Documentation of Historic Transmission Towers in the Eastern Mining Area Transmission System - Tonto National Forest and Tonto National Monument, Arizona

Summary

Beginning in 2021, Salt River Project (SRP) will replace substandard historic-age lattice tower structures along the 130-mile-long Eastern Mining Area (EMA) 115 kilovolt (kV) transmission system located on the Tonto National Forest and Tonto National Monument. The work is necessary to maintain reliability and safety of the EMA system and is being conducted to meet the requirements of the National Electrical Safety Code and the North American Electric Reliability Corporation (NERC), acting under authority from the Federal Energy Regulatory Commission. The existing historic structures would be replaced with new structures in the immediate vicinity of the original structure. As the lead federal agency, Tonto National Forest determined that the EMA system as a whole is eligible for inclusion in the National Register of Historic Places and that tower replacement would result in an adverse effect to the National Register-eligible system. In order to resolve the adverse effect, in 2020 a programmatic agreement1 was implemented and stipulated that 24 historic towers would be subject to documentation to record the six standard structure types and a sample of 18 representative deviations from the standard design, with an emphasis on documenting the variability of structural foundations.

This Resource is Part of the Following Collections

• Salt River Project Digital Library

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Individual & Institutional Roles

Contact(s): Daniel Garcia

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