25. Iso-Froude Lines The Froude Number (Fr) is a dimensionless number used to describe flow conditions and is analogous to the Mach Number defining supersonic flight. If the Froude Number is less than one, flow conditions are described as subcritical. If the Froude Number is greater than one, flow conditions […]
Scattergraph
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24. Sewer Amusement These data are from a flow monitor installed on one of three interceptors arriving at a wastewater treatment plant (WWTP). This unusual and entertaining pattern was created during a rain event when one of the larger interceptors overpowered this one. The Stevens-Schutzbach Method is used to define […]
23. Sewer in the News This scattergraph is a hydraulic mother lode showing three distinct hydraulic events. This flow monitor was installed in a 15-in sewer located just upstream from four consecutive 90-degree turning manholes. The head loss due to this routing causes a capacity loss of 0.5 MGD. A […]
22. Hydraulic Hysteresis This scattergraph displays data from a flow monitor installed in a 21-in trunk sewer. During wet weather, backwater and surcharge conditions are observed in a distinct manner referred to as hydraulic hysteresis. During the intial response to this rain event, downstream storage is available within the system, […]
21. Knife Gate Valve A satellite collection system discharges wastewater to another agency through a 27′ sewer for subsequent conveyance and treatment. The observed minimum and maximum dry weather flow rates are 0.6 MGD and 1.8 MGD. Greater flows were observed during wet weather, creating problems for the recieving agency. […]
20. Inverted Siphon This flow monitor is installed in a sewer just upstream from an inverted siphon comprised of two 8-inch barrels. The incoming sewer has a design capacity of 2.7 MGD. The scattergraph shown here indicates that the first barrel has a capacity of 1.3 MGD. Additional flow is […]