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### Chang, Andy

From: Clark, Adam

Sent: Tuesday, February 09, 2016 7:10 PM

To: Chang, Andy Subject: FW: Wind Data for Drake by Sierra Club

To try and push your awaiting inbox above 1,000 – I uploaded the original attachments from this email to the R8 outgoing solicitation box on OneDrive.

Hope you had a nice trip, and one free from sulfur dioxide.

Adam Clark Air Quality Planning Unit US EPA Region 8 Denver, CO (303)312-7104

From: leslie@weise.us [mailto:leslie@weise.us]

Sent: Monday, February 08, 2016 10:54 AM

To: Clark, Adam <Clark.Adam@epa.gov>

Cc: Jim Riggins <rigginsj@att.net>; Travis Ritchie <tr avis.ritchie@sierraclub.org>; Jane Ard-Smith <janeardsmith@comcast.net>; Sandy Vanderstoep <svan derstoep@sustainablecolorado.org>; Nicole Rosa <nicki@totalmath.net>; Jacquie Ostrom <jostrom@lind seyfam.net>; Laura Van Der Pol <laura.vanderpol@gma il.com>; Sam Masias <sam.masias@gmail.com> Subject: Fw: Wind Data for Drake by Sierra Club

Hi Adam, I am forwarding to you some data that the Sierra Cl ub has compiled concerning the wind patterns near t he Drake Power Plant as compared with the COS Airport. Unlike Jim Riggins' compiled data from weather stations even closer to the plant, this data pulls from the weather monitor at the sole SO2 monitor in Colorado Springs. It has been concluded by the pro fessionals working for the Sierra Club that the dif ferences in wind patterns they compiled and attached to this email are not sufficiently meaningful to warrant dismissing the use of the airport NWS as representa tive weather data for Drake.

And as an update, although Colorado Springs Utiliti es has been collecting weather data from the new to wer they installed at Drake last fall, they have not be en willing to share any of that with the public yet (despite over 3 months of data having already been collected ).

Please let me know if you have any questions or wou ld like more information. Any word on when a draft decision by EPA for Drake's non-attainment designat ion will be released?

Thank you. Leslie Weise cell: 303.523.0016

----- Forwarded Message ----- From: Travis Ritchie < travis.ritchie@sierraclub.org > To: Leslie Weise < leslie@weise.us >; Jim Riggins < rigginsj@att.net > Cc: Jane Ard-Smith < janeardsmith@comcast.net >2 Sent: Friday, February 5, 2016 10:20 AM Subject: Wind Data for Drake



### Hi Leslie and Jim,

I wanted to follow up on our conversation from last week. I'm attaching two comparison wind roses that were run in the area. As you can see, there ar e differences between the two, but they are not dramatically different. Also, importantly, the data from Hwy 24 actually shows differences that would tend to increase the concentrations of SO2 from Dra ke. First, note that the Hwy 24 winds are more NW than the Airport, which means they are blowing m ore toward the mountains, which would tend to cause the plume to stack-up more. Second, the winds at Hwy 24 are lighter, which would also tend to cause higher concentrations of SO2 because the plum e would not disperse as quickly. Both of these differences tend to suggest that if our modeling ba sed on airport met data is inaccurate, it is conservatively inaccurate (i.e. it would show lower concentrations than what we would expect with onsite data).

Of course, we have always acknowledged that having on-site met data would improve the accuracy of the modeling. (More and better data nearly alway s improves modeling.) However, we cannot wait for that better data because all of the information we have indicates that Drake is causing an exceedance of the SO2 limits. That means public hea lth risk because parks, schools, homes and businesses are sitting in bad air that will make pe ople sick.

Please feel free to share this email with your cont act at EPA or others.

Travis Ritchie Staff Attorney Sierra Club Environmental Law Program 

### 85 Second Street, 2nd Floor San Francisco, CA 94105
Phone: (415) 977-5727 travis.ritchie@sierraclub.org