Groundwater monitoring results

31 October 2015

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), but are slowly further decreasing.   In P482 1,1,1-TCA and volatile petroleum hydrocarbons (C5-C8 and C6-C10) have slightly rebounded.  However, concentrations of  all contaminants, except 1,1-DCA, 1,1,1-TCA and volatile petroleum hydrocarbons (C5-C8) remain below the remediation targets.


This groundwater monitoring event confirmed again that all remediation target values have been met in monitoring well P483, even after Perozone injections were stopped in the area around P483.




The groundwater concentrations of all chlorinated solvents measured in the monitoring well P463 are again below the  remediation target.  Although since September 2014 1,1-DCA shows an increasing trend which needs further monitoring. 

In the monitoring wells along the tank farm (P465 and P448), high concentrations of 1,1-dichloroethane significantly decreased from circa 60 mg/l to 40 mg/l.. However, concentrations of  1,1,1-trichloroethane in well P465 increased again above remediation target value.  After in P448,. on the contrary, the concentration of  1,1,1-trichloroethane in well P448 decreased again after an unexpectedly increase in  May 2015. This increasing trend was not confirmed.  Further monitoring is needed.  The other volatile organic compounds  concentrations remain stable and/or below the remediation target values

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) is confirmed.  The concentration of volatile total petroleum hydrocarbons is decreased below the remediation target values.  The TCE-concentration also shows a remarkable decrease.  The concentrations of chloroethanes and other chloroethenes remain more or less stable but relatively low. 


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