Letter

State of Vermont
Agency of Natural Resources
Dept. of Environmental Conservation
Air Pollution Control Division
Building 3 South
103 South Main Street
Waterbury, VT 05671-0402
Tel: 802-241-3840
FAX: 802-241-2590

March 3, 1999

Doug Folle
Foster Wheeler Environmental
Suite 200
02 Research Drive
Norcross, GA 30092

RE: Southern Vermont Gas ^ Proposed Power Plants

Dear Mr. Folle:

In response to our telephone conversation yesterday, I am enclosing an update of Vermont,s Air quality Impact Evaluation Guidelines (1/6/99). This revised document should contain the information on receptors and elevation assignments your staff had questions on (see page 10). I should also mention that in addition to visibility impacts in Class I areas, a deposition model (e.g. nitrogen deposition) would likely be required by the Federal Land Manager (U.S. Forest Service). The current recommended deposition model is CALPUFF. I have attached the cover page of a U.S. EPA document describing the procedures (SEPA-454/R-98-019). Please be aware that impacts on the Great Gulf Wilderness Area in New Hampshire may also need to be assessed. The regional contact at the U.S. Forest Service is Nancy Burt, 802-747-6742, Green Mountain National Forest, 231 North Main Street, Rutland, VT 05701

I also contacted U.S. EPA Region I to discuss Ozone Transport Region (OTR) requirements under the 1990 Clean Air Amendments. Because Vermont is treated as moderate non-attainment for ozone as a result of the OTR, major sources for the pollutants NOx and VOCs are subject to non-attainment provisions, including LAER and offsets. As you know, LAER is the lowest emission rate which has been achieved in practice for a given pollutant. Region I has informed me LAER is at the moment considered to be 2 ppm NOx for gas turbines. Any major NOx application should begin at this level and also include a discussion of other transfer technology which is technically feasible. It is uncertain what level of VOCs or CO are expected from the proposed plants and therefore will have to be addressed accordingly in the application as well.

Finally, we have not made any decision on the need for meteorological pre-construction monitoring. It would be helpful to have a modeling protocol submitted which would provide more detail about these projects. This information would enable Vermont to provide you with a timely response.

Please contact me if you have any questions.

Sincerely,
Brian J. Fitzgerald
Engineering Supervisor
Air Pollution Control Division