2008-07-07_HYDROLOGY - C1983059

• Permit No: C1983059
• IBM Index Class Name: HYDROLOGY
• Doc Date: 7/7/2008
• Doc Name: NPDES ‎(COG-850028)‎
• From: Oxbow Mining, LLC
• To: DRMS
• Permit Index Doc Type: NPDES
• Email Name: JJD
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division
Rationale, Page 3, COG-0850000 Coal Mining General Permit
Table III-2a: Effluent Limitations and Monitoring Requirements -Alkaline Drainage, Coal Preparation Plants and Coal
Preparation Plant Associated Areas and Western Alkaline Coal Mining (additional requirements apply to Western
Coal Mining, See Section Ill A.3 of this rationale)
imitations. Aonitoring 'Satnple
Parameter 30-Dav 7-Day Dully _
' Rationale t
f reQteenc?
7} pe
A Ati
'- Max.
General Permit Requirements
Flow, MGD
Report NA Report
Discharge Evaluation
/
Continuous
Instantaneous'
Recorder
/
In-situ
pH, s. u. N/A NA 6.5-9.0 Water Quality Standards Weekly Grab
Oil and Grease, mg/1 N/A NA 10 State Effluent Regulations Weekly Visual 3
Federal Effluent Limitation Guidelines
Total Suspended Solids, mg/7 35 NA 70 Federal ELG Weekly Grab
Total Iron, mg11
Existing Sources (before 514184) 3.5 NA 7.0 Federal ELG Weekly Grab
New Sources (after 514184) 3.0 NA 6.0
Settleable Solids, m111 Report NA 0.5 Federal ELG Weekly Grab
--Site Specific Limitations
Total Dissolved Solids, mg11 • Report NA Report Salinity Regulations Quarterly Grab
Total Phosphorus (as P), mg11 •• Report NA Various Control Regulations Monthly Grab
Total Recoverable Iron, ug11 *** 1000 NA NA Water Quality Standards Weekly Grab
Other Pollutants of Concern Various NA Various Water Quality Standards Weekly Grab
Whole Effluent Toxicity (WET)
Chronic Stat Diff and IC25 > IWC State Permit Limitations Quarterly
Acute LC50 > 100% State Permit Limitations
3 Grab/Test
Grab
Footnotes 1-4, •, and *•, See Footnotes under Table III-1
*** This limitation will apply and will substitute for the 30-day average total iron limit based upon the ELG, when a total recoverable iron standard is applicable to the
stream segment.
Alternate Limitations For Alkaline Mine Drainage, Coal Preparation and Associated Areas and Western Alkaline Coal
Mining - Table III-2b contains limitations for any discharge or increase in the volume of a discharge from an above ground
alkaline mine (or an underground alkaline mine where the effluent is commingled with other categorical wastewater prior to
discharge), caused by precipitation within any 24-hour period less than or equal to the 10=year, 24-hour precipitation event
(or snowmelt of equivalent volume) may substitute the following limitations for these specific parameters only, subject to
burden of proof requirements described in Part I.B.4 of the permit.
Table III-2b: Alternate Effluent Limitations and Monitoring Requirements - Alkaline Drainage, Coal Preparation Plants and
Coal Preparation Plant Associated Areas and Western Alkaline Coal Mining (additional requirements apply to
Western Coal Mining. See Section IH.A.3 of this rationale)
Limuettio?u - -
30- 7-Day Daih, Monitoring Sample
Parameter Rationale I
Day A?'g ,1Tax• FregtienLy Tlpe
4i'g.
Federal Effluent Limitation Guidelines
Total Suspended Solids, mg11 Report NA Report Federal ELG Weekly Grab
Total Iron, mg/7
Existing Sources (before 514184) Report NA Report Federal ELG Weekly Grab
New Sources (after 514184) Report NA Report
Alternate Limitations For Alkaline Mine Drainage, Coal Preparation and Associated Areas, and Western Alkaline Coal
Mining - Table III-2c contains limitations for any discharge or increase in the volume of a discharge from an above ground
alkaline mine (or an underground alkaline mine where the effluent is commingled with other categorical wastewater prior to
discharge), caused by precipitation within any 24-hour period greater than the 10-year. 24-hour precipitation event (or
snowmelt of equivalent volume) may substitute the following limitations for these specific parameters only, subject to burden
of proof requirements described in Part LB.4 of the permit.
l