Dated
APR
21,
1998
MEMORANDUM
TO:
Diana
Love,
Director,
NEIC
FROM:
David
Bussard,
Director,
HWID
Barnes
Johnson,
Director,
EMRAD
SUBJECT:
Withdrawal
of
Cyanide
and
Sulfide
Reactivity
Guidance
Thank
you
for
your
memorandum
of
February
18,1998
regarding
your
concerns
about
the
effectiveness
of
the
Office
of
Solid
Waste's
guidance
for
evaluating
potentially
reactive
cyanide­
and
sulfide­
bearing
wastes.
These
wastes
are
regulated
as
characteristically
hazardous
(
waste
code
D003)
at
40
CFR
261.23(
a)(
5)
under
a
narrative
description
of
reactivity.
In
July
1985,
OSW
issued
guidance
describing
a
likely
mismanagement
scenario
for
cyanide­
and
sulfide­
bearing
wastes
and
providing
guidance
on
"
safe"
threshold
levels
for
cyanide
and
sulfide
in
these
wastes
in
that
scenario.
The
guidance
also
provided
a
laboratory
method
for
evaluating
these
wastes.
This
guidance
was
later
incorporated
into
Chapter
7
of
SW­
846,
the
Agency's
overall
guidance
document
for
testing
wastes.
Your
memo
expressed
serious
concerns
about
the
effectiveness
of
this
guidance
in
evaluating
the
hazards
posed
by
cyanide­
and
sulfide­
bearing
wastes
over
the
full
range
of
likely
management
scenarios.
It
also
urged
OSW
to
withdraw
the
guidance.

OSW
staff
have
carefully
reviewed
and
discussed
in
detail
the
concerns
you
raised
in
your
memo
and
its
attachments,
and
have
also
reviewed
the
original
guidance
mismanagement
scenario,
derivation
of
the
guidance
threshold
values,
and
relation
of
the
scenario
and
thresholds
to
the
results
of
the
test.
After
this
careful
consideration,
it
is
our
conclusion
that
there
were
critical
errors
made
in
developing
the
guidance,
that
your
concerns
regarding
the
reliability
of
the
guidance
are
well
founded,
and
that
the
guidance
should
be
withdrawn.
This
memo
withdraws
the
July,
1985
guidance.
A
Federal
Register
notice
announcing
the
withdrawal
of
the
guidance
from
SW­
846
will
be
prepared
as
soon
as
is
feasible.
2
Your
memo
raised
several
concerns
about
the
guidance.
These
concerns
and
our
replies
are:

1.
NEIC
Concern:
The
current
test
does
not
evaluate
waste
over
the
full
range
of
pH
values
specified
in
the
regulation
(
pH
2
to
12.5).
While
the
test
begins
with
acid
at
pH
2,
immediately
after
mixing
with
the
waste,
the
pH
of
the
mixture
may
change.
It
may
be
somewhere
within
the
range
of
2
to
12.5
if
the
waste
does
not
bear
much
acidity
or
alkalinity
(
due
to
neutralization
or
stabilization),
but
it
may
not
be
within
this
range
if
the
waste
does
bear
substantial
acidity
or
alkalinity.
Nevertheless,
the
test
evaluates
a
single
pH
condition
and
not
the
range
of
pH
conditions
(
2
to
12.5)
specified
in
the
regulations.

Reply:
You
are
correct,
the
test
will
not
always
be
run
at
the
low
end
of
the
pH
range
specified
in
the
regulation
(
and
does
not
test
at
the
high
end
of
the
range).
However,
the
implications
and
importance
of
this
are
not
clear,
as
solubility
of
the
cyanide
salts
present
also
affects
the
rate
of
conversion
to
HCN.
The
addition
of
a
fixed
amount
of
acid
with
a
pH
of
2.0
to
a
waste
that
may
have
a
substantially
higher
pH
means
that
when
these
are
mixed,
the
resulting
pH
will
be
higher
than
pH
2.0.
The
pH
range
specified
in
the
regulation
was
chosen
because
outside
of
the
pH
range
2
to
12.5,
the
waste
acid
or
base
to
which
the
evaluated
material
is
added
would
be
considered
a
corrosive
hazardous
waste,
and
consideration
of
waste
compatibility
would
be
required
by
40
CFR
264.17
before
the
wastes
are
mixed.
This
would
prevent
many
dangerous
situations
from
occurring.
However,
an
overwhelming
volume
of
waste
acid
at
pH
2
could
be
legally
added
to
other
wastes,
with
potentially
dangerous
effects
if
the
other
wastes
bear
releasable
cyanides.
In
addition,
some
cyanide
salts
are
much
more
soluble
(
and,
therefore,
more
available
to
react)
under
high
pH
conditions;
evaluation
of
hazard
under
these
conditions,
as
well
as
at
low
pHs,
should
be
explored.

