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.

To regulate peak flows, a knife gate valve was installed and positioned at a partially open setting, limiting the incoming flow to 6.4 MGD. This scattergraph displays data from a flow monitor located just upstream from the valve.