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A pump screen that relies on the sweeping flow of the water way to clean debris off the screen. This type of screen is not recommended unless conditions prevent a self-cleaning pump screen from operating properly. Shallow water depths at the pump site are a common justification for using a passive pump screen. Passive pump screens are only allowed when diverting less than 3 cfs.
A screen that is attached to the intake of a pump. There are a number of different mechanisms used to actively remove the debris. The two most common types are as follows: 1. The pump screen rotates around a fixed water nozzle installed inside the screen that sprays debris off the screen. 2. The screen material is fixed in place and water nozzles installed inside the screen rotate within the screen. Material is removed from the screen as the water nozzles spray water at the screen while rotating around to cover the entire screen surface area.
A common screen type that uses the water current to power the rotation of a drum to clear debris and maintain effective screen operation. Site must have sufficient water current to turn the paddle wheel and a consistent water depth to appropriately size and place the drum screen. Shallow water levels at the screen will prevent it from cleaning properly and if water depth increases above the screen design, fish may get over the screen and lost down the ditch. This screen type will pass debris over the screen and down the diversion ditch so it is not generally preferred for municipal water diversions or sites that feed sprinklers due to the presence of debris in the source water.
A common screen type that uses solar power to rotate the drum screen to clear debris and maintain effective screen operation. Appropriate screen submergence is still necessary for the drum to clear debris without allowing fish over the drum. This screen type will pass debris over the screen and down the diversion ditch so it is not generally preferred for municipal water diversions or sites that feed sprinklers due to the presence of debris in the source water. This screen type is generally utilized in areas that are appropriate for a rotary drum screen but do not have enough current to drive a paddle wheel cleaning mechanism. The solar power source is only operable in areas that have sufficient sunlight.
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Traveling belt screens are an effective screen for sites that expect to have a wide range of water depths at the screen site through the period of use. This screen is not as sensitive to water depths as the rotary drum screen. This screen type is generally more expensive than rotary drum screens. Traveling belt screens usually pass debris down the canal but can be modified to collect debris on the back side of the screen and reduce the amount of material in the water delivered to the place of use.
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Vertical panel screens direct the debris and fish towards the bypass and back into the source stream. Water is diverted to the user without the debris load present in systems that use a rotary drum or traveling belt screen. Municipal and sprinkler irrigation operations benefit from the reduced debris load that is provided by a vertical panel screen. These screens usually have one or more wiper brushes that travel along the screen to remove debris which maintains maximum fish protection and water delivery to the user.
The horizontal screen operates with no moving parts and is substantially self cleaning, typically resulting in less maintenance. Water flows over the screen surface, allowing fish and debris to pass quickly over the screen and back to the river or stream, while a portion of the water moves slowly through the screen. This screen works well in high sediment and high gradient systems. This screen does require at least one foot of elevation differential and adequate by-pass flow. If by-pass flow is not available, or there is not atleast a foot of elevation to work with then this screen is not appropriate for the site. This patented screen technology is available through the Farmers Conservation Alliance (FCA) of HoodRiver, OR.
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