From: "Long,	Michael	E"	< Michael.Long@CliffsNR.com >
To: Steven	Rosenthal/R5/USEPA/US@EPA,

Cc: "McWilliams,	Douglas	A."	< DMcWilliams@ssd.com >
Date: 01/07/2013	10:24	AM Subject: Cliffs	Natural	Resources	‐	Regional	Haze	BART	language

Steve,

Below is additional information you requested regard ing managing sulfur inputs to the UTAC indurating

furnaces.

In addition, we are seeking clarification about the app licability of the natural ga s/SO2 limits during natural gas curtailment episodes.

Fuel Sulfur Operating Limit Per our discussion the other day, Cliffs is opposed to setting a redundant operati ng limit to restrict SO2 emissions. Establishing a “secondary operating limit” to restrict sulfur from UTACs solid fuel input is unnecessary because compliance with the UTAC BART SO2 emission limit will be determined through use of SO2 continuous emission monitors (CEMs). Furthe rmore, UTAC is balancing multiple permit and rule obligations that complicate our complia nce strategy. A fuel restriction interf eres with optimal fuel balancing without providing any environmental benefit. Finall y, the BART SO2 determination and emission limits for

UTAC should be consistent with the FIP BART compliance demonstration requirements for the other solid

fuel consumers such as Keetac and Mi nntac. If EPA is not imposing a sec ondary operating limit to restrict

fuel sulfur content at the other i ndurating furnaces, then UTAC should re ceive equal treatment. If EPA is moving forward with a secondary fu el sulfur limit for all, then UTAC is proposing the following:

Proposal for Fuel Sulfur Input Values Should EPA decide a secondary opera ting limit is necessary at UTAC to limit the sulfur content of

the fuel s , Cliffs is proposing to set the total (cumulative) fuel sulfur limit at UTAC considering all fuel inputs (currently coal a nd natural gas) as follows:

a) When Line 1 and Line 2 are operating: Annual average of 0.9 lb S / mmbtu as fuel sulfur input

.

This limit is based on: [529 lb SO2/hr] * [32 lb S / 64 lb SO2] / [410 mmBtu/hr] / [100%- 25% control efficiency] = 0.9 lb S/mmbtu (before existing scrubber controls)

b) During single line operation: 30-day average of 1.5 lb S / mmb tu as fuel sulfur input.

This limit is based on: [529 lb SO2/hr] * [32 lb S / 64 lb SO2] / [230 mmBtu/hr] / [100%- 25% control efficiency] = 1.5 lb S/mmbtu (before existing scrubber controls)

Note: These values are direct conversions of th e 529 lb/hr SO2 emissions rate to fuel sulfur input considering a conservative estimate of 25% SO2 control efficiency in the wet scrubber.

Fuel Sampling Method Fuel sulfur determination to demonstrate comp liance will be performed pursuant to GPP permit condition on page A-51 (line 1) and the same la nguage on A-58 (line 2) for coal (see attached excerpt from GPP Permit #13700113-005) and use of pipeline sulfur data for natural gas.Tilden Natural Gas Curtailment In an effort to clarify the applicability of the T ilden Line 1 natural gas/SO2 limits during natural gas curtailment periods, we are requesting EPA to insert language into the preambl e/promulgated rule to provide a means to temporarily use back-up fuel (cu rrently coal) during natura l gas curtailment periods. Tilden Line 1 has dual fuel capability (natural gas and coal), which mitigates operational downtime risk during supplier induced fuel curtailment periods. If the FIP BART SO2 limit will be set based on 100% natural gas, Cliffs is requesting language in the FIP which will allow temporary use of “back-up” fuel (currently coal) during natural gas supply interruptions due to force ma jeure events. This request is consistent with other back-up fuel provisions in the FIP for furnaces which use natural gas as the “primary fuel” (e.g., The FIP states “These lim its do not apply when the subject emi ssions unit is burning fuel oil”).

Proposed Clarification to the preamble and promulgated FIP: Wherever the Tilden Line 1 natural gas/SO2 limits appears in the FIP, Cliffs requests the following language to be inserted: “This limit does not apply when the s ubject unit is burning its back up

fuel source.”

We appreciate your consideration of this informati on and do not hesitate to call me at 216-694-7359 should you have any questions regarding this information.

Respectfully,

MICHAEL E. LONG Director – Corporate Environmental Strategy and Programs P 216.694.7359 (O) 216-262-8797 (M) Michael.Long@cliffsnr.com

CLIFFS NATURAL RESOURCES 200 Public Square, Suite 3300, Cleveland, OH 44114-2544

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(See attached file: United Tacon ite GPP Permit Term_Coal.Sampling.docx)