BLUE RIDGE PARKWAY TECHNICAL REPORT

1 STIP PROJECT NOS. I 4400/I 4700 DRAFT ENVIRONMENTAL IMPACT STATEMENT INTERSTATE 26 IMPROVEMENTS HENDERSON AND BUNCOMBE COUNTIES APPENDIX HBLUE RIDGE PARKWAY TECHNICAL REPORTBLUE RIDGE PARKWAY BRIDGE OVER INTERSTATE 26 Conceptual Alternatives Impact Topics Considered Environmental Consequences VA/CBA Study Factors July 20, 2016 Prepared by: The National Park Service blue RIDGE PARKWAY 199 Hemphill Knob Road Asheville, North Carolina 28803 and The Federal Highway Administration Eastern Federal Lands Highway Division 21400 Ridgetop Circle Sterling, Virginia 20166 blue RIDGE PARKWAY Bridge over I-26 Page i Table of Contents Introduction.

2 1 Alternatives Development .. 1 Conceptual Alternatives .. 1 Evaluation of Conceptual Alternatives and Evaluation Design Criteria .. 2 Conclusions for PARKWAY Alignments .. 4 Additional Conceptual Alternatives Proposed .. 4 Dismissal of Alternative 6 .. 5 Evaluation Design Criteria for the Bridge Railing .. 5 Conclusions for Bridge Railing Design System .. 7 Summary of Alternatives .. 7 Impact Topics Considered .. 8 Impact Topics Considered But Dismissed .. 9 Impact Topics Carried Forward .. 11 Environmental Consequences.

3 12 Natural Resources .. 12 Vegetation .. 12 Wildlife .. 12 Federally-Listed Species .. 13 Geologic Resources and Soils .. 13 Water-related Resources .. 13 Air Quality .. 14 Cultural Resources .. 14 Historic Structures .. 14 Archaeological 14 Cultural Landscapes .. 14 Visual Resources .. 15 Visitor Use & Experience .. 16 PARKWAY Operations .. 18 Value Analysis (VA) and Choosing by Advantage (CBA) Study .. 20 Factors Carried Forward .. 20 Result of Value Analysis .. 21 References .. 22 Appendices .. 23 blue RIDGE PARKWAY Bridge over I-26 Page ii Appendix A Cross Sections Showing Maximum Excavation Depths.

4 25 Appendix B Profiles .. 31 Appendix C Cut and Fill Limits .. 37 Appendix D Archeological Survey REPORT .. 43 Figure 1. Plan View of Initial Four Alignments .. 2 Figure 2. Railing Along the Grandfather Mountain Section of the blue RIDGE PARKWAY .. 5 Figure 3. Modified Kansas Corral Bridge Railing .. 6 Figure 4. Concrete Barrier Type 80 SW Railing .. 6 Figure 5. Tubular Railing Systems .. 7 Figure 6. blue RIDGE Travel Time without Detour (Google Maps) .. 18 Figure 7. Detour Route (Google Maps) .. 18 Table 1. Impacts Considered by the NPS and FHWA.

5 8 Table 2. Area of Vegetation Disturbance .. 12 Table 3. Potential Threatened and Endangered Species, Buncombe County .. 13 Table 4. Volume of Soil Disturbance .. 13 Table 5. Comparison of Alternatives .. 15 blue RIDGE PARKWAY Bridge over I-26 Page 1 Introduction The North Carolina Department of Transportation (NCDOT), in cooperation with the Federal Highway Administration (FHWA) proposed to widen I-26 from US 25 in Henderson County to I-40 in Buncombe County ( miles) to relieve congestion along the I-26 corridor. Because of the proximity of the existing high piers to the existing travel lanes, this widening requires the replacement of the blue RIDGE PARKWAY Bridge over I-26 in Buncombe County, NC.

6 The Draft Environmental Impact Statement (DEIS), prepared by the NCDOT in coordination with the FHWA, was prepared to satisfy (in part) the requirements of the National Environmental Policy Act (NEPA) of 1969. The National Park Service (NPS) has been designated as a cooperating agency. Upon the completion of the EIS, the EIS should include information necessary for the NPS to adopt the EIS and issue their own decision document. In order for the NPS to issue an approval, an impact analysis and impairment analysis per Director s Order #12: Conservation Planning, Environmental Impacts Analysis and Decision-Making Handbook (National Park Service, 2001b) must be completed.

7 This TECHNICAL REPORT compiles the background information and analysis needed to support the NPS s adoption of the EIS. This TECHNICAL REPORT discusses only the alternatives for the reconstruction or replacement of the blue RIDGE PARKWAY Bridge over I-26. In the Draft EIS, these alternatives are presented as options, since they are part of the larger corridor widening project, which has its own alternatives to avoid confusion. Alternatives Development This section summarizes the development and evolution of the alternatives proposed and evaluated for the reconstruction or replacement of the blue RIDGE PARKWAY Bridge over I-26.

8 This section also discusses the evaluation factors and why certain alternatives were dismissed from further consideration. Conceptual Alternatives Several bridge replacement alignment alternatives are being analyzed for the replacement of the blue RIDGE PARKWAY Bridge. Ideally, the existing bridge would remain open to traffic during construction; however, one of the alternatives under consideration does require closure of the bridge during construction. Reconstruction of the existing bridge is also being considered. A new bridge could be either a concrete box girder or steel plate girder bridge.

9 The bridge would most likely be constructed from the top down using segmental construction. The bridge would have two ten-foot travel ways, three-foot shoulders and a five-foot sidewalk on one side to accommodate the Mountains-to-Sea Trail. A description of the alternatives under consideration is listed below: 1. Under Alternative 1, the bridge would be realigned to the north. In order to tie into the existing motor road, approximately 2,300 feet of the road would be realigned as a single curve (1530 foot radius). Because of its single sweeping curve, it would also be longest bridge alternative.

10 The bridge would be lengthened to 7151 feet, and the entire bridge would be on a curve. Alternative 1 would also require a 2-foot widening of the bridge. 2. Under Alternative 2, the bridge would be realigned to the south and consists of a 3 curve realignment with a 1259-foot radius curve on the bridge. Approximately 4,150 feet of the motor 1 Lengths provided are for a concrete box girder bridge. The use of steel plate girders would result in longer bridge lengths. blue RIDGE PARKWAY Bridge over I-26 Page 2 road would be realigned to flatten the curves at the approaches.