Stormwater Flow Control Device

Opportunity - Wet weather pollution is reported to be the largest water quality problem in the nation with an estimated solution at $400 billion with a regulation driven market for cities and industries to control stormwater and sewer overflows. Studies show that flow control to attenuate hydraulic rates by utilizing available storage will optimize treatment capacity and reduce downstream water quality impacts making it the most cost-effective component of almost every wet weather control system. There is a significant market opportunity for a non-mechanical maintenance-free flow control technology that will not inhibit existing capacities or aquatic biology. Innovation - The WWETCO technology consists of a downward closing flexible bladder containing a static fluid (adjustable) that seals the bladder against all or a portion of a conduit that transports base flow and/or stormwater flow. The hypothesis is that the bladder will open from the bottom to relieve excess flow or solids to maintain a maximum upstream level equal to the contained static liquid level. The bladder will operate to optimize diversion to treatment and/or attenuation of wet weather flows. Operation is passive riding on the optimized drainage system hydraulic gradient, without need for control instrumentation or mechanical devices, is non-clogging, and inverts providing full-bore peak flow-through not altering system capacity. An option allows base flow for combined sewer or stream flow aquatic-biology-tolerant applications. Objectives - Phase I objectives include hypotheses testing under a range of flow and debris conditions. Phase II objectives include design development of a full-scale product, prototype fabrications and verification testing. Effort - The Phase I efforts included pilot testing for hydraulic measurement and observation with debris injection for different static control and backwater levels and an evaluation of different bladder materials. Phase II efforts include recommended material strength testing, pilot-scale grit erosion testing, and full-scale fabrication and field testing. Results - Hydraulic testing demonstrated smooth operation and upstream gradient control requiring minimal head (4-inches) under all constant and rapidly varying flows with bladder automatically adjusting to free any debris. Implication of the demonstrated approach is a simple, low-cost, no maintenance, adjustable flow control, applicable anywhere in the natural or constructed drainage network without inhibiting capacity. Commercial applications include in-line and off line storage and treatment control and optimization.