srgr UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION 10

1200 Sixth Avenue, Suite 900

° Ilt ,rc Seattle, WA 98101-3140

September 18, 2013

MEMORANDUM

SUBJECT: Alcoa Wenatchee Works Cost Analysis for Limestone Slurry Forced Oxidation

(LSFO) Scrubbing - Wenatchee, Washington

OFFICE OF

ENVIRONMENTAL ASSESSMENT

FROM:

TO: Steve Body, Environmental Scientist

Air Planning Unit, OAWT

As you requested, I've prepared a cost estimate for a limestone slurry forced oxidation

(LSFO) scrubber to control emissions of sulfur dioxide (SO2) from Potline #5 at Alcoa's

Wenatchee Works primary aluminum smelter. This memo provides a brief description of

the attached calculations.

1. The cost estimate is primarily based on the cost analysis I prepared in 2012 for a

similar scrubber at Alcoa's Intalco Works smelter in Ferndale, WA. The Intalco cost

analysis for LSFO is described in a technical memo dated November 16, 2012 which

was prepared as part of our evaluation of Best Available Retrofit Technology at that

facility.

2. Two primary changes to the Intalco analysis were necessary in order to produce a

cost analysis which reasonable reflects study level costs (± 30%) for a Potline #5

scrubber at the Wenatchee smelter:

a. Certain capital and operating costs were scaled proportionally based on key

size and/or operating parameters. The Potline #5 scrubber would be

approximately one third the size of the Intalco scrubber evaluated in 2012

based on the volumetric flow rate of the exhaust gas requiring treatment. I

believe proportional scaling of costs results in a general underestimate of

costs for the Wenatchee smelter due to economies of scale. Specifically, a

larger scrubber would be expected to cost marginally less per unit of exhaust

gas than a smaller scrubber. Assuming these costs are equal per unit of

exhaust gas likely underestimates the costs associated with the Wenatchee

Potline #5 scrubber.

*

Pflnfed on Aetycfed Paper
b. The capital equipment cost provided by the scrubber manufacturer has been

adjusted to account for inflation over the 7 years that have passed since the

original equipment cost estimates were prepared in 2006. Alcoa provided

information from one equipment vendor that provided a cost estimate in

2006 stating that expected 2013 costs would be 20-25% higher.

Examination of the Chemical Engineering Plant Cost Index (CEPCI) over the

period 2006-2012 suggests an increase of 17% 1 in terms of general chemical

process industry plant costs. Based on this information, my cost analysis

assumes an increase of 20% for the capital equipment cost.

3. Incorporating these adjustments, I estimate the cost effectiveness of LSFO for

Potline #5 at the Wenatchee Works smelter at approximately $7,500 - $8,500 per

ton of S02 removed. Please see the attached spreadsheet for the detailed

calculations.

If you have any questions about these comments, please call me at 3-1217.

C: Mark Filippini, Unit Manager, ESU, OEA

Debra Suzuki, Unit Manager, APU, OAWT

Juliane Matthews, ORC

1 2006 Annual Index = 499.6. 2012 Annual Index = 584.6. 084.6-499.611499.6 = 0.17. The CEPCI is published by

Chemical Engineering Magazine.

2