The ministry is hereby extending the cobalt interim background groundwater concentration estimate of 20 µg/L.  The value of 20 µg/L was originally established on October 4, 2002.  This measure is in response to a change in the drinking water standard for cobalt, approved under the Stage 11 amendment to the Contaminated Sites Regulation.  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 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”.

Responsible persons may use the interim background groundwater concentration estimate for cobalt of 20 µg/L when assessing the presence of contamination at sites in the Province.  Applications for a Director’s decision under Protocol 9 are not required for use of this background estimate.   Rather, a statement in the site investigation report that cobalt concentrations in groundwater do not exceed the referenced cobalt interim background groundwater concentration estimate will suffice for satisfying CSR 11 (3) that the site is not a contaminated site for cobalt in groundwater.

The 2002 CS e-link relating to this background concentration can be found at:https://www2.gov.bc.ca/assets/gov/environment/air-land-water/site-remediation/docs/archived-e-link-messages/cs-archive-2000-2005.pdf

Any questions about the cobalt interim background groundwater estimate should be directed to site@gov.bc.ca.