1 12 AFFECTED ENVIRONMENT AND IMPACT ASSESSMENT FOR 2 PROPOSED SOLAR ENERGY ZONES IN NEW MEXICO 3 4 5 12.1 AFTON 6 7 8 12.1.1 Background and Summary of Impacts 9 10 11 12.1.1.1 General Information 12 13 The proposed Afton solar energy zone (SEZ) is located in Dona Ana County in southern 14 New Mexico, 21 mi (34 km) north of the border with Mexico and 3 mi (5 km) southeast of the 15 proposed Mason Draw SEZ (Figure 12.1.1.1-1). The SEZ has a total area of 77,623 acres 16 (314 km2). In 2008, the county population was 206,486. The towns of Las Cruces, Mesilla, 17 Mesquite, University Park, and Vado are all within a 5-mi (8-km) radius of the SEZ. Las Cruces 18 is the largest, with a population of approximately 90,000. 19 20 The nearest major road access to the SEZ is via Interstate-10 (I-10), which runs east–west 21 along the northern border of the Afton SEZ. The Burlington Northern Santa Fe (BNSF) Railroad 22 runs east of the SEZ with stops in Las Cruces, Mesilla Park, Mesquite, Vado, and Berino, all 23 within about 1 to 5 mi (1.6 to 8 km) of the SEZ. The nearest public airport is Las Cruces 24 International Airport located directly north of the SEZ and does not have regularly scheduled 25 passenger service. The nearest larger airport, the El Paso International Airport, is approximately 26 58 mi (93 km) to the southeast of the SEZ. 27 28 A 345-kV transmission line passes through the SEZ. It is assumed that this existing 29 transmission line could potentially provide access from the SEZ to the transmission grid 30 (see Section 12.1.1.1.2). 31 32 There is one right-of-way (ROW) application for a solar project within the SEZ, and one 33 ROW application for a wind project that would be located within 50 mi (80 km) of the SEZ. 34 These applications are discussed in Section 12.1.22.2.1. 35 36 The proposed Afton SEZ is undeveloped and rural. The SEZ is located in the West Mesa 37 of the Mesilla Basin bordered on the north by the Rough and Ready Hills and the Robledo 38 Mountain; on the west by the Sleeping Lady Hills, Aden Hills, and the West Potrillo Mountains; 39 and on the east by the Mesilla Valley. Land within the SEZ is undeveloped scrubland 40 characteristic of a semiarid basin. 41 42 The proposed Afton SEZ and other relevant information are shown in Figure 12.1.1.1-1. 43 The criteria used to identify the SEZ as an appropriate location for solar energy development 44 included proximity to existing transmission lines or designated corridors, proximity to existing 45 roads, a slope of generally less than 2%, and an area of more than 2,500 acres (10 km2). In Draft Solar PEIS 12.1-1 December 2010 1 2 FIGURE 12.1.1.1-1 Proposed Afton SEZ Draft Solar PEIS 12.1-2 December 2010 1 addition, the area was identified as being relatively free of other types of conflicts, such as 2 U.S. Fish and Wildlife Service (USFWS)-designated critical habitat for threatened and 3 endangered species, Areas of Critical Environmental Concern (ACECs), Special Recreation 4 Management Area (SRMAs), and National Landscape Conservation System (NLCS) lands 5 (see Section 2.2.2.2 for the complete list of exclusions). Although these classes of restricted 6 lands were excluded from the proposed Afton SEZ, other restrictions might be appropriate. The 7 analyses in the following sections evaluate the affected environment and potential impacts 8 associated with utility-scale solar energy development in the proposed SEZ for important 9 environmental, cultural, and socioeconomic resources. 10 11 As initially announced in the Federal Register on June 30, 2009, the proposed Afton 12 SEZ encompassed 55,810 acres (226 km2). Subsequent to the study area scoping period, the 13 boundaries of the proposed Afton SEZ were altered substantially after further observations by 14 the U.S. Department of the Interior (DOI) Bureau of Land Management (BLM) District Office 15 indicating that the additional area met all criteria for solar development. The revised SEZ is 16 approximately 21,813 acres (4 km2) larger than the original SEZ as published in June 2009. 17 18 19 12.1.1.2 Development Assumptions for the Impact Analysis 20 21 Maximum solar development of the Afton SEZ is assumed to be 80% of the SEZ area 22 over a period of 20 years, a maximum of 62,098 acres (251 km2). These values are shown in 23 Table 12.1.1.2-1, along with other development assumptions. Full development of the Afton SEZ 24 would allow development of facilities with an estimated total of 6,900 MW of electrical power 25 capacity if power tower, dish engine, or PV technologies were used, assuming 9 acres/MW 26 (0.04 km2/MW) of land required, and an estimated 12,420 MW of power if solar trough 27 technologies were used, assuming 5 acres/MW (0.02 km2/MW) of land required. 