2.
NEIC
Concern:
The
test
and
threshold
limits
presented
in
the
1985
memo
fail
to
account
for
Henry's
Law,
which
describes
the
air­
aqueous
partitioning
of
the
toxic
gases.
The
result
is
that
the
amount
of
nitrogen
used
in
the
test
to
recover
the
evolving
hydrogen
cyanide
gas
recovers
only
a
small
amount
of
the
hydrogen
cyanide
gas
generated.
A
similar
problem,
although
not
as
severe,
exists
for
the
evolution
of
hydrogen
sulfide
gas.
Both
theoretical
calculations
and
practical
tests
in
our
laboratory
and
other
laboratories,
demonstrate
recoveries
in
the
range
of
2%
to
3%
of
the
cyanide
present.
Somewhat
higher
recoveries
are
obtained
for
sulfide,
but
still
not
a
quantitative
recovery.

Reply:
In
developing
the
guidance
test,
the
Agency
was
not
seeking
a
method
that
would
achieve
complete
recoveries
of
hydrogen
cyanide
and
hydrogen
sulfide,
but
rather
was
attempting
to
evaluate
the
risks
from
wastes
in
a
particular
mismanagement
scenario.
Because
hydrogen
cyanide
is
extremely
soluble
in
water,
high
recovery
rates
will
not
be
achievable.
Henry's
Law
may
be
important
for
assessing
hydrogen
sulfide,
but
does
not
appear
to
be
critical
to
our
3
judgements
about
highly
soluble
gases
or
to
gases
that
interact
with
water.
This
may
explain
the
differences
in
recovery
between
hydrogen
cyanide
and
hydrogen
sulfide
as
measured
in
NEIC
tests.
We
will
work
with
your
staff
to
better
understand
the
role
of
Henry's
Law
in
the
evolution
of
dissolved
HCN
gas
as
we
develop
revised
guidance.

3.
NEIC
Concern:
The
test
method
and
the
mismanagement
scenario
are
different
with
respect
to
air
volume,
aqueous
solution
volume,
and
the
amount
of
waste.
According
to
Henry's
Law,
this
means
that
toxic
gas
partitioning
between
the
air
and
aqueous
volumes
will
be
different.
The
threshold
limits
fail
to
account
for
these
differences,
and
thus
are
not
founded
in
good
science.

Reply:
We
have
reviewed
the
original
mismanagement
scenario
and
laboratory
test
conditions,
and
agree
that
the
conditions
(
air
volume,
aqueous
solution
volume,
and
waste
mass)
are
different
and
not
correctly
scaled
between
the
mismanagement
scenario
and
test
(
see
Attachment
1).
There
were
also
several
errors
made
in
setting
up
the
calculations
in
the
mismanagement
scenario
(
see
Attachments
2
and
3).
The
fact
that
these
important
parameters
are
mismatched
in
the
laboratory
test
and
the
open
pit
mismanagement
scenario
means
that
the
test
(
under
these
conditions),
and
the
threshold
values,
do
not
evaluate
the
mismanagement
scenario
conditions.
Also,
the
"
dumpster"
and
"
tank"
mismanagement
scenarios,
and
your
theoretical
calculations,
described
in
Attachment
II,
indicate
that
the
open
pit
scenario
used
in
the
1985
guidance
may
not
be
a
true
plausible
worst
case
mismanagement/
exposure
scenario.
The
Agency
clearly
needs
to
consider
these
alternative
mismanagement
scenarios
as
revised
guidance
is
developed.

Until
revised
guidance
is
developed,
we
reiterate
the
RCRA
regulatory
language.
That
is,
40
CFR
261.23(
a)(
5)
specifies
that
human
health
and
the
environment
must
not
be
endangered
by
evolved
toxic
gases
when
these
wastes
are
exposed
to
pH
conditions
between
2
and
12.5.
Any
waste
causing
a
hazard,
when
in
the
pH
range
of
2­
12.5,
would
certainly
be
considered
a
characteristic
hazardous
waste.

