Tom Hanafan River's Edge Park, Phase 1

Challenge

Project Goals

• Ensure that park land and amenities in the floodplain will be resilient for up to a 500-year flood event
• Provide access to 85 acres of waterfront open space for people from the city and region to have a or point of connection - visually, physically, and emotionally - to the Missouri River, where none had previously existed
• Provide new outdoor space for events and recreational public use
• Protect the existing flood protection levee while minimizing its impact as a barrier to waterfront access
• Capitalize on the viewsheds towards the Missouri River and Omaha’s skyline
• Provide an appropriately grand and inviting destination at the landing to the Bob Kerry Pedestrian Bridge, connecting the park to a larger trail network
• Revitalize the riparian forest on the northern and southern portions of the site

• The 4-acre Great Lawn has a customized soil profile that increases infiltration during rain and flooding events.
• Groves provide shaded transition points into the sun-exposed Great Lawn. The Event Grove features 75 honey locusts while 61 trees make up the Picnic Grove, consisting of Sun Valley red maple, Red Sunset red maple, Autumn Blaze maple, and American yellowwood. 
• In the northern portion of the park, 20 acres of riparian woodland along the Missouri River were restored. Native tree species planted include sugar maple (Acer saccharum), eastern black walnut (Juglans nigra), and American sycamore (Platanus occidentalis).
• Two sand beaches, totaling 15,000 sf, are adjacent to a riverfront walking path along the Missouri River.
• 7,200 linear ft of trails link the park to the regional trail system through the eastern landing of the Bob Kerrey Pedestrian Bridge. 
• 3 infiltration basins in the parking lot provide biofiltration and capture stormwater runoff.  The park’s bioswales manage parking lot runoff and have the capacity for up to a 10-year rain event.
• An outdoor amphitheater that can accommodate up to 2,000 visitors is strategically located on top of an existing levee.
• Flood-tolerant species, including biofiltration plants like fox sedge (Carex vulpinoidea) and yellow-fruited sedge (Carex annectens), promote floodplain resilience.
• Custom electrical systems with dark sky compliant lighting are located outside of the 500-year floodplain to increase flood resilience.
• Custom precast seat walls, pavers with a stone dust setting, and plant materials were all sourced locally.
• Integration of an interactive lighting exhibition, Rays by internationally-known artist Dan Corson, is showcased on the Great Lawn.

Although the integrated meadow’s upfront cost of $29,600 was $1 more per sf than conventional turfgrass, which would have cost $9,900, the cost for annual landscape maintenance on a meadow is 3.85 times less than the care of a traditional mown lawn. In 5 years, savings on maintenance will surpass the premium paid to install the meadow, and the park will save $4,700 every year thereafter.

• Through the hydraulic modeling process, designers and engineers worked together to test which areas of the site would be inundated in a flood. The hydraulic modeling process became an important design tool when it suggested drastic and novel changes to the proposed topography by raising and lowering grades and shifting locations of open space elements such as the lawn area. Other elements informed by the hydraulic modeling process include the stormwater management strategies to mitigate on-site flooding. The design process benefited greatly from the hydraulic modeling process as it provided the means to test existing and proposed topographic elevations against major flood events.
• The first phase of construction was interrupted by the 2011 Missouri Flood and could not continue until the flood waters receded several months later. This caused a major, indefinite hold on the project and raised concerns for the City. However, after hydraulically modeling the 2011 flood with the final design, it revealed minimal effect on the park – only a small portion of the road was flooded in the model while the lawn remained unsubmerged. Convinced of the park’s resilience after this test, the City agreed to move forward with the project. With hydraulic modelling, the designers were able to provide the City with qualitative information illustrating the importance of the topographic elevations accounted for in the design. 
• The design of the amphitheater was challenging due to the restrictions for the existing 1954 Army Corps of Engineers levee, as changes to it could jeopardize its structural integrity. As a result, the designers designed the amphitheater to sit on top of the levee, preventing any negative impact to its functionality. However, during the construction process, the stairs of the amphitheater were not constructed according to the designers’ specifications, which highlights the importance of having designers on site during the construction administration period.

Custom Precast Benches: Manufactured by Stonco Incorporated – supplied by Enterprise Properties, Inc
Soil Mix for Lawn: Compost Supplied by Oma-Gro – produced by the City of Omaha
Light Poles: Selux – Olivio Sistema
Stone Dust Paving: Sturgis Rock Solid Solutions – Dusty Red Gran-I-Path   
Meadow Planting Mix: Prairie Moon Nursery – Grand Diversity Mixed Height Prairie Mix
Native Trees: Hermes Nursery
Custom Signs: Enterprise Properties, Inc. – manufactured by Stonco Incorporated

Project Team

Client: City of Council Bluffs Department of Parks, Recreation and Public Property
Landscape Architect: Sasaki 
Civil Engineering: HGM Associates, Inc.; Sasaki Associates, Inc.  
Electrical/Communications: Alvine Engineering, Inc.
Structural Engineering: Richmond So Engineering, Inc.

Role of the Landscape Architect

The landscape architect’s roles and responsibilities for the project were to establish guidelines for the Master Plan, coordinate with a multidisciplinary team of engineers, and set objectives for the performative aspects of the park. They also led the design effort from design development to construction documentation. Later stages of Phase 1 of the project, including construction administration, were performed in coordination with a local civil engineering team.