Supplemental Cultural Resources Survey for the Sonoran Solar Energy Project in Maricopa County, Arizona

Author(s): Adrienne M. Tremblay

Year: 2021


Sonoran Solar is proposing to construct, operate, and decommission a solar-powered electrical generation facility in Maricopa County, Arizona. The Sonoran Solar Energy Project was originally proposed as a 375-megawatt dry-cooled Concentrated Solar Thermal energy generation plant located on 3,620 acres of BLM-managed lands in Maricopa County, Arizona. Because the proposed project was on federal land, the BLM completed a Final Environmental Impact Statement (FEIS) and issued a Record of Decision in 2011. The BLM selected Sub-alternative A1: Photovoltaic as the agency-preferred alternative over the Proposed Action because it needed less infrastructure, needed only two wells, and avoided most major issues with travel corridors, floodplains, and some of the need for wildlife and vegetation removal. Right-of-way (ROW) grants were issued by the BLM in 2012.

Sonoran Solar is proposing to update the selected Sub-alternative A1 while pursuing the final project approvals/Notice to Proceed from the BLM and other federal, state, and local regulatory agencies for development of the Sonoran Solar Energy Project. The current BLM ROW grant covers 2,335.6 acres within the FEIS analysis area; Sonoran Solar’s current plans cover a total of 3,281 acres of BLM land.

In compliance with Section 106 of the National Historic Preservation Act, a cultural resources survey of the entire FEIS analysis area and beyond was conducted by Environmental Planning Group (EPG) (Swanson et al. 2009). EPG surveyed a total of 8,646 acres (8,628.6 acres of BLM land and 17.1 acres of ASLD land); however, 73.92 additional acres outside EPG’s survey area are now needed because the area of potential effects (APE) extends beyond the area surveyed by EPG: 50.40 acres of BLM-administered land, 2.06 acres of ASLD land in an existing ROW for an access road, and 21.46 acres of private land. The 2.06 acres of ASLD land are in an existing ROW; however, it was unclear from EPGs report exactly how much of the ROW was surveyed, so a survey was deemed prudent at this time. The approximately 21 acres of private land is to accommodate pulling sites for a Gen-tie transmission line. The current route of the Gen-tie line was within the area previously surveyed by EPG; however, additional pulling areas will be needed for the construction of the transmission line.

The BLM is a federal agency; therefore, the Sonoran Solar Energy Project is subject to review under Section 106 of the National Historic Preservation Act, which requires federal agencies to assess the effects of a proposed undertaking on historic properties (i.e., archaeological sites, buildings, structures, objects, or districts listed in or eligible for listing in the National Register of Historic Places [NRHP]). The access road on ASLD land is subject to the Arizona State Historic Preservation Act (ARS 41-861 et seq.), which assigns the chief administrator of each state agency responsibility for the preservation of historic properties owned or controlled by the agency.

Sonoran Solar contracted SWCA Environmental Consultants (SWCA) to conduct a cultural resources survey of anticipated additional project area required for the project. The survey was intended to identify any historic properties in the additional project area and therefore support cultural resources review by the BLM and ASLD.

Cite this Record

Supplemental Cultural Resources Survey for the Sonoran Solar Energy Project in Maricopa County, Arizona. Adrienne M. Tremblay. 2021 ( tDAR id: 475374) ; doi:10.48512/XCV8475374

This Resource is Part of the Following Collections

Individual & Institutional Roles

Contact(s): Daniel Garcia

Prepared By(s): Sonoran Solar Energy, LLC.

Submitted To(s): SWCA Environmental Consultants

Record Identifiers

SWCA Project No.(s): 60001

SWCA Cultural Resources Report No.(s): 21-236

File Information

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Tremblay-2021-Supplemental-Cultural-Resources-Survey-for-the-S... 5.72mb Apr 27, 2023 9:23:20 AM Confidential

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Contact(s): Daniel Garcia