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

2. 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. 3 Renewal Issues Phosphorus: — Current limit – 1 mg/L — Proposed interim limit – 0.6 mg/L (current flow) PFOS — too soon to regulate

4. 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. 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. 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. 7 PFOS in Wastewater PFOS concentration appears to increase through wastewater treatment process (global) Precursors/catalyst/mechanism of PFOS formation not reliably identified

8. 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. MRP 2 MPCA Fish Sampling Areas 9 Fish sample collection locations (yellow)

10. 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. 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. MRP 2 MPCA Fish Sampling Areas 12 Fish sample collection locations (yellow)

13. 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. 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. 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