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
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
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.
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 2
Wetland Area 3
Wetland Area 1
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.
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
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.
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
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.
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
under the Reports link.