Grantee Research Project Results
Final Report: Stormwater Flow Control Device
EPA Contract Number: EPD04050Title: Stormwater Flow Control Device
Investigators: Boner, Mark C.
Small Business: WWETCO LLC
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2004 through August 31, 2004
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2004) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , SBIR - Water and Wastewater , Small Business Innovation Research (SBIR)
Description:
Wet Weather Engineering & Technology, Inc.’s (WWETCO) Stormwater Flow Control Device (valve) consists of a flexible bladder within a housing, which contains a static fluid that seals the bladder against all or a portion of a conduit that transports base flow and/or stormwater flow. The hypothesis of the research was that the valve can divert and/or attenuate wet weather flows in a passive operation riding on the drainage system hydraulics, optimizing available upstream storage without the need for control instrumentation or mechanical devices, is nonclogging and self-cleaning, and does not alter system capacity.
The goal of this research project was to determine the hydraulic performance of the WWETCO valve under a range of flow conditions, applications, and materials of fabrication. This research project was developed to answer the following questions: (1) What are the most suitable materials for construction? (2) What are the flow and head loss characteristics around and through the valve? (3) How does the valve open and close, and does this rate need to be controlled?
Phase I included the evaluation of valve materials and fabrication, as well as the construction of a test facility to measure the hydraulic performance of the valve for its intended use. Two prototype valve shapes and two different material flexibilities were made and tested. The test setup allowed for a full range of flows and inlet and backwater conditions to be measured for different valve level settings. Observed operation also was recorded digitally. The research project also included an evaluation of the marketplace and applications, coordination with Foresight Science and Technology, Inc., in developing a preliminary commercialization plan, negotiating and licensing a fabricator, initiating a regional and national representative network, and developing potential Phase II full-scale demonstration projects.
Summary/Accomplishments (Outputs/Outcomes):
This research project proved the hypothesis of the concept and answered the stated objective questions. The most suitable materials include a reinforced neoprene or viton rubber bladder for durability depending on the potential chemical characteristics of the application. It was found that the material flexibility was not a significant factor for valve operation.
The head required to operate the valve was minimal and was the same for all flow rates. There was no leakage through the valve for all upstream flow levels below the bladder containment liquid. The valve self regulated to free any debris fed into the upstream conduit and took the shape required to maintain a consistent and smooth upstream water level at all constant and variable flow levels. The valve also completely inverted at the peak capacity, demonstrating full-bore no-inhibition control. In addition, the valve opened and closed smoothly, causing no hammer effect or valve fluctuations.
Conclusions:
Applications for this technology include control of combined sewer overflows (CSOs), sanitary sewer overflows, and stormwater regulated under the Clean Water Act. The valve is simple and unique. It can attenuate and optimize available inline or drainage system storage, divert flows to or around treatment, and maintain and control waterway levels. The valve is easily adaptable to existing infrastructure and can be applied to allow migration of aquatic biology.
Application, performance, efficiency, and cost innovations of the WWETCO flow control technology can be summarized as follows:
- The WWETCO flow control provides diversion to treatment, bypass around treatment, and/or base flow through the flow control. It optimizes the use of all available upstream storage to the maximum extent possible before the bypass of any excess flow volumes not treated or stored. It also has the ability to bypass peak flow with no system capacity loss requiring no additional head, eliminating any risk of upstream flooding all in one simple passive hydraulically controlled device.
- The WWETCO flow control does not require additional head or a drop in the drainage system to operate. It operates on the energy or head available in the runoff flow. This in turn allows the practitioner to install wet weather treatment controls without additional head; the c control operates on the hydraulic gradient that the flow control creates. This also allows for the placement of flow and treatment controls at any location in the collection network or drainage system where existing infrastructure, available storage, available land, or residual pollutant removals are advantageous.
