Environmental Engineering Reference
In-Depth Information
Ponar dredges (30-70 lbs) must be used. Due to the weight of the equipment, a cable
is required to winch from a boat, bridge or pier for raising or lowering the sampler.
The ponar dredge is used to sample sediments that range in size from silt to granular
materials. The ''petit'' size Ponar can be operated by one person without the use of a
winch or crane. The Petersen dredge is used when a bottom is rocky, in deep water or
in a stream with high velocity. Because of the dredge's large size, a large volume of
water is displaced when the jaws close and fine sediment can be swept away. A
sediment core sampler such as the one shown in Figure 4.6d is needed (1) to compare
recent surficial vs. historical deeper sediments, or (2) to collect undisturbed sediment
samples with minimal
loss of fine-grained sediment fraction and exposure to
oxygen.
Hazardous Waste Sampling
Sampling tools for hazardous wastes depend on the nature of waste and the type of
sources. If waste sludges are sampled, the Ponar or Ekman dredge can be used to
collect waste sludge samples from the bottom of impoundments, lakes, or other
standing water bodies. If solid waste samples are taken (such as from waste piles),
tools used for soil sampling can be used, such as scoop, trowel, and bucket auger.
The composite liquid waste sampler (coliwasa) (Fig. 4.7) is a tool typically used
for sampling stratified liquid in drums and other similar containers. It is a transparent
or opaque glass, PVC, or Teflon tube approximately 60 inches in length and one inch
in diameter. A neoprene stopper at the bottom of the tube can be opened and closed
(a)
(b)
(c)
1
2
6.35 cm (2
”)
61-100 cm,
(24-40”)
61-100 cm,
(24-40”)
152 cm (60”)
1
2
1.27-2.54 cm (
-1”)
Stopper
Sampling position
1
2
1.27-2.54 cm (
-1”)
Figure 4.7 Common sampling tools used for wastes: (a) Composite liquid waste samplers
(coliwasa), (b) Thief (grainer sampler), and (c) Trier (U.S. EPA, 1986)
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