Vista Hermosa

Challenge

Although the site had numerous challenges, one of the most difficult was the site’s toxic history as a turn-of-the-century oil field. It had never been properly capped and required particular mitigation measures for hydrogen sulfide and methane gases that were present in dangerous concentrations deep below the surface.

Solution

When the site design process began, the design team visited other developments that had successfully mitigated underground gases. The solution involved removing the top 36 in of topsoil, adding 18 in of sand, and then placing 18 in of new topsoil on top. This strategy allows escaping gases to percolate horizontally. By forcing the gases to move more slowly beneath the surface, they are released into the air at lower concentrations that are safe for human exposure. Synthetic membranes and vertical risers are used in venting systems to prevent the accumulation of toxic gases under impermeable slabs beneath park buildings and the cistern as well as in the adjacent school buildings.

• 94% of the park’s surfaces are permeable to allow stormwater to infiltrate and minimize runoff. Pollutants are removed as stormwater is filtered by vegetation, upland bioswales, green roofs and an artificial turf base material before entering the municipal stormwater system. 
• A natural basin holds 100,000 gallons of rainwater and contributes to the retention of 95% of stormwater runoff on-site. The park’s steeply-graded topography directs runoff into the basin, creating a microclimate that supports native riparian species as a result of the concentrated moisture. 
• A 20,000-gallon cistern collects stormwater runoff from the regulation-sized synthetic turf soccer field. It is located underneath the 21,000-sf permeable pavement parking lot. The captured water is used to irrigate planted areas on the site.
• A wide range of drought-tolerant native species were planted throughout the site and organized into 3 specific habitat areas. Riparian species include western sycamore (Platanus racemosa) and white alder (Alnus rhombifolia). Chaparral species include toyon (Heteromeles arbutifolia) and coyote bush (Baccharis pilularis). Coastal species include live oaks (Quercus agrifolia) and deer grass (Muhlenbergia rigens). Non-native, but adapted and non-invasive species like bougainvillea provide seasonal variation and interest.
• Drip irrigation is used to minimize water loss through evaporation, which is inherent in traditional spray irrigation systems.
• A total of 2,576 sf of extensive green roofs were installed on all park buildings, including the park headquarters and restrooms. Species planted include orange sedge (Carex testacea), dune sedge (Carex pansa), stonecrop (Sedum reflexum), and springstar (Ipheion uniflorum). 
• A 0.4-mile trail winds through the park and provides choreographed views of the park and the city skyline beyond.
• Play features inspired by California wildlife include natural boulders, a waterfall and stream, logs, and custom-designed play structures.
• The 120-seat outdoor amphitheater hosts educational, formal, and informal events. 
• Educational signage in English and Spanish explains the stormwater features on-site and highlights a selection of native plant and animal species.
• With its native plants, watershed components, and nature trails, the park serves as a living laboratory providing educational opportunities for school pupils and the community. These features complement the State Science Content Standards for California through after-school and extracurricular programs.
• Regular programming, often in both English and Spanish, by the Santa Monica Mountains Conservancy provides social and educational opportunities for local residents. The park is part of the “Transit to Trails” program, which provides free bus service from the park to the Santa Monica Mountains to give access to residents who would otherwise be unable to visit the large natural areas surrounding Los Angeles.
• The park’s gas mitigation and monitoring systems are in place to detect harmful levels of methane and hydrogen sulfide gases that may be released due to the site’s former use as an oil field.

The history of the Vista Hermosa site is complicated and entangled in the legacy of the landscape of the city and its politics. In 1997, the Los Angeles Unified School District (LAUSD) received $2.4 billion in bonds to upgrade existing schools and build new ones. The park became a part of a negotiation during the school building and brownfield recovery originally referred to as the Belmont Learning Complex. Conceived and designed as part of the $2.4-billion initiative, the project was specifically intended to relieve local school overcrowding and allow students to attend school in their own neighborhoods.

Construction began, but in 1999 noxious methane and hydrogen sulfide gases were discovered on-site and construction was halted. LAUSD began the arduous process of exploring how to manage the site safely, performing more than 30 environmental studies and partnering with the Alliance for a Better Community in 2002 to determine if the site could be safely used. As a part of the environmental assessment, a study determined that the site’s oil reservoir was unlikely to re-pressurize, but it also identified a main fault line and a number of minor faults beneath the site. As it was not possible to determine if they were active or not, LAUSD decided to avoid building directly over them, which required the district to create a new plan.

