Wetland Mitigation

The new wetlands are similar to those that naturally occur in southwest Ohio (7081D-249).

DOE is required by the Clean Water Act, Section 404, to replace wetlands that have been disturbed or destroyed during site operations and cleanup.  In June 1995, DOE negotiated a mitigation ratio of 1.5:1 acres (1.5 acres replaced for each acre of damaged wetland) with the regulatory agencies. As a result, DOE’s obligation is to develop 17.3 acres of new wetlands to compensate for the loss of 11.8 acres of wetlands at the Fernald site.

DOE and Fluor Fernald have scheduled wetland mitigation activities in two phases to coincide with site cleanup activities. Fernald created six to seven acres of new wetlands during Phase I, and will create five additional acres of wetlands during Phase II, which began in October 2003. The 12 acres of new wetlands Fernald will create during Phase I and Phase II, combined with smaller wetlands developed during other site restoration projects, will satisfy DOE’s commitment to create 17.3 acres of new wetlands.

Phase I
In 1999, Fernald constructed six to seven acres of new wetlands and six acres of restored upland vegetation along the northeast portion of the site, an area known as Area I, Phase I.  The wetland system contains an 8-basin freshwater cascade connected by gravity flow channels with varied vegetative cover (trees, shrubs, herbs). DOE's goal was to construct a wetland system similar in form and structure to those that historically and naturally occur in southwest Ohio. Using low maintenance design strategies, workers planted 3,327 trees and shrubs within 86 different patches across the project area over a three-year period.  For the first few years, Fernald will discourage nuisance wildlife so the vegetation will flourish.

Phase II
Phase II will involve the restoration of eight acres of land that Fernald used as a "borrow area" to extract soil and clay for various construction projects. Fernald will develop new wetlands on five acres and create diverse native habitats on the other three acres.

Ecologists have designed the wetlands to maximize acreage while minimizing the import or export of soil. The wetlands will include three shallow basins separated by spillways with erosion matting to ensure stability under flow conditions. Using water control structures similar to those used in the Southern Waste Units Restoration Project, ecologists can control the water levels and flow between basins. Wood debris will be placed along the bottom of the basins to create a wildlife habitat and materials will be secured in place to prevent movement during high water and possible damage to water control structures.

The project area will be seeded with native grass and forb mixture. To jump-start vegetation growth in the basins, ecologists will plant grass and wildflower plugs on the basin slopes and install herbaceous plants on inner slopes and in shallow areas of the basins.

The Wetlands Mitigation Phase I and II Projects are two of 15 ecological restoration projects outlined in the Fernald Natural Resource Restoration Plan to compensate for damages to natural resources during site operations and cleanup. The two projects will result in 22 acres of restored land, 12 of which are new wetlands.

Monitoring
Following construction of the Phase I wetlands in 1999, Fernald is required to monitor the wetland’s growing season (March through October) and submit annual reports for a five-year period. The survival rate of vegetation is monitored for the first three years and only soils and hydrology development is monitored in the final two years. The purpose of monitoring is to assess the overall health of the wetland system, determine the progression of replacement features and provide recommendations for design modifications in the early years to improve or enhance wetland functions.

In general, the results of the 2002 evaluation indicated an improved, functioning wetland ecosystem. The hydrology, herbaceous vegetation and wildlife use of the wetland have improved each year since its construction. Woody plants in the wetlands experienced reduced survival due to an extremely wet spring followed by drought conditions in the summer. The plants were already stressed from deer pressure and a drought in 1999. Since the primary goal of the project was the creation of new wetland acreage, DOE and the Fernald Natural Resource Trustees agreed to focus on improving the wetland function rather than replacing woody plant stock.

For the Phase II Wetland Mitigation Project, Fernald will measure water levels and quality, survey wetland plants and analyze soil quality for a three-year period. Plant survival and herbaceous coverage will only be evaluated in the first year after project completion. Ecologists will tag all sapling trees and shrubs with a unique number, which will be recorded on patch-specific data sheets. Mortality counts will be conducted at the end of the first growing season following completion of project area restoration. Fernald will also evaluate prairie areas in 2004 and forest areas in 2005 as part of the site-wide Functional Monitoring Program outlined in the 2002 Consolidated Monitoring Report.

The Wetland Mitigation Phase II Natural Resource Restoration Design Plan, the 2002 Consolidated Monitoring Report and other monitoring documents are available to the public in the Fernald Public Environmental Information Center.

For More Information
Contact Sue Walpole, S. M. Stoller, at 513-648-4026, e-mail: Sue.Walpole@lm.doe.gov .