The Clarifier Research Technical Committee’s draft protocol for evaluating secondary clarifier performance was field applied at the San Jose Creek Water Reclamation Plant, owned and operated by the County Sanitation Districts of Los Angeles County. The test clarifier was a rectangular unit measuring 45.7 m (150 ft) long by 6.1 m (20 ft) wide; the test clarifier’s floor sloped at 1% with an average depth of 3.0 m (10 ft). Sludge collection flights traveled co-currently with respect to the flow through the test clarifier. Accumulated sludge transported by these flights were discharged into two hoppers located at the clarifier’s effluent end.