City of Santa Monica, CA
PACE was responsible for the design of the Advanced Water Treatment Facility (AWTF), which is a key component of the City of Santa Monica’s Sustainable Water Infrastructure Project (SWIP). The AWTF treats a combination of raw wastewater and harvested stormwater, producing 1.0 MGD of purified water for groundwater augmentation. The facility is one of the first to take in raw wastewater and stormwater, fully oxidize the stream via biological treatment, and provide the pathogen reduction requirements to meet California Title 22 regulations for Indirect Potable Reuse (IPR) of 12 log virus, 10 log cryptosporidium, and 10 log giardia all within one facility.
The treatment process consists of a five-barrier stream: membrane bioreactor (MBR), cartridge filtration, reverse osmosis (RO), ultraviolet advanced oxidation process (UVAOP), and chlorine disinfection. The facility is the first to receive pathogen credits through the MBR and cartridge filtration processes by being deliberate in the selection of the equipment and design of the systems to remain within certain operating envelopes. The RO uses Total Organic Carbon (TOC) as a surrogate parameter to measure pathogen reduction, which allows a higher pathogen reduction value to be claimed than typical conductivity values. UVAOP uses free chlorine as the oxidant to reduce the number of chemicals required on-site, with residual chlorine providing downstream process benefits for chlorine disinfection.
The AWTF is situated in a highly urbanized area and is a completely subterranean facility located underneath the City’s Civic Center parking lot. The first level below ground serves as the mechanical treatment area that houses the process equipment. The second level below ground serves as the process tanks, including MBR tanks, filtrate storage, chlorine contact tank, and purified water clearwell.
SWIP protects Santa Monica Beaches by harvesting the polluted stormwater, which would otherwise reach the Santa Monica Bay, by reducing the discharge of polluted stormwater from the Pico-Kenter Outfall to the Santa Monica Bay. SWIP will significantly improve the beach water quality, resulting in cleaner and healthier beaches, an enhanced visitor experience, and move the City closer to compliance with the National Pollutant Discharge Elimination System (NPDES) permit.