In May 2003, LAUSD completed a study of alternative plans and decided to explore the feasibility for what was then called Option 4: Vista Hermosa, which included the construction of Central Los Angeles Area High School No. 11 and Vista Hermosa Park. Plans for two buildings that had originally been situated over the faults were canceled, and a seismic setback buffer zone was established.

While LAUSD maintained control and oversight over the school facilities on the eastern part of the property and would have priority use of certain areas of the park and the soccer field during school hours, the park was to be open to the public. The district looked to local partners to develop and manage the adjacent proposed park as part of its effort to improve not only educational opportunities but also surrounding communities.

LAUSD partnered with the Mountains Recreation and Conservation Authority (MRCA)*, a joint powers authority with the Santa Monica Mountains Conservancy, to fund, construct, operate, and maintain the park through a long-term lease and joint use agreement with the district. Furthermore, the MRCA would provide three types of educational programs: school class programs, extracurricular after-school programs, and family and community programs. The district also formed a second partnership with the Stuart M. Ketchum Downtown YMCA to fund, construct, and manage the soccer field.

A gas mitigation and monitoring system was installed to ensure the continued safety of the site, and a 50-ft buffer was established over the fault lines where no structures could be erected. Through extensive research, modification of the original plans, and partnership with local organizations, LAUSD successfully negotiated the design and implementation of a full community-benefiting educational project on a geologically and historically challenging site.

*MRCA was established in 1985 to create and maintain parkland and preserve open space within the Santa Monica Mountains and other areas of the Los Angeles region. In addition to operating all Conservancy parks, the MRCA provides acquisition and legal services, planning and natural resources expertise, operations and ranger services, construction and special event services, and education and interpretation programs.

Vista Hermosa has an annual operating cost of $199,000, or $20,947 per acre. Nearby Echo Park, a more traditionally designed park that was renovated from 2011 to 2013, has an annual maintenance cost estimated at $1.2 million, or $44,927 per acre. This is $23,980 or 114% more per acre annually than Vista Hermosa. 

• Maintaining the green roofs on site has been challenging, and it has been particularly difficult to keep the sedums alive. The plants have struggled and require extra irrigation and care. Since the park as a whole is designed to minimize water use, a roofing solution that incorporated water harvesting might have been a more appropriate selection. 
• Permeable concrete paving in the parking lot requires vacuuming to clean dirt and natural debris from the spaces between the aggregate. The Santa Monica Mountains Conservancy does not own the necessary maintenance equipment; consequently, proper upkeep is often done behind schedule, and the pervious paving is not optimally functional. Planning and budgeting for this aspect of maintenance would likely have resulted in improved functioning of the material. 

Custom Turtle Play Sculpture: Cemrock
Custom Snake Play Structure and Concrete Slide: LA Engineering
Custom Art Fence: Brett Goldstone
Drinking Fountain: Canterbury International
Benches: Victor Stanley
Waterfall Boulders and Decomposed Granite: KRC Rock
Irrigation: Rainbird; Hunter
Soccer Goals: Porter Athletic Equipment Company
Organic Compost: Earthworks
Concrete Unit Masonry: Angelus Block Company
Modular Green Roof System: Green Grid Roofs
Cistern: Invisible Structures, Inc

Project Team

Owner: Los Angeles Unified School District, City of Los Angeles
Client: Santa Monica Mountains Conservancy, Mountains Recreation Conservation Authority, State of California 
Additional Oversight: Division of State Architect, State of California, Los Angeles Unified School District
Landscape Architect: Mia Lehrer + Associates
General Contractor: Los Angeles Engineering
Civil/ Structural Engineer: KPFF Inc.
Electrical Engineer: M-E Engineers
Architect: ERW Design
Irrigation: Sweeney + Associates
Pond Consultant: EPD Consultants
Methane Mitigation Engineers: SCS Engineers, Meredith & Associates Inc.
Construction Specifications Consultant: Jerry Orland
Cost Estimating: C.P. O’Halloran Associates Inc.
Gate and Fencing Artist: Brett Goldstone Inc.
Public Art (signage, etc.): Art Share

Role of the Landscape Architect

The landscape architect began the process by working with the community and developing the site features from their explicit needs, rather than imposing an expected recreational itinerary. The landscape architect worked closely with the client to understand how specific needs for the park fit into the larger agenda of the parks program of the Santa Monica Mountain Conservancy. Sub-consultants with complementary experience were assembled to create a team that could overcome the complexities of the site, including methane gas mitigation and irrigation needs.