ETL 1110-1-158
28 Feb 95
be given to how the contaminated material will be excavated and
mixed during full scale treatment so that samples are
representative of these conditions. Treatability studies
performed by the Government are sometimes performed on the most
highly contaminated material present. This will provide
assurance that all the contaminated material at the site can be
treated by the S/S process. However, this can also result in
over-design and unrealistically high cost estimates. A better
approach would be to test the most highly contaminated material
present and material representative of average site conditions.
The material representative of average site conditions would
allow the treatment costs to be more accurately estimated during
the design phase. Soil samples can be collected using backhoes,
hollow stem augers, or they can be surface samples collected
using hand tools. Sludge and liquid samples are typically
collected using hand tools. Requirements for preparing a scope
of work for collecting samples for investigations and studies are
described in EM 200-1-3. The amount of contaminated material
needed to perform an S/S treatability study will vary depending
on the complexity of the study. A minimum of 40 liters (10
gallons) of material should be collected. However, most
treatability studies require more material than this and an
estimate of the amount of material needed should be made by
determining the number and type of tests to be performed during
the study.
(1) Sample Locations. In most instances, previous site
characterization will have been performed prior to collection of
samples for the treatability study. Therefore, judgmental
sampling is the most common method of determining sample
collection points. The judgmental sampling approach uses
technical expertise to determine the most appropriate sampling
location based on operational history, visual survey, and
previous sampling. No matter how well a site has been
characterized, heterogeneity may make collection of a
representative sample difficult. To help alleviate this problem,
field screening techniques can be used to quickly ensure the
contaminants present in the samples are representative of site
conditions. Field screening techniques include the following:
soil gas, organic screening, flame ionizing detector (FID), photo
ionization detector (PID), metals screening (geophysical, x-ray
fluorescence), and PCB/PCP test kits. Refer to EPA/540/2-88/005
"Field Screening Methods Catalog, User's Guide" for a
comprehensive discussion of field screening methods.
(2) Sample Homogenization. Prior to initial characterization
of the samples at the laboratory, homogenization and removal of
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