APPCOR13049

• Permit No: C1994082
• IBM Index Class Name: Application Correspondence
• Doc Date: 1/13/1995
• Doc Name: PRELIMINARY ADEQUACY CONCERNS YOAST MINE C-94-082 PERMIT APPLICATION
• From: DMG
• To: SUSAN L BURGMAIER
• Media Type: D
• Archive: No

4) The exhibits for Tab 7, which show the potentiometric
surfaces for the aquifers are missing from the permit
application package. PWCC should provide these maps.
5) The permit application package identifies aquifers only
in very general terms. For example, the PAP speaks of
the aquifers of the Mesaverde Group. Identification of
aquifers should be more specific to aid the Division in
its determination of whether potentially impacted
aquifers are regional or local, and to correlate the
aquifers with the specific stratigraphic formations
within which they occur.
6) Page 44: It is unclear why PWCC uses 1 mq/1 as a point
of discussion for the detection of trace elements in the
Saqe Creek alluvial wells. This should be clarified.
7) Page 66: In its discussion of mercury concentrations in
the Yoast groundwater monitoring wells, PWCC notes
exceedences in some of the wells of up to 1 ug/1 (20
times the drinking water standard). Other exceedences
which are at or near the laboratory's detection limit of
0.1 ug/1 are discounted because of a low level of
confidence for results near the detection limit. The
detection limit is reported as 0.1 ug/1 which is twice
the drinking water standard of 0.05 ug/1. PWCC should
explain what factors cause the detection limit to be
higher than the standard for these samples.
8) Table 7-9: PWCC should explain why there are no values
of hydraulic conductivity, discharge and storativity
reported for some wells.
9) Page 26: PWCC describes Darcy's Law as follows:
Q = Kib
where: Q = discharge
K = hydraulic conductivity
i = hydraulic gradient
b = wetted aquifer thickness
In fact, Darcy's Law is as follows:
Q = KiA
where: A = cross-sectional area of the aquifer section for
which Q is calculated.
Although PWCC's version of Darcy's Law can be used for a
unit width of the aquifer (b=A/width), it should be made
clear in the text that this is what is being done, and
that the calculated results for Q are per unit width of
the aquifer. This should also be reflected in Table 7-9.