2012-10-01_REVISION - M1977311 ‎(12)‎

• Permit No: M1977311
• IBM Index Class Name: REVISION
• Doc Date: 10/1/2012
• Doc Name: AM-01 EEP SUBMITTAL
• From: COTTER
• To: DRMS
• Type & Sequence: AM1
• Email Name: GRM
• Media Type: D
• Archive: No

directions in the area are controlled by recharge areas and the dip of the rock formations.
Both of these factors indicate a similar east - northeast groundwater flow direction.
West of the Dolores River the rocks dip steeply to the northeast off the flanks of the
Dolores River /Lisbon Valley anticline.
There are no mapped faults within the vicinity of SR -13A. There are no mapped faults or
evidence of faulting under stockpiles, future storage areas, or mining areas. There are
several small faults located to the north and southwest of the site but these have no
impact on the site hydrology.
8.3.3 Hydraulic Parameters
There is only a limited amount of hydraulic data available for the geologic formations
capable of transmitting water at the SR -13A mine area. Consequently, estimates of
hydraulic conductivity (permeability) are based on limited site data and reported values
for the type of rocks underlying the mine. Reference values for the Entrada Sandstone
are from Lohman (1965) while sandstone and shale unit values are from Freeze and
Cherry (1979).
Due to the remoteness of the region, the nearest available hydraulic information for the
Navajo Sandstone comes from northwest of the area in Grand and San Juan counties,
Utah where Lowe et al. 2007 reports moderate permeability values and wells that yield as
little as 5 gallons per minute to wells located in fractured portions of the aquifer that yield
as much as 300 gallons per minute. Wells in the area penetrate both the Entrada and the
Navajo Formations, and combined appear to be the dominant groundwater resource in the
area. Lowe et al. (2007) reports that springs, discharging from the Wingate Sandstone,
range from 10 to 240 gallons per minute.
Table 2: Hydraulic conductivity values for selected rock units at the site.
Rock Type
Dakota /Burro Canyon (Kdbc)
Mudstone /Shales (Jms,Js)
Salt Wash Sandstones
Entrada Sandstone (Je)
Navajo Sandstone (Jn)
Wingate Sandstone (Jw)
Hydraulic Conductivity (cm/s)
1.0E -04
1.6E -07
1.0E -06
5.0E -05
1.0E -06 to 3.0E -03
3.0E -05 to 5.0E -04
Assuming saturated conditions in the Salt Wash Sandstone, a porosity value of 0.2, and a
hydraulic gradient of 0.15 (equal to the regional dip of the strata), then calculated
groundwater transport rates for uranium and related constituents from ore bodies would
be less than a foot a year in an east - northeast direction. Average transport rates in the
upper -most aquifer for the area which is the Entrada Formation for the Slick Rock area
are approximately 40 feet per year in the same northwesterly direction. Groundwater
O'Connor Design Group Inc. T - 12