1500 1ST ST RAIL BARGE FACILITY 2016-01-01 MF Import

AVorfechs' Stormwaler Tre:itment System �T Vortechnics typically selects the System that will provide an 80% annual T55 load reduction based on laboratory generated pertormance curves for 50-micron sediment particles, however the Rational Rainfall MethodT" can accommodate other re noval efficiency or particle size targets. It can also be used to estimate annual hydrocarbon loa� reductions. Once a System size is established, the internal elements of the Systern will be designed based on information provided by the site engineer. Flow control slzes a id shapes, sump depth, splll storaaa capacity, sediment storege volume and inlet and outlet orientation are determined for each System. In addition, bypass weir caiculations are made for off-Il��e Systems. Fiow Control 'alculations The Oriflce The lower flow control or"orifice" is typically sized to submerge the inlet pipe when the Vortechsm System is operating at 20% of its'treatment capacity. The uriFlce Is typically a Cippoletti shaped aperture defined by its flat cres[ and Sides which Incline outwardly at a slope of 1 horizontal to 4 vertical. flow througli urifice = Qo„ = Ca •A • (zgh)o.s Where Ce = Oriflce contrection coefficient = 0.56 (558.5) (based or,voreecnn�a taboracory testing) A = Orifice flow area, kz (mz) (calculated by Vortechnics technlcai staff) h = Design head, ft (m) (equal to the inlet pipe diameter) The minlmum orifice crest length (s 3-inches (76 mmj and the minimum orifice height is 4-inches (102 mm). If Flow musf be restricted beyond what can be provided by th(s size aperture, a Fluldic- AmpT" hydro-brake Flow control will be used. The hydro-brake allows the minimum flow constric[ion to remain at 3-inches (76 mm) or greater while further reducing Flow due to its unique throttling action. The Welr The high Flow control or"weir"is sized to pass the peak System capacity minus the peak orifice flow when the water surface elevation Is at the top of the welr. This flow control is also a Clppolettl type welr. The weir flow control (s sized by solving for the crest length and head in the following equation: Flow through weir = Qwe;, = Co •L • (h)'S Where Ce = Clppolettl Weir coefficlent = 3.37 (1860.5) (based on vortechnics laboratory cesting) h = Available head, ft (m) (helght of weir) L = Design weir crest length, ft (m) (calculated by Vortechnics technical staff) Rev 449-04 (1VSG)