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

5.51
The main concern related to surface stockpiles would be the need to protect the ground
and surface waters from being contaminated with stockpile runoff, particularly in the case
of salt. For repositories in salt, one plan calls for an impermeable lining of hypalon
covered by 2 ft of montmorillonite-type clay to be placed over the entire stockpile area
after grading and before stockpiling begins. The hypalon and clay function as a ground-
water protection barrier. Construction of a trench with the same type of protection around
the stockpile could collect runoff water and transport it for any required treatment. If
the mine is located in an area with an arid climate, an evaporation pond may provide the
required treatment. If an evaporation pond is not practical, the runoff water may be
drained into a sump and pumped to a water treatment plant where dissolved salt or other
solids could be removed.
Several methods for disposing of salt in excess of needs for backfilling have been
investigated (D'Applonia 1976). These included disposal at sea, backfilling abandoned
mines, and use in the salt trade. Salt stockpiles crust quickly and industry does not
spread asphalt or chemicals on top of stockpiles to prevent loss of salt through erosion.
However, covering the piles with asphalt or rock and earth may be an appropriate means of
assuring dust control in the long term. Several methods appear to control or satisfactorily
reduce movement of salt by wind and water. The DOE recognizes the potential for contamina-
tion of land by salt and, if a repository is located in salt, is committed to its proper
control or suitable disposal.
Shale could conceivably contain amounts of soluble minerals that would be detrimental
to the environment. Precipitation could leach these minerals and pollute surface and ground
waters. Moreover, in a cold climate, freezing of the wet rock might result in fragmentation
and liberation of particulates, resulting in particulate pollution of the streams. The
shale stockpile area could be covered with a blanket of montmorillonite clay and sloped
toward a collecting ditch. The surface water would then drain into a settling pond to col-
lect silt and sands. From the pond it would be pumped to a water treatment plant where
minerals in solution would be removed before release until surface facilities are decommis-
sioned. (At present no provision is made for water treatment after the surface facilities
have been decommissioned.)
Granite and basalt generally do not contain noxious soluble substances. Therefore, the
stockpile area would not need special treatment and surface water would not have to be
treated.
Sanitary waste will be collected in a sewer system that is connected to a local sewer
trunk, if available, or given secondary treatment at the repository and disposed of in
accordance with local and Federal regulations. Storm drains will be separate from the sani-
tary sewer system and will lead to a storm drainage pond in the general yard area.
Although dust and nonradiological pollutants generated during construction have a
recognized potential for temporary adverse effects, with proper control measures, no long-
term effects are expected to result.