Civil Engineering Reference
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(
)
=
−ε
cz t
2
*, *
10
.
(5.1)
Finally, this characteristic is considered a measure of intrinsic cover vulnera-
bility of the Eocene aquifer.
Using the data of the upper Quaternary aquifer's contamination with
Chernobyl-born
137
Cs, the vulnerability of the second (from the surface) Eocene
aquifer to contamination with this radionuclide is estimated. The assessment is
performed by overlaying the map of the Quaternary aquifer cover vulnerability to
real surface contamination (Figure 5.6) onto the working map of the total atten-
uation capacity of the Quaternary aquifer saturated zone and the underlying Kyiv
marl confining bed. The corresponding protectability index ε
2
= −log
c
2
(
z
2
*
,t*
) was
used to draw the cover protectability map of the Eocene aquifer. As a result, the
vulnerability map of the Eocene aquifer to real surface contamination with
137
Cs
is obtained as shown in Figure 5.12. The map gradations correspond to zones of
total groundwater contamination of the Eocene aquifer for the forecast period of
30 years in units of surface contamination density, kBq/m
2
(Figure 5.12, column
A) and Ci/km
2
(column B). In the same way as for the upper Quaternary aquifer,
by the obtained sum of contamination per unit area of the aquifer with account
of its thickness, the average effective porosity
n
= 0.1, and average distribution
coefficient
К
d
= 10 dm
3
/kg [
Shestopalov
, 2001], an approximate assessment is per-
formed of the full groundwater vulnerability of the aquifer groundwater in units
of
137
Cs concentration (mBq/dm
3
; Figure 5.12, column C).
Similar to the vulnerability map of the upper groundwater, regions of highest
groundwater vulnerability (3 mBq/dm
3
and higher) are observed in the CEZ.
However, their areas here are restricted to sites of relatively low groundwater pro-
tectability (see Figure 5.11). The zones with a groundwater vulnerability of 0.03
mBq/dm
3
and higher in Kyiv conurbation and the Dnieper valley southeast of
Kyiv can be associated with zones of absence or low thickness of the Kyiv marl
confining bed, the presence of hydraulic “windows”, and also the influence of
Kyiv groundwater intakes in the deeper Cenomanian-Callovian and Bajocean
aquifers. In the whole, the vulnerability of the confined Eocene aquifer is signifi-
cantly lower as compared to the upper Quaternary aquifer.
It is worth mentioning that the maximum allowable concentration (MAC
1
) in
drinking water for
137
Cs and
90
Sr according to standards of Ukraine is 1 Bq/dm
3
.
1
The term MAC corresponds to the definition of the Maximum Contaminant Level (MCL) in the
USA. U.S. EPA has established a MCL of 4 millirems per year for beta particle and photon radio-
activity from man-made radionuclides in drinking water. The average concentration of strontium-90
that is assumed to yield 4 millirems per year is 8 picoCuries per liter (pCi/L), which equal to 0.3 Bq/l.
(Reference: EPA Facts about strontium-90, see
http://www.epa.gov/oerrpage/superfund/health/con-
For sesium-137, the criteria is 200 pCi/L, which is equal to 7.4 Bq/l. (Reference: EPA Facts about
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