)E/EIS-0159 FLATIRON - ERIE I 15KV' TRANSMISSION LINE Larimer. Boulder & Weld Counties. Colorado Draft Environmental Impact Statement u.s. Department of Energy Western Area Power Administration Loveland AreaOffice - Loveland. Colorado 1993 DRAFI' ENVIRONMENfAL IMPACT STATEMENT Flatiron-Erie ttS-kV Transmission Line Project Larimer, Weld and Boulder Counties Colorado U.S. DEPARTMENT OF ENERGY Western Area Power Administration Washington, D.C. 20585 May 1993 Table of Contents PAGE CHAPTER 1. SUMMARY ...................................•. 1.1 I.A PROJECT PURPOSE AND NEED. DESCRIPTI ON AND HISTORY ...... 1.1 I.B ALTERNATIVES INCLUDING THE PROPOSED ACTION ............ 1.2 I.C ANALYSIS OF STUDY AREA ENVIRONMENT AND DEVELOPMENT OF ALTERNATIVE ROUTES . .. .. .. 1 . 2 I.D ASSESSMENT OF THE IMPACTS OF THE PRIMARY ALTERNATIVE ROUTES ... 1.4 I.E COMPARISON OF THE PRIMARY ALTERNATIVE ROUTES .......•.. 1.4 I.F NO ACTION, ALTERNATIVE A ........................... .. 1 .5 I.G CONSERVATION OF ENERGY AND RENEWABLE RESOURCES . 1. 5 I.H ALTERNATIVE TRANSMISSION TECHNOLOGIES. 1.6 1.1 SYSTEMS ALTERNATIVES . 1.6 I.J AFFECTED ENVIRONMENT ............................... 1.6 I.K ENVIRONMENTAL CONSEQUENCES ......................... 1.9 CHAPTER 2. INTRODUCTION 2.A PURPOSE AND NEED .........•...............•..•.. 2.1 2.B PROJECT DESCRIPTION . ............................... 2.2 2.B.I The Proposed Action . • . • • . • . • • . • . .•... 2.2 2.B.2 Project Schedule ........................................ 2.2 2.B.3 Project Proponent ....................................•... 2.3 2.C PROJECT BACKGROUND AND HISTORY .........•.•...•....... 2.3 2.D RELATIONSHIP TO OTHER PROJECTS ....................... 2.5 2.E JURISDICTIONS WITH AUTHORIZING ACTIONS ....•.....•...... 2.5 2.F SCOPING PROCESS AND PUBLIC INVOLVEMENT ............... 2.5 the 2.F.I Public Involvement in Earlier Versions of Project................. 2.5 2.F.2 Seoping Meeting, Flatiron-Erie 115-kV Transmission Line Project ......... 2.7 2.F.3 Planning Meeting, Flatiron-Erie 115-k:V Transmission Line Project ......... 2.8 CHAPTER 3. ALTERNATIVES INCLUDING THE PROPOSED PROJECT 3.A ALTERNATIVE A: "NO ACTION" ........................... 3. 1 3. B CONSERVATION OF ENER GY AN D RENEWABLE ENER GY . .. .. .. .. 3. 1 3.C ALTERNATIVE TRANSMISSION TECHNOLO GIES .. .. .. .. 3. 2 3.C.l Conventional Overhead Alternating Current (AC) Transmission ........... 3. 2 3.C.2 Overhead Direct Current (DC) Transmission ....................... 3. 2 3.C .3 Underground Construction .................................. 3. 3 3. D ALTERNATIVE TRANSMISSION SYSTEMS ..................... 3. 5 3. D.1 System Alternative 1: The Existing and Proposed System, Uprate Existing Flatiron-Erie Line . .. .. .. .. .. .. .. .. 3. 5 3. D.2 System Alternative 2: Remove Portions of Flatiron-Erie Line Through Longmont, New Substation Connecting to PSCO System .. .. .. .. 3. 6 3. D.3 Alternatives Considered and Rejected. .. .. .. .. .. .. .. .. 3. 6 3. D.3.a System Alternative 3: Remove Portions of Flatiron-Erie Line ThroughLongmont, Build New Substation South of Longmont, Build New Connection to Longs Peak Substation ....... 3. 