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Project Details - Remediation of heating oil spill under a retail-clothing outlet with no loss of retail capacity

A major real estate company in St. John’s, NL retained fga to investigate if a property that they had acquired in the past contained an abandoned under fuel oil tank. The investigation revealed that the property did contain an underground tank and subsequent investigation via test pits and bore holes showed that the tank had leaked heating fuel oil. Free product was present in the surrounding soil and ground water. Due to the location of the tank a significant quantity of free product was located under the floor slab of the large slab on grade commercial building on the site.

Site remediation options were reviewed with the building owners. The selected option was to comply with provincial regulatory numerical criteria values for Total Petroleum Hydrocarbons and related components in soil and ground water. This would be achieved through physical removal of the contaminated soil and ground water.

fga designed and managed the site remediation. A caveat that the building owners insisted on was that there was to be no interruption of the building occupancy. The building occupancy comprised rental office space and a large retail clothing operation.

The remediation design included soil excavation, water management and reinstatement of the grades and infrastructure outside the building. Additionally a large segment of the floor inside the building together with an employee service area and storage area was removed and reinstated to remove the free product, contaminated soil and ground water under the floor slab.

The work, both interior and exterior was completed without interruption to building occupancy by segregating the work area from the functional retail area with a gas tight barrier system. Air moving equipment was used to maintain a negative air pressure in the workspace with respect to the rest of the building. Access to the segregated work area for heavy equipment was achieved by removing and reinstating a large segment of the building exterior wall.

There was no impact on the air quality in the retail or office space. The quality of the retail clothing was not compromised with fuel oil odors or construction related odors such as diesel engine fumes. Most of the retail customers were not even aware that the work was in progress. This remediation was successfully completed to the owner’s satisfaction without disruption to the office or retail operations in the building.

East view concrete backfilling under footings.