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SAC-2021-00411

USACE
Published Jan. 28, 2022
Expiration date: 2/11/2022

The proposed work consists of the construction of two (2) single-axis tracking PV solar power facilities (SR Lambert I and SR Lambert II) directly adjacent to each other on a 2,082-acre site, of which, 1,249 acres will be developed for the two facilities. The proposed facility would connect to the existing Santee Cooper 230-kV transmission powerline adjacent to the Santee Cooper owned substation, which are both located within or immediately adjacent to the site.  In detail, the proposed project will permanently impact 1.34 acres of wetlands associated with the construction of gravel access roads and inverter pads.  According to the applicant, the proposed project will also temporarily impact 122 acres of wetlands including trenching and backfilling, grubbing and site preparation.  The site contains approximately 10,927 linear feet of non-wetland waters (tributaries) and 393.64 acres of wetlands.  According to the applicant, the “Wetlands have been managed in timber production for over fifty years and are currently undergoing active silviculture management or have been recently cleared.  Wetland hydrology, soils, and vegetation are altered and have very impaired functions.”

 

The proposed site preparation includes surveying and staking, removal of tall vegetation, small trees and stumps, light grading and clearing, installation of security fence, installation of erosion control BMP’s, and preparation of construction laydown areas.  Grading activities will be performed with portable earthmoving equipment.  According to the applicant, “Grading at the site is expected to result in a net zero balanced cut-and-fill quantity of earthwork to the extent practical and therefore not require any off-site or on-site hauling.”  “…minor grubbing and site preparation would occur in the cleared wetlands to drive piles to support the solar panels.  Discharge of fill is not anticipated in the temporary impact areas and wetlands would remain underneath the solar panels.  While these areas would be temporarily impacted to remove pine stumps, through SRC’s Regenerative Energy program, the wetlands would be restored into an herbaceous habitat with improved biodiversity and the potential for pollinator species.” 

 

Approximately 16 to 20-feet-wide gravel access roads, which align with the existing timber roads, would provide vehicular access to construct, and maintain the solar panels and inverters.  The PV panels will be constructed with steel piles installed using a vibratory pile driver with a depth of 6 to 10 feet below grade.  The solar facility would be composed of approximately 583,344 PV panels, each capable of producing approximately 480 watts, mounted together in arrays.  The arrays would connect to a total of approximately 68, 3.425-megavolt-ampere central inverters to convert DC electricity generated by the solar panels into AC electricity for transmission across the project’s electrical collection system and to the Santee Cooper distribution system.  The applicant has proposed to mitigate for impacts to wetlands and/or waters of the United States by purchasing 12.06 compensatory mitigation credits from an approved mitigation bank.  According to the applicant, compensatory mitigation credits are not proposed for temporary impacts as these wetland areas will be revegetated in native, wetland seed mixes, and maintained as herbaceous wetlands beneath the solar panels.  According to the applicant, the project purpose is to develop solar energy resources in support of Santee Cooper’s 2020 Integrated Resource Plan, which includes an initial goal for 500 MW of solar capacity, and an additional 1,000 MW of solar resources to be secured between 2023 and 2032.