HYDRO25625

• Permit No: C1981071
• IBM Index Class Name: Hydrology
• Doc Date: 3/17/1986
• Doc Name: DRAFT PERMIT FOR PUBLIC NOTICE
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH
Water Quality Control Division
Rationale - Page 9
Permit No. CO-0027154
Outfalls 009, 010, 011, 012, 013, 015, 016, 017
Table 6 shows the limitations chosen for these outfalls, the rationale for
their choice and the monitoring frequencies.
TABLE 6
Monitoring
Parameter Limitation Rationale Frequency
Flow, MGD N/A
pH, s.u. 6.5-9.0
011 and Grease, mg/1 10.0
Settleable Solids, ml/1* 0.5
Salinity N/A
h/ See footnotes in previous section
Monitoring Mnthly
WQS Monthly
SES Monthly
BAT Monthly
Monitoring Quarterly h/
*This parameter ie not applicable to discharges caused by precipitation
greater than the 10-year, 24-hour event (or equivalent snowmelt volume).
Outfall 005
Table 7 shows limitations, rationale and monitoring fequenciea for this
outfall.
TABLE 7
Parameter*
Flow, MGD
pH, s.u.
011 and Grease, mg/1
Total Suspended Solids, mg/1
Total Recoverable Iron, mg/1
Total Recoverable Copper, mg/1
Total Recoverable Silver, mg/1
Total Recoverable Zinc, mg/1
Settleable Solids, ml/1
Salinity
Monitoring
Limitation Rationale Frequencies
N/A Monitoring Weekly
6.5 - 9.0 a/ WQS Weekly
10 a/ SES Weekly
35/70 b/ BPT Weekly
1.0/2.0 b/ WQS Weekly
0.01/0.02 b/ WQS Weekly
0.0001/0.0002 b/ WQS Weekly
0.05/0.10 b/ WQS Weekly
0.5 c/ BAT Weekly
N/A Monitoring Quarterly h/
a/ Limitations effective at all times
b/ 30-day average/daily maximum respectively
Limitations effective at all times, except TSS (See c/)
c/ Limitation may apply to discharges caused by precipitation less than or equal
to the 10-year, 24-hour precipitation event in place of TSS limitations.
h/ See footnotes in previous section
*Note: Hexavalent chromium and total meQCUry were limited in the previous
permit. Appendix B shown that effluent quality has remained below applicable
limitations. Thus, no further limitations are necessary.