At many refining and distributing sites soil and groundwater pollution occurs, often resulting in free floating product or LNAPL (Light Non-Aqueous Phase Liquids). Often costly remediation measures have to be undertaken. A practical, robust and (cost) effective remediation program is therefore key important. For a major oil spill in Antwerp Harbor HMVT has successfully designed and implemented the remedial works for a major NAPL of 1.500m3 (!) free floating product of volatile hydrocarbons, diesel and naphtha. The case, design, results and cost of the project will be presented.

The site is located in the Antwerp Harbor. On the site a pumping station of a petrochemical pipeline is present, pumping Naphtha from Antwerp, Belgium to the south of The Netherlands. The Naphtha pollution was caused by a leakage at the pumping station. On the site also petrochemical products are stored. The diesel pollution was caused by a leaking above ground storage tank.

On the site ca. 23.000m2 of soil was polluted with LNAPL with a maximum thickness of 1–1,5m. In total 1.000m3 of product was expected, but during the project ca. 1.500m3 of LNAPL is been removed. On the picture on the right it can be seen that most of the product was present underneath the pumping station and the ‵contractor's village2.

For port construction reasons the ground level has been raised with sandy material up to 4-5 meters in the past. Underneath this fine sandy upper layer the original, clayey soil is present. The water table is found at ca. 2 m-bgl, but this water table fluctuates ca. 1m between summer and winter.

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