PERMFILE107884

• Permit No: C1980001
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: AIR AND WATER PERMITS
• Section_Exhibit Name: 3.7 APPENDIX 3.7-D
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
~ Rationale - Page 3. Permit No. CO-0032638
MONITORING SUMMARY:
The permittee performed two sets of analyses each, from outfalls 003 and OU6.
AL1 stream standards were analyzed. Of all parameters, only cadmium, silver,
manganese (outfall 006 only), and mercury showed a potential impact when
directly compared to the stream standard. Calculations shown in Appendix A
more directly show whether an impact exists after considering dilution.
APPLICABLE RULES AND REGULATIONS:
Outfalls 001. 002. 004. and 005
These four outfalls discharge surface runoff from active mining areas.
Outfall 002 may discharge spoils spring water, but such discharges would be
intermittent and during high stream flow as would surface runoff.
fable 2 below, shows State Effluent Standards (SES), Federal Best Practicable
Control Technology (BPT), Federal Isest Available Technology Economically
Achievable (BAT) and State Water Quality Standards (WQS) applicable for these
outfalls.
The Colorado Mined Land Reclamation Division and the State Engineers Office
require ponds to be dewatered within 3G to 72 hours after a precipitation
event. On this basis, the division believes that discharges will occur when
stream flow is well above the 7-day, 10-year low flow. Thus, no WQS-based
limitations other than pH need be considered.
Table 2
Parameter SES WQS BPT BAT
pH (s.u.) a/ G.0 - 9.0 6.5 - 9.0 6.0 - 9.0 N/A
Oil and Grease (mg/1) a/ 10.0 N/A N/A N/A
Total Suspended Solids (mg/1) 30/45 N/A 35/70 b/ N/A
Total iron (mg/1) N/A N/A 3.5/7.0 b/ 3.5/7.0
Settleable Solids (ml/1) c/ N/A N/A N/A 0.5
Uutfalls U03 and 006
Outfall 003 may contain both surface runoff from a reclamation area and spoils
spring water. The runoff discharge is intermittent, normally occurring only
during high stream flow periods. 1't~e spoils spring discharge is continuous;
its volume is expected to be greater during high runoff periods.
Outfall 006 consists of spoils spring water only. This discharge occurs
year-round and as expected with the spoils spring water from 11003, volume
should be greater during high runoff periods.