Commencing in 2004, Brown and Caldwell worked with the Orange County Sanitation District (OCSD) to implement a 227 million liters per day (MLD) (60 million gallon per day [mgd]) average dry weather flow (ADWF) secondary treatment process for their Plant 2 in Huntington Beach, California. As part of this project implementation, Brown and Caldwell and OCSD performed process modeling under various operational and flow split scenarios and evaluated process and equipment options on a life cycle basis to achieve the most reliable and cost effective process for the given NPDES permit requirements. This paper describes the evaluations, process modeling, and attention to design detail that resulted in a project that consistently produces effluent quality well within permit requirements, operates over a very wide flow variation, and consumes a fraction of the energy used by comparable secondary treatment processes.