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

Vortechs� Slormrr�ler Treotment Sytitem-- --- Bvpass Calculations In some cases, pollutant removal goals can be met withou[ treating peak flow rates and it is most feasible to use a smaller Vortechs'� System configured with an external bypass. In such cases, a bypass design is recommended by Vortechnics for each off-line System. To calculate the bypass capacity, first subtrect the System's trratment capacity from the peak conveyance capacity of the collection system (minimum of 10 year recurrence interval). The result is the flow rete that must be bypassed to avoid surcharging the Vortechs�D S��tem. Then use the following cirrengement of the Francis formula to calcuiate the depth of(low over the bypass weir. Flow over bypass weir = H = (Qom=��/(Ce • �))'" Where Co = Discharge Coefficient = 3.3 (1838.5) for rectanguiar weir H = Depth of flow over bypass we��crest, ft (m) L = Length of bypass weir crest, ft (m) The bypass weir crest elevation is then calculated to be the elevation at the top of the Cippoletti weir minus the depth of flow. t{ydraulic CaoaciN In the event that the peak design flow from the site is exceeded, it is important that the Vortechs� System is not a constriction to runoff leaving the site. Therefore, each Sys[em is designed with enough hydraulic capacity to pass the 100-year Flow iate. it is important to note that at opereting rates above 100 gpm/kZ (407h Ipm/m') of the grit chamber area (peak treatment capacity), captured pollutants may be Iost. When the System is operetina at peak hyd�aulic caFacity, water will be flowing through the gap over the top of the flow control wall as well as the orif�ce and the weir. MAINTENANCE The Vortechs� System sliould be inspected at regular intervals and maintained when necessary to ensure optimum perFormance. The rate at which the ��ystem collects pollutants will depend more heavfly on site activities than the slze of the unit, e.g., unstable sofls or heavy winter sanding will cause the grit chamber to fill more quickly bu[ regular sweeping will slow accumulation, Ins�ection Inspection Is the key to effective maintenance and is easily performed. Vortechnics recommends ongoing quarterly inspections of the accumulated sedlrnent. Pollutant deposition and transport may vary from year to year and quarterly inspections will h��Ip insure that Systems are cleaned out at tlie appropriate time. Inspections shouid be pertormed more often in the winter mon[hs in climates where sanding operations may Iead to rapid accumulatiun�, or In equipment washdown areas. It is very useful fo keep a record of eadi insper_tion. A sim��le form for doing so (s provided. The Vortechs`A Systam should be cleaned when inspecCon reveals that the sediment depth has accumulated to within six inclies (152 mm) of the dry-weather water surFace elevation. This determination can be made by taking 2 measurements with a stadia rod or similar measuring device; one measurement from the manhole opening to the top of the sediment plle and the other from the manhole opening to tlie water surface. The System sl �uld be cleaned out if the difference between the two measuremenfs is six inches (152 mm) or less. Nofe: to avoid underestimating the volume of sediment in tlie chamber, the measuring device must be lowered to rhe top oF the sediment pile carefully. Finer, silty partic:les a[ the top of the pile typically offer less re..istance to the end of tlie rod than larger particles to�Nard the bottom of the pile. Rev 4-29-04 (WSG)