In addition to the time-concentration relationship, it is of interest 
to know the effect of distance from disposal site on the concentration 
for point sources, The maximum relative concentration (C/Co) asa 
function of distance from the site is shown for three cases in figure 4. 
Curve 1 assumes infinite depth of water, curve 2 assumes that the ratio 
of water depth to canister size is 100, and curve 3 assumes infinite 
depth and that all of the waste is not immediately available but diffuses 
from the ruptured canister at a uniform rate under the conditions that 
the diffusion coefficient through the ruptured canister is 10° that of the 
diffusivity in the water. The latter case is discussed below. 
Continuous Source at Uniform Leaching Rate. This case treats 
the situation analogous to the diffusion of contaminant from the concrete 
that remains after the steel casing has corroded and affords no further 
containment. In the development of this case, it has been assumed that 
the amount of contaminant diffusing through the permeable concrete 
walls is directly proportional to the surface area of the container, di- 
rectly proportional to the difference in concentrations inside and imme- 
diately outside the container, and inversely proportional to the thickness 
RELATIVE DISTANCE 1% 
Mox C/C, for 
J ns ton taneous “Box” Source 
on Bottom, D-@ 
@ Max Co for 
Instontoneous "Box" Source | 
an Bottom, D/a = 100 
RELATIVE CONCENTRATION 
6) oo for Continuous “Box” 
ource_of uniform Poot) 
Rata D=a, k/K =10 
DISTANCES FOR V=49aal 
10cm Im tom 100m thm Oxm 100km 
FIGURE 4 
RELATIVE CONCENTRATION VERSUS DISTANCE FROM SOURCE 
23 
