Charlotte Brody Discovery Garden

Challenge

The design of the Charlotte Brody Discovery Garden had to be multifunctional and efficient. The site posed a series of challenges because of its small, 0.96-acre footprint and existing 8% slope. The program required grading for universal access (<5%) to allow children, parents and caregivers with strollers, grandparents, and garden carts to easily navigate the garden. Likewise, integrating demonstration space for school groups of 50+ students would require grading and the tight integration of form and function. As an interactive site, the garden also had to promote free exploration to engage children in ‘hands-on’ discovery opportunities while simultaneously maintaining strong boundaries and sightlines to ensure their safety. Lastly, the design sought to achieve high marks within the Sustainable SITES Initiative (SITES™) pilot program, which added another layer of complexity to successfully address all of the site requirements and user needs.

Solution

Through the removal of 1,400 cubic yards of soil, the garden’s primary pathway was graded at a 4.99% slope. It guides visitors to the main destination: a terraced gathering area at the top of the site, which is anchored by a barn and large pergola. To maximize programmatic opportunities along the path, bioswales, an herb garden, a food forest, and a rain garden are consolidated along its length. Runoff from the barn roof is collected in cisterns and used to irrigate the top terrace vegetable gardens. The pergola marks the upper edge of the garden and provides a shaded place for visitors to rest. Parents can rest under the pergola and let their children explore the garden freely since nearly the entire garden is visible from the top terrace, and a simple wood fence marks the garden boundary.

• Bioretention cells capture stormwater and infiltrate it, discharging excess runoff into a forebay that feeds the Duke Garden pond.
• Two 2,500-gallon cisterns collect runoff from the roof of the restored tobacco barn and store it for use in irrigating the vegetable gardens on the upper terrace.
• A rain garden filters stormwater pollutants using native plant species such as Clethra alnifolia, Itea virginica, Cephalanthis occidentalis, and Juncus effuses.
• Vine-covered pergolas create shaded work areas to reduce summer sun exposure.
• 10.6 tons of salvaged brick and 1.5 tons of reclaimed barn wood were used in the construction of raised planting beds and pergola shade structure.
• The primary circulation is an ADA-accessible path made of stabilized, locally sourced aggregate.
• The garden contains plants native to the North Carolina Piedmont, including winterberry, sweetspire, summersweet, wax myrtle, beauty berry, dogwood, pecan, persimmon, and red cedar.
• A “food forest” area contains apple, peach, pear, plum, and persimmons trees.
• Heirloom vegetables, such as violet jasper tomato, moonglow tomato, rugosa butternut and turban squash, are preserved and grown.
• All of site’s harvested produce is donated to local, charitable food bank organizations.
• 100% organic garden maintenance, including an associated composting program, is practiced on-site.
• Demonstration areas, educational signage and on-site programming teach families how to produce their own fruits and vegetables.
• Compost bins, cold frame seedling beds, and harvesting enrich the visitor experience.
• A low fence safely promotes exploration and free-play within the contained garden space.

The Charlotte Brody Discovery Garden (CBDG) participated in the Sustainable SITES Initiative (SITES™) pilot program and received two stars with 139 out of 250 possible points. A Duke University graduate student (Master of Environmental Management) led the process, working closely with the integrated design team of Duke Gardens staff, designers, and contractors. The project team initially expected three stars but found that some of the criteria were not applicable and some of the credits, particularly within the Site Design category, proved challenging to document, resulting in fewer points than expected.

The SITES pilot program had a heavy emphasis on environmental remediation and reclamation and favored projects with regularly occupied buildings on site. Credits such as “3.3 Protect and Restoring Riparian, Wetland, and Shoreline Buffers” and “3.4 Rehabilitate Lost Streams, Wetlands, and Shorelines” were not applicable to CBDG, as the site was not within reasonable proximity of these natural features. Credits 4.10 and 4.11 gave points to projects that “used vegetation to reduce heating and cooling requirements.” Because CBDG had no regularly occupied buildings on-site with HVAC units, these credits also did not apply. Comments were sent back to SITES after certification was complete, and the updated guidelines reflect observations made by the team. For example, in SITES v2, projects that are not built on degraded sites are not required to do site remediation as a prerequisite.

The project and integrated design team greatly benefited from participation in the SITES pilot program. SITES helped to keep the client and design team accountable to sustainability goals set forth at the beginning of the project. SITES provides a comprehensive framework that can be used throughout the design, construction, and maintenance processes. SITES also emphasizes community involvement in the design process. This emphasis encouraged the integrated design team to consistently involve the community so as to maximize both use and benefit of the garden to the surrounding community. Through SITES, the entire team learned and applied new procedures and saw how each decision influenced the overall sustainability of the site.

Duke Gardens demands excellence and holds its designers and contractors to high standards. While a $950,000 garden that demonstrates organic gardening practices may seem like a high price tag, this budget is only half of what special “destination” gardens often cost. It is common for destination children’s gardens to cost $2 million per acre on average. This high cost is primarily due to the cost of intensive play features with complicated system components, such as water play or thematic hardscapes.

• Although the design team knew the primary pathway had to handle large volumes of foot traffic, they wanted it to feel like a rustic garden path.  To achieve the desired tactile and auditory effects, a stabilized aggregate material was used instead of a hard material like brick, concrete, or stone. Ultimately, this presented drainage and erosion challenges because of the path’s 4.99% slope.  While the aggregate path material held up well to foot traffic, certain areas quickly began showing signs of excessive erosion. The team has since installed a fix that seamlessly melds with and improves upon the original design: a series of shallow, sculptural stone runnels that intermittently run perpendicular to the path to collect and convey runoff, satisfy strict ADA-route vertical tolerances, and add an element of beauty and rhythm along the entirety of the path.
• An unexpected and positive outcome of participating in the SITES™ program was that the program required close monitoring of the project during construction, resulting in a strong relationship with the contractor. Simple practices, such as not allowing engines to idle on site, were well received and have influenced the contractor’s ongoing practices. Often there is a rift between the design team/client expectations and the construction process. SITES provided tangible goals and required specific processes to document and achieve those goals, which resulted in a common understanding of what the design team and contractor needed to do in order to provide a more sustainable process and product.

Stone (vertical and flatwork): Duke University Stone Quarry
Grasses: Hoffman Nursery
Raised Planting Beds: Reclaimed brick
Aggregate Path Material: Chapel Hill gravel

Project Team

Landscape Architect: Lift Environmental Design (formerly Jesse Turner Landscape Architect)
Architect: Ellen Cassilly, AIA, LEED AP  
Project Engineer: EcoEngineering
Civil Engineer: Wilson Engineering Group
General Contractor: LeChase Construction
Carpentry Contractor: Old Log Cabins
Block Masonry: O.C. Mitchell
Vertical Masonry: Cleve Wagstaff
Flatwork Masonry: Brooks Burlson
Metalwork: Storybook Farm Metal Shop
Structural Engineer: Excel Engineering
SITES Coordinator: Sarah Parson

Role of the Landscape Architect

Using 3D digital modeling, the landscape architect worked closely with all members of the design team and Duke Garden staff to develop a master plan that reflects the garden’s mission, “to create and nurture an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture.” Throughout the design and construction process, the landscape architect worked with a Sustainable SITES coordinator to earn the garden a Two Star rating. The landscape architect also acted as the primary construction administrator and, in doing so, was responsible for coordinating with the architect, subcontracting the civil engineering work, and leading the stormwater design.