6 3. D.3.b System Alternative 4: Remove Portions of the Flatiron-Erie Line ThroughLongmont, Build New Connection to Lafayette Substation 3. 7 3. D.3.c System Alternative 5: Remove Portions of Flatiron-Erie Line Through Longmont, Build New Substation Southof Longmont with New Connections toLongs Peakand Lafayette Substations .. .. .. 3. 8 3. D.3.d System Alternative 6: Remove Portions of Flatiron-Erie Line Through Longmont . .. .. .. .. .. .. .. .. .. .. .. .. 3. 8 3. D.3.e System Alternative 7: Relocate the Flatiron-Erie Line Around Longmont 3. 8 3. D.3.f System Alternative 8: Relocate the Longmont Substation Outside the City .............. .. .. .. .. .. .. .. .. 3. 9 3.E ALTERNATIVE STRUCTURE TYPES . .. .. .. .. .. .. .. 3. 9 3.F ALTERNATIVE METHO DS OF CONSTRUCTION . .. .. .. .. .. .. 3. 10 3. G DESCRIPTION OF THE PRIMARY PROJECT ALTERNATIVES .. .. .. .. 3. 10 3. G.l Description of Alternative B, The Proposed Project Action: Uprate Existing Flatiron-Erie Transmission Line " . .. .. .. .. .. .. .. .. .. 3. 11 3. G.2 Design, Construction, Operation and Maintenance of Alternative B, The Proposed Action . .. .. .. .. .. .. .. .. .. .. .. .. .. 3. 12 3. G.2.a Project Specifications and Requirements . .. .. .. .. .. .. 3. 12 3. G.2.b Project Construction Activities . .. .. .. .. .. .. .. .. .. 3. 13 3. G.2.c Project Operation and Maintenance Activities .. .. .. .. .. .. 3. 13 3. G.2.d Standard/Committed Mitigation Measures ................... 3. 14 3. G.2.e Project Work at Substations and Taps .. .. .. .. .. .. .. .. 3. 17 3. G.3 Description of Alternative C. Construct Underground ThroughLongmont . 3. 17 ii 3.G.4 Design, Co nstruction, Operation and Maintenance of Alternative C ... ...... 3. 18 3.G.4.a Project Specifications and Requirements . 3. 18 3.G.4. b Project Co nstruction Activities . 3. 19 3.G.4.c Project Operation and Maintenance Activities . 3.20 3.G.4.d Standard Co mmitted Mitigatio n Measures ... ................ 3.2 1 3.G.4.e Project Work at Substations and Taps . 3.2 1 3.G.5 Descriptio n of Alternative D. Remove and Rero ute Po rtio ns of Existing Line ., 3.2 1 3.G.6 Design, Co nstruction, Operation and Maintenance of Alternative D .,. 3.22 3.G.6.a Project Specifications and Requirements .......... .... 3.23 3.G.6.b Project Co ns truction Activities . 3.24 3.G.6.c Project Operation and Maintenance Activities . 3.24 3.G.6.d Standard Co mmitted Mitigatio n Measures ................... 3.24 3.G.6.e Project Work at Substations and Taps . 3.24 3.G. 7 Co mparison of Primary Alternatives .................. .... ...... 3.25 CHAPTER 4. TIlE AFFECTED ENVIRONMENT 4.A STUDY AREA DEFINITION AND DESCRIPTION . 4.1 4.B ENVIRONMENTAL CATEGORIE S AND COMPONENTS ............. 4. 1 4.B. l Issues Identified As Not Significant and Not Requiring Detailed Study ....... 4.2 4.C EARTH RESOURCES AND HAZARDS .......... .......... ..... 4.2 4.C. l Potential Landslide Areas .............. ..................... 4.2 4.C.2 Sensitive So il/Slope Co nditions . 4.3 4.C.3 Floodplains ......... .................. ················· 4.3 4.C.4 Subsidence Areas .................. ...... .......... ...... 4.3 4. 0. WATER RESOURCES ............. ...................... 4.3 4. 0. 1 Ponds and Reservo irs . 4.3 4.D.2 Major Rivers and Streams . 