Management of Aquifers - Hydrogeology: Objectives, Methods, Applications - page 221

3.2.2 Fight against bottom contamination
a) Denitrifi cation
Denitrification occurs naturally in the soil thanks to carbon. It can
nevertheless be insuffi cient, and liquid organic carbon (methanol, ethanol,
acetic acid) can then be injected into the aquifer. Various procedures are
used, but a major problem is the clogging that these methods induce.
Another procedure consists of pumping water, treating it at the surface
by circulating it through organic material (chopped straw), and then
reinjecting it into the ground.
b) Deferrization and demanganization
Iron and manganese are undesirable in water. Well injection of water
enriched in oxygen through aeration provokes the precipitation of iron,
then of manganese in the aquifer.
c) Radioactive decontamination
Following the Chernobyl catastrophe, groundwater was contaminated. The
CEA (Atomic Energy Commission) put zeolite barriers in place, designed
to trap radioactive material.
4 OPTIMISATION OF THE EXPLOITATION OF KARST
AQUIFERS
Karst springs often have a high variability, and exhibit an alternance between
severe dry periods and high fl ood discharges. It is therefore tempting to try
to manage them so as to sustain dry season discharge by using fl oodwaters.
The fi rst possibility is the creation of dams downstream of karst systems:
Sainte Croix (France) dam regulating the karst Verdon waters, Oymapinar
(Turkey) dam regulating the Manavgat and Dumanlı spring waters (50
m 3 ·s -1 ). But this solution is demanding in terms of space, and, in France, few
sites remain available. However, since limestone, thanks to the size of the
cavities (0.5 to 10%) that it contains, makes up a reservoir, it is interesting
to benefi t from these capacitative properties.