REV03074

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Name: ATTACHMENT 3 CHARACTERIZATION OF AN UPSET CONDITION AT THE CARLTON TUNNEL
• Type & Sequence: AM8
• Media Type: D
• Archive: No

3.0 PRECIPITATION ASSESSNIENT
As part of SMI's investigation of the zinc concentrations in the Carlton Tunnel flows during
1999, the precipitation record was studied to determine what role the precipitation characteristics
had in generating the observed flow condition from the Carlton Tunnel. The investigation of the
1999 precipitation record is discussed below.
3.1 Precipitation Data Record
A combination of historic precipitation data from the Victor weather station and precipitation
data collected at the CC&V Bateman Creek station (Bateman Creek) are representative of
conditions in Southern Teller County and the vicinity of the Carlton Tunnel. These historic data
were used to develop monthly averages used as part of the design criteria for the Cresson Project,
as approved by the Colorado Mined Land Reclamation Board under Amendment No. 7
(Amendment No. 7). The weather station locations, elevations, and monitoring periods used in
this investigation aze presented in Table 1. The Cripple Creek weather station (Cripple Creek)
was included in this investigation to establish longer historical averages for the site.
Additionally, weather stations at Florissant Fossil Beds (FFB) and Guffey (Guffey) are included
in this analysis for a regional comparison and because these two stations have quality historic
records and daily precipitation records through August 1999. A weather station at a private
residence in Victor (Hunter) also provides nearby data. The average monthly precipitation data
for the four National Weather Service (NWS) weather stations (FFB, Guffey, Cripple Creel, and
Victor) along with values used in the Amendment No. 7 characterization are summarized in
Table 2. Detailed monthly precipitation data for the four NWS weather stations aze available
from the Colorado Climate Center and are shown in Tables 3 through 6. Monthly precipitation
totals for the years 1995 to present for [he Bateman Creek and for 1999 for the Hunter weather
stations are summarized on Table 7. Collectively, Tables 2 through 7 show the historic
precipitation conditions in the vicinity of the Carlton Tunnel.
3.2 Average Monthly Precipitation
The historic average monthly precipitation values for the four NWS weather stations along with
• the average conditions used in Amendment No. 7 for precipitation characterization are shown in
Figure 1. The FFB and Guffey weather stations are included in this figure to indicate that
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