatially distributed data. In fact, transmission line siting can be thought of as a special case of land suitability analysis that drove much of GIS’ early development.

Authority to use land is critical for electric transmission lines. GIS siting methodology attempts to use sound science and technology to expedite approvals, getting projects built on time and at lower costs. The National Environmental Policy Act (NEPA) and best-management practices require documentation that constrains project siting. The purpose of documentation isn’t to generate reams of paperwork, but to foster excellent siting decisions. However, the site selection process can take years and millions of dollars, and it often disenfranchises affected parties.

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The documentation process doesn’t mandate a standard routing procedure or particular substantive results. It does require, however, a thorough study of consequences of proposed actions. It requires proponents to look at the effects of alternatives as well as articulate satisfactory explanations, including rational connections among facts found and choices made.

Adopting GIS methodology streamlines the decision documentation process and promotes consistent, quantitative and defensible “standards” for examining data, articulating explanations and demonstrating connections among facts and choices. GIS siting procedures help proactive companies implement strategies that anticipate critical land-use issues affecting transmission line placement.

Approach Overview

The EPRI Transmission Line Siting Methodology is analogous to a funnel into which geographic information is input and a preferred route emerges (see Figure M-1). Geographic information is calibrated and analyzed in phases with increasing resolution. Proceeding down and through the funnel, the suitability analysis process continuously refines the corridor(s) most suitable for transmission line construction.

Figure M-1 The Route-Selection Process can be Conceptualized as a Funnel that Successively Refines Potential Locations for Siting a Transmission Line

For example, at the macro corridor level, statewide data based on 30-meter satellite imagery are used to identify the study area, whereas at the alternate-routes step, four-meter grid cells are used to capture highly resolved information such as the position of buildings to identify preferred routes.

Geographic features are organized by scale (resolution) and discipline. To rank individual features by suitability and weight feature groups by relative importance, internal and external stakeholder input is gathered using the “Delphi Process” that builds consensus as well as the “Analytical Hierarchical Process” (AHP) for pair-wise comparison. Four separate suitability surfaces are created, placing more decision-making preference on the following:

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1. Optimizing engineering considerations

2. Built environment consequences

3. Natural environment impacts

4. Averages of preference factors

After the four preference surfaces and a map of areas to avoid (e.g., airports, large water bodies) are available, Photo Science Inc.’s Corridor Analyst software is used to measure the accumulative preference for all possible routes connecting the endpoints. The total accumulative preference surface from the start and endpoints is classified to delineate the top 3 percent of all possible routes. The process results in four alternative corridors reflecting the routing preferences contained in the suitability surfaces (see Figure M-2).

Figure M-2 Alternate Routes are Generated by Evaluating the Siting Model Using Weights Derived from Different Group Perspectives

Adding Data

Within the alternative corridors, additional data are gathered (e.g., buildings and property lines), and a team of routing experts define a network of alternative route segments for further evaluation (see Figure M-3). Statistics, such as acreage of wetlands affected, number of streams crossed, number of houses within close proximity, etc., are automatically generated for each of the alternate route segments.

Segments with connectivity are defined, and segment statistics are summed to create alternative route statistics. Based on spatial data and other factors, the siting team uses AHP pair-wise comparison to assign weights to the alternative routes, resulting in a relative ranking of each route alternative. The highest-ranking route identifies the preferred route corridor (see Figure M-4).

Detailed field surveys are conducted along the preferred route (collecting data using Global Positioning System, photogrammetry, light detection and ranging, and conventional surveying techniques) to map cultural, ecological, topographical and physical features. Engineers make slight centerline realignments and then design the final pole placements and construction estimates based on the information.

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Figure M-3 Within the Alternate Corridors, Additional Data are Gathered Such as Exact Building Locations from Aerial Photography

Figure M-4 A GIS-Generated Preferred Route is Adjusted as Necessary Based on Detailed Field Information and Site-Specific Construction Requirements

Input for determining the calibration and weighting of routing criteria was gathered from subsets of the stakeholders appropriate for the group’s focus, whether engineering, natural environment or built environment.

Preference values were assigned based on a standardized process predefined by the model-development team. For each of the engineering layers (slope, linear features and selected land uses), individual stakeholders valued each feature (from 1 to 9) for a range of opportunities. The value 1 indicated the most-preferred feature in the map layer, while 9 was assigned to the least preferred. For example, 0-15 percent slopes identified the best conditions, 15-30 percent was moderate, and greater than 30 percent identified the worst conditions.

