In-situ soil remediation within one year

In-situ remediation can be done quickly – faster than many people think. Orvion designed an in-situ remediation for the Bilthoven site and provided environmental guidance. This remediation was completed within one year; the intervention value in soil and groundwater has been amply achieved.

There was a gas station at the location. Because the location was being developed for housing, the soil had to be remediated. The soil remediation was first excavated to a depth of approximately 3 meters. The deeper soil and the groundwater were then remediated by means of biosparging with a small addition of ozone to the injection air.

With fully biological treatment, the remediation period was estimated at 1.5 to 2 years. Because this would take too long for future residents of the new homes to be built, it was decided to add a small amount of ozone to the injection air. It was estimated that this would reduce the remediation time to nine months. The remediation was carried out by Bunnik Milieu, T&K service, Hoste Milieutechniek and Orvion.

The oxygen concentrations in the groundwater rose soon after the start of the remediation (see attached graph). Nutrients were also dosed so that the bacteria could grow quickly and effectively break down the oil/aromatic contamination. The kink in the graph (April 2019) was caused by a brief glitch in the system.

Before the start of the remediation, the concentration of mineral oil and aromatics in all 8 monitoring wells was above the intervention value (average 3,000 µg/l of mineral oil). On 21 June, so more than 6 months after the start of the remediation, the concentrations had already fallen below the Intervention Value in all monitoring wells. The mean concentration of mineral oil had decreased to 80 µg/l. A decrease of 97%. Subsequently, the concentration in soil was also determined on 20 soil samples. These all met the intervention value, with 16 samples even below the detection limit (< 20 mg/kg DM). These excellent results show that in-situ remediation can also quickly lead to results. Do you also want to remediate quickly and effectively in-situ? Contact Marc van Bemmel to discuss the possibilities!

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