Basalt River Restoration

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DHM

basa lt r i v er r es to r at i o n Basalt, CO



BASALT RIVER RESTORATION

PROJECT TEAM

Basalt, Colorado

DHM Design

PROJECT SUMMARY

Town of Basalt

The Roaring Fork River bisects the mountain town of Basalt, creating both opportunities and challenges for this Western Slope community. DHM Design teamed with Matrix Design Group and Sopris Engineering to restore and realign the river and to provide safe access for the community. The process included removal of an outdated levee and the alteration of hydrological patterns to address sedimentation and erosion. The floodplain was adjusted and wetland systems were expanded. Developable land was created adjacent to the downtown core outside of the floodplain and new park spaces were created adjacent to the river within the floodplain. The project resulted in opportunities for people to interact with the river and provided a vital, visual and physical connection to the river. The project benefited from the distinct advantages of each discipline and was spearheaded by our in-house team of Landscape Architects and Ecologists who worked in tandem to achieve multi-purposed project goals: restoration of the river corridor, evaluation of hydrological and ecological systems, and improvement of the natural systems. Through an internal commitment to ground all decisions in a strong ecological foundation, the team achieved sustainable and creative solutions to restore the overall health of the corridor. The Roaring Fork River is now better connected to the adjacent downtown core, serving as an integral part of the community’s identity for years to come. The restoration project is a model of community stewardship allowing for human interaction and connection to a riparian corridor that embodies a healthy and beautiful ecosystem.

Matrix Design Group Sopris Engineering Connect One Design

AWARDS ASLA Colorado 2017 Merit Award



The rivers are important economic drivers for the community, drawing visitors from afar to experience gold medal fishing and other instream activities.

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A mobile home park that was precariously situated in the floodplain behind an outdated levee presented significant public safety and health concerns; relocation of the residents and removal of the levee were catalysts for the river transformation. 4


EXISTING CONDITIONS Design goals included removal of the levee, modifications to the floodplain, abatement of erosion, adjustment and stabilization of the river channel, along with the creation of active and passive park spaces for the community. None of these goals were possible with the old levee and mobile homes in place. A redefined floodplain created the opportunity for new developable parcels within the downtown core. Those parcels have attracted and become home to environmentally focused non-profits such as the Roaring Fork Conservancy and the Rocky Mountain Institute.


INTEGRATED ECOLOGICAL SERVICES The success of the project lies in DHM Design’s in house ecological services team. We were able to understand the resource, analyze the ecological components of the site and devise solutions that were fundamental to the overall health of the environmental systems. In collaboration with the hydrologist, the team restored the riverbank and surrounding wetland areas with strategies that not only control flooding and erosion, but help to reestablish the ecological value of the riverine system.



PERMITTING AND WETLANDS The project required careful coordination for the permitting process with various regulatory agencies. River improvements were conducted through a series of three nationwide permits. Additionally, in order to remove a section of the site from the floodplain, a number of poor quality wetlands were impacted. The Army Corps of Engineers assigned a mitigation ratio of 2.1 : 1 for every acre of wetlands impacted. It was a challenge to create the .78 acres of new wetlands within the project site, but this ultimately led to the creation of some of the most beautiful natural areas on the site. The resulting wetland areas provide educational opportunities and are experienced through a series of accessible boardwalks which link the Town core and adjacent developed parcels to the river corridor.



Mitigation Wetlands (during construction): The project included newly constructed wetlands to meet Army Corps of Engineers requirements as an offset to impacted wetlands.


Mitigation Wetlands (Completed)


RIVERBANK RESTORATION The team proposed a series of jetties along the riverbank to redirect the energy of the river current into the center of the waterway, rather than towards the edges. This intervention effectively increased the velocity of the water reducing sedimentation deposits and redirecting the water forces away from the river edges to mitigate the forces of erosion. Removal of the levee also created an opportunity for expanding and naturalizing the riverbanks, a vast improvement to what existed previously.




The Landscape Architect developed a series of cross-sections for various locations and grades of the riverbank; while these crosssections informed the construction process, they were also important visual tools to communicate complex ecological systems to the community. The design approach achieved bank stabilization in a way that struck a balance between protection and a natural appearance, while satisfying underlying regulations. Large boulders were placed along the bank to provide additional protection and armoring. Planting pockets were intermixed with the boulders above the high water line and live willow and cottonwood stakes were planted between the boulders on steeper slopes. The native plantings helped to return the river to a balanced ecological system, providing critical habitat for insects, birds and fish. The boulders ensure bank stabilization at all water levels, while small details, like softening the grade, and bringing plant material to the edge create a natural feel. The team set bank elevations that work with and accommodate seasonal changes in water levels.



Side channels were restored in coordination with the Colorado Parks and Wildlife to create ideal spawning habitat


A COMMUNITY ASSET Removal of the levee and restoration of the river’s edge, created an opportunity for the transformation of Basalt’s downtown core. Once views to the river were opened from downtown, the community felt a deepened sense of connection to the river corridor. Excitement grew for this parcel as an ideal location for an expanded riverside park. Subsequent phases of the project are slated to include installation of a more active community riverfront park: an event lawn, river access, and a children’s water play area all in response to an extensive public process.

A series of boardwalks4 connects the river and adjacent developed areas while maintaining and protecting the wetlands in between.





The Basalt River Restoration started as a hydraulic and engineering puzzle, but through close collaboration between the disciplines, the end project emerged at the harmonious intersections of science and art, safety and recreation. With Landscape Architects and Ecologists working together, literally side by side, design decisions were grounded in the natural health of the corridor.



Walking along the river today, it feels like a part of nature was given back to itself, and in the process, the design sets a course for better interaction between river and human development well into the future.



www.dhmdesign.com


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