GENERAL32961

• Permit No: M1999002
• IBM Index Class Name: General Documents
• Doc Date: 8/18/1998
• Doc Name: COMMERCIAL MINE PLAN SUBMITTED TO BLM SECTION 7
• Media Type: D
• Archive: No

• The Upper Aquifer near the Piceance Site commonly has values above the proposed
Colorado groundwater quality standards for drinking water because it is too high i n
fluoride and pH. Iron levels are also marginal. Upper Aquifer water also does not
meet the standard for irrigation water because of high pH, molybdenum, and
fluoride. However, compared with the Lower Aquifer, the Upper Aquifer contains
lower concentrations of TDS, fluoride, and chloride and elevated concentrations of
calcium, magnesium, and sulfate.
7.4.4.3 Lower Aquifer
Lower Aquifer water is generally classified as a sodium bicarbonate-chloride type.
TDS concentrations of the Lower Aquifer range from about 500 mg/l to greater than
60,000 mg/1 and are dependent on depth and location. Data indicate that the salinity
of the Lower Aquifer increases and the water quality deteriorates as the Dissolution
Surface is approached (Welder and Saulnier 1978, Daub 1996). In the central
Piceance Creek Basin, stratigraphica]]y discrete groundwater samples taken within
the vicinity of the Dissolution Surface had consistent TDS values greater than 20,000
mg/1. Values in excess of 60,000 mg/1 TDS have been measured from wells in the
northern and central parts of the basin and at the Ca and Cb oil shale tracts. The
extremely poor water quality of the Lower Aquifer is largely the result of natural
leaching of the saline minerals in the Saline Zone. TDS levels are extremely high,
and, near the Dissolution Surface, the water is nearly saturated with sodium
• bicarbonate/sodium carbonate.
Water quality data collected during the initial drilling of solution mining well 20-3
indicate water in the Lower Aquifer at 1,411 feet (close to the base of the Leached
Zone and just above the Dissolution Surface) with a TDS level of 26,600 mg/I
(Steigers 1997a, Steigers 1997d). This value is consistent with water quality testing
performed by Shell Oil Company (Shell Oil) in the early 1970s, in which a drill stem
test conducted at a depth of 1,133 to 1,242 feet (with the top of the interval 263 feet
below the base of the Mahogany Zone in the L-5 Zone and the bottom of the interval
315 to 352 feet above the Dissolution Surface) produced water with a TDS content of
25,500 ppm (Steigers 1997d). Water quality data collected at the Dissolution Surface
during initial drilling of monitoring well 20-1 reflect a TDS level of 61,600 mg/1.
The Lower Aquifer does not meet the proposed Colorado groundwater quality
standards for drinking water because of marginal pH and high concentrations of
fluoride, arsenic, cadmium, chloride, iron, mercury, manganese, lead, and
selenium. Elevated levels of barium, boron, lithium, copper, chromium, and
strontium are also common. Lower Aquifer water also does not meet the standards
for irrigation water because of excessive molybdenum and fluoride and marginal
pH.
The fact that the EPA issued a Class I Underground Injection Control (UIC) permit
. to American Soda that would allow experimental test phase nahcolite solutions to
be disposed of by underground injection into the Lower Aquifer is verification of
American Soda, L.L.P. 7_27
Commercial Mine Plan
August 18, 1998