We
understand
that
withdrawal
of
the
guidance
today
means
that
waste
generators
who
have
relied
on
this
guidance
in
the
past
will,
in
the
near
term,
have
somewhat
greater
uncertainty
about
determining
the
regulatory
status
of
their
cyanideand
sulfide­
bearing
wastes.
However,
the
Agency
believes
that
generators
of
sulfideand
cyanide­
bearing
wastes
can
recognize
the
acute
toxicity
of
sulfides
and
cyanides
without
relying
on
the
test
in
the
guidance.
Where
wastes
with
high
concentrations
of
soluble
sulfides
and
cyanides
are
being
managed,
generators
have
relied
on
their
knowledge
of
the
waste
to
classify
them
as
D003.
The
Agency
expects
that
generators
should
continue
to
classify
their
high
concentration
sulfide­
and
cyanide­
bearing
wastes
as
hazardous
based
on
the
narrative
standard.
4
Regarding
LDR
treatment
requirements,
there
are
numerical
treatment
standards
for
cyanide
waste
in
40
CFR
268.40
(
compliance
with
these
standards
is
based
on
different
tests
than
the
tests
under
consideration
in
this
memo;
nothing
in
this
memo
changes
those
standards
in
any
way).
However,
the
reactive
sulfide
treatment
standards
require
that
the
waste
be
"
deactivated",
without
specifying
numerical
treatment
standards.
Withdrawal
of
the
guidance
may
leave
some
generators
uncertain
about
the
type
and
degree
of
treatment
needed
to
meet
the
standard
for
sulfide­
bearing
wastes.
The
treatment
methods
described
in
40
CFR
268
Appendix
VI,
when
operated
appropriately,
can
effectively
treat
sulfide
reactive
wastes.

Going
forward,
OSW
staff
will
contact
your
staff
to
begin
the
effort
to
delete
the
cyanide
and
sulfide
guidance
values
and
test
methodology
from
Chapter
7
of
SW­
846.
We
will
also
coordinate
with
your
staff
to
create
a
working
group
to
explore
the
development
of
more
specific
alternative
guidance
that
relies
on:
(
1)
our
improved
modeling
tools
for
evaluating
hazards
posed
by
cyanide­
and
sulfide­
bearing
wastes;
and
(
2)
better
chemical
analysis
tools
for
measuring
HCN
and
H
2
S
release.

Attachments
(
3)
5
ATTACHMENT
1:
COMPARISON
OF
CYANIDE/
SULFIDE
TEST
CONDITIONS
AND
MISMANAGEMENT
SCENARIO
CONDITIONS
Issue
Treatment
in
test
Treatment
in
mismanagement
scenario
Air
Volume
60
ml/
min
X
30
min=
1.8L
=
0.0018m3
(
Test
uses
nitrogen
flow
through
enclosed
flask)
15m
X
1.5m
X
4
m=
90m3
(
A
fixed
block
of
unmixed
air
moves
across
the
pit)

Liquid
volume
250
ml
less
waste
vol
Not
specified
in
scenario.
Approx
15m
X
15m
X
2.5m=
600m3
Time
30
min
X
60
sec/
min=
1800
sec
Assumes
10
seconds
for
a
fixed
air
volume
to
move
across
the
pit
and
become
contaminated
Mass
of
waste
available
to
react
10
g
waste
sample
10%
per
second
of
6130
kg
(
for
10
seconds)

Total
HCN
released
to
cause
10
mg/
m3
HCN
10
mg/
m3
X
0.0018
m3=
0.018
mg
HCN
10
mg/
m3
X
90
m3=
900
mg
Ratio
air
vol/
mass
waste
0.0018
m3/
0.010
kg=
0.18
m3/
kg
waste
90
m3/
6130
kg=
0.015
m3/
kg
waste
Evolution
rate
of
HCN
per
kg
waste
present
(
0.018mg/
1800
sec)/
0.01
kg
waste
=
0.001
mg­
sec­
1/
kg
waste
(
900
mg/
10
sec)/
6130
kg=
0.015
mg­
sec­
1/
kg
waste
Theoretical
HCN
evolution
rate
0.018
mg/
1800
sec=
1
X
10­
5mg/
sec
900
mg/
10
sec=
90
mg/
sec
Total
HCN
needed
to
be
evolved
per
kg
waste
present
to
cause
10
mg/
m3
HCN
0.018
mg
HCN/
0.010
kg
sample=
1.8
mg
HCN/
kg
waste
900
mg
HCN/
6130
kg
=
0.15
mg
HCN/
kg
waste
6
March
25,
1998
ATTACHMENT
2:
ANALYSIS
OF
CALCULATIONS
IN
JULY
1985
RELEASABLE
SULFIDE/
CYANIDE
GUIDANCE
Calculation
presented
in
mismanagement
scenario:

