Good Medicine: The Benefits of Green Infrastructure

by Thomas Benjamin

The evolution of Kent Hospital’s Sustainable Campus Landscape Initiative was both capital project and Master Plan driven. In the early 2000s, Kent, located in Warwick, RI, embarked on planning major upgrades to the Emergency Department and Emergency Room, including a 1,393 square meters +/- (15,000 square-foot) Women’s Imaging Center addition, substantial new parking, driveways and street frontage retaining walls. The campus’s new 4,645 square meter +/- (50,000 square foot), five-story Trowbridge Data Center was also being planned at the time. In seeking stormwater permits from the state, Kent learned that it was approaching its runoff discharge limits and additional impervious surfaces would produce runoff volumes far in excess of those limits.

A raingarden at the Trowbridge Data Center replaced a high-maintenance lawn.

A raingarden at the Trowbridge Data Center replaced a high-maintenance lawn.

The solution lay in aggressively infiltrating stormwater through naturally landscaped LID features favored by the state. Kent first developed plans for a rain garden to serve the new Women’s Imaging Center (now Breast Center) and naturalized landscape improvements to the Emergency Department. Replacing a high maintenance lawn, the 465 square meter +/- (5,000 square foot) rain garden consisted of two gently graded depressions or lobes that accept both the Center’s roof runoff via downspouts and surface runoff from surrounding walkways. In total, the garden pretreated runoff from a roughly 930 square meter +/- (10,000 square foot) catchment area.

Rain Gardens for Stormwater

A glass cabana-like canopy structure covering the Breast Center’s approach walkway provided a key visual element around which to develop the rain garden. The garden was heavily planted with a diverse mix of low maintenance, deep rooting native wildflowers and grass species, edged with dense, low native shrubs and punctuated by a flowering understory with canopy trees planted to provide shade. Plantings offered a light, softening, beach-like effect harkening to the campus’s coastal location. Hospital patrons and staff enjoyed a sequence of bloom from early spring through fall, and colorful berries and interesting textures to view through the colder months. Butterflies, other beneficial pollinating insects, and songbirds became frequent visitors as well.

The rain garden utilizes a diverse mix of low maintenance, deep rooting native wildflowers and grass species

The rain garden utilizes a diverse mix of low maintenance, deep rooting native wildflowers and grass species

Across the street from the rain garden, Kent also created a 280 square meter +/- (3,000 square foot) linear bio-retention swale along the Trowbridge Center’s street frontage to occupy the space between street and sidewalk. By extension, a similar native planting palette replaced lawn and higher maintenance plantings along the campus’s 457 meter +/- (1,500 linear foot) main frontage on Toll Gate Road, and highlighted the Emergency Room entrance with conspicuously bright red-berried shrub plantings. Parking islands in the new Emergency Department Patient Lot became planted with salt-tolerant native grasses, helping to visually stitch together the surrounding naturally landscaped areas into a coherent whole. Given the emphasis on native grasses, perennials and groundcovers, these natural landscapes established rapidly, often providing nearly full vegetative cover within one to two growing seasons following installation.

Completed in 2004, Kent soon realized the benefits of these first sustainable landscape projects in terms of stormwater management. The rain garden and bioretention swale easily accepted and passively pretreated runoff without any erosion or overflow including a number of 100-year storm events or larger during the first several years. Special attention to soil preparation and use of a protective “compost-mulch” covering greatly reduced the need for irrigation of the newly planted areas and prevented erosion. The compost-mulch helped increase biological activity in the soil or “soil life”, thereby providing optimal conditions for plant growth. Infrequent weeding and cutting back flowers and grasses replaced regular mowing and blowing activities, freeing up maintenance staff to focus efforts elsewhere and sparing the campus constant engine noise, dust and exhaust from maintenance equipment. The Kent community liked what it saw and wanted more.

Gardens for Healing

As early as 2004, Kent set to work on a comprehensive Campus Landscape Master Plan for expanding the sustainable landscape approach across the entire campus. The first draft Master Plan focused particularly on additional upcoming capital building projects. In 2007-09, the next major piece of Kent’s sustainable landscape expansion, a healing Serenity Garden, was developed in association with a new cancer Infusion Center/PETScan facility. The new Infusion Center featured the very sustainably-minded reuse of an existing equipment warehouse structure. Around the building Kent removed six precious parking spaces to create the healing garden space on a prominent knoll adjacent to the Center. Large windows faced out into the garden space, and a quiet stone fountain provided a central focal point and soothing ambiance.

The Serenity Garden includes many fragrant herbs and medicinal plant species that also help pretreat surface runoff.

The Serenity Garden includes many fragrant herbs and medicinal plant species that also help pretreat surface runoff.

