Estimating the Volume of Fine-Grained Sediments

1
Estimating the Volume of Fine-Grained Sediments
Behind Four Low-Head Dams, Kalamazoo River,
Michigan.
In cooperation with the Michigan Department of
Environmental Quality, Environmental Response
Division (MDEQ-ERD), the U.S. Geological Survey
is estimating the volume of fine-grained
materials within the impoundments of four
low-head dams (Plainwell, Otsego City, Otsego,
and Trowbridge), located on the Kalamazoo River.
2
Problem The restoration of natural flow regimes
to rivers can have significant environmental and
aesthetic benefits. In many cases, restoring the
natural flow regime requires the removal of
non-functioning low-head dams. A series of dams
exists on the Kalamazoo River between Plainwell
and Allegan, Michigan. All are under
consideration for removal in the future. Removal
of these dams will return the Kalamazoo River to
its pre-dam flow, increase recreation uses and
safety of the river, and improve aquatic habitat
in this section of the river. The removal of any
dam comes with some risks. The two most common
problems encountered are the movement of
contaminated sediment downstream and the
migration of invasive species from the Great
Lakes upstream to the headwater areas. Since
additional dams downstream of the project will
remain in place, migration of invasive species
should not be an issue however, movement of
contaminated sediments is a major concern. The
USEPA has designated the Kalamazoo River from the
city of Kalamazoo to where it discharges into
Lake Michigan as a Federal Superfund site. The
bed sediments are known to contain PCBs from
paper-mill carbonless copy paper production (up
to 150 ppm PCB--Blasland, Bouck, Lee, 1994).
Therefore, it is essential that the volume,
grain-size distribution, degree of contamination,
and potential for down-stream movement of
sediments from behind these dams be known before
any dam removal can take place. This ongoing
multi-phase study will provide valuable
information for dam removals on the Kalamazoo
River and other dam removal projects in the Great
Lakes watershed. This multi-year effort has
provided estimates of volume of fine-grain
sediment behind three dams is currently
collecting sediment coring data below the
Plainwell Dam plans to continue monitoring
streamflow and sediment transport before, during,
and after dam removals and proposes an
additional volume estimate at the Otsego City
Dam. A sediment-transport model on the upstream
Plainwell Dam could be designed and calibrated
and would be useful in predicting downstream
sediment movement before dam removal takes
place. Objectives Estimate the volume, grain-size
distribution, and potential for down-stream
movement of sediments from behind the Plainwell,
Otsego City, Otsego, and Trowbridge Dams.
Continue to operate two daily-discharge gaging
stations one above and one below this multi-dam
reach. Continue to collect background suspended
sediment data (before removals) using automatic
samplers at the downstream Trowbridge gage.
Design and calibrate a sediment-transport model
at the upstream Plainwell Dam that will predict
sediment movement from the City of Plainwell to
the Otsego City Dam and possibly project similar
effects at other dam sites downstream. Document
the effects of removal of these dams on the
Kalamazoo River environment, including
suspended-sediment, bed load, and stream flow.
Figure 2. (A) Using auger to determine water
depth and sediment thickness. (B) Collecting a
core sample.
A
B
3
Figure 2. Transect locations. In addition to
collecting data along transects,
Figure 4. Depth of Water grid. Generated using
contours with a 1 ft. contour interval.
miscellaneous points were used to collect
information at random locations between
Grid cell size is 2 ft.
the transects (shown in yellow).
Figure 6. Thickness of fine-grained material
grid. Generated by subtracting grid in
Figure 5. Depth bottom of fine-grained material
grid. Generated using contours with
figure 4 from that in figure 5. Grid cell size
is 2 ft.
a 1 ft. contour interval. Grid cell size is 2
ft.
While the figures depicted illustrate the grids
for the Plainwell dam, the above procedure was
identically applied to each dam in the study.
4
Benefits Although engineering studies and
construction efforts have addressed the
stabilization of some of these dams on the
Kalamazoo River (CDM, 1999, 2000, 2001), the
consequences of the removal of the dams are
basically unknown. The study of these sites
provide an opportunity to monitor the actual
mobilization, transport, and ultimate fate of
contaminated sediment and has substantial
potential to advance the understanding of these
hydrologic processes and transfer knowledge to
other sites. Refinement and improved accuracy of
mathematical approaches to contaminated-sediment
transport and other impacts at the Plainwell Dam
removal site may mean that future downstream dam
removals may only require pre-removal snapshots
of sediment availability and geomorphic
assessments, rather than long-term monitoring, at
substantial decrease in cost. Data from the
proposed study will aid in making decisions
regarding removal of the downstream structures
more cost effective and scientifically based.
Products Technical results of the project will
be published in a USGS Water-Resources
Investigations Report (WRIR) on the stratigraphy,
sedimentology, and volume of fine-grained
sediments behind each dam. References Blasland,
Bouck Lee, Inc., 1994, Allied Paper,
Inc./Portage Creek/Kalamazoo River Superfund Site
Remedial Investigation/Feasibility Study draft
technical memorandum 10--Sediment
Characterization/Geostatistical Pilot
Study. Blasland, Bouck Lee, Inc., 2000,
Sediment behind the Plainwell, Otsego, and
Trowbridge Dams Project --645.24.116 2, 14
p. Camp Dresser McKee, 1999, Evaluation Report
of Plainwell Dam--Kalamazoo, Michigan January
1999, 5 p. Camp Dresser McKee, 1999,
Evaluation Report of Trowbridge Dam--Kalamazoo,
Michigan January 1999, 5 p. Camp Dresser
McKee, 1999, Baseline Ecological Risk
Assessment--Allied Paper, Inc./Portage
Creek/Kalamazoo River Superfund Site June 1999,
various pagination. Camp Dresser McKee, 2000,
Otsego Dam--Evaluation and phase II investigation
report April 2000, 8 p.