Post-remediation monitoring

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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.

Monitoring subspecies


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 created.

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, Th232, Sr.

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.


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