Metropolitan Council

Metropolitan CouncilEnvironmental 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




MCES

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




MCES

3

Renewal Issues

Phosphorus:— Current limit – 1 mg/L

— Proposed interim limit – 0.6 mg/L(current flow)

PFOS — too soon to regulate




MCES

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




MCES

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)




MCES

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




MCES

7

PFOS in Wastewater

PFOS concentration appears to increase through wastewater treatment process (global)

Precursors/catalyst/mechanism of PFOS formation not reliably identified




MCES

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

MRP2 MPCA Fish Sampling Areas

9

Fish sample collection locations (yellow)




MCES

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




MCES

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

MRP2 MPCA Fish Sampling Areas

12

Fish sample collection locations (yellow)




MCES

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




MCES

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




MCES

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

Documents

Metropolitan Council