Basic Design Information This Section Shall be filled out by the Designing Engineer. Hydrology Design Targets This basin is designed with a subsoil permeability rate of _________ inches/hour (pre-construction) and __________ inches/hour (post-construction - tested on / / ). (MM) (DD) (YYYY) The design detention time of this basin is __________ hours. The design drain time is __________ hours. Note: The design detention time is not equivalent to the design drain time. A basin’s detention time is defined as the time from when the maximum storage volume is achieved until only 10 percent of that volume remains. The design drain time is the time to drain 100 percent of the storage volume, which may be significantly longer than the design detention time; however, an extended detention basin shall be completely drained within 72 hours or less after the most recent rain event. The elevation of the seasonal high water table of this basin was observed on / / and it was _________ feet below the basin bottom surface, (MM) (DD) (YYYY) at EL._______ feet. The basin is designed to achieve a TSS removal rate of ________ %. This basin will be discharged to (municipal stormwater sewer system/ combined sewer system/ stream (stream name).) Hydraulic Design Targets Design parameters Water Quality 2-year 10-year 100-year Design storm storm storm Storm Rainfall Depth 1.25 inch ___ inches ___ inches ___ inches (inches) in 2 in 24 hours In 24 hours In 24 hours hours Runoff Volume (cubic feet) Peak Flow Rate (cfs) Water Surface
Basic Design Information This Section Shall be filled out by the Designing Engineer. Hydrology Design Targets This basin is designed with a subsoil permeability rate of _________ inches/hour (pre-construction) and __________ inches/hour (post-construction - tested on (MM) / (DD) / (YYYY) ). The design detention time of this basin is __________ hours. The design drain time is __________ hours. Note: The design detention time is not equivalent to the design drain time. A basin’s detention time is defined as the time from when the maximum storage volume is achieved until only 10 percent of that volume remains. The design drain time is the time to drain 100 percent of the storage volume, which may be significantly longer than the design detention time; however, an extended detention basin shall be completely drained within 72 hours or less after the most recent rain event. The elevation of the seasonal high water table of this basin was observed on (MM) / (DD) / (YYYY) and it was _________ feet below the basin bottom surface, at EL._______ feet. The basin is designed to achieve a TSS removal rate of ________ %. This basin will be discharged to (municipal stormwater sewer system/ combined sewer system/ stream (stream name).) Hydraulic Design Targets Design parameters Water Quality Design Storm 2-year storm 10-year storm 100-year storm Rainfall Depth (inches) 1.25 inch in 2 hours ___ inches in 24 hours ___ inches In 24 hours ___ inches In 24 hours Runoff Volume (cubic feet) Peak Flow Rate (cfs) Water Surface