EIS-0113_Section_11 - Hanford Site

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3.5.1.83
3.5.1.39
soction,.penetration of the 1.5-meter fine-soil zone by roots and
burrows, especially in combination with erosion or
subsidence-induced runoff catchment basins, threatens serious
blamed! tIn of the moisture barrier performance. Why was this
potential problem not addressed in section 5.4?
M-23 The ri p-rap layer is proposed to be 'loosely consolidated'
, pag e M.13), and the minimum porosity of the fine soil layer is
apparently about 43 percent (Figure M.2, page M.5). What data
exist to ensure that settlement of the barrier surface will not
occur, given these relatively lbw constructed densities?
APPENDIX N RADIOLOGICALLY RELATED HEALTH EFFECTS
chemical framework for transport in these systems is described, to the
extent it can be characterized within present knowledge.
Conceptual models are presented for a) hydraulic flow within the
saturated and unsaturated zone, b) release of contaminants to the saturated
groundwater system, and c) retardation of contaminants within the
groundwater systems. Computer simulation is not attempted for the
unsaturated system, but formulation and calibration of a numerical hydraulic
model of the saturated flow system is described.
Most important with respect to the results of transport modeling
reported elsewhere in the DEIS, two recharge scenarios, for "drier' and
wetter" climates are proposed, a long with a limited rationale for their
development.
Dgneral Canmente
Err, rs_or Uncertainties
wA
4.2.3.5
The human health effects that result from different radiological doses
to the various organs of the body are discussed in this appendix. While the
immediate (acute) effects of large doses are fairly well understood, the
problem is much more difficult for very small doses which are the same order
of magnitude as the background, since only a small portion of the population
exposed shows any effects and those effects may be be delayed for decades or
appear in the next generation.
-
Errors or Uncertainties
A specific page reference is required for the quote on pages N.2 and
N.3.
The sundry of the types of genetic disorders oa page N.8 is misleading
and has very different implications especially for thegeneral -reader) than
the descriptions in the source references.
Table N.4 deserves more. discussion, especially the fact that the total
line does not appear to reflect the values above it in the table.
Ouee5t4@
As is pointed out repeatedl y in the DEIS, characterization of
unsaturated soil hydraulic properties and of chemical .retardation factors is
nadequate at present to permit credible numerical simulation. Although
this position is taken consistently throughout most of Appendix 0, it
ap pears to be contradicted with respect to chemical retardation by a
statement in the introductory section that there is relatively good
understanding of contaminant behavior in the saturated zone from previous
site monitoring.
Significance of Previous Hpnitori no Experience. The , last paragraph of
the introduction to Appendix (page 0.2) includes the statement, 'Over
forty years' experience in monitoring this .unconfined aquifer with hundreds
of wells has resulted in a relatively good understanding of the behavior of
various contaminantsin this zone. Such data have been used to calibrate
numerical codes used to simulate groundwater movement in the unconfined
aquifer'. This statement is directly contradicted on page 0.28 (first
paragraph). where the DEIS states' calibration and hence validation of
the transport model is limited to our confidence in the travel time
distributions supplied by the unconfined aquifer. model. Longitudinal
dispersion models applied to the ... unconfined aquifer ... have not been
calibrated.'
3.5.2.25
3.5.2.20
None.
APPENDIX 0 STATUS OF HYDROLOGIC AND GEOCHEMICAL MODELS USED TO SIMULATE
CONTAMINANT MIGRATION FROM HANFORD DEFENSE WASTES
General Comment=
This Appendix summarizes and discusses the conceptual and numerical
models used to estimate patent ill movement of toxic contaminants away from
waste facilities that are proposed to be disposed or stabilized in place.
The path of potential transport of contaminants is envisioned to occur
partly above the water table in unsaturated (vadose zone) soils and partly
In the underlying water-table (unconfined) aquifer. The physical and
rundwat r Recharge Rates. Probably the most significant aspect of
the conce ptual model erms in tof its conservatism or non-conservatism with
respect to contaminant travel times is the aroundwater rechar g e scenario.
This aspect of the model is given relatively little attention in Appendix G
or elsewhere in the DEIS. The lysimeter studies conducted to date at
Hanford used artificially reconstituted soils.- It is not clear whether any
experiments have been conducted at Hanford that would indicate lack of
long-term deep drainage and associated recharge under natural conditions.
As discussed in Section 0.3.2. (page 0.12), the DEIS assumes 0.5 and
5.0 cm/yr average recharge rates under drier and wetter conditions,
respectively. These figures are the basis of many calculations in this and
other parts of the DEIS. We feel that the DEIS estimates of recha rg e are
3.5.3.2
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3-21
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