ETL 1110-1-158
28 Feb 95
interpreting the results of the TCLP are provided in the
following paragraphs.
(1) The TCLP is designed to simulate the leaching potential
of a waste within an unmanaged landfill designed for municipal
refuse. Such landfills are known to generate organic acids
during decomposition of organic matter in the refuse. The
purpose of acetic acid in the leachant is to simulate those
acids. However, the test does not simulate the conditions of
most present-day hazardous waste landfills because these
landfills often contain very little biodegradable organic matter.
(2) If the TCLP is used for cement-based waste forms, it may
not yield maximum concentrations of contaminants. This is the
result of the acetic acid solution not being able to sufficiently
reduce the elevated pH caused by the crushed cement. Thus, an
unground sample could exhibit more leaching than a ground sample
in the TCLP test.
(3) Some metals are amphoteric which means they are more
soluble at both low and high pH values. Solidified waste is
generally caustic and, when mixed with the acetic acid solution,
could lower the pH to the point where the metals exhibit minimum
solubility. If this occurs, the quantity of metals leached would
be lower than those leached under natural conditions.
(4) The goal of S/S is to protect the environment, not
simply to pass the TCLP test. Other extraction tests can be used
to assess maximum leachate concentrations and to better simulate
actual field conditions. A partial summary of other leaching
test procedures is presented in EPA/625/6-89/022. No leaching
test can simulate all real world conditions that the treated
waste may be exposed to and no information regarding the long-
term performance of S/S processes is available. Therefore,
physical tests such as durability, strength, and permeability can
be used to help evaluate the long-term effectiveness of the S/S
process. Surface area effects can also be studied by crushing
the leach test samples to varying degrees.
m. Sampling and Analysis Plan. A Sampling and Analysis Plan
(SAP) should be incorporated into the treatability study work
plan if the contractor will also be responsible for sample
collection. A SAP is prepared to ensure that test data, acquired
during both sample collection and performance of the treatability
study, is of sufficient quality to meet the intended uses. Data
quality depends not only on how carefully a test method is
carried out, but also on the sample point selection, sampling
procedures, sample integrity and test methods selected. Data
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