Again, a dense groundcover, in this case including many fragrant herbs and medicinal plant species, helped pretreat surface runoff from internal walks and surrounding areas. Flowering groundcovers extended down and protected a steep escarpment from the Serenity Garden to the campus’s main drive located just below the garden site. The project’s groundcover plantings impressively established within one growing season. Within two seasons protective tall grasses and shrubs on the garden’s edges provided substantial visual buffering of surrounding driveways and parking areas, thereby enhancing a sense of privacy and quiet to the for the garden’s visitors.

Gardens as Nurseries

By 2008, when the first gardens were four years old, Kent began to realize additional cost-saving benefits from its sustainable landscape areas. As perennial wildflowers and grasses filled in, they also benefited from periodic divisions to best maintain their vigor and aesthetic qualities. Division of one plant might produce four new plants that could then be transplanted to other areas on campus. Kent realized that its established gardens could serve as nurseries to expand the sustainable landscape program campus-wide per the initial Master Plan’s vision. Further, the repetition of successful species throughout the campus would unify and strengthen the total visual image and even help patrons with way-finding through many large parking lots. Reuse of existing plants, by the hundreds, would also create substantial savings for new installations.

Runoff from the Plaza of Honor feeds into a bio-retention swale.

Runoff from the Plaza of Honor feeds into a bio-retention swale.

Plants in the bio-retention swale have filled in and provide plant divisions that can be transplanted in other areas.

Plants have filled in and provide plant divisions that can be transplanted in other areas.

In 2010, Kent added the Plaza of Honor, another important sustainable landscape feature, to the list. The Plaza featured three large flag poles and a wall of memorial bricks to honor community members and donors to the Hospital. The entire 1,115 square meter +/- (12,000 square foot) plaza slopes toward a bio-retention garden that receives much of the site’s surface runoff. Again, densely planted with native flowers and grasses, the 93 square meter (1,000 square foot) bio-retention garden pretreats and infiltrates all runoff from the surrounding plaza and walkways.

Located in a peripheral area of the campus, irrigation was not an option for establishing gardens here. With the exception of a water truck providing irrigation during the first season in 2010 (a dry year), no additional irrigation has been provided, and plantings reached full establishment during the 2011 growing season. Very little maintenance has been performed since planting this area, and the site, framed by large ledge rock outcrops, retains a controlled wildness.

Gardens for Staff

In 2011, Kent refined and finalized the Landscape Master Plan to provide a road map for transitioning the campus’s remaining 20,000 unpaved square meters +/- (5 unpaved acres) to sustainable landscapes within five years. The Master Plan also provided a detailed Maintenance Plan to help guide management of the sustainable areas far into the future, covering such topics as control of invasive plant species. The Maintenance Plan features an easy-to-read, color-coded maintenance schedule focused on annual tasks such as deadheading spent flowers or dividing plants for transplant. One project that immediately emerged from the Master Plan included a new Staff Garden for raising vegetables and flowers. The Staff Garden was so successful during its first season in 2012 that Kent doubled its size for the 2013 season.

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Today natural grasses, wildflowers and native trees and shrubs cover the most prominent portions of Kent’s campus in gardens and landscape strips that passively pretreat stormwater. Most features are small in scale, ranging from 9 square meters +/- (100 square feet) up to 1,000 square meters +/- (one quarter acre). These small, localized catchments typical treat catchment areas that are similar in size, depending upon the site’s layout relative to the surrounding buildings and terrain. These rain and healing gardens, and bio-retention swales, quietly clean impurities from rainwater runoff while providing low maintenance beauty throughout the seasons. In total, Kent’s green infrastructure also serves as an on-site nursery that is allowing Kent to expand its naturalized low maintenance landscape campus-wide in a most economical manner.

In 2012, Kent Hospital received an Environmental Merit Award from EPA for its leadership in connecting community wellness with environmental health through its sustainable landscape program. In 2013 and again in 2014, Kent received the Sustainable Operations Award from Hospitals for a Healthy Environment in Rhode Island (H2ERI) that recognized both Kent’s green infrastructure work and the larger sustainability efforts it inspired for the entire facility including energy conservation, waste reduction, and promoting healthy, locally-grown food options. Later in 2013, the Infusion Center at Kent’s Serenity (Healing) Garden achieved recognition with Healthcare Design magazine’s first Landscape Architecture Award for Healthcare Environments.

About the Author

Thomas Benjamin is a landscape architect, LEED AP, and educator with more than 20 years of experience specializing in sustainable, low-input resilient design, habitat-ecosystem restoration, and therapeutic wellness gardens. Tom’s designs integrate energy, waste, water, and food systems and often encompass the creation and enhancement of natural, passive stormwater filtration systems. He has pioneered a number of best practices with low-input, native plantings for residential and commercial clients including medical institutions, senior housing facilities, public facilities, commercial buildings, residential developments, and private residences. Tom may be reached at tom@wellnesscapes.com.