EIS-0113_Section_11 - Hanford Site

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interface zone between the u pper fine-textured soil and the coarse
species can beexpected to readily penetrate the u pper 1. 5-meter
(riprap) moisture barrier. Conceptual design of the protective
capillary barrier with roots or burrows, including Russian
barrier, described in section M2 and figure M.3 (pages M.6-M. a),
thistle, rabbitbrush, sage brush, prairie dogs, end ground
indicates a 0.3-meter-thick graded gravel layer will separate the
squirrels. Plant species in particular may be attracted by the
upper fine sail from the lower 12- to 25-cm size riprap. The
relatively high moisten content of the upper zone. Die-off of 3. 5.1.84
thickness of this intermediate gravel layer is thus roughly
plants as by fire, disease, er extended drought and subsequent
comparable to the size of voids in the upper surface of the riprap
decay could result in extensive formation of macropores in the
layer. A silica glass geotextile is proposed between the upper
barrier. These holes could provide conduits for rapid
> soil layer and the intermediate gravel, to prevent migration of
infiltration through the fine-textured layer during intense
3 .5.1. 27
stores
fines that would decrease the effectiveness of the capillary
or snow-melt periods (Questions M.9 antl X.22).
break. our concerns in this area include the stability of the
fine soft/ri prap interface and, the strength and durability of the
Macropores will provide a particularly rapitl avenue for water
geotextile (Questions M.6, M.19, and M.23).
infiltration through the barrier in low spats (catchment basins)
- that collect runoff and Soowmelt. The u pper - fine-soil layer is
Because slice glass geotextiles may have limited puncture and
proposed to be very loosely densified (minimum porosity of about
tearing resistance, the surface upon which the geotextile is laid 43 percent- as indicated by moisture content oa Figure M.2, 3.5.1.84
must be extremely smooth and stable. The larger the gravel, the
page M.5).. Catchment basins are. likely to form in the upper
more tendency there will be for tearing the geotextile where it
surface of this loose material by a) differential settlement of
attempts to bridge between points of grain contact in the gravel.
the waste and barriermaterials over time, and b) wind and water
However, the finer the gravel, the greater its tendency to flow
erosion. Armoring to prevent such erosion is limited by moisture
dpwnwartl irregularly and unpredictaEl y Into the large interstices performance considerations (Question M21). , Development of
3.5.1.92
of the riprap, especially under dynamic stresses such as could be
catchment basins will lead to concentration of recharge in certain
expected during construction of the upper soil zone or from
areas of the barrier, causing in turn Soil saturation and drainage
.earthquake shaking. Our concerns in this area include the
through the barrier.. Soil desSiation structures may develop to
stability of the fine soil/riprap interface and durability of the
further increase drainage.
geotextile . (Questions M.6 and M.19),
e o tack of Overall Sy stemEvaluation - b p barrier feat re p . and
The slice glass tnv
le must. also ha e sufficient tensile
ways t measures would likely DE degrade ode b rrier ace in
strength and elongation properties to span across across Dtal
ways that are cored in the DEIS: Adverse t s of this
see in the
the coarse
granular layers that may result from
Piecemeal approach conceptual design include development of
3.5.1.36
CJI
settlement
of wastes beds aican
w1 on of the riprap and/or gravel
settlement-induced basins because of law of msur it of barrier
Qq
The riprap is described
of
'loo
l eso than max on page to
material (Question X.23), concentration vapp by iobsurface
C) imittc t o of the gravel will less l than maximum due en
marker Question X t mulches ion of evapotranspiration vent
by
limitations mexacted pe o
construction equipment.
Non-uniform rr
may
ensuring on ('stone 20o mulches-) ches-)') to prevent erosion by wind and
Water .(Questi
ad
be expected ever e time in these materials, due to rearrangement
uakeY s of
Uesti onso M. .26 and N.21)-.. -
particles caused by dynamic forces such as earthquake shaking
and
traffic vibrations. o - — 5t m qL at i Perform on of Barrier nc es. . The DEIS states (page M.19, first
- paragraph), The intent of theModelingg to effortwas a use the beet
o Unrecognized asp o Disruption thato -- the DEIS fails to address cover btechniques
on oppiran io to ge the efateve wst venesi of the mutfil ayer
aspects
of ron that would lonely contributoe to degraded cover ti stoppingng infiltration iof water in the
We found the
moisture barrier pe
or
perfformance. Section M.3.2 discusses
parame Pate to be unclear, ear; or non-conservativve with respect to various input
bids burwn. control and focuses on methods prevent plant rants rameters, moi soul. moisture (question es t ) n precipitation pat
and burrowing animals from contacting and transporting toxic
X.201, soil moisture characteristic curves ( q m. 2
.The
uestions n pi and M:12)), plant
3.5.1.84 wastes directly. The riprap layer is oted in tl be the key
growth cycle (Question M.13), and ootenty transpiration (question 3.5.1.37
barrier to biological
e noted n in the firs[ paragraph
The DEIS
concludes (page key result that the stud
on page however, , 'chann
i
i
a a n
' channell s created by plants and anim als may indicated "tone-textured p ool overlying coarse layers will storee and
also promote
rans
a
mote the infiltration of surface rater into the waste.' transmit the water so that evapotranspiration
anspiraton processes
can effectively recycle
The capillary barrier well be ineffective to the extent that water he p recipitation,
recept ion, tbu5 preventing drainage even under etglq rainfall
Referencesf
the riprap layer after passing through
such channels. conditions (30 we fin m' Apart
from concept or theoretical
Re erences cited tetl to the DEIS indicate 'a number of plant and animal considerations, e Find this conclusion questionable for the
specific
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