11th groundwater monitoring event groundwater monitoring results

08 May 2017

Excavation zone:

Over-all more than 90% compared to the initial concentrations of beginning 2013 already decreased.

Results of the last campaigns show an increase of the contamination concentration  in the groundwater of well P481 and P482 mainly of chloro-ethanes.  This indicates that there are still source areas with high concentrations in the soil or even pure product.  The reason why this product is released since February 2017 needs to be further investigated.  On going civil works in the surroundings could have influenced the remediation area with these results. 



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



Since February 2016 1,1-DCA showed a slow decreasing trend, this trend continues. Since Juin 2016 all concentrations, except vinylchloride in April 2017, stay below the remediation targets. 


In the monitoring wells along the tank farm (P465 and P448), high concentrations of 1,1-dichloroethane and 1,1,1-trichloroethane-concentrations continue decreasing and this most explicitly in P448.  Only 1,1-dichloroethane, cis-dichloroethene and vinylchloride stay above the remediation target values in P465A.  The other volatile organic compounds concentrations remain stable and/or below the remediation target values.  Further monitoring is needed. 



 Tank farm:

The remarkable decrease of the concentration of volatile total petroleum hydrocarbons after only 2 months of injections in the small source area of the tank farm (P451) stays confirmed.  The concentrations of chloroethanes and other chloroethenes remain more or less stable but relatively low.  The concentration of volatile total petroleum hydrocarbons mainly the chloroethenes are slowly increasing again since Juin 2016 above the remediation target values.  Since the start of the second area in the tankfarm (big source area), the injection in small source area has stopped due to limited capacity. 


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 more then a year 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.