For monitoring the pumping rate and to provide historic data for future upgrading, the discharge flow shall be metered with a flow meter on the discharge header or forcemain.

Flow meters of the Venturi Tube type are available for forcemains sized three inches and larger. Flow indication (digital one-quarter-inch LED readout) is required at the pumping station at the control panel and an analog flow signal is to be transmitted over the SCADA system to the WSSC Control Center. For this purpose the Venturi flow element shall be connected to a Rosemount 1151 GP Smart Option transmitter capable of producing a four to 20 mA DC signal proportional to the wastewater flow. A water purging system is not required.

Electromagnetic flow meters with an output of four to 20 mA DC proportional to the flow are available for pipe sized one-half-inch and larger.

A straight approach pipe length of eight pipe diameters, or as recommended by the manufacturer (whichever is greater) shall be provided immediately upstream of the flow measuring device.

Acceptable manufacturers:

Venturi flow measuring device: Wyatt-Badger, BIF, Primary Flow Signal.

Magnetic flow meter: Bailey-Fischer and Porter (ABB), Endress+Hauser, Foxboro, Rosemount, Sparling Instruments. (Design Guideline DG-08 § 8.0, dated August 2006)