2007-11-07_HYDROLOGY - M1977300

• Permit No: M1977300
• IBM Index Class Name: HYDROLOGY
• Doc Date: 11/7/2007
• Doc Name: Hydrologic evaluation of mine closure & reclamation
• From: Whetstone Associates
• To: Cotter Corpoartion
• Media Type: D
• Archive: No

Schwartzwalder Mine -Hydrologic Evaluation of Mine Closure and Reclamation 44
6.1 Surface Water Quality Standards
6.1.1 Discharge Permit Limits
The discharge permit (#CO-0001-244) issued by the State of Colorado listed effluent limits for water
discharged from the water treatment plant operated at the site. Those limits included specific metals,
uranium (0.776 mg/L) and radium 226/228 (3 pCi/L), as shown in the following table.
Table 19. Discharge Permit Effluent Limitations

Effluent Parameter Effluent Limitations
Maximum Concentrations
30-Da Avera a Dail Maximum
Flow, MGD 0.288 Re ort
COD, m 1 100 200
Total Sus ended Solids TSS , m 1 20 30
Potentiall Dissolved Uranium, u 1 776 1243
Radium 226 +228 total , Ci/1 3 10
H, s.u. minimum-maximum NA 6.5-9 d/
Oil and Grease, m 1 NA 10 d/
Total Recoverable Antimon , u 1 6 Re ort
Boron, m 1 0.75 Re ort
Total Recoverable Chromium, u l 11 16
Potentiall Dissolved Co r, u 1 5.4 7.7
Potentiall Dissolved Silver, u 1 0.027 0.73
Potentiall Dissolved Zinc, u l 71 71
Weak Acid Dissociable C anide, u 1 NA 5
Fluoride, m 1 NA 2
Totak Recoverable Thallium, u 1 0.5 NA
Whole Effluent Toxici ,Chronic Lethali
Cerioda hnia s ecies NA IWC = 100%
Fathead Minnow (Pimephales promelas) NA IWC = 100%
The discharge permit applied to the single discharge point (Outfall 001), the pipe at which water from the
treated water retention pond was released to Ralston Creek. In the 29 reporting periods leading up to the
discharge permit renewal in 2005, CDPHE identified only four limit excursions: pH (1 event), thallium (1
event), silver (1 event), and ceriodaphnia WET test results (1 event). The Discharge Monitoring Reports
have reported no discharge since the water treatment plant was shut down in June 2002.
6.1.2 Stream Standards
The Colorado Department of Public Health and Environment (CDPHE) Water Quality Control
Commission (WQCC) has published in-stream water quality standards for this reach of Ralston Creek.
Located in the Clear Creek Basin, Reach 17b includes the "mainstem of Ralston Creek from the source to
the outlet of Arvada Reservoir, including Ralston Reservoir and Upper Long Lake" (SCCR 1002-38).
Regulation Number 38 (SCCR 1002-38) lists the specific numeric standards for Stream Segment 17b, while
Regulation Number 31 (SCCR 1002-31) gives the basic stream standards and methodologies applicable to
all state waters.
The applicable water quality standards for cold water biota in Ralston Creek Stream Segment 17b are listed
in Table 21. Acute and chronic standards for metals are based on dissolved concentrations, except where
noted otherwise in Table 21. The numeric criteria for cadmium, chromium III, copper, lead, manganese,
nickel, silver, uranium, and zinc are hardness dependent, and are calculated according to the following
equations:
4109B.071116 Whetstone Associates