- A flow control option of the WWETCO valve includes a semicircular rigid section built into the bottom of the flexible membrane for pass-through low flows. The low-flow passageway allows a base flow at all times, either for sewage transport in a combined sewer, or for aquatic biology passage for a natural waterway. For wet weather flows above the base-flow capacity, the flow control reacts in the same manner as described above to divert (if desired), to attenuate optimizing available upstream storage, and to bypass excess flows and has the same self-cleaning ability. The WWETCO base-flow control valve can be used for inline collection system storage (CSO program controls) or for inline natural waterway attenuation.
- The same WWETCO flow control (with or without the base-flow option) can be used for combined and sanitary sewer systems, treatment plant equalization or split-stream process control, wet weather treatment facilities or treatment process split-stream control, stormwater piping networks and drainage channels, stormwater dry or wet storage basin control, influent and effluent lake and pond controls, natural stream attenuation controls, irrigation channel level control, stream restoration to maintain water levels and augment groundwater recharge, or for any application in which an upstream water level is to be maintained, flow attenuation is an objective, a diversion or split stream control is needed, and/or a base flow is desired.
- The WWETCO flow control uses a static water level over a flexible membrane to close and seal a stormwater transport conduit providing the diversion of upstream flow, and/or it limits and maintains a maximum upstream water level equal to the static water level over the flexible membrane.
- The WWETCO flow control operates on a simple hydraulic balance between the upstream level and the contained liquid static level to allow excess flow above the available upstream storage volume that is not diverted to treatment to be released pass the flexible membrane.
- The flexible membrane takes on the shape to create the head loss required to maintain the upstream water level and yet pass the excess flow to the downstream level.
- The flow control will pass the peak flow capacity of the transport conduit, at which time the flexible membrane totally inverts to allow full-bore unobstructed flow-through.
- The flow control is simple, unique, requires no mechanical devices or control instrumentation, and requires no maintenance.
- The level control is completely adjustable and can be modified at any time and to any degree within the constraints of the collection network or drainage system topography and acceptable upstream water levels.
- If debris catches under the flexible membrane, the head loss increases correspondingly, and the flexible membrane opens to adjust for the change to maintain the fixed upstream level, and thereby releasing the trapped debris. The WWETCO flow control is self-cleaning and cannot clog.
- The flexible membrane opens from the bottom, with scouring velocities created by the differential pressure and the shape of the flexible membrane, and thereby releasing any accumulated grit and keeping the flow control valve clean of all debris.
- The thick, flexible membrane is to be made with a 5-10 safety factor for ruggedness and is composed of reinforced neoprene or viton, depending upon the wastewater characteristics, to be fully resistant to corrosive environments. The bladder attachments located within the static liquid containment structure will be made of noncorrosive materials and are not exposed to the sewage or stormwater flow environment. The containment structure static water level is maintained by a simple overflow and makeup water supply.
- In most cases, the WWETCO flow control is comprised of a bladder and a simple precast manhole over top of an existing conduit, of which the bottom half is used in the flow control (the top half of a pipe section is horizontally cut on two sides and lifted off). A poured concrete bench embeds the bladder attachment frame, making up the completed containment structure. The costs for technology implementation are size dependent, but are expected to be very competitive.
Supplemental Keywords:
small business, SBIR, EPA, stormwater, flow control, wastewater management, bladder, head, wet weather flows, valve, combined sewer overflow, CSO, drainage system, aquatic biology, waterway attenuation, membrane,, Scientific Discipline, Water, TREATMENT/CONTROL, Wastewater, Wet Weather Flows, Ecology and Ecosystems, Engineering, Chemistry, & Physics, Environmental Engineering, Urban and Regional Planning, Water Pollution Control, wastewater treatment, urban runoff, stormwater, aqueous waste, combined sewer overflows, flow controls, wastewater discharges, flow monitor, sewage, control technologies, stormwater runoff, aqueous waste streamSBIR Phase II:
Stormwater Flow Control Device | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.