These two photos are of Parshall Flumes, one is a newly manufactured flume, and the one on the right is the flume that is in use at the wastewater treatment facility, located in the Influent building. Parshall flumes are a fixed hydraulic structure commonly used to measure municipal sewer flows. They can vary in size depending on the design capacities of a plant. The plants flume is an 18 inch and at the time the photo was taken the flow was at 1,042 gallons per minute (gpm) or 1.5 million gallons a day.
Measuring the Flow
We have two ways of measuring flows with the Parshall flume one is by a staff gauge that is mounted inside the flume that shows inches of flow. These inches correspond with a chart, which cross references the inches with flow in gallons per minute (gpm) and million gallons per day (MGD). The other device is an Ultra Sonic flow measuring sensor that also measures the inches of flow and sends the data to our ‘Supervisory Control and Data Acquisition’ (SCADA) system located in the operations building. The Ultra Sonic device is gray and is at the top middle of the right hand photo.