Monday, October 18, 2010

Updated Groundwater Contaminant Standards in Minnesota

The Minnesota Department of Health (MDH) has proposed some amendments to its Health Risk Limits, or HRLs. The proposed amendments to the Health Risk Limits rules for Groundwater (Minnesota Rules, Chapter 4717) are about health-based guidance called “health risk limits” (or HRLs) for contaminants found in groundwater that may be used for drinking purposes. The proposed rules will insert updated HRL values for groundwater contaminants in Part 4717.7860 and delete outdated HRL values from Part 4717.7500.

The proposed updated HRLs are for the following chemcials:

  • Acetochlor ESA
  • Acetochlor OXA
  • Acetone
  • Dichlorodifluoromethane
  • 1,1‐Dichloroethene
  • Ethylbenzene
  • Ethylene glycol
  • Metolachlor and s‐ metolachlor
  • Metolachlor ESA
  • Metolachlor OXA
  • Perfluorobutane sulfonate (PFBS)
  • Perfluorobutyrate (PFBA)
  • Toluene
  • Xylenes


Based on MDH recent review of HRL values for 27 of the contaminants listed in Minnesota Rules, part 4717.7500, MDH intends to repeal the outdated guidance promulgated in 1993‐1994. Of the 27 contaminants reviewed, updated guidance was promulgated for 15 contaminants in MDH’s 2009 rule revision and the current 2010 proposed rules include updated HRL values for 8 contaminants. MDH has issued alternate public heath‐protective guidance for the remaining 4 contaminants.

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