Environmental Case Studies

Case Study 1

The site was situated at a residential property in Belfast. The occupant first discovered a strong hydrocarbon smell in the kitchen. Upon investigation oil was found to have been leaking from the fittings of the oil tank and boiler situated in the courtyard between the kitchen and the boiler house. The amount of oil lost was estimated at approximately 200 litres.

AES-Marconi was requested to perform a contamination survey at the above-mentioned property in order to ascertain the extent of contamination present and submit a proposal and costs to remediate the site.

On arrival at the site there were obvious signs that a pollution incident had occurred. There was an amount of oil present on the surface of the cobbles in the rear section of the courtyard. A small excavation had been cut as part of the on-going boiler maintenance programme, which contained an amount of oil at the time of the survey. Several bags of oil absorbent granules were distributed around the site to halt any further migration of contaminants. An AES-Marconi plumber was called to the scene to replace the damaged and still leaking fittings.

The contamination had migrated outwards from the tank into the main courtyard, extending around the corner of the kitchen for a few meters. The contamination had also found its way through the foundations of the kitchen and toilet. The bulk of the lost kerosene had travelled by way of the existing gradient into the main boiler room covering a large section of the sub-soils there in.

AES-Marconi were authorised to proceed with the recommended remedial strategy which consisted of combination of excavation and in-situ treatment. The combination was recommended due the access constraints and also to reduce the disruption to the occupants of the property.

Contaminated soil and fill was removed to a depth of 1 metre whereupon a cut off system comprising a collection trench and automated pumping system was installed along the foundations of the kitchen in order to capture any mobile hydrocarbons for subsequent safe disposal.

When all of the contaminated ground had been identified an intensive treatment programme was employed using propriety bacterial cultures and saponics.

When all of the affected areas had been successfully treated, and any temporary modifications had been performed, the site was independently verified and the structural components of the site were reinstated the customers satisfaction.

Project Cost - £8,000

Timescale – 7 weeks

Case Study 2

These 2 neighbouring sites were situated in Armagh. The occupants of the two properties at No 26 and 28 became aware that a spillage of oil had occurred from their neighbours’ oil tank when it was vandalised. The fire brigade were called who installed absorbents to try and prevent further migration towards the dwelling. It was estimated that the amount of Kerosene lost was in excess of 1000 litres.

AES-Marconi was requested to perform a non-instrusive site survey to ascertain the extent of contamination present and submit a proposal and costing to remediate the site. The occupant was duly contacted to arrange a convenient time for the survey. The survey was carried out by AES-Marconi in the presence of the occupant. Upon completion of the site survey it was apparent that contamination had spread from the spill source throughout the rear patio and lawn of No 28 and proceeded to migrate into the rear patio and the raised earthen slope of No 26.

Unfortunately we were not permitted to survey the spill source but it was recommended that this site was remediated in conjunction with the other two properties.

AES-Marconi were subsequently authorised to perform the remedial works on both No. 26 & 28 but not the spill source.

Remedial works commenced the next day upon receipt of instructions to proceed whereupon the garden shed and boundary fence was dismantled and put in storage in our depot. Protective measures were placed throughout both sites prior to any excavation works. Once the site was fully secure the patios and lawns from both houses were excavated to a depth of 1 metre. Residual contamination at depths greater that one metre were treated utilising site-specific bioremedtaionsaponics and cultures.

Soil and gas samples were retrieved throughout the remedial process. Once levels had been reduced to below guidelines an Environmental consultant verified the remedial works, whereupon reinstatement commenced.

Unfortunately due to the fact that the spill source had still not been remediatied it was highlighted by AES-Marconi that a high environmental liability still existed to the sites at No 26 and 28 from recontamination. In order to complete the works on No. 26 & 28 it was necessary to design a recovery system along the borders of both properties in order to capture and control any future migrating contamination. Once the recovery system was fully operational all areas affected by the remedial works were reinstated to the occupants satisfaction.

Project Cost - £12,000

Project Timescale – 10 weeks