Landscape Architect Articles

Santa Rosa Demonstration Garden01-18-18 | Feature

Santa Rosa Demonstration Garden
A Model for Water-use Efficiency and Low Impact Development

Landscape Architecture by Gates + Associates

For the city of Santa Rosa, Calif., Gates + Associates designed a water efficient demonstration garden with low-impact development features. The rendering imagines the garden fully grown in.

The city of Santa Rosa received a grant from the State Water Resources Control Board to convert 34,000 square feet of existing lawn and irrigation at the front of city hall into a demonstration garden modeling water-use efficiency and low impact development (LID) features.

Santa Rosa (pop. 174,170) is the county seat of Sonoma County, and lies 55 miles north of San Francisco. This is wine country, of course, and Santa Rosa is wine country's largest city. There are over 400 wineries in Napa and Sonoma counties. This fertile, coastal land was home to the Pomo Indians and was not founded by settlers until 1833. The city takes its name from Saint Rose of Lima, Peru, a lay member of the Dominican Order. The design of the demonstration garden was a collaborative effort that included a design charrette with sustainable landscape industry leaders (local landscape architects, nonprofit organizations, private industry experts and city staff) from Sonoma County and beyond.

A 2,200-gallon galvanized steel rainwater-harvesting cistern was craned into place next to the outdoor classroom. It collects roof water via down spouts. It takes a 2" rain to fill the cistern. Santa Rosa averages about 52" of rain a year. There's an overflow spillway at top, plus a ???(R)???AE?" dia. drip manifold near the bottom of the tank to distribute water. The cistern is mated to a weather-sensitive irrigation controller. Note: The water tank company (American Tank Co. of Windsor, Calif.) has field-erected a 105,000-gallon tank at a private residence in Sunol, Calif., just to give you an idea of how large these tanks can be. The graffiti resistant concrete picnic tables are from Quick Crete. The blue "hydration station" is designed ("ezH2O') to quickly fill water bottles.

The project includes:
1) Use of Russian River-Friendly Landscape Practices and Principles
2) A public gathering space with permeable hardscape
3) Rainwater harvesting demonstration system coupled with high efficiency irrigation technology
4) Stormwater treatment via vegetative swales and retrofit of existing parking lot storm drain system without eliminating any parking spaces
5) Educational, interpretive signage system
a) Online educational interface with "how-to" videos and information about implementing sustainable landscape practices.

Integration with Setting
The design character is consistent with the historic bold lines of the 1960 Mid-Century Modern architectural character of the city hall. Strong, architectural diagonal bands of planting are used to direct the eye towards the gathering area. The existing horse sculpture is highlighted in the new design, intertwined with the geometric patterns. The tall, cylindrical rainwater harvesting tank is the iconic focal point of the gathering area.

Six 3" caliber "Valley' oaks were planted at the entry as a "project statement," explains the landscape architect, to "give the eye a space to rest" and to demonstrate that a place of minimal planting can be equivalent to other lush areas of the project.

Corrugated metal has been selected as the tank skin to reflect the authenticity of materials and function consistent with city hall architecture. This 2,200-gallon tank collects run off from 1,600 square feet of the existing city hall roof.

Over a typical year, the tank will fill up and drain at least five times, saving 11,000 gallons of water. Overflow from the tank will follow a swale along a meandering, gently sloping course lined with plants and rocks over the course of 250 feet; the water will have the chance to soak into the soil and/or be absorbed by the plants around it.

Existing redwood and crepe myrtle trees have been preserved as anchors for the new landscape design. The selection of plant material has been carefully vetted for long-term performance. It is also appropriate for the public, civic setting and will provide year-round visual interest as well as habitat value.

An oak grove was introduced in the corner plaza as a focal area from the downtown area. The plant palette emphasizes the use of California natives that are also adaptable for homeowners.

In keeping with Russian River-Friendly practices, plant materials have been selected both for their habitat value and low maintenance needs. Plants are spaced to accommodate their ultimate growth reducing need for pruning and decreasing "green waste."

The dry creek is a vegetated swale of cobbles and grasses. It mimics Santa Rosa Creek, which is culverted under the Santa Rosa downtown. The 22-mile creek originates in the Mayacamas Mountains in Sonoma County. The swale's steps and weirs are granite, which was salvaged from the demolition of the Santa Rosa Courthouse in 1966.

