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 extremely poor water quality of the Lower Aquifer at the Piceance Site (EPA
1998).
Parachute Creek Basin
Historic groundwater quality data were collected from wells in the Parachute Creek
watershed from the mid-1970s to the early 1980s (ACOE 1985). These data indicate
that the alluvial waters are slightly alkaline, ranging in pH from 7.2 to 8.2. The
major anions are sulfate and bicarbonate. Total dissolved solids (TDS)
concentrations range from 366 to 7,033 mg/1 (ACOE 1985).
7.5 METEOROLOGY AND AIR QUALITY
7.5.1 Meteorology
The climate of the project area is classified as semi-arid continental with a growing
season of approximately 100 days (BLM 1982). This type of climate is characterized by
low relative humidity, sunny days and clear nights, low precipitation with high
evaporation, and large diurnal temperature changes. It receives an average of 13.77
inches of precipitation a year, with total precipitation ranging from as much as 20.37
inches (1986) to as little as 8.53 inches (1966). Spring and late summer are the wettest
periods of the year. August is the wettest month with an average of 1.56 inches,
• while January is the driest month with an average of only 0.74 inches. On average,
there are 51 days a year with measurable precipitation (>_ 0.1 inches). In the past, the
number of days with measurable precipitation has varied from as many as 84 days to
as few as 30 days. The maximum daily precipitation was 2.3 inches, which occurred
on August 6, 1986. Snowfall has been measured in all months except July and
August. An average of 73 inches of snow falls each year. Historically, snowfall has
ranged from as much as 124 inches (1979) to as little as 38 inches (1982).
Table 7-5 illustrates some of the climatic conditions in the vicinity of the project
area. The temperature differences are largely due to the location of the
meteorological stations (valley vs. plateau) as well as their elevations.
The climate of the Piceance Site is characterized as follows using climatological
parameters observed from the Little Hills meteorological monitoring station
(Station No. 55048) between 1948 and 1991. The station is located approximately 8
miles northeast of the Piceance Site at latitude 40.00°N, longitude 108.12°W, and
elevation 6,140 feet mean sea level.
The mean monthly temperature is 43°F. July is the hottest month with an average
temperature of 65°F; January is the coldest month with an average temperature of
20°F. Temperature extremes vary from as low as -48°F (1963) to 101°F (1989), On
. average, there are 12 days a year with temperatures greater than 90°F and 239 days a
American Soda, L.L.P. 7-28
Commercial Mine Plan
August ]8, ]998