New landscape strategies can save water, create healthier environments and help owners meet stormwater management requirements.
Communities around the country are imposing stricter regulatory requirements on stormwater, forcing building owners to find better ways to manage water on site. In most areas of California, codes now require that they develop and implement a stormwater management program to reduce the discharge of pollutants to the “maximum extent possible.”
“The regulations are changing the game and creating more challenges for owners,” says LPA Director of Landscape Architecture Kari Kikuta. “We really need to be creative in our stormwater design approaches.”
New ideas and strategies, developed in collaboration with different disciplines—including civil engineers and environmental experts—can save money and turn the regulations into a guide map for a better project. A properly designed Best Management Practices (BMP) plan for managing stormwater can reduce flooding and associated property damage, decrease pollution and protect the site’s landscaping. The multidisciplinary approach weaves stormwater management into the core of the project, finding passive, green strategies that can save money in both the short- and long-term.
In the past, “stormwater systems and the landscape framework were often treated separately and independent from each other,” says LPA Principal Keith Hempel. “Mechanical solutions were used when a more thoughtful approach could have avoided unsightly and expensive systems.”
An Early Start
“It’s important to start the stormwater discussions early with the integrated team prior to establishing the site and building design,” says Kathereen Shinkai, LPA’s Director of Civil Engineering. Stormwater and landscape options become much more limited once the building has already been sited and designed. “Being part of the process from the very beginning makes a huge difference,” Shinkai explains. “We know all the project constraints and can go over everything as a team.”
For Tarbut V’Torah (TVT) Community Day School in Irvine, California, the stormwater discussions were interwoven with the educational and architectural campus goals. The design process began with key questions: What amount of stormwater do we need to treat? Where should the stormwater retention be located? What kinds of plants could be used? How deep do we want the biofiltration area to be?
Ultimately, the team used a design that manages and directs water into infiltration basins seamlessly incorporated into the surrounding landscape, and a 400-square-foot green roof.
In addition, the site embraces the stormwater and landscape design as a teaching tool. Signage in strategically-placed locations demonstrate how all of the roof rainwater is captured and directed by steel plate scuppers into concrete rain wells and how a green roof connected to a bio-detention basin treats the stormwater and recharges the aquifer.
Similarly, at Los Angeles Valley College Monarch Center in Valley Glen, California, the stormwater design doubles as an educational space, highlighting the path and flow of the rainwater. Starting from the roof and spilling down to the ground, students can witness how it flows through a bioswale, boulders, cobbles and mulches until it reaches a detention basin.
“The design demonstrates to the students an ideal way to use the stormwater to irrigate the plants, soak into the ground and recharge the soil, as opposed to putting it in a pipe and getting it off site and into the ocean as quickly as possible,” explains LPA Director of Landscape Architecture Rich Bienvenu.
For projects where stormwater management education is not necessarily a focus, building owners are looking to camouflage the stormwater systems to the greatest extent possible. For Pitzer College in Claremont, California, a large open area slated for later building development was turned into a beautiful garden with trees, cacti, plantings and stone. The area doubles as a social gathering space and garden walkway from the dorms to the classrooms. Permeable paving and soils naturally absorb the rainwater with no need for mechanical equipment.
“We’re creating people spaces,” Kikuta says. “We want them to experience the environment and not know that these systems actually exist.”
The Big Picture
In many ways, stormwater management can’t be efficiently approached as an isolated element of the design. For the recent design of the Edwards Lifesciences headquarters in Irvine, California, the potential for construction-related disruptions and new State of California Water Resources Control Board requirements were all part of the planning mix. The designers collectively evaluated a number of considerations, including the local climate, site topography, quality of the soil and the space available for stormwater retention and/or detention.
With a larger campus to work with, the team ultimately selected modular wetlands, a bioswale system, biofiltration and a vegetated façade to accomplish the dual purpose of managing stormwater and displaying a sustainable and lush, green campus. At 3,500 square feet, the façade is believed to be California’s largest living wall installation. In addition, two 30,000-gallon stormwater tanks were installed—the first in Irvine.
Civil engineers and landscape architects collaborated to determine exactly how the bioswales would work, sorting through key questions such as how much space would be required to support the system, how much water needed to be cleaned and what kinds of plants could be sustained in that environment.
In other cases, constraints on space play a key role. For St. Junipero Serra Catholic School in Rancho Santa Margarita, California, there was a small footprint available to comply with the required predevelopment stormwater flow rates. A drywell and precast concrete storage system were selected as the best way to access the deeper soil strata with infiltrating characteristics. The drywell treats the water while the hydromodification storage slowly releases the stormwater to the site, thereby meeting local regulations.
A Long-Term Approach
As part of the increased focus on stormwater management, LPA conducts extensive post-occupancy evaluations (POE) of projects. While the tendency is to want to move on to the next project, “we are taking a more formal post-occupancy process embedded into our projects,” Shinkai explains. “We are designing and constructing projects, but sometimes we need to step back, and go back to the project sites and make sure they’re working the way they are supposed to be working.”
The POEs often reveal surprises and areas for improvement. For example, research shows that designing and installing the system is not enough—training and a continuing education process for the client are essential to make systems effective. In some cases, facility managers are not aware of the system operations/maintenance and how to keep them working efficiently.
Ultimately, evaluating the performance once a project is up and running ensures the systems are operating at high level and owners are reaping all the potential benefits. The process also informs future projects, making sure innovation and lessons learned are part of the design discussion.
This story originally appeared in Catalyst Issue 3 2019. Subscribe today to receive Catalyst, a quarterly publication that takes a deep dive into design ideas, industry leaders and initiatives.