2010-08-19_REVISION - M1977285 ‎(2)‎

• Permit No: M1977285
• IBM Index Class Name: Revision
• Doc Date: 8/19/2010
• Doc Name: Operator Acceptance of Amendment Requirements ‎(Sunday Mine)‎
• From: Denison Mines
• To: DRMS
• Type & Sequence: AM3
• Email Name: RCO
• Media Type: D
• Archive: No

Section 11
Water Quality Monitoring Plan
mean ambient water quality from the subsurface monitoring wells nest samples
multiplied by two times the standard deviation of the concentrations. In the event that
the water quality at the downgradient wells exceeds the compliance limit, the
frequency of sampling at the compliance well will be increased to monthly and the
Division will be notified. In the event that ambient water quality is exceeded at any
downgradient well for a continuous period of three months or more, potential
additional actions will be developed by Denison in consultation with DRMS.
The two compliance wells would be installed at the locations specified on Figure 11-1.
These two wells are located on public lands and will be subject to BLM approval. The
wells would be installed in accordance with DRMS and CDPHE requirements, and
would be screened within the Salt Wash Member of the Morrison Formation to
provide samples of water within the hydrogeologic unit affected by Denison mining
operations. In order to accurately identify the proper screening interval, down hole
geophysical logging for each compliance well will be completed. The log analyses and
interpretations will be performed by a qualified log analyst. Plans and specifications
for the wells will be submitted to DRMS prior to construction and well logs and
construction completion diagrams would be submitted after installation. The plan for
sealing and closure of the wells will also be submitted to DRMS as part of the plans
and specifications package.
Groundwater sampling would include measuring the static water table with a well
probe; purging the well in accordance with best practices; measurement of field
parameters, and collection of samples for laboratory analyses. Exhibit 11-1 provides a
list of analytical parameters that will be sampled as part of the quarterly groundwater
monitoring program. This parameter list is based on the approved analyte list
developed in the Groundwater Characterization Data Collection Work Plan to
Address Designated Mining Operations (DMO) Status Sunday Mines Group, San
Miguel County, Colorado (CDM 2008e).
Exhibit 11-1. Compliance Monitoring Analytical Parameters
Analytes Method Reporting Limit (Ng/L)l
pH Field ---
Conductivity Field ---
Dissolved Oxygen Field ---
Oxidation Reduction Potential Field ---
Total Dissolved Solids SM 2540C 10,000
Hardness SM 2340C NA
Chloride EPA 300.0 1000
Fluoride SM 450OF-C 100
Sulfate EPA 300.0 1000
Gross Alpha EPA 900.0 MDC
Gross Beta EPA 900.0 MDC3
Nitrate EPA 353.2 50
Nitrite EPA 353.3 100
Aluminum EPA 200.8/200.7 100
Antimony EPA 200.8/200.7 1
Arsenic EPA 200.8/200.7 1
11-2
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