Article 7

     The  prior  investigations  referred to in Articles 4 and 5 shall
include  examination  of  the  hydrogeological  conditions of the area
concerned,  the  possible purifying powers of the soil and subsoil and
the risk of pollution and alteration of the quality of the groundwater
from  the  discharge  and  shall  establish  whether  the discharge of
substances  into groundwater is a satisfactory solution from the point
of view of the environment.