2005-12-02_PERMIT FILE - C1981019

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 12/2/2005
• Section_Exhibit Name: Exhibit 07 Item 02 CDPS Permit, SMP, SPCC Plan
• Media Type: D
• Archive: No

Colowyo Coal Company COG-0045161
U
Table 4
Site-Specific Metals Water Quality Standards for the
Colowyo Mine Discharges to Segment 03e
Table Value Standazds (TVS} Contained in the Colorado Department of Public Health and
Environment Water QuaIit Control Commission Re ulation 31
Calculated Using the Following Value for Hardness as CaC03: 400mg/1
In-Stream Water
Parameter ual' Standard Formula Used
Acute 281 (1.46203-0.1457121n(hardness)][e(1.273(W(hardness))-1.46)]
ad, Dissolved
ChrORIC
10.9
(L46203-0.1457I21n(bardness}](e(`~ 73(In(hardness))-4.705)]

i ACllt 4738 µ e(0.333](Jn(hardness))+6.4676)
ssolved
nganese, D
Chronic
2618 (0.3331Qn(hardness))+5.87x3)
e

l
d Acute 1513 e(0.846(In(hardnes:))+z.2r]
ickel, Disso
ve
Chronic
168
I (o. 46(In(hazdness)}+0.055a)
e
ACUt 18.4 µ Numeric standards mvided, formula not Gcable
Selenium, Dissolved
ChrOn1C 4.6 Numeric standards rovided, formula not a tipble
Acnt 22 µ 7~2 e(1.72(ln(hazdness))fi.52)
Silver, Dissolved
Chronic
3.47
µ
e(1'72(m(bamness)~-9.06)
i
Di
]
d
Acute
379.3
e(0'8a73(ht(haranessp+o.s61s)
nc,
sso
ve Chronic 382.4 µ e(0.8473(In(hardness)) .8699)
Ambient Water Ouality: This water quality assessment includes ambient information about Wilson
Creek. The limited water quality data consists of the best available information and is felt to be
representative of the ambient water quality at the discharge locations. The WQCD collected water
from Wilson Creek at County Road 51 (WQCD 11341) on August 23, 2000.
The WQCD evaluates ambient water quality based on a variety of statistical methods. Dissolved
oxygen (DO) is evaluated at the 15°i percentile and compared to the standard. Fecal and Escherichia
coliforms aze evaluated by the geometric mean of the sample data: Total recoverable metals aze
evaluated at the 50th percentile and compared to the standazd. Dissolved metals aze evaluated at the
85`" percenti]e and compared to the standard. Water qua]ty standards are in attainment when the
statistically analyzed value is below the numeric standard except for DO and pH. DO is considered
meeting the standard if the 15`s percentile value is greater than the standard. The pH is evaluated for
the 15`s and 85`a percentile values then compared to the standard range.
Table 5, Water Quality Data Summary for Wilson Creek presents a summary of the statistical
analysis and chronic water quality standazds for Wilson Creek. The data aze limited to one sample
from August 23, 2000. All pazameters presented in the table met the water quality standazds.
Table 5
Water Quality Data Summary for Wilson Creek` (COLCLY03e)
i
WQA 5 Revised U24/2005