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Appendix M

A modified Delphi Process was used to gain consensus for preference values. The values assigned by group participants to each category were averaged, and the standard deviation was calculated. If the deviation of the individual preference values for a particular feature was small, the group agreed that there was consensus and assigned the average preference value for the feature. If the deviation for a feature was large, the group proceeded to discuss the range of values and developed consensus through a sequence of re-evaluations.

Engineering Considerations

Those participating in the engineering analysis included engineers and scientists from utilities and state infrastructure agencies involved with site selection for transmission lines. The group was selected to provide specific knowledge regarding the collocation of power lines with other linear features, including transmission lines, roadways, railroads and other utilities.

After all the layer features had been evaluated, the selected preference values for all features were used to create a raster surface of preferences for the individual engineering layers. The AHP process was used to weight the map layers to reflect relative importance, and a weighted average was calculated to derive the overall engineering preference surface. This procedure for calibrating and weighting map criteria also was used for assessing the project effect on the natural and built environment Perspectives.

Natural Environment

Numerous federal and state laws such as the Endangered Species Act, the Clean Water Act, National Pollution Discharge Elimination System, and wetlands and riparian buffer regulations drive the selection of environmental criteria. Many of the rules require obtaining permits from regulatory agencies and often require mitigation of impacts. Additional environmental criteria have been established as part of GTC’s business policies, such as avoiding lands with private conservation easements as well as state and federally owned lands.

The natural environment stakeholder group included members of the regulator community such as the U.S. Army Corps of Engineers, U.S. Environmental Protection Division and Georgia Department of Natural Resources as well as local representatives from non-government organizations in the environmental community.

For the most part, the group reached consensus for factors that had good regulatory foundations. For criteria without regulatory rules, such as public-land issues and other land-use categories, it was more difficult to reach group agreement. A few of the factors initially considered by the environmental group, such as intensive agriculture and small water-retention ponds, turned out to be better considered by the engineering or built groups.

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Built Environment

NEPA and various state-level policies require consideration of aspects of the built environment, such as historic sites. However, the most important obstacle to siting new transmission lines has been opposition from homeowner and community groups. An effective transmission line siting method can’t be blind to community and neighborhood preferences.

The built environment stakeholder group provided input on community concerns for appropriate calibration and weighting of preference surfaces. The group included professionals in historic planning, regional planning, community development and local government as well as representatives from homeowner and neighborhood organizations. The stakeholders first calibrated the scale for each measure and then determined the importance weighting for the following built environment layers: proximity to buildings, proximity to cultural resources, building density, proximity to proposed development, visual vulnerability and proximity to excluded areas.

Actual buildings were handled as avoidance areas, and a fairly high level of consensus was reached. The same process was conducted with a group of utility professionals, and similar results were achieved.

Lessons Learned

In January 2004, a workshop was held with transmission line siting professionals from 10 utility companies. The professionals were asked to review and comment on the methodology described in this article. The GTC/EPRI methodology is generally similar to the processes that other utilities currently are using. All were using some type of GIS-based system, and most used a process that focused on more-detailed data as siting alternatives were narrowed.

Most utility representatives thought that this new methodology was more organized, comprehensive and consistent than their current practice, and most thought the methodology would produce consistent routing based on sound and documented science. Particular interest was expressed in the efficiency of the macro corridor analysis technique to guide the collection of successively more-detailed data.

Probably the most important difference among utilities was in how they handled public involvement. Some utilities ask stakeholders to identify criteria and weight them for each project; others develop alternative routes and ask stakeholders to select from that set; still others rely on an internal siting team with little involvement from the public.

Our experience found that asking citizen stakeholders to work directly with weights and criteria among group perspectives didn’t produce a viable model. Citizens tried to “game the system” in setting weights to favor their perspective, often producing unintended results. Our final approach combines the criteria and weights identified by citizen stakeholders with those identified by professionals. This process incorporates public opinion and professional experience to create a consistent model that can be used on a range of projects.

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Appendix M

In addition, we found that stakeholders often confused proximity measures with the feature itself. When stakeholders set large proximity zones around features they considered valuable, they would inadvertently force the route into other valuable areas. We also found that it was important to include data about land use in the model.

