The recently adopted Stage 11 Amendments to the Contaminated Sites Regulations (CSR) included new groundwater standards for metals such as cobalt, lithium and thallium that are less than the commonly observed background concentrations for these metals in groundwater in BC.  In response, the ministry has recently extending the cobalt interim background groundwater concentration estimate of 20 µg/L (vs. a drinking water standard of 1 µg/L).   The value of 20 µg/L was originally established on October 4, 2002.  The interim background groundwater concentration estimate for cobalt is expected to remain in effect while the ministry concludes the development of background groundwater estimates for selected metals (expected to include cobalt, lithium and thallium) on a region by region basis for the Province.  If this work is successful, regional Background Groundwater Estimates will subsequently be incorporated into a revised Protocol 9 “Determining Groundwater Background Quality”.  In the interim, the background groundwater concentration estimate for cobalt of 20 µg/L can be used when assessing the presence of contamination at sites and cobalt concentrations in groundwater that exceed the drinking water standard but are less than the background estimate will not be considered contaminated.

For more information on how Keystone Environmental can assist you with this and other Environmental issues, please call Raminder Grewal at 604-430-0671 or email