The proposed $100 million project includes design and construction of three regional interceptors and an expanded treatment plant at the Suburban Sanitary District 1 site. Twenty years of planned growth in the Central Valley Water Reclamation Facility Board (CVWRFB) service area will be provided by expanding present facilities from 57,000 m3/day to 189,000 m3/day (15 to 20 mgd) average annual daily flow (AADF). Effluent quality will be improved to 10-10-5 (BOD5, suspended solids, and ammonia-nitrogen) by addition of the nitrification process and specially designed secondary sedimentation tanks. Design criteria of these and other unit processes of the new regional plant shows on Figure 1 are listed in Table 1. The coupled trickling filter activated sludge process shown schematically in Figure 2 was discussed in last year’s proceedings of the Utah Water Pollution Control Association, April 1980 (Bouey).