In an effort to reduce cost, the research team initially considered all buildings the same regardless of use. It became evident that it’s necessary to have the model distinguish among residential, commercial and industrial buildings. Most stakeholders considered residential buildings more sensitive than commercial and industrial structures, and the model needed to be able to resolve at least this crude level of land-use distinction.

GTC intends to apply the methodology for all future transmission projects. The structure and rigorous procedure is no substitute for the judgment, values or perspectives of the stakeholders, and it depends – more than ever – on the skill and experience of the professional staff involved.

The GTC/EPRI routing methodology provides a structure for infusing diverse perspectives into siting electric transmission lines. Traditional techniques rely on expertise and judgment that often seems to “mystify” the process by not clearly identifying the criteria used or how it was evaluated.

The GIS-based GTC/EPRI approach is an objective, consistent and comprehensive process that encourages multiple perspectives for generating alternative routes, and it thoroughly documents the decision process. The general approach is readily applicable to other siting applications of linear features such as pipelines and roads.

Note: For more information on routing and optimal path procedures, visit the Web at http://www.innovativegis.com/basis/MapAnalysis, select Topic 19, Routing and Optimal Paths. Links to further discussion of Delphi and AHP in calibrating and weighting GIS model criteria are included.

Georgia Transmission News Release

Community Groups Examine Transmission Line Siting Research GTC, EPRI Conduct Final Workshop and Begin Preparing Final Report

TUCKER, Ga. – More than 25 community stakeholder groups gathered here March 10 with Georgia Transmission Corporation (GTC) and the Electric Power Research Institute (EPRI) to evaluate a national transmission line siting research effort that promises to deliver a standard process for selecting transmission line corridors.

The meeting was the final of four workshops conducted as part of an effort to develop a standard geographic information system (GIS) tool and business processes for improving site selection. Called the EPRI Transmission Line Siting Methodology Research Project, it is scheduled to conclude in June with a supporting software program and report to the industry. Workshops were held with Georgia’s Integrated Transmission System (ITS) participants, government agencies, utilities, elected officials and community organizations from Georgia and neighboring states.

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http://www.innovativegis.com/basis/MapAnalysis

http://www.innovativegis.com/basis/MapAnalysis

Appendix M

The one-day March workshop featured an overview of a proposed siting method and the supporting software program. The method being evaluated was developed with these same groups at a workshop last year. Participants represented agribusiness, chambers of commerce, educators, regional development agencies, local governments, environmental and conservationist groups, homeowners and planners.

“Throughout the country, the Federal Energy Regulatory Commission, electric utilities and state regulatory agencies are under pressure to help the electric utility industry become more accountable in its site-selection processes,” said Bob Fox, GTC manager of Transmission Projects. “We believe the method we’ve developed with EPRI is impartial, consistent and addresses the relevant issues that participants said were most important.”

The proposed siting method includes identifying avoidance areas, calibrating and weighting siting criteria and developing potential transmission line corridors based on that information. The software program utilizes satellite imagery and GIS analysis to select macro corridors and create alternate routes. For GTC’s purposes, the weighting criteria are based upon input from external stakeholders and ITS members, which consist of GTC, Georgia Power Company, MEAG Power and the city of Dalton. The research was led by EPRI and Dr. Joseph Barry, University of Denver, Dr. Steven French, Georgia Institute of Technology, Dr. Elizabeth Kramer, University of Georgia and Dr. Paul Zwick, University of Florida.

“We have received excellent participation in this project with more than 200 stakeholders attending our workshops, and this has been key in the successful development of our methodology,” said John W. Goodrich-Mahoney, EPRI program manager. “We plan to keep stakeholders engaged and involved. Once we’ve tested the methodology in real-time for one-year, we will revisit its effectiveness with stakeholders for possible revisions.

GTC is a not-for-profit cooperative with more than $1 billion in assets, providing electric transmission service to 39 electric membership cooperatives throughout Georgia. EPRI is a nonprofit organization that manages global research, technology development and product implementation.

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© 2006 Electric Power Research Institute (EPRI), Inc. All rights reserved.Electric Power Research Institute and EPRI are registered service marks ofthe Electric Power Research Institute, Inc.

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Program:Rights-of-Way Environmental Issues in Siting, Development, and Management

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