02-19-21 | Feature

Creek Restoration Enhances Ecosystem

Landscape Design Helps Control Stormwater
by Rebecca de Boer PLA, ASLA, LEED AP, Saiki Design, Inc.

The Bee Branch Creek Restoration in Dubuque, Iowa features a new open channel which accommodates a water flow capable of supporting a healthy stream ecosystem. To preserve the wellbeing of this system, the design team aided by landscape architecture firm Saiki Design from Madison, Wisconsin incorporated several sustainable water quality improvements, including 2,500' of pervious roadway, 50 pervious parking stalls, four hydrodynamic stormwater separators, and five bio-infiltration basins. Seen here is the waterway from the 24th Street Bridge punctuated withv
A boardwalk floats over the reclaimed landscape which contains Karl Foerster Feather Reed Grass, Karmina Gernium, and several other grasses and plantings. Additionally, 28 trees species were included in the design which emphasized the inclusion of native plant material. Photo courtesy of City of Dubuque.
egmental retaining walls protect the green space during stormwater swells. Photo courtesy City Dubuque.
The design of the limestone spillway highlights the stormwater overflow from street to creek. Even with all of the infrastructure improvements, 22nd Street can still flood. This spillway provides a way for floodwater to flow from the street to the creek without eroding the surrounding soils. The spillway was designed as a cascading waterfall with natural limestone pillars, a pedestrian bridge, and seating area. When stormwater is not running through the space spring water is pumped through the upright limestone blocks to create a water feature. Photo courtesy City Dubuque.
This limestone water feature conveys water from a geothermal field to the larger body of water below and is daylighted in this process. The water feature hugs the side of the amphitheater. Photo courtesy City Dubuque.
Tiered retaining walls covered in native vegetated mat provide an instant prairie and pollinator habitat. Photo courtesy of City of Dubuque.

The Bee Branch Watershed encompasses historic neighborhoods where over 50 percent of Dubuque, Iowa residents live or work. From 1999-2011, six Presidential Disaster Declarations were issued for this region due to flash flooding, resulting in damages estimated at $69.8 million.

The Landscape Architect team with Madison, Wisconsin's Saiki Design, Inc. was part of a multidisciplinary consultant team selected to take this project from inception to completion including over $100 million in construction through phased implementation of the master plan, providing integrated design, documentation, and coordination. While major portions of this project have been completed, the Railroad Crossing, which will increase stormwater capacity and provide a pedestrian connection between Upper and Lower Bee Branch, is currently under construction.

The Landscape Architects were tasked with creating a design that conveyed a base flow of groundwater discharge as well as stormwater flow during and after construction. Through this, they achieved their goal of improving the stormwater quality. Additionally, they created a linear open space that serves the local neighborhood and the community at large by establishing a connection to the Heritage Trail, a regional, scenic, all-season, multi-use trail. The team also wanted to enhance other outdoor recreation opportunities available through the integration of specialty landscape areas such as rest areas, stormwater features, and play spaces for children. Within the play spaces and other areas throughout the site, the design team added educational opportunities centered around sustainability themes in the form of signs along the Bee Branch. These signs elaborate and educate on the history of the site, the local habitats and wildlife, prairie restoration, flash flooding, and sustainable water quality improvements.

A major focus of the project was put into re-introducing the freshwater ecosystem to Bee Branch by daylighting a subgrade stormwater conveyance which was accomplished by creating an open channel of water. The manmade floating island system in the lower section of the site was designed to help support the fish, turtles, amphibians, beavers, and bird species that can be found there. Birds of prey and waterfowl can be seen along the creek, even in the middle of winter when most bodies of water are frozen over, the warm baseflow provides an open spot of water where the Upper Bee Branch flows into the Lower Bee Branch - so many bird species gather in this spot.

This creative stormwater management solution allows large volumes of stormwater to move safely through the area, while protecting over 1,300 homes and businesses from flooding. The daylighted creek simultaneously forms a picturesque linear park and provides active, outdoor spaces for community residents and visitors. Park amenities include a multi-use trail, an amphitheater, scenic overlooks, recreational areas for children, educational signage, a community orchard, green alleys, numerous interactive stormwater management features, and a floating island system.

The multi-phase Bee Branch Creek Restoration project transformed nearly 1-mile of an underground storm sewer into an open waterway and adjacent 60-acre open space that is reminiscent of the one that traversed the area nearly a century ago. The water is daylighted at 24th street and runs to the Mississippi River.

The project demonstrates a commitment to Sustainable Dubuque, a framework to create a viable, livable, and equitable community today and for generations to come. The project aesthetic was driven by the historic nature of the site - daylighting a creek that had been buried around the turn of the 20th Century. This aesthetic is conveyed using salvaged clay pavers, Dubuque limestone, traditional hoop railings, traditional light fixtures, and arched bridges.

Team List
- Client: City of Dubuque
- Project Manager and Civil Engineering Design: Strand Engineering.
- Landscape Architect: Saiki Design
- Architecture and Structural Engineering: IIW, P.C.
- Landscape Contractor: Nauman Nursery
- Signage Graphics: City of Dubuque
- Special credit must go to the City of Dubuque Engineering and Leisure Services Departments, elected officials and staff for their continuing efforts toward completion of this multi-year renovation of Bee Branch Creek.

As seen in LASN magazine, January 2021.


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