Management of Commercially Generated Radioactive Waste - U.S. ...

5.54
chlorosis of young trifoliate leaves. Effects on vegetation will depend on air concentra-
tion and time of exposure as well as humidity. Generally, an air concentration above
10 Pg/m 3 will alter distribution and growth of plants (Bernstein and Hayward 1958). Because
fenceline ground level concentrations for salt dust released from surface storage and
handling operations will exceed this level, a significant affect would be expected. The
deposition rates are in the range of 40 to 95 gm/m2/yr for observable leaf-burn on such
plants as beans. Based on the assumptions made for determining salt depositions, mitigating
procedures would be needed to reduce salt dispersal at least two orders of magnitude to
ensure that emission concentrations are well below levels toxic to plant life. Once con-
taminated, salt-affected soils will require special remedial measures and management prac-
tices to restore them to their original productivity.
Potentially, salt would be deposited as dust on the land and would also be transported
by runoff to nearby surface waters. Salt concentrations on the order of 8000 parts per mil-
lion (ppm) are lethal to freshwater fish under conditions of acute exposure (Jones 1964),
and the recommended limit for chronic exposure is 80 ppm or 0.01 of the acute toxicity level
(NAS 1972). The possibility exists for surface waters, particularly shallow, catch basin-
type ponds, to receive amounts of salt sufficient to damage indigenous aquatic plants and
animals. Resident species might also be replaced by more salt-tolerant forms.
In addition to effects from dust deposition, localized effects occur from leaching
around the surface storage area. Fluctuations in concentrations of soil salinity would
depend on precipitation, drainage, seepage, wind and rain erosion rates, and salt concentra-
tions in water and air that come into contact with the soil. Increased salinity around the
storage area would decrease or eliminate plant growth, because high salt concentrations in
soil reduce the rate at which plants absorb water. This would limit the use of vegetation
to increase the aesthetic qualities of the storage area and to control dust.
5.4.4.2 Ecological Effects for a Repository in Granite
A deep geologic radioactive waste repository in granite would be potentially less eco-
logically damaging than a salt repository and as a consequence would require fewer mitigat-
ing measures. During construction, about 8 x 107 MT of rock would be mined and 4 x 107 MT
would require disposal. For convenience of operation the granite would probably be crushed
in the mine before being brought to the surface, thereby reducing the airborne dust contami-
nation at the surface.
Possible methods of disposal include removal for use in construction projects (e.g.,
dams, highways) or surface disposal. Neither of these alternatives pose serious ecological
problems. Apart from land use associated with surface storage of the mined material,
several hundred tons of airborne particulates may be released yearly. Environmental release
of this material to land or surface water could be limited by establishing a vegetation
cover for the stored rock, and by proper draining and ponding the surface runoff.
During construction of a granite repository, as with shale and basalt, water may enter
either through downward flow from the overlying strata or through upwelling from lower