REV15730

• Permit No: C1980004
• IBM Index Class Name: Revision
• Doc Date: 6/9/2006
• Doc Name: Adequacy Review Response
• From: J.E. Stover & Associates
• To: DMG Grand Junction Field Office
• Type & Sequence: TR15
• Media Type: D
• Archive: No

Dan Mathews 3 June 9 2006
c) DMG -Please update the discussion in permit Section 4.1.2.5 regarding effects of the operation
on the East Salt Creek alluvial valley floor to incorporate the update PHC projections. Amended
narrative should address effects to both alluvial groundwaterand to East SaR Creeksurface water used to
irrigate the cropped AVF parcels depicted on Figure 4.1-2.
CAM -Updated Section 4.1.2.5 to include possible effects of the operation on the East Salt Creek alluvial
valley floor.
d) DMG - An additional mass balance analysis is requested, and should be included in Section 4.1.2.5.
The analysis is necessary to assess the projected effect of mine discharge on average irrigation season
salinity (conductivity) on East Salt Creek waters diverted for irrigation of the AVF downstream of the
confluence of McClane Creek and East Salt Creek. The analysis requested would be a refinement of the
table presented on amended page 3 of Appendix N. The Appendix 3 table uses worst case assumptions
for minewater TDS; East Salt Creek data is presented for specific sampling events.
DMG -Several modifications are requested to provide an analysis that will address whether mine
discharge salinity may have the potential to materially damage the quality of East Salt Creek water used to
irrigate downstream alluvial valley floors. First, salinity data should be presented as conductivity values, to
allow for comparison with suspect levels and evaluations as presented in the Division's 1987 material
damage guidelines. Second, for East Salt Creek, a flow rate salinity level that reflects average irrigation
season values will need to be used in the analysis. A corresponding average discharge water conductivity
value (rather than worst case) may also need to be used in the evaluation. If initial analysis based on
these factors indicates that mine discharge would increase the average irrigation season conductivity on
East Salt Creek (and the conductivity would exceed 1.0 mitiimhos/cm), further site specific investigations
may be warranted as described in the guidelines.
CAM -Included additional mass balance analysis in Section 4.1.2.5 and Appendix N
CAM - Data gathered for SW-1 and GW-3 are presented in Appendix N. The Division's 1987
Material Damage guidelines require any measured salinity values over 1000 umho/cm be reported as
'suspect' values. Since baseline values for SW-1 and GW-3 far exceed the Division's 'suspect' levels,
the Operator compiled data in order to demonstrate mine discharge does not add salinity to the
already high values, rather, can only lower the salinity in SW-1 and GW-3 during the irrigation season.
By improving the salinity of the waters in East Salt Creek and the East Salt Creek alluvium,
downstream farmers will not suffer loss of production due to the addition of mine discharge. See
Section 4.1.2.5.
Responses based on AHR 2005 Adequacy Review (using adequacy review numbering)
3) DMG -The baseline groundwater data for the Alluvial Wells No. 1 through No. 6 is presented in the
McClane permit in Tables 4.2-1 through 4.2-5. There appears to be some baseline data missing or
possibly it was never collected. The current minimum requirements for baseline groundwater
information are given in Rule 2.04.7 (1). No data are given in Table 4.2-1 through 4.2-5 for Alluvial
Well No. 3 (possibly dry), and iron and manganese analyses are not provided for Alluvial Well Nos. 5
and 6. No baseline data could be located for newer wells GW-7 and GW-S.
DMG -There is also uncertainty as to which of the original alluvial wells (for which baseline data has
been provided) correspond to the wells in the current approved program. This needs to be clarified in
the permits. In the Munger permit, Table 2.5-1 lists groundwater monitoring site numbers and
corresponding well numbers but this does not clear up the confusion regarding which of the "GW"
wells were monitored during the baseline data program. For wells in the approved program, it is
unclear if Alluvial Well No.s 1 and 6 correspond to GW-1 and GW-6, respectively. Well GW-3 appears
to correspond to Alluvial Well No. 2.
CAM -The alluvia( wells are confusing since they are not discussed in detail in the permit, and there
are no completion diagrams for them. Some of the alluvial wells are located close to the groundwater
monitoring wells, but they are not the same. For example, AW-6 was near GW3. However, when
you compare baseline data for the two, they are remarkably different, GW-3 conductivity is 7,000+,
AW-6 is 1,250. To eliminate the confusion between the alluvial wells and the ground water monitoring