Sustainable Design, Amenities Enhance Creek Restoration

Dubuque Project is More Than Just Flood Protection

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Deron Muehring is a civil engineer with the city of Dubuque, Iowa.

Posted: Wednesday, April 26, 2017 2:29 pm

In the heart of Dubuque, Iowa, the Bee Branch Creek runs along residential neighborhoods at the city’s north end, through the Highway 151 commercial district, and to the 16th Street Detention Basin before reaching its ultimate destination: the Mississippi River.

The Lower Bee Branch Creek Restoration Project, completed in 2011, and the Upper Bee Branch Creek Restoration Project, currently under construction, are part of a multi-faceted approach to addressing the severe and frequent flash flooding experienced in Dubuque’s Bee Branch Watershed.

However, this stormwater conveyance channel does more than simply improve flood protection, it also increases community aesthetics, provides additional recreational opportunities, and improves stormwater quality through sustainable design practices, and in its own small way helps to improve the water quality of the Mississippi River.

Over the past 15 years, Dubuque has experienced increasingly intense, localized rainstorms. Between 1999 and 2011, six presidential disaster declarations were issued because of flash flooding. During each of these declarations, homeowners and businesses were forced to repair or replace damaged property. The area of the community hit the hardest is located within the 6.5-square-mile Bee Branch Watershed, where more than 50 percent of Dubuque residents either live or work. In addition, the watershed encompasses some of city’s most affordable housing. Many of the residents in this area have a low to moderate income and are those least able to recover from repetitive flood loss.

Deron Muehring, a civil engineer with the city of Dubuque, witnessed the flash flooding firsthand. “The flash flooding has been devastating to hundreds of families in the Bee Branch Watershed,” Muehring said. “Residents have had to deal with street closures, loss of power, and flooded basements. Imagine worrying every time it rains, worrying about getting several feet of water in your basement. This was definitely a priority for us.”

To respond to the issue of flooding, the City of Dubuque created the 12-phase Bee Branch Watershed Flood Mitigation Project. Two of these phases are focused on restoring the Bee Branch Creek. In the early 1900s, the creek was enclosed within a large-diameter storm sewer to accommodate rapid urbanization. Daylighting of the buried Bee Branch Creek will allow stormwater from flash floods to safely move through the area without flooding adjacent properties.

Though the primary goal of the project was to provide flood protection in the watershed, the city also used the Bee Branch Creek Restoration as an opportunity to develop usable green space for the community — increasing the area’s aesthetics, encouraging its recreational usage, and promoting sustainability.

In 2008, Strand Associates, Inc., in partnership with IIW Engineers & Surveyors, P.C., was hired to lead the design and construction administration efforts for both the Lower and Upper Bee Branch Creek Restoration Projects with Ken Saiki Design, Inc., serving as the landscape architect. The Lower Bee Branch Creek Restoration involved the dredging of the 16th Street Detention Basin and excavation of an open channel for approximately half a mile. The project started in fall 2010 and was completed in November 2011.

Development in the district adjacent to the existing detention basin had stalled because of concerns over flooding, but has begun to move forward since completing the restoration. In the past five years, two restaurants and a convenience store have been constructed, with development of a commercial retail center also planned.

The positive effects of the Lower Bee Branch Creek Restoration have not only been flood protection and economic growth; restoring this lower portion of the creek has had environmental benefits as well. In June 2014, the Iowa Department of Natural Resources conducted a fish survey and found that the stream segment contained 15 species of fish — six of which are considered valued-game fish, including northern pike, bass, and yellow perch. All these species migrated upstream to the creek naturally from the Mississippi River. Bald eagles have also been spotted at the Lower Bee Branch. In response, the city has initiated educational bird-watching events along the creek.

Unlike the Lower Bee Branch Creek, which borders commercial and industrial properties, the Upper Bee Branch Creek runs through a residential neighborhood. As a result, the recreational elements of the project were more pronounced. The team designed a structure that serves as both an overlook and an outfall structure where the creek emerges from the culvert. It then meanders by a community orchard, an amphitheater, a creek aeration feature, a slide play area, and three stormwater biofields until it crosses beneath the Canadian Pacific railroad tracks and flows into the Lower Bee Branch Creek.

By adding more landscaping elements to this portion of the project, the city hoped that it would create a space in which residents could gather and enjoy the natural beauty of the creek. The amphitheater encourages families and nearby Audubon Elementary students to stop, sit, and enjoy the scenic view. The slide play area planned between E. 22nd and E. 24th streets allows youngsters to enjoy the space as well. The community orchard and stormwater biofields add sustainable features by encouraging residents to harvest produce and learn about native plant species.

“Feedback from the public directed a design to create space appealing to Dubuque residents. And it is already attracting visitors, even some from outside of Iowa,” said Muehring. “The linear park-like corridor, which provides a trail connection to the multi-state Mississippi River trail system, has an abundance of benches, walking paths, interpretive signs, and native plantings for all to enjoy.”

For the Upper Bee Branch Creek, the city is continuing to develop a suitable fish environment and amenities that encourage anglers. On the east side of the channel, a sidewalk abuts the limestone channel edge. Limestone fishing platforms are being constructed that hang out over the edge of the creek where deeper fishing holes and wooden fish lunkers are constructed to promote fish habitation.

Construction of the Upper Bee Branch Creek presented numerous construction sequencing challenges. Local roads and utilities had to be abandoned and re-constructed in stages in order to meet traffic demands and maintain utility services to businesses and residents. In addition, the construction sequencing needed to account for the stormwater conveyance of the watershed. A thorough construction phasing plan was developed in coordination with city traffic engineers, city utility engineers, and private utility providers. The phasing plans allowed flexibility for contractor input and modifications during construction to optimize the sequencing of the work.

According to Eric Vieth, Strand Associates project manager, extensive coordination with project stakeholders during design was critical. “The daily communication among city staff, design engineers, and contractors was also essential,” said Vieth. “This hands-on and involved approach during construction really helped avoid any major disruption of services for city residents.”

Although the Bee Branch Creek is appealing for its beautiful aesthetics and recreational amenities, the city’s long-term savings truly make the Bee Branch Creek Restoration project a worthwhile and responsible investment. Because of the stormwater management elements implemented in this project and other phases of the Bee Branch Watershed Flood Mitigation project, the city of Dubuque anticipates saving an estimated $582 million in damages over the 100-year design life of this project. These savings – which will be realized through fewer flood-related emergency response activities, fewer necessary infrastructure repairs after flood events, and reduced debris clean-up and removal – more than make up for the $219 million price tag of the various improvements.

The Upper Bee Branch Creek Restoration will reach substantial completion in July 2017, after which the city will focus on connecting the upper and lower sections of Bee Branch Creek by placing large-diameter culverts under the Canadian Pacific railroad yard. This final element of the restoration will enable stormwater to drain more efficiently from the upper to the lower creek, and will be completed in 2019.

“On the whole, we’re really pleased with how the project has turned out,” said Steve Sampson-Brown, the city’s construction project manager. “Both Strand Associates and IIW have done an excellent job assisting the city with the design and construction administration of this project. When complete, once flood-prone homes and businesses will now be protected and our community will have another beautiful space in which to gather.”

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