Petersburg Wetland Mitigation State Game Area Receives a New Addition
The Petersburg State Game Area in Monroe County is a 616-acre wildlife space between Toledo and Ann Arbor. Spicer Group was hired for the planning and design of a new wetland mitigation bank project at this location which included preparing construction plans, permitting, bidding documents, and obtaining a geotechnical evaluation of the site.
The project was undertaken by the Michigan Municipal Wetland Alliance (MMWA), a non-profit organization dedicated to establishing, preserving, enhancing, and developing wetland mitigation sites to help municipalities and agricultural producers abide by wetland mitigation requirements. When a municipal project, such as road or drain improvements, impact surrounding wetlands, the municipality can either create a wetland elsewhere on the site, create an off-site wetland mitigation bank, or purchase credits from an existing wetland mitigation bank. The MMWA makes these credits available at a lower cost thereby offering financial efficiency for municipal projects.
For the Petersburg Wetland Mitigation project, the MMWA provided funding for construction, while the Michigan Department of Natural Resources (DNR) provided the land and will maintain the site once the wetland is completed. The wetland, once fully functional, is placed under a conservation easement to ensure its indefinite preservation.
The funding came through the State of Michigan legislature and was secured by the MMWA.
“The project aimed to allocate the grant to MMWA for restoring pre-settlement hydrology, which refers to the natural water flow prior to the area’s development,” said Steve Shine, Wetland Bank Administrator at the Michigan DNR. “We wanted to mimic the state of the land before it was used for farming in order to create more recreation opportunity for the public.”
Within the Petersburg State Game Area, the wetland mitigation project area totals roughly 34 acres, including 9 acres of scrub shrub, 15 acres of wet meadow, and 10 acres of emergent, all within the River Raisin Watershed and Western Lake Erie Basin. The site consists of two fields separated by the Stacy Drain. The site’s design considered its proximity to the Stacy Drain, incorporating berms and water control structures to keep water on the wetland site. The project design also included a geosynthetic clay liner which allowed for sand to be used for the berm fill material without allowing water to escape the wetland.
“The design and construction of a wetland is more of an art than a science,” said Project Manager Steve Roznowski, P.E. “It’s a tricky thing and different from a lot of other projects we do.”
The project site is divided into eastern and western sites. The eastern side of the site, which is higher in elevation, was more challenging to convert to wetlands because the water was inclined to run off. Conversely, the western side of the site was chronically wet, low-production farmland. The DNR purchased the western parcel of land to maximize the wetland and habitat potential of the site. Before construction began, the site was carefully monitored to ensure it would retain sufficient water for wetland creation. Groundwater monitoring wells were installed to track the water table and are checked every 3-4 months to assess the level of the water table onsite.
Designing a wetland involves creating a water budget and using hydrology to determine the necessary water levels to keep plant root structures hydrated most of the year.
“Although wetlands don’t need standing water, they require hydration within about a foot of the ground surface during the growing season to support wetland plant growth,” Roznowski said.
Construction of the Petersburg Wetland Mitigation project kicked off in 2023, with Spicer Group providing construction oversight and Salenbien Trucking and Excavating performing the construction work. Material from the wetland excavation was used to build a berm around the site.
“Due to the berm around the outside of the project, we had very little worry about sediment leaving the site,” Roznowski said. “It also minimized our erosion concerns because the perimeter is secured with the berm and liner.”
A drain crossing in poor condition, initially located in the middle of the project site, was also removed and a new crossing was installed near the northern end of the site. This new crossing connected the west and east sites and allowed the berm to serve as a walking path for visitors.
An additional and essential aspect of the wetland project was the creation of habitat structures which included cut trees, logs, earthen mounds, and other natural elements. These structures were strategically placed to provide habitats for wildlife such as turtles, beavers, frogs, and birds.
The project work has recently been closed out. Once the wetland is fully established, a biologist will conduct an assessment to ensure the site meets the required criteria for a wetland mitigation bank. This will be followed by a five-year monitoring period to confirm proper establishment. Spicer Group will handle the survey in collaboration with Streamside Ecological Services, who will oversee the wetland delineation and monitoring. This meticulous planning and execution aims to establish a thriving wetland environment, contributing to the preservation and ecological health of the Petersburg State Game Area.
