Environmental Engineering Reference
In-Depth Information
To be consistent with previous work, all results reported by
Murray et al. (2004) were total recoverable levels of metals. Each
metal analysis selected for inclusion in this study followed iden-
tical laboratory quality control procedures established by the
MDNRE and mandated by the State of Michigan under Public
Act 451, Part 201. The near-surface samples were collected from
the upper 0.5 m of the surficial soil in the vicinity of the site
being investigated. Soil collection standards typically require
the collection of a soil sample at the base of the soil's A horizon
using a stainless-steel hand trowel, or a manual or mechani-
cally driven sampler. Subsurface samples were collected at
depths ranging from 0.5 to 20 m typically during the installa-
tion of groundwater monitoring wells or soil borings used to
determine the areal and vertical extent of contamination dur-
ing a site investigation. Soil samples were generally collected
using a 0.6 or 1.2 m-long steel sampler that was hydraulically
pushed into the ground using a Geoprobe
®
, or by a steel split-spoon sampler, which was
pounded into the ground at various depths using a truck-mounted drill rig equipped with
hollow-stem augers. Subsurface soil samples would have limited exposure to automobile
emissions and road runoff and should therefore have less of an anthropogenic signature.
The samples were analyzed using USEPA 6000 or 7000 series methods (USEPA 1983) and
followed all USEPA protocol (SW 846 Test Methods). Specific analytical methodologies for
each metal are presented in Table 9.2.
The surficial soils and topographic relief within the study area result from several gla-
cial advances and retreats during the recent geologic past. The resulting glacial drift has
produced moraines, outwash deposits from braided streams, lake bed plains, and adjacent
beach deposits. Each of these glacially derived deposits produces a texturally characteristic
soil type, for example, moraines composed of glacial till are prominent in the northwestern
part of the watershed and are mixtures of clay, sand, and gravel deposited by ice during
glacial periods. Due to the unsorted nature of these deposits, they may have locally low per-
meability and moderate porosity where the clay content is high. Physical features associated
with glacial terrains also include outwash plains, eskers, kames, irregular drainage patterns,
wetlands, and lakes. Soils associated with many of these features consist of well-drained
loams and sandy loams, with some areas of poorly drained sandy soils. Erosion potential is
the highest in this area because of the steep slopes created by the terminal moraines.
Glacial outwash deposits are present in the northeastern portion of the watershed
and are present between the linear moraine deposits (Farrand 1982, 1988; Rogers 1997a).
Outwash consists of deposits from flowing meltwater at the margins of glaciers. They
are generally well-sorted and contain large amounts of sand and gravel, with minor silt
and clay. Soils are medium textured and moderately well drained and have a moderate
slope. Beach and fluvial deposits formed along the western perimeter of a former glacial
lake during the retreat of the Lake Erie lobe. These deposits are found in a northeast-
southwest trending belt in the middle of the watershed. They tend to form very uniform,
well-drained sandy soils.
Lake beds are the prominent feature in the remainder (southeast part) of the watershed
(Farrand 1982; Rogers 1997a). These lake beds, characterized by low, gentle slopes consist
of clay units of lacustrine origin. They are distinguished within the Rouge River water-
shed by the percentage of silt and sand present and are classified as a sandy and silty clay,
TABLE 9.2
Metal Analytical Methods
Metal
EPA Method
Arsenic
7061
Barium
6010
Cadmium
6010
Chromium
6010
Copper
6010
Lead
6010
Mercury
7470
Nickel
6010
Selenium
7740
Silver
6010
Zinc
6010
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