I thought this might be of interest to folks on Eng-Tips:

Storm Water Challenge: Flow Restrictor Design

The Chicago Department of Water Management seeks designs for the next generation of Flow Restrictors to be installed in catch basins throughout the City sewer system. Flow Restrictors allow stormwater to temporarily pond on the street reducing sewer surcharges and flooded basements. The City is looking to improve upon the current Flow Restrictor, Vortex Restrictor, being used in residential catch basins.

This is an public crowdsourcing challenge. The Chicago Department of Water Management is using this innovative, open-source approach to:

* Encourage participation through a global network of engineers, problem solvers, and institutions (Universities, etc&Forged Steel Valves).
* Maintain transparency throughout the design, evaluation and procurement process.
* Minimize design and development costs by condensing the overall design timeline and required administration.
* Emerge with a product that meets all design specifications.

The Challenge includes $10,000.00 to each design that scores high enough for prototype development. The development of the prototype will then be field tested and one will be selected for a sole-source contract for the winning design team to supply the restrictors (est. $3-10M). Submissions will be received from across the globe and scored by the City of Chicago.

Chicago has a combined sewer, and they already restrict flows with a restrictor.  They are searching a new design, one which has lower maintenance, ie less clogging.
The restrictor is located in the catch basin, and thus has no interaction with sewage.  Freezing has not been a problem, as the detention time is short ~ 4 hrs, furthermore, there are few storms or snow melts that produce enough flow where it gets restricted to the point of ponding.  I suggest you give the crowd source a chance, or at least see if it generates better design/more innovation and thus an improved environment.

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