HYDRO31322

• Permit No: C1980001
• IBM Index Class Name: Hydrology
• Doc Date: 6/6/2007
• Doc Name: Authorization to Discharge Under the Colo Discharge Permit System
• From: Department of Health Department
• To: DRMS
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

Pittsburg and Midway Coal Company Edna Mine Water Quality Assessment CO-0032638
In lieu of being subject to the ADBACs, facilities have the option of selecting non-impact limits
(N1Ls), which are concentration limits based on their current permitted load and the proposed design
flow. By agreeing to meet the NILs, new or increased impacts will not occur and thus ADBACs will
not be required to be considered in CDPS permits. For those pollutants for which permit limits have
not yet been established, an implicit load allocation is determined and an implicit permit limit is
established. An implicit limit was determined for total recoverable iron and potentially dissolved
manganese at both outfalls based on the Division's standard approach that specifies that implicit
limits be developed based on the maximum concentration during the antidegradation period. Note,
however, that because total recoverable iron data were available only after May 2001 the
summarized data used were for total iron.
For all pollutants evaluated, a summary of the current permit limits (including implicit limits), the
current permitted load, the new WQBELs, the new WQBEL load, ADBACs, and NIIs are contained
in Table A-13 and A-14 for Outfalls 004 and 007, respectively.
Table A-13
WQBELs, ADBACs, and Non-Im act Limits Summa for Outfa11004
~,.. ..Current Cterrent ~'~' ~ Non-
e
Pollutant .: ':
Perm:t ' Permitted New

' 'WQBEL

'
,4DBACA: _
Impact";

L[m[t :'_ Laad
~ WQBEL
. Load
Limit

(ms/day)
-
~_(Ibs/dayJ ~
~ , . .
Fe, TR (ug/1) 1900 30 1000 16 253 780
Mn, Dis (u 1 1550 25 2618 41 503 1550
Table A-14
W BELs, ADBACs, and Non-Im act Limits Summa for Outfal1007
' Current New
C[trrent . Non-

Pollutant
~
Permit ~ Permitted
~ New
~ ~ .WQBEL
~ADB.4C
Impact
Load ; WQBEL Load
~ ~

-' Limit ~ =
(Ibs/day) .
'
(16s/ddl')
.Limit ~
Fe, TR (ug/1) 960 21 1054 23 245 960
Mn, Dis (ug/1) 960 21 2781 60 506 960
The current permitted load, the new WQBELs load, and the NIL were calculated using the following
equations:
Current permitted load = Mpermirred X Qpermmed X 8.34
New WQBELs load = MZ X QZ X 8.34
NIL =Current permitted load - QZ - 8.34
Appendix A ~wQn ar version a-s Fnsc> Page 18 of 19 Last Revised September 2, 2005