J_2024 05 09_West Orange Stormwater Management Plan

Northern Bioretention (2C) Hydrology Design Targets 1. The bioretention system is designed as an online system. 2. The design drain time is 27.50 hours. 3. Due to the water-tight, concrete cell the bioretention is located inside, along with underdrains in the gravel layer, the seasonal high-water table does not exceed beyond 1’ in elevation above the inside bottom of the bioretention cell. 4. Due to the water-tight, concrete cell the bioretention is located inside, along with underdrains in the gravel layer, the field soil permeability is not a factor in the design. Hydraulic Design Targets 9. Design parameters Water Quality Design Storm 1.25 inch in 2 hours 0.006 ac-ft 2-year storm 10-year storm 100-year storm 3.4 inches 5.2 inches 8.7 inches Rainfall Depth in 24 hours In 24 hours In 24 hours (inches) 0.029 ac-ft 0.050 ac-ft 0.093 ac-ft Runoff Volume (ac-ft) 0.22 cfs 0.37 cfs 0.64 cfs 1.16 cfs Peak Flow Rate (cfs) 171.73 172.26 173.23 173.83 Water Surface Elevation (feet) Note: The design engineer shall fill out the table in accordance with the design of the stormwater management measure. If the item is not applicable, enter N/A in the table. 10. The emergency spillway is at EL. ______N/A_____ feet (if applicable). Basin Configuration Targets 6. Pretreatment is not provided. A concrete outlet structure is used. 7. Planting Soil Bed o The depth of the soil planting bed is 4.5 feet. o Mixture of the planting soil consists of 85-95% of sand. (with no more than 25% of the sands as fine or very fine sands; no more than 15% silt and clay with 2% to 5% clay content). The organic matter shall be within 3% to 7%. o The pH of the planting soil should be in the range of 5.5 and 6.5. o Filter fabric is not placed along the sides of the soil planting bed. o The system is designed with a planting soil permeability rate of 1 inches/hour (pre-construction) and __________ inches/hour (post-construction – tested on (MM) / (DD) / (YYYY) ). 8. Outlet Information: April 2015 Bioretention System Page 32/49