Last month we began a series of articles based on issues arising
from the EPA Land Ban Regulations. We briefly mentioned a new
test that the Third-Third Regulations officially sanctioned called
the Toxicity Characteristics Leaching Procedure (TCLP). It is
an attempt on behalf of the EPA to improve upon the old leaching
procedure with which you may already be familiar, EP Toxicity.
EP Toxicity
The EP Toxicity test was the EPAs first attempt at simulating
what goes on inside a landfill. The test dates back to 1980 when
the RCRA regulations were first finalized. The EPA theorized that
the natural leaching of metals from landfills under the worst
case conditions could be simulated by mixing a sample of sludge
with 100 times its own weight of water, adjusting that mix to
a pH of 5.0 (acid rain simulation) and keeping it at that pH for
24 hr. After 24 hr of leaching, the waste mix is filtered, under
pressure, through a membrane filter. What passes through the filter
is analyzed by atomic absorption spectroscopy or by plasma emission
spectroscopy.
The EP Toxicity test was used to determine if a generated waste
was hazardous even though it was not listed as such by the EPA.
The Table included in this months column lists the original EP
Toxicity leachable metal maximums and the new TCLP regulated maximums.
The regulated levels listed in the Table were arrived at by consideration
of concentrations affecting human health and then multiplying
these concentrations by 100 to take into account the rate at which
a given chemical leaches through the ground, etc. All of this
is done by computer modeling.
Using the old EP Toxicity regulations, if a waste contained any
leachable metals at concentrations above those listed, it was
deemed hazardous and was given the hazardous waste code listed
in the Table.
One of the major deficiencies of the EP Toxicity test was that
it could not determine if a waste could leach organics into the
groundwater (with the exception of a few pesticides).
This deficiency has now been eliminated and the TC Rule is in
effect (you can find details on this rule in 40CFR 261.24) .
TCLP
The TCLP procedure can be found in 40CFR 268 Appendix I. If the
toxic characteristics of your waste are metallic in nature, the
TCLP test is similar to the EP Toxicity procedure except that
after 24 hr of leaching, the waste mix is filtered through a membrane
with larger pores (0.6 to 0.8 am vs.0.45 jam for EP Toxicity).
The larger pores allow more solids to go through; therefore, you
can expect higher metal concentrations with the TCLP than the
EP.
If your waste contains organics along the lines of those in the
Table, you will need to have them quantified with the TCLP test.
For such cases, the TCLP does not resemble the EP Toxicity, and
a new device called a Zero Headspace Extractor is used. This device
allows organics within the sample to be leached out over an 18-h
r period using an acetic acid solution at a pH of 5 without loss
of organics to any air inside the device. (The term zero headspace
refers to there being no air within the extractor in which organics
may be lost). The extracted organics are quantified by GC or GC/MS
as appropriate. The EPA published the TC Rule on March 5, 1990.
Small-quantity generators (those that generate between 220 and
2200 Ib/month) have one year to comply. Large generators had until
September 5, 1990. Generators who have not previously done so
are responsible for:
In most cases, waste haulers have already contacted their clients,
have informed them of this new requirement and have taken care
of these responsibilities for them.
A complete TCLP test will cost about $1,000. At least one disposal
firm will allow the generator to characterize its waste based
on "knowledge" (no analysis). This can save money in
the short term, but the generator assumes responsibility for his
or her "knowledge." Therefore, we recommend having at
least one test performed.
Typical organics that are on the regulated list and can be expected
to be present in some metal finishing waste streams are:
More information can be obtained from the RCRA hot line at 800/4249346
or 800/553-7672 from 8:30 a.m. to 7:30 p.m. EST Monday through
Friday. Other places to locate information include:
What if a Waste Fails the TCLP? Wastes that do not meet TCLP regulated
limits must be treated in accordance with the Best Available Technology
per the Third-Third Land Ban Regulations until the waste passes
the TCLP. Such treatment is performed by a treatment disposal
storage (TDS) facility for a fee. Costs vary significantly, depending
on the technology employed (incineration, encapsulation, etc.).
Costs ranging from $300 to $2000/ton have been quoted on various
hazardous wastes. It is not clear what can be done with wastes
that cannot be treated to TCLP regulated levels. A variance petition
would be one possibility.
If your waste fails any of the TCLP metals limits, you may want
to consider modifying your waste treatment system by adding lime,
magnesium hydroxide, sodium bicarbonate and/or other commercially
available anti-leaching compounds to your pH adjust system ahead
of the clarifier and instead of, or in addition to, caustic soda.
If you can increase the alkalinity of the waste you generate,
the leachable metals concentrations should decrease because the
TCLP (and EP Toxicity) has a maximum amount of acid that can be
used. If all this-acid is neutralized by the alkalinity in the
waste, and the pH level stays on the alkaline side after the addition
of the acid, then the metals will stay in an insoluble condition.
l caution anyone considering the addition of alkali to the waste
after it is generated. This is not allowed unless you have an
EPA permit as a treater.
Modifying your method of waste treatment is okay. Modifying your
waste after it is generated is not okay, unless you meet the requirements
of a TDS facility. I know of no way to reduce leachable organics
in waste. It may be possible that if activated carbon was part
of the waste, the leachable organics would be reduced, but there
is no data at this time. The best answer would be to eliminate
the organics at the source, if at all possible. All rooms in which
organics are used should be free of floor drains, and drag-over
into process areas must be carefully controlled by drying volatiles
and absorbing non-volatiles.
Chemical solutions based on nitrobenzene compounds (some strippers) should be isolated from the waste stream and disposed of separately. You may also wish to consider replacing them with formulations that do not contain nitrobenzene.