R=
Guidance
threshold
level
=
Amount
of
toxic
gas
that
has
to
be
released/
length
of
test
(
1)
Mass
of
waste
available
to
release
H
2
S
(
or
HCN)

Adding
values
to
the
calculation:

R=
(
V)
(
C)
(
1800/
10)
(
2)
(
M/
10)

Where:
V=
the
contaminated
air
volume=
90
m3
C=
air
threshold
level=
10
mg/
m3
1800=
Seconds
in
laboratory
test
10
(
numerator)=
Seconds
in
mismanagement
scenario­­
i.
e.,
it
takes
10
seconds
for
the
slice
of
air
to
move
across
the
pit
M=
mass
of
waste
=
6130
kg
10=(
denominator)
percentage
of
pit
area
available
to
contaminate
air,
per
second=
10%­
sec­
1
Note:
Not
all
values
were
labeled
with
units
in
the
guidance
memo;
assumed
units
based
on
information
provided
in
the
guidance
are:
the
1800
seconds,
10
seconds
(
numerator)
and
10%­
sec­
1(
denominator).

R=
(
90m3)
(
10
mg/
m3)
(
1800sec/
10sec)
(
3)
(
6130kg/
10%­
sec­
1)

R=
264
mg­
sec
HCN/
kg
waste
(
4)
7
March
25,
1998
In
performing
the
above
calculation,
the
units
fail
to
cancel
to
the
units
of
the
threshold
value
of
250
mg/
kg
waste.
There
is
an
extra
"
seconds"
left
over
which
makes
the
units
of
the
calculation
mg­
sec/
kg
waste,
a
nonsense
result.

Also,
in
moving
from
the
initial
form
of
the
calculation
(
1)
to
addition
of
values
(
2),
the
equation
appears
to
change.
In
(
1)
the
total
mass
of
HCN
needed
to
contaminate
the
air
is
divided
by
the
length
of
the
test.
In
(
2),
the
total
amount
of
HCN
needed
to
contaminate
the
air
volume
is
multiplied
by
the
ratio
of
the
time
in
the
laboratory
test
to
the
time
it
takes
the
slice
of
air
to
move
across
the
pit
and
become
contaminated.

However,
the
more
fundamental
error
is
in
introducing
time
into
the
equation
at
all;
there
are
two
time
errors.
The
first
is
in
introducing
the
test
time
frame
(
1800
sec)
into
the
mismanagement
scenario
calculation.
This
results
in
an
1800­
fold
error
in
the
resulting
threshold
value,
and
a
trailing
"
seconds"
unit.
The
second
time
error
is
in
requiring
10%
per
second
of
the
waste
be
available
to
contaminate
the
90m3
of
air
as
it
moves
across
the
pit
in
10
seconds.
The
values
and
units
here
cancel
out,
but
there
is
still
the
trailing
"
seconds"
from
the
1800
seconds
on
test
that
results
in
nonsense
units
on
the
answer.

Because
the
air
volume
to
be
contaminated
is
fixed
and
unmixed,
the
only
important
calculation
is
the
total
amount
of
HCN
evolution
required
to
contaminate
the
90m3
slice
of
air
above
the
pit.
If
we
want
a
standard
in
relation
to
the
amount
of
waste
present,
then:

R=(
90m3)
(
10
mg/
m3)
6130
kg
waste
R=
0.147
mg
HCN/
kg
waste
If
this
result
is
multiplied
by
the
erroneously
included
1800
seconds,
the
result
is
264
mg­
sec
HCN/
kg
waste,
the
incorrect
guidance
value
in
the
1985
memo.

The
attached
table
(
Attachment
1)
shows
that
this
calculated
result
is
unrelated
to
the
laboratory
test
it
was
associated
with.
If
we
want
to
relate
this
result
to
laboratory
test
results,
additional
calculations
that
correctly
scale
the
static
8
March
25,
1998
conditions
of
the
mismanagement
scenario
to
static
test
conditions
would
be
needed.
Time
(
or
gas
evolution
rate)
could
be
added
to
this
guidance
value
and
the
laboratory
test
with
additional
development
work.
Developers
of
the
guidance
and
test
apparently
believed
the
rate
of
gas
evolution
was
important
(
since
they
included
it
in
the
calculations),
they
simply
included
it
incorrectly.

