Each clarifier is 117 feet square and 20 feet deep and is capable of treating up to 23 million gallons of water per day. Source water is dosed with aluminum sulfate coagulant as it flows into the center recirculation drum where it is mixed with solids brought up from the bottom by the turbine. As the recirculated solids and aluminum sulfate are slowly mixed flocculation occurs. The flocculation process continues as the water flows out of the recirculation drum and is forced downward by the reaction well hood .
Sedimentation begins as the floc particles reach the bottom of the reaction well hood.
This blanket helps filter out the floc particles that are too light to settle. These rakes also have sludge inlets which collect solids for recirculation. The sludge that is raked into the center trough is removed periodically through the underflow pipes. Air injection and the air torque drum are for emergency use when the turbine fails. The last time they were used was during the Loma Prieta Earthquake when 3 of the 4 clarifiers were damaged due to wave action created by the earthquake.