New Park launches green space model through sustainable designs

The inspiration behind Earvin “Magic” Johnson Park was to transform a widely used community park into something more sustainable, including the use of storm water treatment systems

The award-winning Earvin “Magic” Johnson Park is a 126-acre park located in the South Los Angeles community of Willowbrook – the largest open space in the area. Renovation of this park began in 2014 when multidisciplinary design and planning firm MIG drew up the full concept plan to show what a full makeover could look like, including new leisure facilities and innovative approaches to sustainability. some water. With Phases 1A and 1B of the Magic Johnson Park Revitalization Project complete, the park is hailed as the Gold Star for Sustainable Park Design.

The $83 million Phase 1A, which opened in January 2021, demonstrated the latest technology in stormwater treatment systems. The project diverts and captures runoff from the community’s 375-acre watershed, which is part of the larger Compton Creek watershed. Stormwater is then treated by a process system including natural biofiltration through attenuated wetlands surrounding one of the park’s two lakes. Treated water is stored in the two lakes and reused for on-site park irrigation. The freshwater marsh also creates important habitat for resident and migratory birds, insects, and other urban wildlife. This technology, combined with existing lakes, enables the capture, storage, treatment and recycling of water and acts as a catalyst for urban greening and meaningful outdoor space throughout Southern California.

Prior to the renovation, the park used 100% potable water for landscape irrigation and to fill the two existing artificial lakes. To minimize the use of potable water, the park was redesigned in conjunction with the Los Angeles County Development Authority, Los Angeles County Department of Parks and Recreation, and Los Angeles County Public Works. Angeles to provide a new sustainable water source using unique stormwater management. watershed runoff recycling system. This system captures urban and stormwater runoff (wet and dry weather flows), treats the captured flows, and then fills existing lakes, while improving water quality in Compton Creek, the Los Angeles River, and the the Pacific Ocean.

How does the stormwater system work

So how does it work? The first wet weather flow out of the Compton Creek watershed is first captured by a stormwater diversion structure, which was built to tap into an existing 84-inch-diameter storm sewer maintained by the works. Los Angeles County public. This storm sewer diverts flows of up to 33 cubic feet per second (cfs) to a new pump station that sends the flows to a new treatment facility at the park. The water is then treated and discharged into constructed attenuated wetlands surrounding one of the park’s two lakes. Treated stormwater fills the two lakes totaling 15 acres and is then used to irrigate the park. It is estimated that the park’s irrigation demand can be met by storm sewer diversion flows for a significant portion of the year, amounting to approximately 7 acre feet (2.3 million gallons) of flows from a significant wet weather event.

A pump recirculates water from the North Lake (low elevation), through the treatment plant at approximately 2,500 gpm, to the South Lake (high elevation), to the creek and back to the North Lake. This provides a horizontal circulation system to avoid stagnation in the two lakes. This also helps maintain water quality and ensures the flow of the aesthetic stream between the two lakes. The processing facility also includes irrigation and splash guard wet wells, irrigation and splash guard pump skids, filters, oxygen generator and chemical storage rooms .

This stormwater management system also improves water quality by removing heavy pollutants, such as bacteria, oil, excess nutrients, metals and waste that would otherwise have made their way to the Pacific Ocean. via Compton Creek and the Los Angeles River. Runoff streams are treated with aluminum sulfate (alum) for coagulation and sedimentation with an in-line static mixer, dye to reduce photosynthesis, and ozone to disinfect pathogens while reducing color and turbidity.

RELATED: San Antonio River Authority Develops Green Stormwater Infrastructure Plan

How wetlands work

Submerged wetland planting areas along the edge of the lake further improve lake water quality through natural physical and biological processes. Treated water from the treatment plant is discharged into boxes distributed around the perimeter of the lake in the planting areas of the wetlands. The sediment particles are then separated from the water by gravitational settling. This process removes suspended solids, particulate nitrogen, oils, chlorinated hydrocarbons and most heavy metals from the water column. The velocity of the water discharged from each box is low allowing sedimentation as the treated water flows through the lake wetland plants. Sediment can be removed from these boxes through regular maintenance and does not accumulate on the bottom of the lake. After the treated water enters the lake, it is returned to the treatment pump station where further treatment takes place.

The Earvin “Magic” Johnson Park not only benefits the environment by improving stormwater quality for existing lakes, but also serves as a stormwater treatment system and landscape infrastructure that both benefits the environment natural and socio-ecological.

Through this project, the restoration of some vital southern California native plant communities, such as Coastal Sage Scrub and Freshwater Marsh Wetland Habitats, has been achieved. The constructed wetland and restored lakes of this project provide important habitats for resident and migratory birds, pollinators, fish and other urban wildlife by providing food, shelter and nesting places. Some of the species that now frequent and nest in the park are the gray heron, black-crowned night heron, red-tailed hawk, and black-necked sloth.

It was also important to integrate and present the stormwater treatment center both as a community amenity and as a facility that will educate future generations about water conservation. Other park amenities include:

  • 20,000 square foot community event center
  • A ½ mile community lakeside loop trail with picnic areas
  • fitness equipment
  • Panoramic viewpoints
  • A children’s playground with paddling pool
  • Outdoor classrooms and educational interpretive graphics telling the environmental story of the park
  • Community social spaces
  • wedding lawn
  • ¾ mile of walking trails
  • South Los Angeles’ first off-leash dog park
  • California Native Habitat Educational Gardens
  • An informal natural amphitheater
  • A flexible community lawn space

stormwater treatment

The importance of an interactive space

The inspiration behind the project was to transform a widely used community park into something so much more: an interactive and vibrant hub of learning, nature and engagement fueled by environmentally sustainable design. It is intended to be a hub for the community to come together, recreate, celebrate and learn.

As prime design consultant through the Los Angeles County Development Authority and Los Angeles County Parks and Recreation, MIG collaborated with more than 20 sub-consultants on the project, including Pacific Advanced Civil Engineering Inc. (PACE), which designed the environmentally sustainable treated stormwater treatment system.

The project closed 2021 with six awards to its credit, including American Society of Civil Engineers Sustainable Engineering Project of the Year, American Society of Landscape Architects Achievement Award – Southern California Chapter and United States Green Building Council Project of the Year – Los Angeles.

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