28 29 Availability of transmission from SEZs to load centers will be an important consideration 30 for future development in SEZs. The nearest existing transmission line is a 345-kV line that runs 31 through the SEZ. It is possible that this existing line could be used to provide access from the 32 SEZ to the transmission grid, but the 345-kV capacity of that line would be inadequate for 33 6,900 to 12,420 MW of new capacity (a 500-kV line can accommodate approximately the load 34 of one 700-MW facility). At full build-out capacity, it is clear that substantial new transmission 35 and/or upgrades of existing transmission lines would be required to bring electricity from the 36 proposed Afton SEZ to load centers; however, at this time the location and size of such new 37 transmission facilities are unknown. Generic impacts of transmission and associated 38 infrastructure construction and of line upgrades for various resources are discussed in Chapter 5. 39 Project-specific analyses would need to identify the specific impacts of new transmission 40 construction and line upgrades for any projects proposed within the SEZ. 41 42 For the purposes of analysis in the PEIS, it was assumed that the existing 345-kV 43 transmission line which passes through the SEZ could provide initial access to the transmission 44 grid, and thus no additional acreage disturbance for transmission line access was assessed. 45 Access to the existing transmission line was assumed, without additional information on whether 46 this line would be available for connection of future solar facilities. If a connecting transmission Draft Solar PEIS 12.1-3 December 2010 TABLE 12.1.1.2-1 Proposed Afton SEZ—Assumed Development Acreages, Solar MW Output, Access Roads, and Transmission Line ROWs Assumed Distance Area of Total Acreage Maximum Distance to and Capacity Assumed and Assumed SEZ Output Nearest State, of Nearest Transmission Distance to Developed for Various U.S. or Existing Line ROW Nearest Acreage Solar Interstate Transmission and Road Designated (80% of Total) Technologies Highway Line ROW Corridord 77,623 acres and 6,900 MWb I-10 0 mi and 0 acres; Adjacent 62,098 acresa and 0 mie 345 kV 0 acres 12,420 MWc a To convert acres to km2, multiply by 0.004047. b Maximum power output if the SEZ were fully developed using power tower, dish engine, or PV technologies, assuming 9 acres/MW (0.04 km2/MW) of land required. c Maximum power output if the SEZ were fully developed using solar trough technologies, assuming 5 acres/MW (0.02 km2/MW) of land required. d BLM-designated corridors are developed for federal land use planning purposes only and are not applicable to state-owned or privately owned land. e To convert mi to km, multiply by 1.609. 1 2 3 line were constructed in the future to connect facilities within the SEZ to a different, off-site, grid 4 location from the one assumed here, site developers would need to determine the impacts from 5 construction and operation of that line. In addition, developers would need to determine the 6 impacts of line upgrades if they are needed. 7 8 Existing road access to the proposed Afton SEZ should be adequate to support 9 construction and operation of solar facilities, because I-10 runs from east to west along the 10 northern border of the SEZ. Thus, no additional road construction outside of the SEZ is assumed 11 to be required to support solar development. 12 13 14 12.1.1.3 Summary of Major Impacts and SEZ-Specific Design Features 15 16 In this section, the impacts and SEZ-specific design features assessed in Sections 12.1.2 17 through 12.1.21 for the proposed Afton SEZ are summarized in tabular form. Table 12.1.1.3-1 18 is a comprehensive list of impacts discussed in these sections; the reader may reference the 19 applicable sections for detailed support of the impact assessment. Section 12.1.22 discusses 20 potential cumulative impacts from solar energy development in the proposed SEZ. 21 22 Only those design features specific to the proposed Afton SEZ are included in 23 Sections 12.1.2 through 12.1.21 and in the summary table. The detailed programmatic design 24 features for each resource area to be required under BLM’s Solar Energy Program are presented 25 in Appendix A, Section A.2.2.