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HomeMy WebLinkAboutSW3211202_Stormwater Narrative_20220223Date: December 12, 2021 CYPRESS CREEK RENEWABLES Project: Old Pageland - Monroe Road Solar Farm, LLC 919 Old Pageland Monroe Road Monroe, North Carolina 28112 Union County PROJECT NARRATIVE The purpose of this narrative is to summarize the as -built improvements for the Old Pageland - Monroe Road Solar Farm, LLC project ("Project"), which was built in 2015; discuss post -construction drainage conditions and demonstrate compliance with NC DEMLR's post -construction stormwater permitting requirements. Cypress Creek Renewables (CCR) performed an internal audit and discovered that the project was missing said permit — i.e., it was not obtained by the previous Developer/Engineer prior to beginning construction. The CCR Engineering Team verified that the project is in a State Post -Construction Stormwater Permitting jurisdiction, gathered the available project documentation, completed the NC DEMLR stormwater management application forms, and issued a fee payment check with the goal of bringing the operational solar facility into compliance. The project is a 5-Megawatt (MW) AC (7.07 MW DC) solar power generation facility located on a total 35.74-acre lease -controlled area within two adjacent parcels in Union County. The facility consists of fixed tilt solar photovoltaic (PV) panel tables supported on driven steel piles (posts) and pad -mounted inverters. The solar PV system is connected to the Duke Energy Carolinas (DEC) utility electric grid at a Point of Interconnection (P01) within the northwest portion of the overall lease boundary, on the south side of Old Monroe - Marshville Road (See As -Built ALTA Survey). No significant site grading was performed — only minimal vegetation clearing, utility trenching, subgrade preparation for a gravel drive, concrete equipment pads and two DOT -permitted access driveways with 15-inch diameter culverts (off SR-1941). A chain link perimeter fence encloses the facility. The solar site is functioning adequately as a Low -Density Project with stormwater released as dispersed flow. The project site areas are completely vegetated and match pre -construction terrain, except for a gravel drive and concrete equipment pads. The two site areas have retained their existing sloping topography that sheet flows overland drainage to existing unnamed tributaries (Jurisdictional Ditches) at the north, central and southern project areas. The northern tract slopes from northwest (elevation 588 ft) to northeast and southwest directions, with a maximum elevation drop of 30 feet due east. The southern tract slopes radially from a mid -center elevation of 586 feet, with a maximum drop of 26 feet due north (See Civil Plan Sheet C-4). The two tracts were connected by a new road crossing and culvert installation within the central ditch upon approval of a 401 Water Quality Certification (NC DWR) and Nationwide Permit (USACE). The tributaries flow east to existing wetlands, and then offsite to Flag Branch (Class C; Yadkin Pee -Dee River Basin). Downstream vegetation areas provide natural stormwater treatment and dissipation of sheet flow runoff before it enters the tributaries. Onsite, the grass areas beneath the solar panels and between rows allow for rainwater infiltration, dissipation, and dispersal as overland drainage sheet flow to downstream areas. The project also functions as a Disconnected Impervious System (DIS), complying with the design criteria outlined in the NCDEQ Stormwater Design Manual Section E-6. Solar Farms, which considers ground mounted solar panels as pervious when they are configured in accordance with Recommendation 2. The project calculated Disconnection Length is 88.6% of the total solar panel width (See BUA Calculations Package: Row Spacing: 10.92-ft; Solar Panel Width: 12.33-ft; Slope: 6.5%, average). The solar panel heights are below 10-ft, design complies with Recommendation 6 (See Solar Panel and Racking System Details). The CCR Operations and Maintenance (0&M) Team performs regular inspections on a quarterly basis. 0&M personnel perform grass mowing; minor seeding/replanting of bare areas; debris and trash removal; panel washing/cleaning; onsite road repairs; and electrical equipment testing. The submitted Operation & Maintenance Agreement will enhance and/or reinforce the Maintenance Plan that is already in -place for the project; thereby, meeting Post -Construction Stormwater Permit requirements. Cypress Creek Renewables, 5310 S. Alston Ave. Bldg. 300 Durham, NC 27510 919.240.4815