Groundwater monitoring results 8th monitoring

01 July 2016

A groundwater monitoring was performed about half a year after the start-up of the remediation of the big source area in the tankfarm. 

Excavation zone:

The evolution since 2013 of groundwater concentrations of the most important contaminants is illustrated in the charts below. The red lines indicate the remediation goals as defined in the remedial action plan. Each graph shows the evolution of one contaminant for the three monitoring wells in and around the excavation zone.

After a more or less stable period between end 2013 and end 2014 a further decline is obtained for most of the parameters in wells 481 and 482.  Only the chloro-ethanes still stay more or less stable.  In P482 the remediation targets for all contaminants, except 1,1-DCA and 1,1,1-TCA, are reached.  The contaminant concentrations in the groundwater around P481 are still high for 1,1-DCA and VC.  The remediation goals for 1,2-DCE and 1,1,1-TCA are nearly reached. 


This groundwater monitoring event confirmed again that all remediation target values have been met in monitoring well P483.



Since September 2014 1,1-DCA showed a slow increasing trend, this trend continues. Except for 1,1-DCA the groundwater concentrations of all chlorinated solvents measured in the monitoring well P463 are again below the  remediation target.  Further monitoring is needed. 

In the monitoring wells in the midway along the tank farm (P447, P448, P450 and P465) the remediation target values were reached for almost all contaminants except for volatile TPH in most wells and chloro-ethanes in P448 and P465. 


After fluctuating concentrations, 1,1 dichloro-ethane in P448, met in June 2016 the remediation goal for the first time.  In P465A 1,1-dichloroethane continues showing fluctuations.  Further evolution needs to be checked in the next monitoring events but the results for P448 are very encouraging for P465A.  Further monitoring is needed. 


Tank farm:

After only 2 months of injections in the small source area of the tank farm (P451) the concentration of volatile total petroleum hydrocarbons had decreased already remarkably. 
Except for 1,2-DCE all the remediation goals were reached in December 2015.  The last phase of the remediation (big source area in the tankfarm) has started in January 2016.  Because of capacity reasons the injections in the small source were stopped in January. Since then 1,2-DCE remains more or less stable. 
Both PCE and TCE decreased within the start of the injection. However these concentrations demonstrate a rebound since February 2016.  Further remediation is necessary and evolution of the concentrations needs to be checked in the next monitoring events. 


Since January 2016 the big source area in the tankfarm was started up.  Exceedance of remediation goals are only observed in wells P473 and P475.  After one month of injections in the big source area of the tank farm the concentration of volatile total petroleum hydrocarbons and also the chloro-ethanes has decreased remarkably in these wells.  After six months these concentrations  remained more or less stable above the remediation goals. 





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First phase of in-situ remediation completed. Second phase of in-situ remediation on-going, ISCO and SVE operational.