Landscape and Vegetation Characteristics

ERDC TN-DOER-C22

September 2001

Landscape and Vegetation Characteristics

Monroe, MI. This CDF, located within a state park along Lake Erie, is typical for many CDFs in

the Great Lakes area that have been in existence for several years or more. It is composed of a large

ponded area on the discharge side transitioning upwards into mud flats and wetland areas. The site

is still in use for the disposal of dredged material. The upland area was occupied largely by trees,

among which willow and cottonwood predominated. The site showed signs of recent (1999)

dredged material disposal onto established vegetation in the upland area.

Manitowoc, WI. This CDF is located on the shore of Lake Michigan alongside a marina with

associated park facilities, with the top of the inland dike serving as a concrete walkway for

pedestrians visiting the marina or park. It is composed of a large ponded area, transitioning into a

mud flat, wetland, and upland. The site is still in use for disposal of dredged material, which is

pumped over the lake-bordering dike into the CDF. The vegetated portions of the site include from

lower to higher elevation low rosette-forming crucifers, Phragmites australis (common reed) in

the second- or third-year growth stage, and various Urtica species (nettles). The site was extensively

used by birds, including nesting gulls and geese.

Bayport at Green Bay, WI. This CDF, located on the outskirts of Green Bay on the shore of Lake

Michigan, is composed of at least six cells. The sites chosen for sampling are situated within Cell 6.

Cell 6 is still in use for the upland disposal of dredged material, and received its last addition in

1999. The dredged material was unstable, and the groundwater table about 5 cm below the dredged

material surface. Cell 6 had a uniform elevation, and was completely vegetated by P. australis in

2000, but lacked vegetation in 1999.

Dredged Material. At each CDF, three dredged material samples were collected from the soil

surface to approximately 0.3-m depth, one in the wettest area (usually close to the point of outflow),

one at an intermediate area, and one at the driest area (often the point of entry of the dredged material

into the CDF). This sampling strategy was chosen based on the assumption that after entering the

CDF, the fine-grained particles in the dredged material are transported toward the point of outflow

carrying most contaminants, and the sandy particles settle close to the point of entry. At Monroe,

the samples were taken within the recent disposal area following the described sampling strategy.

Sampling coordinates for the first sample were 03-06-523 E, 17 46-42-842 N; for the second sample,

03-06-514 E, 17 46-42-869 N; and for the third sample, 03-06-491 E, 17 46-42-853 N. Visual

inspection indicated that the dredged material was characterized by a high clay content, and would

likely classify as a silty clay or clay loam soil. At Manitowoc, the samples were taken at the edge

of the mudflat, halfway between the upland, and within the upland area. Sampling coordinates for

the first sample were 4-48-212 E, 16 48-82-813 N; for the second sample, 4-48-213 E, 16 48-82-835 N;

and for the third sample, 4-48-188 E, 16 48-22-750 N. Visual inspection indicated that this dredged

material was more silty than at Monroe, and would likely classify as a silty loam soil. At Bayport,

the samples were taken 15 m away from the dike (i.e., near the weir, halfway, and within the upper

end of the cell). Sampling coordinates for the first sample were 4-18-477 E, 16 49-33-556 N; for the

second sample, 4-18-444 E, 16 49-33-584 N; and for the third sample, 4-18-392 E, 16 49-33-644 N.

Visual inspection indicated that this dredged material was far more organic than at the other locations

and somewhat silty.