However,
another
significant
concern
about
presenting
the
guidance
in
this
form
(
i.
e.,
mg
HCN/
kg
waste)
is
that
the
guidance
value
is
totally
dependent
on
the
waste
volume
(
and
air
volume)
used.
A
tenfold
change
in
the
waste
volume
or
static
air
volume
results
in
a
tenfold
change
in
the
guidance
threshold,
a
clearly
unsatisfactory
result.
Revised
guidance
will
need
to
incorporate
the
need
to
consider
mismanagement
scenarios
different
from
the
one
presented
in
the
guidance.
Attachment
Attachment
3
Mismanagement
scenario:

A
truckload
of
waste
is
discharged
into
a
pit
containing
acidic
waste.
As
a
result
of
the
reaction
of
the
waste
with
the
acid,
a
rapid,
high
level
release
of
toxic
gas
ensues.
The
objective
of
the
characteristic
is
to
identify
those
wastes
which,
if
such
an
activity
were
to
take
place,
pose
a
hazard
to
those
persons
in
the
general
vicinity
fo
the
disposal
site.

Assume:

1.
The
truckload
of
waste
contains
6130
kg
of
waste
(
about
a
5
yd3
dump
truck
@
100
lbs/
ft3).
2.
The
velocity
of
the
wind
is
150
cm/
sec
(
3.4
mph).
3.
A
person
is
standing
10
meters
from
the
edge
of
the
disposal
pit.
4.
Exposure
to
concentrations
of:
HCN
above
10
mg/
m3
or
H2S
above
20
mg/
m3
pose
an
acute,
immediate
danger
to
human
health.
5.
The
area
of
the
pit
over
which
the
toxic
gas
is
generated
covers
225
m2.
6.
Before
reaching
an
exposed
individual
the
plume
of
contaminated
air
disperses,
in
a
linear
manner,
to
a
height
of
4
meters.

Then:

1.
The
minimum
toxic
gas
release
rate
that
would
have
to
be
present
to
exceed
the
danger
level
can
be
calculated
using
the
following
model.

2.
Total
Available
Toxicant
level
then
that
poses
a
hazard
can
be
calculated
as
follows:

V
is
a
hypothetical
volume
of
air
to
which
an
individual
is
exposed.
Since
the
pit
is
15
meters
wide,
and
V
is
assumed
to
be
1.5
m
thick,
V
=
15
m
wide
x
4
m
high
x
1.5
m
thick
=
90
m3
is
the
time
it
takes
for
a
given
volume
of
air
to
travel
across
the
surface
of
the
pit
and
become
contaminated
with
toxic
gas.
Since
the
wind
speed
is
150
cm/
sec,
and
the
volume
slice
is
assumed
to
be
1.5
m
thick,
T
=
10
seconds
C
is
concentration
in
mg/
m3
of
toxicant
that
poses
a
danger.

A
is
the
amount
of
toxicant
contained
in
V
when
V
is
contaminated
to
a
level
that
poses
a
health
hazard.
A
=
V
x
C.
Since
a
given
"
slice"
of
air
takes
10
seconds
to
move
across
the
pit,
this
amount
of
toxicant
can
be
generated
over
10
seconds.

M
is
mass
of
waste
dumped
into
the
pit.

R
is
the
total
available
toxicant
necessary
to
pose
a
hazard
as
measured
using
the
attached
test
protocol.

=
Amount
of
toxic
gas
that
has
to
be
released/
length
of
test
Mass
of
waste
available
to
release
H2S
=
(
A)(
1800/
T)
(
M/
Percent
of
pit
area
available
to
contaminate
air
volume
in
any
given
unit
of
time)

=
(
V)(
C)(
1800/
T)
(
M/
10)

=
(
90)(
C)(
1800/
10)
(
6130/
10)

=
(
90)(
C)(
180)
(
613)

=
26.4
(
C)

=
264
mg/
Kg
total
available
cyanide
=
528
mg/
Kg
total
available
sulfide
3.
As
an
added
margin
of
safety,
we
accordingly
recommend
the
action
levels
of:

Total
Available
Cyanide:
250
mg
HCN/
Kg
waste
Total
Available
Sulfide:
500
mg
H2S/
Kg
waste
