Environmental Engineering Reference
In-Depth Information
can improve the quality and reduce the quantity of water entering the wet-
land restoration site, which may help offset a higher watershed ratio and
support a higher quality wetland restoration.
These studies in the Red River basin of Minnesota have provided important
relationships between floodwater performance and the biological diversity of
wetlands. The biological diversity and productivity of the historic and restored
Mesopotamian marshes may respond similarly to the same variables. These
studies demonstrate the important link between watershed and wetland land
uses, acreages, and the outcomes of wetland restoration. To restore a living land-
scape for human sustenance, floodwater uses in wetlands, water system turnover
rates and processes will greatly affect the health of human foodstuffs and their
reliable production.
KANKAKEE SANDS, RENSSELAER, INDIANA
The Nature Conservancy purchased 7,300 acres of former drained wetland and gla-
cial lake basin in northwestern Indiana. AES was retained to design, permit, and
build the first two thousand acres of this restoration project. This land was purchased
because once restored, it could serve as a conservation link to nature preserves to the
north, east, and south.
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estoration
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A long history of land drainage and farming and the presence of significant infra-
structure such as center pivot irrigation systems, over two hundred miles of legal
drainage ditches (Figure 9.3), thousands of miles of buried drain tile (Figure 9.4),
and annually maintained surface drainage ditching on this very low-relief landscape
greatly affected the restoration design, engineering, and implementation program.
We initially hired new aerial photography and 6' aerial topographic maps for the
entire project area and a slightly enlarged area beyond the property (Figure 9.5).
On-site ground control and horizontal and vertical surveys of surrounding infra-
structure, such as roads, drainageways that crossed property lines, tile inverts shared
by adjacent property owners, enabled the surveying the locations of the house foun-
dation and septic, and road surface elevations, center lines and road edges, and
cross-sections of the drainage ditch systems. Because of the adjacent private proper-
ties needed to maintain the agricultural land use and the drainage infrastructure,
we walked all ditches, found and located shared tiles, and surveyed in property
boundaries.
Many ditches were legal drains that could not be modified by the restoration
efforts (Figure 9.6). Mapping of the ditch system and legal and regulatory constraints
associated with the modification of each was an important step in the process. We
conferred with the local county surveyor and engineer to understand the regulatory
constraints on our use and modification of any ditches.
Shallow surface ditches maintained annually by each property owner were shal-
low, 1-2 feet in depth and 2-6 feet wide (Figure 9.7). These ditches had no legal
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