Place making/Livability
As a civic space, the entry to city hall provides a welcoming and comfortable environment for visitors and staff. It will also reflect Santa Rosa's leadership in environmental initiatives.

The design connects the central gathering space surrounding urban fabric via a cross axial connector to Santa Rosa Avenue; as well as entries from 1st Street and the parking areas.

Multiple opportunities are provided for informal gatherings, quiet contemplation, outdoor classroom participation or a lunch break. Benches, boulders, steps, seat walls, and tables, as well as a hydration station, are provided for public use.

A system of interactive signage further enhances the user's approach of the space. The public spaces are designed to feel safe and be visible from surrounding areas for surveillance. The layout of site elements and selection of plant material avoids any "blind" areas.

In addition to modeling and inspiring the use of sustainable practice for stormwater management and water-use efficiency, the garden also demonstrates repurposing of materials salvaged from the city's maintenance yard.

Granite treads from the original courthouse steps demolished in 1966 are used as architectural weirs to bridge swale crossing. A large remnant concrete slab has been repurposed as a seating platform in the proposed corner oak grove.

The city has many programs to encourage residents to reduce their indoor and outdoor water usage. The outdoor programs include paying people to remove water-thirsty lawns, giving rebates for gray water reuse systems and rainwater harvesting systems, and education people and businesses about "water wise" gardens.

The city hall project will allow the city to "walk the walk" when it comes to the water conservation and stormwater measures it requests of residents and requires of developers.

"This garden is a great way to show people that there is a choice," Vice Mayor Robin Swinth said. "They don't have to choose between green and brown; they can actually make a third choice that is beautiful and great for the community."

Gates + Associates worked with the city of Santa Rosa and its community to convert 34,000 square feet at the front of city hall into a demonstration garden modeling sustainable features. Water saving features include a drought tolerant and low-water use plant palette, high-efficiency irrigation, a cistern for rainwater harvesting, vegetative swales with granite weirs, bioretention areas and permeable hardscapes.

Team
Landscape Architects: Gates + Associates
Client: City of Santa Rosa
Rainwater harvesting system: Andrew Bolt, Architectural Solutions
Landscape Contractors who specialize in ecological restoration: Baelin, Inc.

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Russsian River-Friendly Landscaping Best Practices (rrwatershed.org)
1) Landscape locally
-Select/evaluate site carefully
-Assess soil and test drainage
-Survey/protect flora & fauna
-Consider potential for fire
-Use local, natural plant communities

2) Landscape for less to the landfill
-Select appropriate plants
-Keep plant debris on site
-Prune selectively and properly
-Water and fertilize judiciously
-Use goats/sheep for weed control and creating firebreaks
-Use salvaged items and recycled content materials
-Reduce and recycle waste
-Separate plant debris for clean green discounts

3) Nurture the soil
-Remove and store topsoil before grading
-Protect soil from compaction
-Defend against erosion
-Amend the soil with compost before planting
-Mulch regularly
-Aerate compacted soils
-Feed soils naturally
-Avoid synthetic, quick release fertilizers
-Minimize use of chemical pesticides

4) Conserve water
-Create drought resistant soils with compost and mulch
-Grow drought-tolerant California native or Mediterranean plants
-Minimize or eliminate the lawn
-Implement hydrozoning"?ugroup plants by water needs
-Design for onsite rainwater collection, recycled and/or graywater use
-Design/install high efficiency irrigation
-Install dedicated meter to monitor landscape water
-Manage irrigation per need
-Maintain irrigation system (every drop counts)
-Request irrigation audit

5) Conserve energy
-Shade buildings to moderate temperatures
-Reduce the heat island effect
-Shade air conditioners
-Design lighting carefully
-Choose and maintain equipment for fuel conservation
-Specify low embodied energy materials

6) Protect water and air quality
-Use integrated pest management
-Eliminate high input decorative lawns
-Minimize site disturbance
-Choose and maintain your materials, equipment and vehicles carefully
-Keep soil and organic matter where it belongs
-Minimize impervious surfaces
-Plant and protect trees
-Maintain and manage the irrigation system carefully
-Design a system to capture and treat water

7) Create and protect wildlife habitat
-Diversity
-Provide water and shelter
-Use organic pest management
-Conserve or restore natural areas and wildlife corridors

As seen in LASN magazine, January 2018.