Self-Cleaning Coandă Screen Deposits Boardman Canal Debris in Dumpsters

As part of the Gold Run improvements, Bennett Engineering Services developed three design alternatives for screening raw water from PCWA’s Boardman canal at the Monte Vista Water Treatment Plant (MVWTP) and one intake alternative at the Monte Vista Spill (MVS).

Ultimately the team designed a self-cleaning Coandă-effect screen and structure system for the pipeline intake at the MVWTP.  The resulting screen is designed to pass 100% of the flow, has 1mm openings, and is self-cleaning.  The need to pass 100 percent of the flow is an important design consideration.  Typically Coandă screens are designed to pass a small percentage of flow with the flow not passing the screen used to flush debris and sediment from the screen to achieve a self-cleaning effect.  The structure was designed to handle 52 cfs in anticipation of the agency acquiring more water rights but is capable of operating down to below 6 cfs.  Debris collected is deposited by gravity into dumpsters.

The design included fitting the facility within the existing Monte Vista Water Treatment Plant site.  Development of the design involved discussion with several operators of existing Coandă screens and use of the US Bureau of Reclamation design criteria as modified for 100 percent flow passage.

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