Garage Tank Removal

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MDW Environmental Services was engaged to supervise and record the removal of three underground storage tanks and validate the excavations, post removal, in order to prepare a previously operating fuel station and auto workshop site for sale.

The three tanks were located in two excavations; each tank was removed and inspected for corrosion and damage. Soil from around the tanks was excavated and the overburden was removed, inspected for signs of contamination, and stockpiled onsite. Samples were collected from the stockpile and sent to a NATA accredited laboratory for analysis.

Samples were also collected from the walls and base of the excavation for field screening using an Ion Science Firstchek 5000 Photo Ionisation Device (PID). Headspace screening was completed after 20 minutes of volatilisation. All readings above 20ppm were registered as ‘fail’ and additional excavation was completed to remove material from the ‘fail’ zones. The field screening process was repeated until all results were below 20ppm.

On completion, the excavation was deemed suitable for validation. Samples were collected from each excavation as per the Department of Environment and Conservation (DEC) guidelines.

Soil samples were also taken from the stockpile for waste classification, as per guidelines established by the DEC, to ensure the soil materials could be disposed of appropriately and would be received at a landfill facility.

A Quality Assurance/Quality Control program was implemented throughout the investigation to ensure the accuracy and precision of the data obtained.

Soil results from the excavation and tank removal all came back below the relevant guidelines, with the exception of BTEX being detected in one location. Further investigation of the result could not be completed due to the proximity of the pit to the building. If the excavation had continued the structural integrity of the building could have been compromised. As a result, works were ceased due to safety concerns.

If the buildings were to be demolished MDW Environmental Services would strongly recommend further investigation of this location.