Jennie Henthorn
Henthorn Environmental Services LLC
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Permit limits are in terms of total recoverable
aluminum
Water quality criteria are in terms of dissolved
aluminum
Applying the dissolved Al criteria as a total Al
effluent limits can be overly restrictive
A translator is an attempt to fix the disparity
between the dissolved criteria and total
recoverable effluent limits
 “...the
fraction of total recoverable
metal in the downstream water
that is dissolved”
The Metals Translators Guidance
 Allows
for higher permit limits
that better reflect potential
toxicity (usually, only a fraction of
the total Al will be dissolved)
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Warm water (end of pipe)
Trout water (end of pipe)
Ave Mon (mg/l)
Max Daily (mg/l)
Ave Mon (mg/l)
Max Daily (mg/l)
0.433
0.750
0.083
0.143
The translator is a fraction:
Fd = Cd/Ct
The effluent limits are divided by the
translator to calculate the new limits
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Translators require a study
with multiple samples
The spreadsheets used to
calculate translators are
changing (and hopefully will
continue to do so…)
Study must be well designed
Decisions on how to
proceed can be evasive.
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Translator must be protective of critical flow
 this is not the necessarily the same as
7Q10 flow
The amount of dissolved Al is dependent on
parameters such as TSS, pH, hardness 
sampling should occur when the combination
of parameters makes it so there is the most
dissolved Al in stream
 this is “critical flow” or “design flow”
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But… no way to determine what these
conditions are without a separate study – and
results can be less than clear
DEP has determined that the default “critical”
flow is when precipitation induced discharges
are not occurring.
◦ Low flow usually has low TSS = higher dissolved Al
◦ Simplifies preparation and review of a study plan
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Time/season of sampling  Low flow is
usually July- October in WV
DEP now requires 20 samples collected no
more frequently than once per two weeks.
The time to collect samples can easily stretch
to a year or more due to precipitation
requirements.
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EPA guidance suggest sampling should occur
at edge or beyond mixing zone
But…in most circumstances for mining
permits, no mixing zone is usually available
(EOP limits)
Often, the nearest downstream monitoring
point used for instream sampling is used.
Watershed approach may be more
appropriate
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Take a sample or two – make
some informed decisions
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Prepare a sampling plan and
get DEP’s approval
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Remember, translators are not
just for aluminum! Do you
need to consider other
parameters?
Choose your path carefully, or you may fall
flat on your face (or worse)
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Dissolved Al
Total Al
TSS
Precipitation
Hardness
Others
“A complete data set allows for more complete
understanding of the environmental fate and
transport processes and may result in a more
accurate permit limit because of reduced
variability and uncertainties.”
EPA guidance
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Recall that, translator is determined by
dividing the dissolved Al by the total Al 
this gives the translator for each sample
◦ fD=CD/CT
This means that you have 10-20 different
translators- how do you decide which one to use
for determining permit limits???
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Determine if translators are lognormally
distributed (Shapiro-Wilks)
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Determine if translators are TSS-dependent
using regression analysis
◦ If translators are lognormally distributed and are
NOT TSS-dependent, use the geometric mean for
permit limit caculations
But what if the translators are not log-normal????
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Attempt to make translators lognormal by
transforming the data (arcsine square root)
◦ If translators are lognormal transformed and NOT
TSS-dependent, use the transformed geometric
mean for permit limit calculations
OR
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Use the 95th percentile of the translators
But what if the translators are TSS-dependent?
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Although sampled at low flow, translators will
be used over a wide variety of flows and TSS
concentrations
Translators can be developed relating
dissolved Al to other parameters, such as pH
or hardness
 TSS usually has the largest influence and
therefore is the focus of EPA guidance
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Develop regression equation relating TSS and
translator
Use “critical TSS” in regression equation to
determine appropriate translator
◦ The critical TSS is representative of a TSS that would give
the highest dissolved Al in the stream
◦ The EPA guidance gives little information on how to
determine critical TSS
OR
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Use the 95th percentile of the translators
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Use DEP’s current spreadsheet to calculate
effluent limits!
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Requires 20 samples exactly
Determines if data is lognormal using
Shapiro-Wilks
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Determines if data are TSS-Dependent
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Requires rain data to determine critical flow
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Only accepts data taken during critical flow
◦ If a TSS-dependent equation is being developed,
critical flow should not be used
◦ Uses only one method for determining “critical” flow
– other methods include TSS concentration, and
25th percentile of low-flow
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Does not have a regression equation for TSSdependent translators
◦ If translators are TSS-dependent, it defaults to
using the 95th percentile
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If data are not lognormal, spreadsheet does
not determine if data are lognormal
transformed
The combination of these problems amounts to
using the 95th percentile as a default, when
other values may be equally defensible
(regression equation, transformed geometric
mean).
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Addition of lognormal transformed calculation
Addition of regression analysis for TSSdependent data sets
Potentially the addition of using the arithmetic
mean when data are normally distributed (and
not TSS-dependent)
These changes will determine translators that more
accurately represent the stream!