Long Beach Municipal Urban Stormwater Treatment Project – Diverting and Treating Urban Runoff for Compliance and Water Supply Augmentation
The Long Beach Municipal Urban Stormwater Treatment (LB-MUST) Project is a an ambitious, comprehensive, and innovative project that will intercept and treat dry weather runoff and a percentage of the first-flush storm flows generated within the City of Long Beach prior to discharging to existing storm drain outfalls flowing into the Los Angeles (LA) River. In other words, the project will connect the drops of water from several pump stations and treat them with limited discharge to the sea. The LB-MUST facility is not a traditional solution to water quality treatment, but instead represents a creative and innovative regional approach, which has the financial backing of Caltrans and the San Gabriel and Lower Los Angeles Rivers and Mountains Conservancy.
The City of Long Beach is a highly-urbanized municipality and the dry weather runoff and stormwater runoff generated within the City is collected through a complex system of storm drains and pump stations with a total tributary area of approximately 29,980 acres. Approximately 41% of the City’s watershed area (12,200 acres) discharges through outfalls on both east and west sides of the LA River and Estuary. Most of the City’s urban drainage systems are older facilities originally designed for flood protection but no treatment.
Water quality standards are governed by the municipal National Pollutant Discharge Elimination System Permit, which includes Total Maximum Daily Loads. The LB-MUST facility will assist in the compliance with the Permit requirements and provide the opportunity as a source for alternative water supply. Intercepted flows from different locations within the City’s watersheds will be collected and diverted to a centralized downstream advanced treatment facility. A portion of the treated water will be used for non-potable irrigation of City parks and to create wetlands. Additionally, the Project will incorporate educational features to inform the public of the Project benefits.
The LB-MUST facility will be able to treat non-brackish and brackish influent flows separately, without blending at any stage in the process train. The treatment plant will have an initial capacity to treat 2 million gallons per day (mgd) and a future capacity of 4 mgd. The state-of-the-art technology chosen is an integrated treatment system consisting of ceramic ultrafiltration (CUF) and Photo-Cat Ultraviolet Advanced Oxidation (UV/AOP). This system will treat urban runoff of total suspended solids, turbidity, oil and grease, metals, pathogens, and dissolved organics. CUF is a robust silicon carbide ceramic membrane with proven performance and represents a quantum leap forward in water purification. The CUF has no pretreatment, no filtrate loss, and will last 25 years. Photo-Cat is a high performance, sustainable, water purification technology that provides low lifecycle costs to destroy dissolved chemicals such as pesticides. The ancillary processes include process pumping, process storage tanks, chemical feeding, and air supply. A pilot study was conducted to evaluate the efficacy of the treatment processes. The facility will also provide educational elements including hands-on classroom opportunities, as well as guided public educational tours of the treatment plant processes and external LID features.
Wetlands will be constructed next to the treatment facility to provide additional treatment/water polishing following the treatment facility and will be a landscape amenity.
Project engineers selected this technology because it will provide the City of Long Beach with many advantages:
• Sustainable – extreme reduction in chemicals
• Robust – durable technology that will last over 25 years
• Secure and Safe – no open vessels or odors
• Simple – no pretreatment required
• Able to treat highly variable contaminants/concentrations
• Treats wide range of flow rates
• Handles both brackish and non-brackish water
• Automated – can be operated remotely