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Wayne County Preliminary Wetland Inventory Map

Inkster Wetlands Project

The Inkster Valley Constructed Wetlands Project site is located in the Inkster Valley Golf Course within the City of Inkster, north of Michigan Avenue between Inkster and Henry Ruff Roads. The study wetlands are located in three areas situated adjacently to the Rouge River. A summary of the study wetlands is available. The Inkster Valley Golf Course has a total of seven wetland mitigation and enhancement areas throughout the golf course. A summary of each of these areas is also available. The ultimate intent of this demonstration project is to determine the effectiveness of, and develop design guidelines for, the use of existing and created freshwater wetlands for treating nonpoint source pollution. The evaluation will include identification of pollutants removed by the wetlands, the efficiency of the removal processes, and the effects of sediments on removal efficiency. Specific objectives of the wetland demonstration project include the development of a site selection strategy for assessing the use of existing and restored wetlands and for the development of a methodology that would facilitate the identification of feasible locations for the design and construction of new wetlands.

Site selection techniques were developed, presenting an integrated approach, incorporating elements of the ecological features, wetland hydrology, water quality considerations, watershed characteristics, and surrounding land use. The design of the sites incorporated features that allow for manipulation of storm water flow quantity and duration, and allow for the direct comparison of the effectiveness of nonpoint source pollution control in existing and created wetlands receiving storm water runoff from a single watershed.

Design criteria for each of the wetland areas were developed from modeled hydrological data in combination with characteristics of the available treatment area. The wetland creation and enhancement areas contain similar design elements that provide comparable experimental data which can be related to known design parameters. These elements include the incorporation of a sediment forebay to filter large particles before the storm water enters the wetland system; treatment of "first flush" for most storm events; designed discharge outlets to the Rouge River with monitoring capabilities; and intermediate monitoring points where applicable.

Site Diagram
(wetlall.pdf-149k)

A five-year monitoring program is in place to measure the impacts of storm water runoff on the plants and other biota of the flood plain wetlands areas. By annually monitoring the vegetation, and comparing the results to the baseline data compiled in 1995 ( prior to the construction of the storm water retention system ), it will be possible to discern and measure any major changes. Monitoring is also being done of aquatic macroinvertebrate populations in these areas. These data will be important for understanding long-term environmental impacts of water resource management in wetland ecosystems.

 

Wetland Area 1
Wetland Area 2
Wetland Area 3

 

Wetland Area 1

Site Characteristics
The area is located on the north side of the Rouge River between Inkster and Middlebelt Roads. It is located within an existing 12-acre upland field with grasses and herbaceous vegetation centrally located on the site. The site is bordered by steep slopes to the north and east, which is predominately single-family residential, and by the Rouge River flood plain to the south. The entire site is within the 100-year flood plain of the Rouge River. A 6.2-acre forested wetland is located along the south edge of the site, extending to the banks of the Rouge River. The forested wetland contains box elder, green ash, cottonwood and American elm.

Design Characteristics
The objective is to demonstrate the efficiency of storm water treatment by a newly created emergent wetland. The wetland area was designed to be sustained by the contributions from the existing storm sewer area. Approximately 3.0 acres of emergent wetland was designed and constructed to collect storm water from an approximately 48-acre older residential neighborhood. The design elements of this area include a sediment forebay, designed to capture storm water flowing from the 42-inch storm sewer and filter large particles before entering the wetland system. All of the storm water from each rain event is directed to the wetland system via the sediment forebay and vegetated swale. Soil boring information was acquired to document and test wetland creation designs with varying soil types. The area will continue to function as an emergent wetland after completion of the demonstration project.

 

Wetland Area 2

Site Characteristics
Area 2 is located south of the Rouge River between Inkster and Middlebelt Roads. The site contains an existing 3.0- acre forested wetland dominated by cottonwood, American elm, box elder and willow. The existing topography slopes to the east, and the wetland naturally discharges to the Rouge River at the eastern end of the wetland. It is bounded by steep fill on the south and a low berm to the north and west. The entire site is within the 100-year flood plain of the Rouge River. The existing wetland hydrology was maintained by precipitation, runoff from adjacent land and groundwater. Historically, storm water from approximately 165 acres of mixed land use was discharged directly to the Rouge River via a 60-inch pipe located at the far eastern point of the site.

