HYDRO28488

• Permit No: C1981041
• IBM Index Class Name: Hydrology
• Doc Date: 9/15/2004
• Doc Name: Amendment No. 1 to CDPS Permit No. CO-0027146
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

Snowcap Coal Co. Inc WWTF Water Quality Assessment CO-0027146
Table A-3
TVS-Based Metals Water Quality Standards For CO-0027146
Based on the Table Value Standazds Contained in the Colorado Department of Public Health
and Environment Water Quali Control Commission Re ration 37
Calculated Using the Following Value for Hardness as CaC03: 257 mg/1
rameler = -~G -~ , ~ ~
~ ~•
~
.
Fo~mula~Us ±~>,~„ x
r~s~;~~ b~'='~~ u _ ,tstandard ~ . ,;,~-k a

d
i
Di
l
d
C ACUte 12 ng/1 [I.13667-0.041841n(hanlness)][e(1.128(In(hatdness)}3.6867)]
m
um,
sso
ve
a
Chronic 4.5 ug/1 [1.10167-0.041841n(hardness)][e (0.7852(ln(harrlness)}2.715)]
Hexavalent Chromium, Acute 16 ug/1 Numeric standards provided, formula not applicable
Dissolved Chronic 11 llg/1 Numeric standards provided, formula not applicable
Acute 33 ug/1 e(0.9422(In(hanlness)}1.7408)
Di
l
d
C
opper,
sso
ve
ChrOIDC 20 llg/1 a (0.8646(In(hardness)}1.7428)

Di
l
d
L
d Acute 177 Ug/1 [1.46203-0.1457121n(bardnccs)][e(1.273(In(hardness)}1.46)]
sso
ve
ea
,
ChiOIllC 6.9 ug/1 [1.46203-0.1457121n(hardness)][e (1.273(In(bardness)}4.705)]
Manganese Acute 4089 ugJl e (0.3331Qn(hardness)}f6.4676)
Acute 1041 ug/1 e(o.846pn(hardness))+z.z63)
l
Ni
Di
l
d
k
,
c
e
sso
ve
Chronic 116 ug/1 a (o.s46(In(na„jnes5))w.oss4)

i
Di
l Acute 18 ug/1 Numeric standards provided, formula not applicable
um,
sso
ved
Selen
ChronlC 4.6 Ug/1 Numeric standards provided, formula not applicable
Acute 10 ug/1 ~ e (1.72(In(hardness)}6.52)
Di
l
d
Sil
ver,
sso
ve
Chronic 1.6 ug/1 e(1.72(In(hardness)}9.06)
Acute 261 ug/1 e (osa73(In(hardness))+0.8618)
Di
l
Zi
d
sso
ve
nc,
Chronic 263 ug/I a (0.8473(In(hardness)}t-0.8699)
To conduct an assessment of the ambient water quality upstream of the Snowcap W WTF, data were
gathered from three sources: USGS water quality station 09095500, Riverwatch station 552, and
WQCD station 11103, all of which aze located approximately 3 miles upstream from the facility.
Data for the USGS station were available for a period of record from January 1995 through
September 2001. Data for the ltiverwatch station were available for a period of record from
December 1945 through February 2002. Data for the WQCD station were available for two data
points collected on August 11, 1999, and October 12, 1999. Data from these three sources were
combined to reflect upstream water quality. These data aze summarized in Table A-4.

Appendix A Page 5 of 12 Last Revised 9/15/2003