How to remediate contaminated soil beneath buildings and structures at an active fueling station without the need for expensive demolition and excavation, and without loss of revenue? This was the challenge Uno-X Automat presented to Ejlskov.

The solution

Ejlskov provided a tailor-made plan using our unique Trap & Treat® BOS 200® in-situ technology. The result was immediate risk removal and achievement of remedial targets set by the authorities within targeted project period. The solution caused no or very little loss of revenue to Uno-X and was completed at a price close to 50 % of the cost of traditional solutions, e.g. excavation.

Services provided by Ejlskov

Full-scale application of Trap & Treat® BOS 200® in-situ remediation, including:

• Installation in sections to maintain fuel tank area accessible to customers during entire remediation work
• Specialized drilling and injection technology to treat areas under buildings and in between subsurface installations
• High resolution site investigation and calculation of contaminant mass distribution in soil
• Unique 3D-mapping software for precise and efficient remediation

Remediation process and results

The biggest challenge at the Præstø Uno-X Automat fueling station was the large oil contamination plume that lay beneath buildings up to 5.5 m depth. An added difficulty was the shallow groundwater table. Ejlskov’s site surveys showed that there was approximately 5000 kg of oil contamination in the soil.

As a leading European expert in the revolutionary Membrane Interface Probe (MIP) technology, Ejlskov completed a high-resolution site characterization that modelled the geology and the contaminant plume, and enabled efficient planning of the injection of Trap & Treat® BOS 200®. A total of 505 injections to a depth of 5.5 m were made in just over 3 months at the 1400 m2 site. Ejlskov’s flexible drilling equipment and technical expertise enabled a unique approach to remediating soil beneath buildings, drilling from within the building. Ejlskov also used a triangular injection grid pattern with vertical offset injection levels, high pressure top-down injection techniques, and adjustment of the lateral and vertical injection spacing in relation to the buildings and subterranean utilities.

All remedial installations were executed without any demolition or excavation, and with minimal disturbance for Uno-X Automat. The station was kept operational during the entire remediation work. The mechanisms of Trap & Treat® BOS 200® provided immediate contaminant mass-reduction and plum control, and over a period of 3-5 years the biological degradation of BTEX and MTBE brought the underground contamination on the site to safe levels below the standards set by the Danish Environment Authority.