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In order to achieve specific levels of turbidity for experiments, a raw water feeder is used. The raw water tank turbidity is monitored with a turbidimeter and clay from the stock tank is added as needed with a pinch valve. The process control file turns on the valve of the clay stock feed whenever the turbidity of the raw water tank drops below the specified level. The valve then remains off until the turbidity drops below the specified level again. 
Procedure for Maintenance of the Raw Water System
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