William G. Milliken State Park, Phase 2 Lowland Park

Challenge

The site was to be developed as a park/stormwater management demonstration facility that would manage the runoff from adjacent properties in order to make those properties more attractive for redevelopment. Current municipal regulations require the construction of costly stormwater detention systems as part of any intensive development. Creating a park to manage stormwater from the surrounding land would eliminate the need for this infrastructure on the adjacent parcels. The design challenge was two-fold: first, designers needed to create a wetland large enough to filter runoff during storm events, while still receiving enough water to keep the wetland charged during dry periods. Second, the site contained contaminated soil left over from the previous industrial facility that once occupied the site.

Solution

Based on calculations of maximum and minimum surface flows from adjacent properties, the designers built the largest wetland the site can reasonably accommodate to treat runoff from the largest surrounding area possible. During periods of minimal inflow, supplementary river water can be pumped into the wetland to keep inflow and outflow in equilibrium. The contaminated soils were capped in-place as the wetland was perched on top of the existing brownfield, separated by a clay layer to minimize infiltration and exfiltration.

• Over the past 200 years, urban fill has extended the Detroit River shoreline by 500 feet. Construction of the park involved keeping the shoreline as is but removing concrete shipping docks, railroad turntables and underground utilities.
• The park tops approximately 4 acres of contaminated brownfield soils with a wetland consisting of shallow ponds, emergent/submergent and upland prairie vegetation. The wetland is home to 10 aquatic plant species, 32 native forb and grass species, and 20 native tree and shrub species.
• The wetland treats stormwater from 12 acres of adjacent land. First, the stormwater is piped in and passes through a swirl separator to remove suspended solids, oil and grease. The stormwater is then pumped into a 4 ft deep sediment forebay, allowing additional sediment to drop out before entering 3 ft deep pools with emergent plants. Finally, it passes through 18 in-deep braided wetland streams in order to increase vegetation and stormwater interaction for maximum filtering; then the stormwater passes over a weir before entering the Detroit River.
• 5 interpretive shelters with signage illustrating the native, industrial and social history of the riverfront are easily accessible for visitors.
• The park provides opportunities for lunch time and after work hours educational and recreational activities to the nearly 11,000 people working in the nearby GM Renaissance Center complex, a cluster of seven skyscrapers which includes the GM world headquarters, a hotel and shopping center. GM sponsors the DNR (Department of Natural Resources) Explorer program twice a week at the Renaissance Center to share information, conduct tours and answer questions about the park and the riverwalk. Programs and topics addressed include: Fishing 101, What Kind of Fish is This?, Detroit Riverfront Birding, Bird Conservation through Citizen Science, Michigan State Parks: Connecting Michiganders to Nature and History, and What is the Michigan DNR?
• Park amenities such as concrete hardscapes and stainless steel cable railing provide over 500 ft of riverfront fishing accessibility.
• A memorial to Peter Stroh featuring a bronze bust, plaque, water feature and a 800 sf concrete courtyard with seating is centrally located in the park. The memorial commemorates this noted conservationist who advocated for public access to the riverfront.

• The creation of Lowland Park topped 25,813 cubic yards of contaminated soils in-place compared to complete soil removal and remediation thus saving $256,740 in removal costs or about 17.6% of the project cost.

• Because soils on-site raised concerns about lead, arsenic, petroleum, and other trace contaminants, topsoil was brought in from off site. However, the imported soil had not been thoroughly cleaned of invasive phragmites residue and the reeds quickly took hold on site. Project landscape architects learned that on-site construction supervision and quality control are paramount in preventing this problem in the future.
• Even with sterile soil, phragmites and other invasive species proved difficult to control during the initial construction of the wetlands and required repeated mechanical removal to allow native plants to become securely established. The Parks Explorer program mobilized older youth volunteers to assist the DNR in periodically removing invasive species from the wetland.

Project Team

Client: Michigan Department of Natural Resources
Landscape Architect: SmithGroupJJR
Cultural Resources Investigations: Commonwealth Cultural Resources Group, Inc.
Geotechnical Investigation and Construction Testing: NTH Consultants, Ltd.
Brownfield Environmental Consulting: MACTEC Engineering and Consulting
Electrical Engineering: Applied Power and Controls
General Contractor: Anglin Civil Constructors

Role of the Landscape Architect

SmithGroupJJR coordinated the efforts of a multidisciplinary team, including landscape architects, surveyors, civil and geotechnical engineers, electrical engineers, horticulturists, aquatic biologists, interpretive designers, urban demographics specialists, development economists, and stakeholders. The role of the landscape architect was to synthesize the technical, social, and ecological expertise of the team towards a cohesive and functional design that improves the image of the city.