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HomeMy WebLinkAboutSW3211202_BUA Allocations_20220223/1111111///// ItA CAROB Project: Old Pageland Monroe [load Solar Farm, LLC Union County, NC Date: 12/12/2021 By: J. Graham, PE Checked: M. Carreon PE 1. SSW-SWU-101 BUA Calculations Backup 1 (0i 15 8PIZ 11,ffifill �r Total Property Area (ac) 35.74 ac Civil Plans (sheet C1, 4/10/2015) Total Coastal Wetlands Area (ac) 0.0 ac Surface Waters (ac) 0.0 ac Total Project Area (ac) 31.2 ac LOD per Civil Plans (sheet C1, 4/10/2015) Basin Information Drainage Area 1 Receiving Stream Name Flag Branch Yadkin Pee -Dee River Basin Stream Class C Stream Index Number 13-17-36-8-2 Total Drainage Area (sf) 1,359,072 On -site Drainage Area (sf) 1,359,072 Off -site Drainage Area (sf) 0 Proposed Impervious Area Of) 5439 0.12 ac % Impervious Area (total) 0.40% 31.08 lac (Grassed .areas) Impervious Surface Area (See BUA max. below) Drainage Area 1 On -site Buildings/Lots (sf) 0 On -site Streets (sf) 4126 DWG On -site Parking (sf) 0 On -site Sidewalks (sf) 0 Other on -site (sf) 1313 1104 Equipment Pads (DWG) 209 Foundation Posts (Piles); assume 4-inch diameter (Total No. of Posts =2,396 ) Future (sf) 0 Off -site (sf) 0 Existing BUA (sf) 0 Total on 5439 2. NOTES a. Union County is a Phase 2 Tipped County b. Subject to MS4 requirements per iSA NCAC 02H.1016 c. BUA is 24% max. Project: Old Pageland Monroe Road Solar Farm, LLC Union County, NC Date: 12/12/2021 By: 1. Graham, PE Checked: M. Carreon, PE 3. NCDEQ Stormwater Design Manual (Rev. 12-13-2018) E-6 Solar Farms 1111111111" 11 �OQOFESsio 045182 '""111111101`` 1,W1A74eA Regulatory Requirements: DEMLR allows solar panels associated with ground -mounted solar farms to considered pervious Other structures associated with the solar farm - buildings, entrance roads, transformers (concrete pads) and footings are still considered impervious. Recommendation 2: Disconnect runoff from solar panel arrays The project has been installed to allow for vegetation under and in between the solar arrays; and the terrain slopes are less than 8% along the disconnection flow path (see dimensions below). Recommendation 6: Limit vertical clearance to less than or equal to 10 feet The project solar panel maximum heights are less than 10 feet, which helps prevent erosion and scoung along the dripline (see Solar Panel and Racking System Details provided). Solar Panel Width (ft) 12.33 per As -Built ALTA (11/2/2015); approx. average across site Row Spacing (ft) 10.92 per As -Built ALTA (11/2/2015); approx. average across site Average Slope (%) 6.5% per Civil Plans (sheet C4, 4/10/2015) < 8% DL Ratio 88.6% >80% Yes Figure 1: Disconnection of flow path between solar panels when average slope is less than 8%. Solar Panel Width n X R Disconnection Length 2 X ft Solar Panel Width . X ft iDSGa1Ei�Et�titatlfloa,uP th Avg Siope 5 8% In general, the minimum disconnection length between two rows of solar panels is equal to the width of each row, as shown in Figure 1. However, some panel layouts include horizontal gaps between individual modules that allow stormwater to drip off the panels at intervals much smaller than the width of each row. In these instances, the solar farm can be designed with a smaller disconnection length, provided that they will not cause concentration of stormwater runoff. The disconnection length should not be less than 80% of the total solar panel width.