Illinois Proposed Sulfate Standard: Industry Comments
The following comments are directed toward the Illinois Environmental Protection
Agency’s (IEPA) proposed sulfate standard and the corresponding documentation:
Preliminary Technical Justification for Changing Water Quality Standards for Sulfate,
Total Dissolved Solids and Mixing Zones and Concept Document Regarding Proposed
Regulatory Amendments for Sulfate, TDS and Mixing Standards. While the proposed
changes provide for a much more reasonable and scientific approach than currently
exists, as will be noted, there are still some areas that should be addressed.
Illinois EPA has stated publicly that no harmful environmental effects are occurring as a
result of modern mines in the State of Illinois. Studies that specifically targeted the
effects of coal mines on aquatic life have shown healthy macroinvertebrate communities
existing downstream of mine discharges (Soucek 2004, ILEPA 2004). Sulfate is not a
conventional toxic chemical as compared to heavy metals, pesticides, or volatile organic
compounds. Conversely, sulfate is a necessary nutrient for the normal functioning of
cells and both plants and animals benefit from its availability. For vegetation, sulfate
salts are essential to cation delivery, and sulfur increases the protein content of the plant,
which are reasons that sulfate is commonly found in fertilizers. In animals, chrondroitin
sulfate and glucosamine sulfate are beneficial to the longetivity and functioning of joints.
Overall, the beneficial characteristics of sulfate and the fact that the US Environmental
Protection Agency (USEPA) has no parallel standard, question the reasoning for
imposing a sulfate standard altogether. Nevertheless, the following comments are
directed towards the sulfate standard as it is proposed.
The proposed standard is based on the hardness and chloride concentrations downstream
of the effluent. The equations used to derive a sulfate standard result in daily maximum
concentrations between 500 mg/L and 2,600 mg/L. There are many coal mine effluent
concentrations that regularly exceed these concentrations of sulfate. As identified in the
State of Illinois 2005 economic impact analysis, a system designed to achieve a 2,000
mg/L effluent limit using excess lime and hydrochloric acid would have an annualized
operating cost of $542,000 and an annualized capital cost of $471,500 for every 100 acres
of drainage, resulting in a total cost of $10,953,000 projected over a ten year period (ICCI
2005). This will discourage potential and existing mine operators from mining or
remining in Illinois due to the high cost that is associated with this and alternative
methods of treatment (e.g. pipelines).
The consequences of implementing the proposed sulfate standard will directly affect the
coal mining industry. The development of the proposed sulfate standard was contrary to
the USEPA guidelines which state, “The development of such standards and limitations,
however, might have to take into account such additional factors as social, legal,
economic, and hydrological considerations, the environmental and analytical chemistry
of the material, the extrapolation from laboratory data to field situations, and
relationships between species for which data are available and species in the body of
water of concern” (USEPA 1985). The Illinois EPA does not account for the social and
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economic impacts that would result from the loss of jobs and state income that the coal
mining industry provides to Illinois.
With regard to the proposed monthly average sulfate limit of 2,000 mg/L, a review of
literature regarding the effects and tolerance of livestock from drinking water containing
sulfate indicate that while short-term laxative responses may occur, a suggested safe
tolerance limit can be up to 2,500 mg/L sulfate without long-term effects (Digesti and
Weeth 1976, Louper and Waldner 2002, Embry et al. 1959, Anderson and Stothers 1978,
Paterson et al. 1979, Gomez et al. 1995).
A specific tolerance level higher than 2,500 mg/L is dependent upon individual metabolic
rates and total water intake factors. There are studies that indicate long-term effects may
occur. These studies are inconclusive as to the appropriate sulfate concentration that
causes long-term effects and conflict with a study that showed “no adverse effect” at a
sulfate concentration of 7,000 mg/L. However, none of these studies cited lasting
impacts at sulfate concentrations below 3,000 mg/L (Patterson et al. 2005, Zimmerman et
al 2002, Weeth and Hunter 1971, Embry et al. 1959).
The data on effects of drinking water sulfate concentration on livestock support a level of
2,500 mg/L sulfate with no long-term effects or loss of performance. Therefore, the
existing monthly average sulfate limit for livestock watering of 2,000 mg/L should be
changed to a recommended upper sulfate limit of 2,500 mg/L.