Design Characteristics
Wetland Area 2 is demonstrating the efficiency of storm water treatment by an existing forested wetland. Approximately 3.0 acres of forested wetland has been enclosed by berms designed to retain a specified amount of storm water from the storm sewer area. The area utilizes a lift station to deliver a specified portion of the storm water from the storm sewer to the wetland. Storm water is transported to the wetland area from the storm sewer via an underground pipe into a catch basin designed to function as a sediment forebay. This wetland previously discharged water to the Rouge River at one location at the eastern point of the site. Overflow from Area 2 continues to discharge from this location, although the outlet has been modified to control the outflow rate and allow for monitoring activities. Implementation of this project involved altering the area's hydrologic regime. The forested wetland is maintained by both surface drainage and groundwater contributions. The volume of surface runoff entering the system is increased from original levels during the demonstration period. It is unlikely that substantial changes to the original forested wetland system will occur in this limited amount of time. The site's hydrology will return to its standard condition upon completion of this period.

 

Wetland Area 3

Site Characteristics
Area 3 is located south of the Rouge River between Inkster and Middlebelt Roads, approximately 1,800 feet west of Area 2. The entire site is within the 100-year flood plain of the Rouge River. The site is bisected by an 80-foot long channel which historically conveyed storm water runoff from the 183-acre, residential and commercial watershed directly to the Rouge River. The ditch had partially filled with sediments resulting in some storm water flow being diverted to the wetlands on the east and west sides of the channel. The 4.7-acre wetlands on the east side of the channel contains forested/scrub/shrub/emergent and open water communities. Existing vegetation includes willow, cattail, water plantain, elm, cottonwood, sedges, rushes and snags. Water discharges from this wetland to the river via surface flow from a shallow swale along the site's eastern river bank.

Approximately 2.4 acres of emergent/scrub/shrub wetland are located along the west side of the channel. This wetland also receives storm water from the existing sewer line due to the sedimentated ditch. This wetland contains primarily willow, dogwood, and cattail. Moderate base flow in the channel indicates groundwater may also contribute to the wetland hydrology.

Design Characteristics
Wetland Area 3 contains two separate treatment areas, 3-East and 3-West. A sediment forebay is located at the inflow of each wetland area. Three outlets were constructed in this basin to direct first flush and small storm event flow to wetlands 3-East and 3-West, and overflow from larger storms is discharged directly to the Rouge River.

Wetland Area 3-East - This area is an existing wetland system that supports forested, emergent, scrub/shrub, and open water systems. The objective of the design is to enhance the flow through this wetland to utilize each of the wetland types in the treatment of storm water. The designated area is enclosed by 18 inch berms. Storm water flow from the sediment forebay is discharged into the existing wetland. Berms do not impede the 100-year flood flow from the Rouge River flood conditions. Overflow from this area will continue to discharge from a low point located along the eastern boundary. The outlet has been modified to control the flow rate and allow for monitoring activities.

Wetland Area 3-West - This area contains an emergent and a scrub/shrub wetland created within a former upland area. The created wetland was apportioned into two areas- one and two acre wetland cells. The water flows through this two-tier system to an outlet to the Rouge River. This outlet is located at a naturally occurring low point within the forested wetland along the river's banks. A controlled outlet structure was installed at the outlet point to control retention time, water depth and allow for monitoring activities. These wetlands were created in conjunction with wetland mitigation; therefore, they are designed to function as wetlands with minor modifications, if any, after the demonstration period is completed.

Photographs of the wetlands are available. Additional photographs are available in the annual monitoring summaries prepared under the Reports link.

Reports


Last Updated: 8/2/2004

Please address all comments and suggestions about the contents of this Web page to rougeweb@co.wayne.mi.us.

The Rouge River National Wet Weather Demonstration Project is funded, in part, by the United States Environmental Protection Agency (EPA) Grants #XP995743-01, -02, -03, -04, -05, -06, -08 and C-264000-01.