What Happened
Following a stormy night a homeowner in Co Meath discovered that the tank gauge was lying on the ground and oil had escaped into the soils in the area.
Further inspection revealed that the fitting near the top of the tank which holds the gauge pipe in place had completely broken off. We suspect that some debris has struck the tank during the storm, breaking the gauge pipe off the tank.
Unfortunately, like most people the customer was not in the habit of turning off the gauge at the tank fittings, so home heating oil was free to flow out of the top of the gauge, emptying the remaining contents of the tank.
Investigation
- Gaea arranged with the customer to attend at their earliest conveinience, which was the following day. The gauge was temporarily repaired so that a delivery of oil could be made.
- The property was surveyed in a 1m gris by drilling boreholes to 1 metre below ground level and then examining the borehole for soil volatile organic compounds (VOC’s). This allowed us to build up a picture of where the oil may be residing, based on the relative concentrations of soil vapours. A motorised auger was then used to retrieve soil samples from different depths across the site. The soisl were examined for soil vapours and this more targeted examination allowed us to them appraise the spill on a three dimensional basis. Examination of the soils also allowed us to rule out areas that just contained vapours and not actual spilled oil.
what we found
- Our scientific team were able to establish where exactly the oil spill was below ground and where it was heading. It was possible to identify that the oil spill had found a field drain and was migrating along that potentially to a fresh water receptor.
- Recommendations were made to intercept this immediately and prevent any impact to sensitive ecological receptors. Authority was granted by the customer insurers straight away and this was dealt with the same day.
Once the off site risk had been mitigated things were a lot more straight forward. The oil spill had impacted just over 20M2 of the rear gardens to a depth of 0.75m.
Remedial works
The oil spill clean up program commenced seven days later once full approval had been received from the customers insurance company.
A detailed options appraisal had been conducted at the reporting stage and due to the high clay content of the soils it was determined that the most cost effective methodology for cleaning up this oil spill was to dig it out and replace the spoils with imported material.
Firstly,
- The tank was relocated outside the work area temporarily where it was reconnected. The base was then demolished and disposed of.
- The oil plume as delineated during the investigation was then excavated by Gaea’s Oil Spill Clean Up teams. This required the removal of 22T of soil in four skips.
Validation
- Seven soil samples were taken from the bottom and sides of the excavation and sent for analysis at an independent accredited laboratory.
- The results clearly demonstrated that the sufficient material had been removed and that any remaining soils were well below accepted Environmental and human health thresholds.
- A validation report was compiled detailing the remedial process and how we scientifically validated the property.
Reinstatement
- Following successful validation the excavations were backfilled with clean stone which was compacted.
- A new tank base was constructed and allowed to set. A new tank was then placed on the base and the contents of the old tank transferred t the new tank.
- The stone was then capped with thirty cm of fresh topsoil which was raked out, compacted and then covered with roll out turf.
Turn around - savings
- Once notified, Gaea attended site the following day.
- Our report was available to insurers within 36 hours.
- Once authority was received to proceed with the works Gaea were on site within four days.
- The work took a total of six days to complete.
- Only four skips were required and the material was recycled rather than disposed of.
- Both home owner & Insurer were delighted.
