GENERAL45645

• Permit No: C1981044
• IBM Index Class Name: General Documents
• Doc Date: 2/28/1994
• Doc Name: PROPOSED DESISION & FINDINGS OF COMPLIANCE FOR RN2
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

The White Sandstones are a aeries of three massive and cross-bedded
sandstone aquifers. Bach sandstone is separated from the adjacent
sandstone by a thin series of shales and thin coals, which act as
aquicludee and aquitards. The lowest sandstone, the first White Sandstone,
ie about 150 feet thick in the general mine area. Thin sandstone aquifer
ie located an average of 130 feet above the Bagle No. S Mine workings. The
northern limits of mining at the Trapper Mine will remove portions of the
first White Sandstone. The aquifer will be in direct Y~ydrologic
communication with reclaimed spoils at the Trapper Mine. Empire Energy
Corporation monitored water levels and prepared piezometric maps for the
first White Sandstone (Nape III-6B and 6C of the permit application).
Ground water monitoring in the White Sandstone was discontinued after the
No. 9 Mine was allowed to flood and ground water in the White Sandstone
recovered to earlier levels.
The applicant performed aquifer tests on two former White Sandstone wells
(81-04 and 81-19) The values for permeability obtained were 0.6 gpd/ftr
and 0.14 gpd/ftr, respectively, and an estimated storati.vity of 0.0015 from
well 81-04. Geologic information submitted by Empire Energy states that
the second and third White Sandstones have lithologies and depositional
histories equivalent to the first White Sandstone. The company postulates
from this that the aquifer characteristics of these sandstones are similar
to the first White Sandstone.
Data from the Trapper Mine permit application shows that limited ground
water also occurs within the discontinuous, lenticular sandstones
associated with coal seams and the coal seams themselves within the
Mesaverde Group. The permeabilities of these water-bearing units are quite
low, generally an order of magnitude less than the fractured sandstone
aquifers.
The F and P coal seams have low permeabilities, except r~here the seams have
been fractured by natural and induced stress applied to the coal seams.
Utah International, Inc. conducted aquifer tests on coals and interburden
strata in the Upper Williams Fork Formation. Tranemiesivity values ranged
from 174 to 2,760 gpd/ft. Horizontal permeability values ranged from 30 to
50 gpd/ft~ and etorativity values ranged from 0.00032 to 0.0083.
Ground water within the Iles and Williams Fork Formations of the Mesaverde
Group ie predominantly calcium and sodium bicarbonate types. However,
water. in .contact with coals is a calcium sulfate type and can contain
fluoride, iron, manganese, selenium, and sulfate concentrations in excess
of D.S. Public Health Service drinking water standards (:erogden and Giles,
1977), with the water contained in the coals and thin discontinuous
sandstones generally being of poorer quality than that from the massive
regional sandstone aquifers. Because of the poor quality and limited yield
of water-bearing unite associated with coals and because of the depth of
drilling, the ground water in the coals and the thin discontinuous
sandstones is not currently used for agricultural or domestic purposes.
The potential for future use of this ground water for these purposes is
low. Ground water from the coals and the thin sandstonef; does flow into
the underground workings. These inflow waters are used by the mining
operations for cooling, dust suppression, fire protection, and other
industrial uses.
Limited ground water yields have been obtained from the Lewis Shale, but
use of water from this unit is considered insignificant i.n the Big and
Round Bottom Synclinal Basins. Where the Lewis Shale is present in the
ground water study area (the Big and Round Bottom Synclir.~al Basins), it
acts as an impermeable confining layer creating artesian conditions within
the underlying aquifers of the Mesaverde Group.
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