9th groundwater monitoring event monitoring results

28 October 2016

Excavation zone:

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

The contaminant concentrations in the groundwater around P481 stay high (especially for 1,1-DCA) and more or less stable.   In P482 1,1-DCA is slowly decreasing in. 


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 are again 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 stays above remediation target value 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 9 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.