Groundwater monitoring results

06 June 2015

The declining COD-values show that the overall contaminant mass in the groundwater is clearly decreasing. The results show the volatile petroleum hydrocarbons (C6-C10) are broken down first and that the chloroethanes are the most difficult constituents to oxidize chemically.  The results are evaluated in more detail and per zone in the sections below.

Excavation zone:

Since the start of the remediation beginning 2013, the results can be considered spectacular. 
After a more or less stable period between end 2013 and end 2014 a further decline is obtained for most of the parameters.  Only the chloroethanes still stay more or less stable.  In P482 the remediation targets for all contaminants, except 1,1-DCA, are reached.  The contaminant concentrations in the groundwater around P481 is still high (especially for 1,1-DCA), but has over-all already decreased with about 90% compared to the initial concentrations of beginning 2013.



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 low groundwater concentrations measured in the monitoring well P463 confirm that the remediation target is reached in the area around this well.  

In the monitoring wells along the tank farm (P465 and P448), high concentrations of 1,1-dichloroethane (around 60mg/l) are still present. The other parameters are low (below the remediation target values) or have decreased significantly. In P448 1,1,1-trichloroethane has increased (unexpectedly). This needs to be checked in the next monitoring event..  

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 has decreased remarkably.  The chloroethanes and chloroethenes remain more or less stable. 


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