2020-10-22_PERMIT FILE - C1981012A ‎(4)‎

• Permit No: C1981012A
• IBM Index Class Name: Permit File
• Doc Date: 10/22/2020
• Section_Exhibit Name: Section 2.05 Operation and Reclamation Plan
• Media Type: D
• Archive: Yes

One sample from the Preparation Plant thickener was acquired. The
preparation plant currently recycles water from the thickener to use in
the processing of raw coal. Basin estimates that each raw ton of coal
requires 20.1 gallons to process. Historical losses of water to the
refuse pile and on the final coal product have resulted in the
acquisition of an equivalent 11 gallons of water from the Purgatoire at
the end of each raw ton. As new water is mixing with water in the plant,
the thickener achieves a chemical equilibrium. The thickener is an
alkaline sodium bicarbonate water of moderately high salinity and low
hardness. The total iron concentrations are high in the slurry. The
preparation plant process uses magnetite in the separation phase. It is
presumed that there is some digestion of this magnetite. In addition, a
large percentage of the iron is assumed to be plated on the coals and
shales as iron hydroxides.
The quality of the slurry water is compared with water from a
monitoring well which intersects the Maxwell coal seam, LA 221A, the
seepage from the Allen Mine Waste dump, and the MLRD Material Damage
Limitations and Recommended Water Quality Standards for the Colorado
Department of Health in Table 26A. The original, pre -mine water quality
as reflected by the coal aquifer analysis showed a concentration of 775
mg/1 total dissolved solids. This exceeds the MLRD recommended suspect
level for domestic use of 250 mg/1 and the MLRD recommended suspect level
of 500 mg/1 for flood irrigation. In addition the coal seam aquifer also
exceeds MLRD suspect levels for stock watering for iron and manganese.
'The water quality of water from the preparation plant slurry
differs from that found in the coal aquifer. Comparison of the slurry
with WQCC standards shows that the slurry exceeds the irrigation material
damage standard for specific conductance and total dissolved solids and
that selenium exceeds the recommended water quality criteria standard for
aquatic life.
Table 26B projects the quality of the water in the flooded workings
following five years of pumping and upon discharge through the East
Portal, should it occur. The mine currently contains 5.7 x 108 -gallons
of water. Each year, mine inflows of 0.78 acft/day or 9.3 x 107 gallons
are added to the flooded workings for a total of 6.63 x 108 gallons at
the end of year one. Assuming that Basin pumps 3.69 x 108 gallons of
slurry into the mine in the first year at 66% water by volume, pumping
over the course of one year will yield 2.43 x 108 gallons per year.
After the first year of pumping, the water quality in the mine will
reflect a mixing of 63.3% of the original flooded workings water and
36.0 of the thickener water. At the end of year 4, the quality in the
mine will reflect the thickener water.
Mine Inflow. In response to Stipulation 13, mine inflow studies
were conducted during the month of August to determine the quantity and
quality of water flowing into the mine. Areas which were examined {
RN -6
2.05-98 (Repaginated 10/21/16)