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 The proposed rules will insert updated HRL values for groundwater contaminants in Part 4717.7860 and delete outdated HRL values from Part 4717.7500.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review of HRL values for 27 of the contaminants listed in Minnesota Rules, part 4717.7500, MDH intends to repeal the outdated guidance promulgated in 1993‐1994.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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New TSCA Lead Dust Health Risk Standards

EPA has been petitioned under the Administrative Procedures Act (APA) to lower the residential lead dust hazard standards. Pursuant to section 403 of the Toxic Substances Control Act (TSCA), EPA promulgated regulations on 2001 to establish standards for lead-based paint hazards in most pre-1978 housing and child-occupied facilities.

Under these standards, lead is considered a hazard when equal to or exceeding 40 ug/sf of lead in dust on floors, 250 ug/sf of lead in dust on interior window sills, and 400 ppm of lead in bare soil in children's play areas or 1200 ppm average for bare soil in the rest of the yard.

In addition to the petition, the Clean Air Science Advisory Committee (CASAC) has advised EPA that based on recent epidemiological studies the current hazard standards are insufficiently protective. Therefore, based on the APA petition and CASAC recommendation, EPA is currently analyzing current science to determine if new regulatory standards are required under TSCA section 403. EPA expects new standards would be published in 2012.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Environmental Review and Environmental Impact Assessment.

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