Stormwater Flow Control Device

Wet weather pollution is reported to be the largest water quality problem in the nation. In a regulation-driven market, a solution is estimated to be $400 billion 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 nonmechanical, maintenance-free flow control technology that will not inhibit existing capacities or aquatic biology. The Wet Weather Engineering & Technology (WWETCO) device 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 the need for control instrumentation or mechanical devices. It is non-clogging and inverts, providing full-bore peak flow through that does not alter system capacity. An option allows base flow for combined sewer or stream flow for aquatic biology-tolerant applications. Phase I objectives included hypotheses testing under a range of flow and debris conditions. Phase II objectives include the design development of a full-scale product, prototype fabrications, and verification testing. 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. Hydraulic testing demonstrated smooth operation and upstream gradient control, requiring minimal head (4 inches) under all constant and rapidly varying flows, with the bladder automatically adjusting to free any debris. The 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 inline and offline storage and treatment control and optimization.