The City of Los Angeles Department of Public Works (DPW) Bureau of Sanitation (SAN) is expanding Terminal Island Water Reclamation Plant (TIWRP) Advanced Water Purification Facility (AWPF). The AWPF Ultimate Expansion will increase the advanced water purification treatment of tertiary effluent from 15.77 m 3 /min (6.0 mgd) to 31.55 m 3 /min (12 mgd), which will be delivered to other areas of need throughout Los Angeles. The AWPF Ultimate Expansion will include an additional microfiltration (MF) and a reverse osmosis (RO) system. Advanced oxidation process (AOP) system will be implemented for the new facility and replace the existing chloroamination disinfection process. A 7,570 m 3 (2.0 mg) tertiary effluent equalization tank upstream of the AWPF and a set of upgrades to the existing pumping stations and chemical addition system and utilities are also included in the project (Figure 1). The additional purified water will be distributed to Dominguez Gap Barrier, Machado Lake, Harbor Generating Station, Harbor Irrigation, and industrial users ( Figure 2). The reclaimed water will replace the potable water and reduce the need for potable water imported/provided by the Los Angeles Department of Water and Power (LADWP).Candidate processes for primary disinfection and removal of organic contaminants of emerging concern (CECs) include commercially available AOPs used in the treatment of drinking water and in indirect potable reuse: peroxone (O 3 /H 2 O 2 ), photolysis of hydrogen peroxide (UV/H 2 O 2 ), and UV/NaOCl. The UV/NaOCl AOP process configuration was included due to a secondary disinfection requirement for the distribution system, with chlorine residual in the 2-3 mg/L range in the distribution. This paper focuses on the TIWRP AWPF water quality matrix, evaluation of candidate AOPs through bench-and pilotscale testing, AOP selection, and the key process design criteria that were developed to meet the California Department of Public Health (CDPH) Groundwater Replenishment Reuse Regulations (GRRRs; CDPH, 2014). GOALS AND OBJECTIVESIn potable reuse, the AOP technology has historically been a low pressure UV system and a major driver for that technology choice was a requirement for 1.2-log of NDMA removal in the 2008 Draft of the California Department of Public Health (CDPH) Groundwater Recharge Regulations (GRR). As a result, WEFTEC 2014Copyright ©2014 Water Environment Federation 2736 2 | P a g e the UV equipment supplier maintained much of the industry's AOP expertise. As industry becomes more knowledgeable on the application of AOP in potable reuse, opportunities for different AOP technologies have emerged that may yield cost savings and this has been fortified with the elimination of the requirement for 1.2-log of NDMA removal in the 2013 Draft CDPH GRR. With this context, the primary goal was to select the most effective AOP for the TIWRP AWPF water quality matrix and implementation for the AWPF Ultimate Expansion including migration of existing disinfection (chloramination) to AOP/disinfection through bench ...