For an estimation of efficiency of
the performed remediation works and for surveillance of the Radioactive
Tailings Pond and a state of environment in its area of influence the two-phase
monitoring program of Sillamäe Radioactive Tailings Pond is prepared. 1 phase
of the monitoring program was an integrated part of the remediation project
itself, which was carried out in 2002-2008. 2nd stage of the monitoring program, which is the post-remediation
monitoring, was started in 2009.
The purpose of the post-remediation
monitoring is the surveillance of the Sillamäe Radioactive Tailings Pond and
its areas of influence, recording of essential changes and assessment of the efficiency
of the accomplished remediation works. During the post-remediation monitoring
radiation safety of the site is also under attention in order to deepen the public
confidence regarding the safety of the site.
1. Tailings pond visual monitoring is performed 6 times a year (once within 2 months). During
monitoring integrity of the tailings pond final cover, vegetation, and also
cleanliness and workability of wells, drainage trenches and diaphragm wall is
reviewed; the visual check of roads, system of monitoring of surface
settlement, viewing wells, lysometers and weather station is carried out.
2. Gamma radiation monitoring
is performed 4 times a year (once in a
quarter), consists of carrying out of measurements in the 10 GPS pre-set points
defined, by means of radiometer at height of 1 m above the ground surface.
3. Monitoring of radon exhalationis performed 4
times a year (once in a quarter) in five points during dry weather, using
special equipment for Radon exhalation measurement.
4. Geotechnical monitoring:
monitoring of geotechnical stability of a dam is carried out, necessary to
prevent further risks connected with the stability of the dam. The network of geotechnical stability monitoring
consits of 7 inclinometric and 7 piezometric measurement points.Monitoring is
performed 6 times a year (once within 2 months).
5. Monitoring of surface settlementis performed 4
times a year (once a quarter), it gives the initial information on reliability
of model - for this purpose on tailings pond the network from 187 points is
6. Monitoring of water level in wells: during
monitoring 4 times a year are measured water levels in 36 monitoring wells.
7. Monitoring of the functional performance of the
tailings pond final cover by means of lysometers:
monitoring is performed in order to assess the efficiency of of the tailings
pond final cover; quantities of infiltrating
water are constantly registered, collection of information is performed 4 times
a year (once in a quarter).
8. Chemical composition monitoring of the seepage water: In 12 control
wells of the tailings pond 4 times a year (once in a quarter) in seepage water
are defined the values of pH, F, SO4, the dry matter, Ntot, Ptot, NH4,
NO2, NO3, Ba, Zn, Cu, Pb, Ni, Nb, U238, Ra226,
9. Service and maintenance of the tailings pond: grass mowing in
the tailings pond area and maintenace of drainage systems will be undertaken. In addition once a year equipment servicing - weather
station and lysometers – power supplies will be checked; at necessity,
replaced, and/or cleaning and calibration of the equipment undertaken.
Works are carried out and/or organised by Ökosil Ltd environmental laboratory according to the contract agreement
between the Estonian Environmental Investment Centre and Ökosil Ltd.
In 2014 began the so-called second
period of the post-remediation monitoring of the tailings pond with a reduced
frequency of monitoring in accordance to the program approved by the Ministry
of environment, which is based on sentences of the post-remediation programs
designer and supervisor Wismut GmbH.