Puente Hills Regional Park and Hilda L. Solis Environmental Justice Center

Puente Hills Regional Park and Hilda L. Solis Environmental Justice Center
Cultivating a Sustainable, Resilient Park for All
Puente Hills Regional Park (PHRP) will transform what was once the second-largest landfill in the U.S. into Los Angeles County’s first new regional park in 30 years and the site of its first-ever Environmental Justice Center. This regenerative project aims to heal the multi-generational impacts on those living near the landfill and empower the community with a design that demonstrates and fosters impactful environmental stewardship.
Our multidisciplinary design team is leading the architectural and engineering efforts, including solid waste engineering, in close collaboration with LA County's Department of Public Works, Parks & Recreation and the Sanitation Districts.
Landscape and Architecture as Change Agents
In Phase One, the Hilda L. Solis Environmental Justice Center (EJC) embraces regenerative building design within a restored, native landscape. A large interactive exhibit and an active learning center enhance the experience and communicate the value of all visitors — humans of all ages, wildlife, rescued raptors and native plants.
New public transit, a park shuttle, school bus and rideshare drop-off, parking, pedestrian, bicycle and horse trails emphasize accessibility and welcome. A central rotunda connects visitors to an immersive exhibition, classrooms, a makerspace, a lecture hall, an outdoor amphitheater, a media studio and a special enclosure to meet “animal ambassadors.”
The EJC serves as a teaching tool, demonstrating the best of today’s sustainable practices and rethinking waste through recycling, composting and salvage with a focus on healthy building strategies and utilizing the native landscape. The design is on target to achieve LEED Gold, net zero energy (operational carbon), a 50%+ reduction in embodied carbon and a 50% reduction in potable water consumption.
A Landfill is Always a Landfill
Since the landfill’s closure in 2013, the LA County Sanitation Districts have maintained the site in accordance with their state-approved closure plan, featuring a well-protected clay soil cap and a gas collection system that captures methane to generate electricity and reduce greenhouse gas emissions. All the Phase One buildings are intentionally located on native soil, but they are still within proximity of the buried waste. HDR developed a multifaceted mitigation system with membrane barriers, a passive venting system and continuous monitoring systems to protect all occupants within enclosed spaces.
Initially cautious about opening the site to public access and landscape, the Sanitation Districts were reassured by HDR’s solid waste management expertise and recommendations. Through careful regrading and selective soil placement, the team demonstrated it was possible to protect sensitive infrastructure, safely plant new trees and provide accessible routes and recreational areas in Phase One and beyond.
The next phase of the park will focus on passive, nature-oriented recreation atop the closed landfill, which continues to settle at rates ranging from one to five inches per year.
Key Design Consultants: OJB Landscape Architects; Hunt Design – Exhibits and Signage
