concerns at the
No.2 Mine?
infiltration of water through the coal waste dissolves minerals from the waste, which
enter the groundwater. These concerns will be addressed separately below.
What steps has
Monterey taken to
address the dust
problem?
Several different methods have been used to reduce dust problems. First, it must
be pointed out that the coal waste looks like a mound from the outside, but there is
currently a basin in the middle. In the September and October of 2001, Synthetic
spray-on dust suppressants were applied to the flat areas to keep the fine-grained
dust from blowing. In October 2001, silt curtains were installed around the edge of
the basin to prevent more fine-grained material from washing off the inside walls of
the basin, and onto the sprayed area. If the fine-grained material enters the basin
area, it is more likely to blow. Also during October 2001, straw bales were placed to
reduce erosion into the flatter, more open areas prone to blowing. From October to
December of 2001 reed grass test plots were planted in an effort to vegetate the
basin. Nearly 600 bales of straw were spread during May and June of 2002. Where
possible the straw was partially incorporated into the surface of the waste to create
a more irregular surface, which reduces wind speed and the amount of blowing
dust. Also in the spring of 2002, Monterey reduced the pumping of water out of the
waste piles, to decrease the amount of dry exposed waste. Water was formerly
being pumped out of the waste to reduce the amount contaminants entering the
groundwater. In an effort to vegetate drier portions of the basin, 100 loads of dairy
bedding were spread in July and August of 2002, with test plots of grass in two
areas. In September of 2002 another 200 bales of straw were spread to reduce the
amount of exposed waste.
What
contaminants are
being found in the
groundwater at
the No. 2 Mine?
The metals listed above are not typically associated with coal mine waste. As with
the soil, it is not uncommon to find these metals in groundwater, but the
concentrations are typically below concentrations that are harmful to human health.
The monitoring history from the Monterey monitoring wells confirms that the above
listed metals do occur in groundwater, but not at levels that are a concern to human
health. The contaminants typically associated with mine waste are sulfate, chloride,
total dissolved solids, iron and manganese. There is a long history of groundwater
monitoring results at the No. 2 Mine. The groundwater near the waste piles contains
high concentrations of sulfate, chloride, total dissolved solids, iron and manganese.
The typical coal mine contaminants also occur naturally. Potable wells sampled by
the Illinois EPA contained concentrations of the typical coal mine contaminants, but
the concentrations were much lower than levels near the piles. With the exception
of manganese, none of the typical coal mine contaminants were detected in private
wells at concentrations of concern to human health. The geographic distribution of
manganese suggests that manganese is sometimes present naturally, at relatively
high concentrations.
What steps has
Monterey taken to
address the
groundwater
problem?
Monterey has installed a line of groundwater extraction wells along the west and
south sides, down gradient, or “down slope” of the coal waste piles. The extraction
wells pump large amounts of contaminated groundwater out of the ground, so the
contaminated groundwater is captured by this line of wells. The groundwater is then
treated and discharged into the Grassy Branch. Monterey has an Illinois EPA permit
to discharge the water into Grassy Branch. Therefore, the water pumped into
Grassy Branch is regularly tested to assure that contaminant concentrations do not
exceed permitted amounts. This water has also been tested for the metals listed
above. None of the metals listed above exceeded water quality standards in the
water entering Grassy Branch.
What steps will
Monterey take as
the permanent
cover for the coal
waste is being
designed?
The reshaping and final cover of the coal waste will end dust problems. In addition
to preventing dust problems, the shape of the waste disposal areas will be
recontoured to promote runoff, and minimize infiltration. An underground Slurry
wall, made of clay, will be installed to the south of the waste piles. The slurry wall
will prevent the flow of groundwater to the south, and divert the flow to the west.
Groundwater extraction wells to the west of the waste pile will continue to pump out
contaminated groundwater. The contaminated groundwater will be pumped by a
pipeline to the Kaskaskia River. As with the water that is currently being pumped
into Grassy Branch, the water that is pumped into the Kaskaskia, will be regularly
tested to insure it meets all of the permit requirements. 4 Printed on Recycled Paper
Monitoring wells will continue to be tested to assure that the groundwater extraction
Fact Sheet #1 - Monterey Coal Mine #2 Page 2 of 5
http://www.epa.state.il.us/community-relations/fact-sheets/monterey-mine/monterey-mine-... 5/24/2012
