Geotechnique can provide consultancy services in relation to the assessment and/or remediation of underground storage tanks and waste oil tanks. These services include investigations, preparation of remedial action plans, and project management during tank removal.
Underground fuel storage tanks (UST) and waste oil tanks, particularly if left in the ground for a long period of time, can often lead to contamination of soils and groundwater in the vicinity of the tank. The potential contaminants associated with the UST and waste oil tank are lead, petroleum hydrocarbons, BTEX, and Polynuclear Aromatic Hydrocarbons (PAH), many of which are volatile or semi-volatile. Soil and/or groundwater contamination can be a major concern, particularly if the tanks are buried in permeable soils that permit migration of stored products from the tank excavation (if leaks occur).
The investigation of potential tank leakage and subsequent soil and/or groundwater contamination, typically comprises an assessment of the tank condition (if possible), as well as soil and groundwater sampling in the vicinity of the UST. Groundwater monitoring wells provide useful information on groundwater flow directions as well as access for water sampling. Hand held photo-ionisation detectors are available to detect volatile compounds in the ambient conditions and in recovered samples.
Removal of a UST in NSW must be carried out by appropriately licensed contractors. The removal process must be carried out in a manner that does not inadvertently cause additional contamination to surrounding soils through spills or leaks.
Remediation of contaminated soils and/or groundwater associated with USTs can include, amongst others, landfill disposal, land farming, bio-remediation, vapour extraction, sparging, or air stripping. Remediation costs vary depending upon the extent of contamination and the contaminant present.