ETL 1110-1-158
28 Feb 95
MR = Weight of Reagent
Weight of Waste
Mixing can be performed using mechanical devices with
intermeshing ribbon or blade beaters. Various chemical and
physical tests are used to judge the effectiveness of the mix
ratios. A typical set of tests might include the following: an
extraction procedure such as the TCLP to determine the amount of
contaminants leaching from the treated material; unconfined
compressive strength to provide an indication of physical
stability; and additional physical properties established on a
site-specific basis. Paragraph 4.i. describes some of the more
common physical tests used during a treatability study.
Additional chemical characterization testing may also be required
for some treatability studies.
(1) Initial Testing of Mix Ratios. A treatability study is
often performed in stages. Simple tests are performed in the
initial stages to eliminate mix ratios which are obviously not
going to be successful. Since physical characteristics are the
easiest to test for, they will normally be addressed first. The
initial test matrix will usually be a series of different
reagent/waste/water combinations. A typical set of mix ratios
might be created by using four reagents or reagent mixtures, each
at two or more reagent to waste mix ratios and two or more water
to waste ratios. The first parameter measured is strength
development. Strength is determined using a cone penetrometer or
an unconfined compressive strength test. Strength tests are
usually performed after one to three days of curing. The
required level of strength of the treated material is determined
on a site specific basis. However, the treated material is
usually required to have an unconfined compressive strength of at
least 50 psi to ensure adequate bonding. The rationale for
selecting this value is an attempt to require a bonding level in
excess of that achieved by sorbents. A minimum compressive
strength limit of 50 psi should also ensure the treated material
will provide sufficient strength to support a landfill cover
placed over the top of the material. In addition to strength
test results, observations about the following attributes of the
treated samples are often recorded:
-Is the sample spongy, powdery, granular, etc.?
-Is the surface softer than the underlying material?
-Is there excess water on the sample surface?
-Does the sample exude fluid when subjected to finger
pressure?
-Is the fluid reabsorbed when the pressure is released?
-Has the color or odor changed?
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