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 a pipe curve based on dry weather data (between 3 and 11 MGD). The fact that the subsequent wet weather data coincide with this pipe flow at greater depths in free flow conditions validate the appropriateness of this method.