The monthly maximum sulfate standard is being applied to all discharges into waters of
the state. There are numerous cases where the discharge will be episodic and result only
as a consequence of precipitation events. The sulfate derivation method used by the
Illinois EPA was based on 96-hour toxicity tests, whereas episodic flow as a result of a
precipitation event is often of shorter duration than 96-hours. The conclusions drawn
from 96-hour toxicity tests will not be applicable to flows that result in shorter exposure
periods to the aquatic organisms. Similarly, many smaller order receiving streams only
flow as a result of stormwater runoff and in these cases aquatic life is probably not
present in the receiving stream. Imposing a standard for a designated use that does not
exist in the receiving stream is erroneous in itself. Alternatively, the sulfate standard
and/or mixing calculations should be imposed only on receiving streams which warrant
an aquatic life designated use.
The sulfate aquatic life water quality standard proposed by Illinois EPA is based on data
from recent studies that found associations between the chloride concentration and
hardness of water, and the osmotic imbalance toxic effect on aquatic organisms from
sulfate. The data used to establish the Illinois proposed sulfate water quality standard
were based on two test species that are commonly used for laboratory toxicity testing.
The two species,
Ceriodaphnia
(water flea) and
Hyalella
(scud), were also selected
because these organisms were known to be less tolerant (more sensitive) to sulfate
exposure than other tested aquatic biota including fish, clams, mussels, and other benthic
macroinvertebrates. These two species do not necessarily inhabit every type of Illinois
surface water, but are historically used by USEPA to derive water quality criteria.
However, the USEPA protocols used to derive water quality criteria recommend toxicity
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data for aquatic biota from 8 different taxonomic families be generated, from which
toxicity data for the most sensitive 4-5 organisms are most often used to derive the water
quality criteria. Use of the two organisms most sensitive to sulfate in the derivation of an
Illinois water quality standard for sulfate, while a policy decision at the time of
consideration, provides a higher margin of safety to accommodate resident aquatic biota
in lakes and streams than would otherwise be provided using EPA methods. While the
inclusion of additional species will likely not alter the slope of the equation, the intercept
point of the regression would increase and result in less stringent numerical standards for
the same hardness and chloride characteristics than the current equation provides.
In certain cases,
H. azteca
has been found by the Illinois EPA monitoring network in
waters with sulfate concentrations above 2000 mg/L and in waters with low chloride
concentrations, both of which were identified as waters that
H.
azteca would be intolerant
of. The fact that
H. azteca
is found in natural waters with sulfate and chloride levels that
contradict those determined to be “toxic” through the development process, questions the
application of the standard as proposed at these sites.
Another issue with the proposed standard involves the range of values over which it is
valid. The proposed standard provides equations based on hardness and chloride when
hardness is between 100 and 500 mg/L and chloride is between 5 and 500 mg/L. If these
ranges are exceeded, the sulfate standard is limited to 2000 mg/L. However, if hardness
were set equal to 500 mg/L, and chloride were varied between 5 and 500 mg/L, the range
of returned values for the sulfate standard is between 2020 and 2720 mg/L. Once the
range is exceeded however, the standard is reduced to 2000 mg/L. This arbitrary
reduction in the sulfate limit when the range of values is exceeded is unsupported.
Instead, the sulfate limit should be set equal to the limit obtained directly prior to
exceeding the range.
In addition to the proposed sulfate standard, there are proposed changes to the mixing
zone methodology. The changes will directly affect the dilution ratio that is used in
mixing zone calculations. The dilution ratio that a mixing zone is allotted is based on the
7Q1.1 flow of the receiving stream, which is the low-flow statistic that is being used to
describe “small headwater streams”. There are several methods of calculating the 7Q1.1
value on receiving streams at a point of discharge. It is suggested that the regulation
allow for use of the method that best fits the particular watershed situation.
Lastly, if this standard is adopted as proposed, it will be applied retroactively, meaning it
will be applied to all NPDES permit holders disregarding when the permit was originally
obtained. This policy presents a barrier to all active and future holders of NPDES
permits in the state of Illinois. When an operation is in its initial planning stage, there is
no reasonable way to account for the cost associated with future regulations. On the
contrary, the success of the business must be based on the cost of complying with present
rules and regulations. Expecting a business to achieve standards retroactively, that were
not and could not be accounted for in the original operational plan, is unjustified.
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