Erie Street Plaza

Challenge

The goal of the design competition was to create a significant public place that would become a critical component of Milwaukee’s waterfront and new development in the Third Ward. Because the site was a surface parking lot in an urban context of infrastructure and industry, the future users, function, and programming were all undecided at the beginning of the project’s design. The existing grade of the site was within a few feet of the mean high water mark in some areas, so the design would need to consider this, as well as the wider ecological condition along the Milwaukee River.

Solution

The uncertainty and open-endedness were at the core of the plaza design. With no set program and no immediate stakeholders, flexibility was key. The plaza was conceived as a simply articulated and open-ended civic plain that could accommodate a range of potential uses from large gatherings and day-to-day activities. To address both high water levels and stormwater runoff from the site, the plaza includes a lower “steel marsh” at the river’s edge to serve as a biological filter. By lowering the grade along the existing sheet pile seawall a basin was created to manage runoff from the site. Slits cut into the top edge of the wall allow water to exit during flood conditions and, during the 20-year high water cycles of Lake Michigan, allow river water to enter and inundate the plaza’s lower elevations.

• In order to address contamination on the site and improve the hydrological performance of the park, contaminated soils were regraded and then capped to create a 2.5% slope from the street down to the water.
• The park waterfront is bordered by a corrugated steel bulkhead, which was used to create the site’s signature “steel marsh.” The grade was lowered along the wall, creating a basin that manages stomwater runoff from the site. Slits of varying sizes were cut into the top of the wall, allowing water to exit during flood conditions to protect the marsh habitat. The slits will also allow river water to enter and inundate the lower levels of the plaza during the intermittent high waters of Lake Michigan, which are present in 20-year cycles.
• 20 different species of native marsh grasses, wetland plants, and mesic prarie plants thrive within the marsh area. These plantings were given a 6-8” soil depth to stabilize and establish vegetative structure.
• Existing subsurface anchor structures were located and used as foundation elements for new concrete walls, which delineate upper lawn and paver areas.
• The plaza surface includes wood decking, pavers and lawn areas that create a hybrid “plaza green.” The pavers are placed at variable densities and orientations, providing visual variety and encouraging flexible use of space.
• On the western side of the plaza, 6 linear poplar groves lead from the upper portion down to the water’s edge. The groves are positioned to provide shelter from winter winds, while still allowing visibility across the park.
• Irregularly shaped and placed, illuminated fiberglass benches are the plaza’s most distinguishing feature, providing opportunities for group and solitary seating. The benches both reflect light and project it from within, brightening the park at nightfall.
• Exposed aggregate concrete provides ADA-compliant fishing access at the waterfront, which is one of three accessible fishing and boating public piers in the city.
• Lawn areas accommodate group fitness classes during warm weather from the adjacent Ellipse Fitness center, located approximately 500 feet away.

• Value engineering on the project led to switching from a custom to a standard unit paver and eliminating 1,600 sf of paved area, which then became “soft” vegetated surface. This reduced the cost of the plaza by $44,499.
• The design competition entry featured not a poplar grove but a bamboo grove, accompanied by heated steam pits that would allow the bamboo to grow and survive in winter. Elimination of the steam pits during the design process saved $118,860 in construction costs associated with electrical utilities, water distribution and labor. This helped reduce final project costs by nearly 12%.

• The winning design competition entry featured groves of cold-hardy bamboo in buried steam pits, which would create a microclimate and sustain the bamboo. However, a contingent of community groups and stakeholders did not support this design element, particularly given the cost implications. These groups voiced their concerns, and gained recognition from the City of Milwaukee. In the end, the designers eliminated the steam pits and used poplar species instead of bamboo, as City officials concluded that bamboo would not survive during Midwestern winters. While some of the original design intent was lost, from an economic standpoint, the elimination of the steam pits and bamboo lowered project costs and contributed to the project being an example of successful TIF development.
• Designers should work closely with local groups to establish a comprehensive maintenance plan. At Erie Street Plaza, many of the plantings require annual pruning to maintain size and vigor. Currently, landscape maintenance of this kind is performed by the Historic Third Ward Association.

Project Team

Client: City of Milwaukee
Landscape Architect: Stoss Landscape Urbanism
Urban Design: Vetter Denk Architects
Lighting Design: Light THIS!
Structural, electrical, mechanical engineering and wetland science: MAGRAEF

Role of the Landscape Architect

The landscape architect won the 2006 international design competition for the site and then worked closely with the City of Milwaukee and stakeholders to incorporate community input and lower project costs through design modifications. Ultimately, the designers formulated a solution which restored ecological integrity to the site while creating a popular recreational and social space.