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9. Comment: Answered in TNOD1 response.
10. Comment: Regarding Matrix-dominated flow (Volume 3, Figures 6.6-5a and 6.6-7): The
figures do not seem to illustrate the overlying OAG or the uppermost Triassic strata. It appears
that no lateral flow from these shallow units is considered in the modeling. Consideration of
lateral flow is important as a possible pathway for leachate from the facilities.
Requested Action:
• Please refer to our response in Comment 2, above, in the same section. Lateral flow
is discussed only in the context of transport out of the landfill. Please discuss lateral
flow as a means to increase the local vertical flux and how, in a wetter climate, the
percolation flux through the landfill cover could increase and increased recharge
from the playas could also generate locally saturated conditions.
• Relative to computing the flux through the liner, the method of multiplying
precipitation rates by a factor of two and not changing any of the other HELP
parameters (Volume 10, Appendices 8.0-6 and 8.0-7) is not satisfactory. Wetter and
colder climates as predicted for the next few thousand years will likely increase the
precipitation rate. The infiltration rate will also increase since evapotranspiration
will be less. (The Yucca Mountain Project may have predicted climatological data
for Hobbs, NM). Please demonstrate that the infiltration rate is not significantly
different in the latter case and that the multipliers used in TOUGH2 simulations
(Volume 3, p. 6-34) are conservatively realistic.
• Please provide additional cross sections.
11. Comment: Page 10 of the geology report by Lehman and Rainwater (2000) in Volume 4,
Appendix 6.2-1, describes Baker Spring as probably being an ephemeral point of discharge for
water from the OAG: “groundwater appears to be discharging from these deposits [Gatuña
Formation] at Baker Spring.” The section, Discharge of Groundwater (Volume 1, page 2-54),
however, does not address this.
Requested Action: Please include Lehman and Rainwater’s observations from Volume 4,
Appendix 6.2-1 in the text of the application. The revised application excludes the
observation of Lehman and Rainwater that a natural seep is present at Baker Spring, and
the revision does not preclude the possibility that the ponded surface water is augmented
by some natural discharge from the OAG, even though ephemeral or minor in volume.
Lehman and Rainwater’s observations would seem to be as valid, or more so, as the
opinion of the mine manager, especially since photos from 1939 show a pond, and the mine
manager probably was not present during operations that ceased at Baker Spring in the
1950s. We note also that the Applicant’s response refers to revisions that were made to
Attachment 2
Second Technical Notice of Deficiency
1/30/2006 Page 33 of 51