The 72" type A Megaflex included spool pieces to simplify the installation in the vault within a major city street.
Click here to enlarge imageCalling on the expertise of a major engineering firm, a control strategy was identified that would minimize combined sewer overflow volume and frequency through the optimization of the collection and treatment system.
To accomplish these goals, Triad Engineering Inc. designed a system that uses Type A Megaflex pinch valves manufactured by Red Valve Co. to regulate and or divert flow to portions of the pipeline network that have storage capacity. The design calls for a 72-inch and 66-inch pinch valves.
By modulating the inflation pressure of the 72-inch valve, the city has the ability to use approximately 11,900 linear feet of interceptors that range in size from 42 inches to 66 inches. The total storage capacity of these interceptors is 46,732,965 gallons.
Monitoring devices located throughout the network of collection pipelines send flow data via telemetry to a central control station. In turn a control signal is sent to one of the Megaflex valves to partially close the valve. Modulating or partially closing the pinch valve regulates or diverts the flow into underused portions of the collection system for storage or sends the flow to a treatment plant with available capacity.
This system reduces the volume of overflows at 15 locations. Computer modeling of the system shows that in a 1-inch rainfall event, modulating the system with the 72" pinch valve will save 6 million gallons from overflowing, or 240 million gallons in one year based on an average of 40 inches of rain per year. With the 66-inch valve installed, the modeling shows that an additional 480 million gallons will be saved from overflow.
In selecting the Megaflex pinch valves, the city required that the valves were to be retrofitted into the existing interceptors with no loss of conveyance capacity. And, that the installation would require a minimum of bypass pumping.
The pinch valve vault and the control structure were built around the interceptor. When the valve was delivered, the contractor cut away a section of the existing interceptor and slipped the valve in place. The valve was supplied with spool pieces to facilitate this process. The installation required about 12 hours of bypass pumping.
The Type A Megaflex was selected for this system because the full line size valves are like a straight piece of pipe when open and the partial closing capability of these valves provided the ability to isolate or control the flow.
For more information on Red Valve's line of pinch valves, check valves, knife gate valves, pressure sensors, air diffusers and rubber products, visit the company's Web site at www.redvalve.com.