2010-09-29_REVISION - M1981185 ‎(13)‎

• Permit No: M1981185
• IBM Index Class Name: REVISION
• Doc Date: 9/29/2010
• Doc Name: Conversion Application for a 112‎(d)‎ permit Part 3 Exhibit T-1 thru Exhibit T-4
• From: Wildcat Mining, Co
• To: DRMS
• Type & Sequence: CN1
• Email Name: WHE
• Media Type: D
• Archive: No

May Day Idaho Mine Complex 112 (d) Permit Application
• 6.4.20(11) Surface Water Quality Data
(a) Existing Surface Water Receiving Water Stream Standards
The Stream Classification is as follows:
Region: 9
Basin: La Plata River, Mancos River, McElmo Creek, and San Juan River in Montezuma
County and Dolores County
Stream Segment Description: Mainstem of the La Plata River, including all wetlands,
tributaries, lakes, and reservoirs, from the source to the Hay Gulch diversion south of
Hesperus.
The following classifications are applicable to this segment:
• Aquatic Life Cold 1
• Recreation P
• Water Supply
• Agriculture
(b) Surface Water Quality Data
• Surface water quality samples for two quarters have been collected from five locations as
described in Attachment T-5. The Division has agreed that a 112(d) permit may be
issued, if all of the requirements of the Act are met, prior to completion of five successive
calendar quarters of surface water sampling, with appropriate limitations on mining
activities which might potentially impact surface water pending completion of all five
quarters of sampling. The following is a summary of analytical results to date:
• Sulfate concentrations above the reporting limit were recording at all locations.
The highest sulfate concentration was recorded for the sample collected from the
discharge at the Idaho No. 1 Portal, however there was no increase concentration
reported downstream of the seep in the La Plata River;
• There were no exceedances of either Acute of Chronic Aquatic Life Standards
for dissolved metals.
• Total Recoverable Aluminum concentrations above the Chronic Life Standard
was reported for samples collected from the La Plata River down gradient of all
permit areas and within Little Deadwood Gulch immediately below the May Day
No. 2 Operational Area. Regulation 31- The Basic Standards and
Methodologies for Surface Water were amended on 8/9/2010 to become effective
1/1/2011 and incorporated a hardness-based criterion for Total Recoverable
Aluminum where surface water pH values are greater than 7.0. This equation
was used to re-calculate values for Chronic Life Standard for Total Recoverable
Aluminum. The concentration of Total Recoverable Aluminum reported
May Day Idaho Mine Complex 112(d) Permit Application
September 21, 2010
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