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Proposed Changes to Metro Permit: PFOS Limits and Phosphorus Regulation Impact

On August 24, 2010, the Metropolitan Council presented significant proposed changes to the Metro Permit reissuance, focusing on the introduction of limits on PFOS and stricter phosphorus regulations. The PCA aims to propose a phosphorus limit of 200 MT/year with an interim limit of 0.6 mg/L. Concerns arise regarding the PFOS limit's proposed values, considered too stringent given the current data. The MCES argues that Metro is not a contributing factor to PFOS impairment, calling for evaluation time post-remediation before implementing new limits.

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Proposed Changes to Metro Permit: PFOS Limits and Phosphorus Regulation Impact

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  1. Metropolitan Council Environmental Services Metro Permit Reissuance Proposed Changes and Potential Impacts Presented to the Environment Committee August 24, 2010 Keith Buttleman, Assistant General Manager EQA Department, MCES A Clean Water Agency

  2. Background Information • Metro Permit expired in April, 2010 – still in effect until new permit issued • PCA proposes to add new PFOS limit and tighten P limit in permit • No PFOS limit in existing permit (but monitoring at BL and Seneca

  3. Renewal Issues • Phosphorus: • Current limit – 1 mg/L • Proposed interim limit – 0.6 mg/L(current flow) • PFOS • too soon to regulate

  4. Proposed Phosphorus Limits • PCA proposing Metro interim limit of 200 MT/yr • Limit of ~0.6 mg/L at current flow rate; ~0.46 mg/L at permitted flow rate • Current discharge 0.3-0.4 mg/L • Current P discharged – under 100 MT/year • 2005 P discharged about 160 MT/yr

  5. Concern with Numeric P Limit • Once number in permit, virtually cannot be raised; federal antibacksliding rules • Lose opportunity for “bubble permit” through post-TMDL permitting • Possible federal action on P (and N)

  6. PCA Approach to PFOS Limits • PFOS limits: • 10 ng/L monthly average • 17 ng/L daily max • PCA asked MCES to propose final compliance date • Re: PCA • source control will meet PFOS limits • PFOS in fish tissue is 3M and Metro issue

  7. PFOS in Wastewater • PFOS concentration appears to increase through wastewater treatment process (global) • Precursors/catalyst/mechanism of PFOS formation not reliably identified

  8. Too Soon to Regulate PFOS • No Total Maximum Daily Load (TMDL) developed • Impairment is localized section of Mississippi River Pool 2, not entirety • Unknown precursors makes source control and timing estimate impossible

  9. MRP2 MPCA Fish Sampling Areas Fish sample collection locations (yellow) 9

  10. Too Soon to Regulate PFOS (cont’d) • Source for fish is sediment, not water • Contaminated sediment removal in 2011 • Question whether fish advisory continues post-remediation

  11. Concern with Numeric PFOS Limit • Once number included in permit, federal antibacksliding rules prohibit increasing • Impairment applied to entirety of Mississippi River Pool 2 – should be focused on downstream area • PCA controlling as water column issue; data show is localized sediment source issue

  12. MRP2 MPCA Fish Sampling Areas Fish sample collection locations (yellow) 12

  13. PFOS – MCES Proposal • Allow time to: • evaluate impairment post-remediation • understand PFOS behavior and control in wastewater • PCA develop TMDL for PFOS & precursors • If still impaired, allocate loadings through TMDL

  14. PFOS – Too Soon to Regulate • Limit (10 ng/L) way below drinking water standards (300 ng/L); may be unattainable • Unknown how plant effluent increase occurs • No consistent list of PFOS precursors • Impairment isolated to small area in Pool 2, not near Metro discharge point • Sediment, not water, is source of PFOS in fish • 3M cleaning up contaminated sediment in Pool 2, may remove impairment

  15. Next Steps • MCES continues to make the case to MPCA that Metro does not “cause or contribute” to PFOS Impairment, so should not be regulated through permit limits • PCA planning to send draft permit shortly • May be need to contest permit

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