Readers may be interested to know that although MTBE (a prominent GEO compound) was thought to have been banned in Australia for many decades, it was recently found in impacted groundwater underlying an operational petrol filling station in Western Australia, at concentrations exceeding 2mg/l.
Although it was accepted that small quantities of MTBE would inevitably enter the country from Asia as residue in bulk-tankers, this occurrence at this level came as something of a shock to both Government and the petroleum industry! The Department of Environment immediately issued guidance to all practitioners and Auditors to be on the look-out for MTBE, (particularly where light fraction TPH concentrations were inconsistent with corresponding BTEX levels) and other occurrences were soon identified.
DEC published a screening risk assessment level for MTBE (set at 0.012mg/l) in WA CSMS guideline “Assessment Levels for Soils, Sediments and Groundwater” (DEC, 2010) and this is to be adopted as a national standard in the NEPM review. This was based on existing US EPA Regional Screening Levels (RSLs) and reflects the compounds relatively low toxicity (and eco-toxicity?) but significant potential for low concentrations to “taint" potable valuable and scarce groundwater supplies, rendering them unusable.
Furthermore, as MTBE is highly mobile and fairly persistent (particularly in anaerobic groundwater conditions), its potential to exacerbate the transport of existing hydrocarbon contamination in groundwater cannot be overstated.
David E Jackson
David E Jackson: Peer Review Services
(Former WA DEC Regulator)
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