Frontier Project

Challenge

The design team sought to create a sustainable landscape which not only would inspire, inform, and instruct visitors on how to incorporate energy efficient and water-wise design into their homes and workplaces, but that could capture, treat, and reuse or infiltrate all stormwater runoff on site. Additionally, the planting palette needed to contain species that were low-maintenance and drought tolerate, yet visually engaging, so as to dispel the myth that drought-tolerant California landscapes must look like a desert. An added challenged for the planting design was to use plants that could be readily available to residents for purchase at local garden centers.

Solution

Inspired by the indigenous eco-tones of the Cucamonga Valley Watershed, the landscape contains a variety of climatically adapted succulents, grasses, shrubs, and trees that also provide habitat to local insects and birds. To capture and treat all stormwater runoff on site, the design team created a treatment train. A green roof, rain garden, and cobble swale collect rainfall and direct runoff into an underground cistern where it is stored and used for irrigation. Excess water flows into an overflow infiltration basin made of gravel-filled structural cells. Descriptive signs across the site educate visitors about the many sustainable features on display, including plant names.

• Stormwater runoff from the rooftop and grounds is directed into a 2,000 gallon rainwater cistern buried beneath the site’s water-less demonstration garden. When full, the cistern can theoretically supply all of the site’s irrigation needs for 2-4 weeks (depending on the season), thereby reducing the amount of potable water needed for irrigation.
• A rain garden and cobble swale direct runoff into drains connected to the underground cistern.
• When the cistern is at full capacity, excess water overflows into an adjacent 50,000 gallon sub-grade infiltration basin made of gravel-filled structural cells that allow the water to slowly percolate into the ground and recharge the groundwater.
• 7,154 sf of porous paving and decomposed granite walkways promote infiltration and groundwater recharge.
• The site is planted with 19,594 sf of native and naturalized plantings, which were chosen for several environmental and aesthetic factors, including: low-irrigation requirements, low-maintenance requirements, resiliency to both drought and flooding, habitat value for native birds and insects, and year-round visual interest. An additional consideration was availability at local garden stores, so as to encourage visitors to purchase the plants seen in the demonstration gardens.
• To optimize water use, the landscape is irrigated by a water-efficient drip system. A weather controller monitors temperature and soil moisture and adjusts irrigation amounts accordingly. In coming years (as the infrastructure becomes available), the potable water irrigation source will be re-plumbed to supply reclaimed water from the local treatment plant.
• To protect the existing mature trees (10 pines and 4 palms) and to reduce hauling and disposal costs, the site’s grading plan creatively balanced cut and fill, using soil excavated from the infiltration basin to create a sweeping berm for the Chaparral Hillside garden.
• The 1,110 sf green roof was the first in the Inland Empire area of Southern California. It utilizes two different systems – 4-in shallow trays and 9-in deep soil – to test the viability of green roofs in the area. Observational analysis indicates that plantings in the deep soil system are viable, with irrigation.
• Locally sourced landscape materials, including boulders for the cobble swale and decomposed granite for the pathways, reduced costs while supporting the regional economy.
• Interpretative signage, plant labels, and information kiosks educate visitors about the site’s many sustainable design features and technologies.

• The Frontier Project is estimated to cost $58 per year to irrigate, whereas irrigating a similarly-sized conventional Southern California landscape would cost $234 per year. This represents an annual savings of $176.

• The value and need for long-term specialized landscape care needs to be understood and agreed upon by all parties involved. During schematic design, the landscape architects recognized that in addition to utilizing low-maintenance plant species, further cost-savings and long-term environmental benefits could be achieved by hiring a master gardener to oversee the landscape’s long-term health. However, this vision was not mutually shared amongst consultants, and a typical “mow-blow-and-go” maintenance company was hired instead.
• Educating the construction crew about the imperative for adequate soil preparation – especially in non-traditional landscape situations – is essential to ensure successful plant establishment and long-term health. After installing the subgrade infiltration basin, the contractor parked heavy equipment on top, ignoring the construction specification to double dig and adequately prep the soil prior to planting the water-less demonstration garden. Severe soil compaction resulted in poor drainage and caused the initial plantings to fail. The species palette was revised, to better match the new soil conditions, and the garden was replanted.
• Though the Frontier Project utilizes numerous sustainable features and technologies onsite, a protocol for ongoing monitoring and performance data collection was never developed. Partnering with a university or research institution early in the design process could provide an opportunity for this type of long-term research.
• Though the plant palette was designed to reduce water use for irrigation by over 86% as compared to a conventional Southern California landscape, this study discovered that the plantings are being watered more than the intended amount. The plantings are not showing signs of stress, however, due to their adaptable nature. To ensure design intent is fully realized and upheld, a knowledgeable maintenance staff must regularly monitor and audit water use.

Project Team

Owner: Cucamonga Valley Water District (CVWD)
Client: Frontier Project - Non-Profit affiliated with CVWD
Architect: HMC Architects
Landscape Architect: EPT Design
Civil Engineering: RHA Engineers
Stormwater Consultants: RBF
Mechanical, Electrical, and Plumbing: DCGA
Contractor: Turner Construction
Landscape Contractor: DMA Greencare
Landscape Maintenance: Casa Verde

Role of the Landscape Architect

EPT Design established the initial site design goals, collaborated with a multi-disciplinary team to develop the site’s grading and stormwater concept, and led the site design from concept through construction.