4.4 4.E BIOLOGICAL RESOURCES . 4.4 4.E. l Major Po tential Wetlands ................ ........ ........ ... 4.4 4.E.2 Critical Plant Associations . 4.4 4.E.3 Rare Plants . 4.5 4.E. 4 Designated Critical Wildlife Habitat . 4.5 4.E.5 Waterfowl Production & Stopover Areas . 4.5 4.E.6 Prairie Dog To wns ......... ......... ............ .... ..... 4.6 4.E. 7 Go lden Eagle Nest Areas ................................ .. 4.6 4.E.8 Bald Eagle Use .................... ..................... 4.6 4.E.9 Heronries .. 4.6 4.E. I0 Mule Deer & Elk Winter Range . 4. 7 4.E. ll Natural Areas ....... .............. ..................... 4. 7 4.E. 12 Rare Small Mammal Locations . 4.7 4.E. 13 Colorado Rare Fish Habitat . 4. 7 4.E. 14 Rare Insect ... ........... ........ .................. '. 4.8 iii 4.F EXISTING LAND USE ...................•................ 4.8 4.F.1 Residential Land Uses ............................•........ 4.8 4.F.2 Retail/Office Land Use .................................... 4.8 4.F.3 Institutional Land Uses .................................... 4.8 4. F . 4 Industrial. Heavy Commercia] and Utilities Land Uses ........ ...... ............................. 4.9 4.F.5 Extractive Land Use ..................................... 4.9 4.F.6 Recreation and Open Space ................................. 4.9 4.F.7 Agricultural Land Uses ................................... 4.9 4.F.8 Air Transportation Uses ................................... 4.10 4.F.9 Telecommunications Facility Protection Zone ...................... 4.10 4.F.l0 Radio Tower Sites ..... ............... .•.................. 4.10 4.G EXISTING ELECTRICAL UTILITIES .........................• 4. 10 4.H PLANNED LAND USE ...................•.............•.. 4.11 4.H.1 Planned Residential Land Uses ............................... 4.11 4.H.2 Planned Commercial Land Use ............................... 4.11 4.H.3 Planned Institutional Land Use ............................... 4.11 4.H.4 Planned Industrial Land Use .............................. 4.11 4.H.5 Planned Public Recreation/Open Space .......................... 4.12 4.1 CULTURAL RESOURCES ................................. 4.12 4.1.1 Cultural Sites or Areas On or Officially Eligible for the NR HP ........... 4.12 4.1.2 Cultural Sites or Areas Potentially Eligible for the NR HP .............. 4.12 4.1.3 Cultural Sites or Areas Probably Ineligible for the NRHP .............. 4.12 4.1 VISUAL RESOURCES ................ ..................•. 4.13 4.K DEVELOPMENT OF A SYSTEM OF ALTERNATIVE ROUTES ........ 4. 14 CHAPTER S. ENVIRONMENTAL CONSEQUENCES 5.A INTRODUCTION ...................................... 5.1 5.B EART H RESOURCES .................................... 5.2 5.B.1 Alternative B. The Proposed Action: Uprate Existing Flatiron-Erie Transmission Line ....................................... 5.2 5.B.2 Alternative C. Construct Transmission Line Underground Through Longmont .................. 5.3 5.B.3 Alternative D. Remove and Relocate Through Parts of Longmont ....................... ... 5 . 4 5.C WATER RESOURCES ................................... 5.4 5 .C . 1 Alternative B. The Proposed Action: Uprate Existing Flatiron-Erie Transmission