Los Angeles SoFi Stadium Stormwater Management and Water Recycling

Inglewood, CA

PACE completed mechanical and water quality design for the multi-purpose 5-acre lake at Hollywood Park, the new SoFi Stadium site. The lake serves as the site’s central stormwater management system and includes state-of-the-art water conservation and recycling features, making it among the most advanced integrated lakes in existence.

The lake incorporates many advanced features to enhance water resource management at the site, including:

• The lake serves as a stormwater treatment system for much of the stadium and entertainment district, controlling pollutants and peak discharges to the environment.
• Recycled wastewater and stormwater are integrated seamlessly within the lake and fed into an on-site irrigation system.
• During dry weather, recycled water obtained from West Basin Water District serves as the supply source for lake make-up water. An on-site treatment system provides further treatment of the recycled water using an innovative ion exchange with zeolite treatment system before the water enters the lake.
• The lake water irrigates the surrounding site, eliminating the need for potable water use in irrigation.
• The lake serves as a short-term flood attenuation basin, reducing pre-existing flood risks downstream of the project site.

The combination of reclaimed water and stormwater in this lake system represents a first of its kind in California. Current permitting regulations are not set up to address this water resource management approach. Therefore, the lake’s stormwater discharge required a unique and lengthy permitting process before an individual National Pollutant Discharge Elimination System (NPDES) stormwater discharge permit for the lake was approved by the Los Angeles Regional Water Quality Control Board in June 2020. This permit authorizes the discharge of excess water from the lake during storm events, which will consist of a mixture of recycled water and stormwater. The individual permit represents a step forward for water recycling and illustrates the need for permitting rules to advance as technology advances.

Advanced Recycled Water Treatment System

A 200-gallon-per-minute recycled water treatment process was developed to improve the existing Title 22 rated effluent quality proposed for use in the lake system, saving approximately $1.5 million in capital cost (30%) compared to a previously proposed membrane treatment system. The recycled water source contains high levels of odorous ammonia, which colors water, is toxic to aquatic biology, and creates other water quality problems. The recycled water also contains high phosphorus levels, which could cause high levels of nuisance algae, turning the water green and turbid.

A custom treatment solution was pilot-tested to demonstrate its effectiveness. The treatment system consists of ion exchange with zeolite, alum, and filtration to support phosphorus removal. Within the lake, the water is continuously recirculated and treated with ozone and additional alum. The lake and treatment system supports the lake make-up water needs and irrigation for the stadium property. Additionally, the system may be used for other non-potable water demands such as toilet flushing, cooling towers, and evaporative coolers in the future.

Key Features:

• Lake stormwater treatment system for much of the stadium and entertainment district
• Recycled wastewater and stormwater are integrated within the lake
• Lake obtains recycled water from West Basin Water District during dry weather
• On-site treatment system for further treatment of the recycled water
• Lake water irrigates the surrounding site
• Lake serves as short-term flood attenuation basin, minimizing flood risks