The issues of soil contamination will need to be addressed and the abandoned tank removed for reasons of safety and structural stability.
The local agency responsible for the environment may have to be consulted to determine the magnitude and extent of risk of environmental contamination the leakage poses. That agency may also require to be consulted before an appropriate remediation programme is adopted and the soil contamination cleaned up. Following are a few remediation techniques published in the Oil Remediation Index that we could choose from:
1. Dig and dump - As the name suggests this method involves removing all the contaminated soil and disposing it off to the nearest landfill site. While excavation and dumping is becoming increasingly expensive, this is the most effective of the methods for removal of contamination and possibly most appropriate for your site as we are already in the process of excavation.
2. Soil Vapour Extraction - This is an in-situ process that involves inducing an air flow through the soil to remove the volatile components of the contaminant. Since oil is not as volatile as say petrol, this technique might not be very appropriate here.
4. Bio-remediation - This method involves using micro-organisms such as fungi, bacteria etc to degrade organic contaminants.