Environmental Sampling Techniques - Fundamentals of Environmental Sampling and Analysis - page 90

reservoir formed by impoundments of rivers or streams. Coarser grain sediments are
found near the headwaters of the reservoir, while bed sediments are composed of
fine-grained materials that have elevated contaminant concentrations. Contaminants
tend to concentrate in the fine-grained sediment in depositional zones.

Practical tips

Before digging soils, provide a detailed site map and check with local
municipalities if the possibility of underground lines exists.
Use sampling tools made of stainless steel or Teflon tools only. They are
expensive, but it is less costly than re-sampling. The U.S. EPA states
''equipment constructed of plastic or PVC should not be used to collect
samples for trace organic compounds analyses'' (Bodger, 2003).
Do not use equipment made of galvanized metal as it contains Zn. Garden
tools and cheap kitchen items are not recommended for sampling purpose as
they are often chrome-plated.
Make sure to scrape off part of the soils/sediment in direct contact with the
sampler. For metal analysis, use stainless steel tools and plastic bucket to
homogenize.
For sampling deep soils (60-100 ft), a direct push Geoprobe method

developed for EPA is desired. This direct push device has reduced costs in
comparison with traditional drilling methods (HMTRI, 2002).
When decant water after the collection of sediment samples, make sure that
you do not lose the fines within the sediment.
Sampling devices must be carefully cleaned prior to and between each
sample to avoid cross contamination.
Plan ahead, air-dry, and sieving could take a long time. Not to forget
subsample for moisture measurement of soil and sediment.

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4.2.4 Hazardous Waste Sampling

Wastes come from a variety of sources, including drums, storage tanks, lab packs,
impoundments, waste piles, surfaces, and debris. Sampling approaches, therefore,
vary considerably for each type of these wastes. Of critical importance is to first
research all available documents, packing slips, and labels for the contents and
associated health and safety precautions. Use proper PPE when open containers and
sample wastes from drums, lab packs,orwaste tanks with known chemical
identities. For unknown wastes in drum and lab packs, open them remotely. Do not
move drums with unknown chemicals since some chemicals may be potentially
shock-sensitive, explosive, or reactive after a period of storage time. If the contents
have multiple phases, sample each phase separately.
For waste impoundments, contaminant concentrations mostly will be stratified
by depth and vary horizontally from the point of waste entry to the further end of