Landscape Architect Bill Wenk of Wenk Associates in Denver, CO, says the most successful stormwater projects seem to come from a collaboration of civil engineers and landscape architects. The engineers ensure that the design criteria are met, and the landscape architects provide what is often a more creative view. When the two disciplines collaborate, they draw from the strengths of each. “I know construction processes and materials as well as engineering principles, and engineers respect that, which speeds up the process,” he notes.Wenk also believes “change happens very slowly,” but as sustainable projects are completed, people see the results and the push to integrate stormwater management as part of a multifunctional agenda grows. He recalls a 20-year-old project in Aurora, CO; the plan was to channelize a stream in concrete, but the neighborhood protested, so other options were considered. Wenk Associates proposed a softer, ecologically friendly approach incorporating what have now become more conventional ideas: widening and deepening the channel, vegetating the slopes, and installing check dams that stabilize the streambed. The new plan met engineering criteria, and the neighborhood was happy with the final result.Because of upstream development, Goldsmith Gulch in Denver lacked flood capacity for downstream areas and threatened a community park it passed through. The neighbors were concerned that flood-control improvements would threaten the park’s open-space qualities. Wenk Associates worked with the local neighborhoods and constituents to develop concepts for improvements that would enhance open-space qualities and participated in site walks to aid neighbors in visualizing the proposed improvements. The channel was reconstructed, and contoured boulder drop structures were put in to slow the flow of water, creating better habitat, improving water quality, and controlling bank erosion. As a result, the neighborhood has been pleased with the improvements. Another example, Denver’s Creekfront, transformed an underutilized, concrete-lined stream channel into a more natural-looking city open space. Cherry Creek along Speer Boulevard is a major tributary in Denver, providing flood control in the city. Wenk Associates stabilized the streambed, retaining soft bottoms, vegetation, and flood-control requirements while providing a new multiuse resource in the heart of downtown. To provide recreational use, parts of the concrete walls were removed and small parks and plazas were installed, allowing for access to the bottom of the creek. Bike trails were built along the creek, integrated with the primary engineering function of unimpeded conveyance of floodwaters. Drop structures, constructed as part of the project, work to stabilize the channel bottom and protect the channel walls. At the same time, they provide a series of informal pedestrian seating areas that are oriented to the stream. Urbanization in the Shop Creek drainage basin had caused severe channel erosion in Cherry Creek State Park, which surrounds the Cherry Creek Reservoir. Sedimentation and phosphorous pollution had become significant problems in the reservoir. The solution developed by Wenk Associates and the project engineer was a radical departure from standard landscape architectural and engineering approaches to stream channel stabilization. Soil cement drop structures were designed and the channel was shaped to preserve its original alignment. Extensive wetland areas were created, providing new areas of habitat and removing 50% phosphorous. This sustainable, more natural solution was less expensive than typical channelization. Since the completion of the project, water-quality goals have been met and a diverse ecology has developed. The project has received national and state engineering and landscape architectural design awards for its innovative response to the broad range of engineering, aesthetic, and ecological issues it addressed.
