The Flow Equalization Tanks (FQ Tanks) consisted of two 4 million gallon concrete tanks below grade. The existing plant could receive flows as high as 160 MGD of raw sewage and low flows of 100 MGD. The goal for the Sanitation District of Los Angeles County was to maintain a consistent flow averaging 130 MGD. The FQ Tanks are used to store primary effluent coming from primary treatment tanks during the high flows and will later be cycled through during the low flows back into the primary treatment tanks. The construction for the FQ Tanks included excavating and hauling the excess dirt offsite, beam and lagging shoring with tie-backs, structural concrete, mechanical pipe and associated equipment, and an odor control system.