# MANE-VU

Mid-Atlantic/Northeast Visibility Union

444 North Capitol St, NW, Suite 638 Washington, DC 20001 Phone (202) 508-3840 Fax (202) 508-3841

August 31, 2006

Re: MANE-VU response to stakeholder comments on Contributions to Regional Haze in the Northeast and

Mid-Atlantic United States: MANE-VU Contribution As sessment

Dear Stakeholders:

The Mid-Atlantic/Northeast Visibility Union (MANE-V U) appreciates the comments and feedback received o n our draft report Contributions to Regional Haze in the Northeast and Mid-Atlantic United States: MANE-VU

Contribution Assessment

which was released in May, 2006. MANE-VU is a reg ional planning organization formed to support the planning efforts of its members as t hey prepare to comply with visibility requirements under the regional haze rule [64 Fed. Reg. 35714 (July 1, 199 9)]. The organization’s membership includes: Conne cticut, Delaware, the District of Columbia, Maine, Maryland , Massachusetts, New Hampshire, New Jersey, New Yor k, Pennsylvania, the Penobscot Indian Nation, Rhode Is land, the St. Regis Mohawk Tribe, Vermont, as well as federal land management agencies and the U.S. EPA.

Numerous issues have been raised with regard to pot ential improvements and refinements to our report. Each comment has been carefully considered by the author s of this report and many of the proposed improveme nts have been incorporated directly into the final draft. T he most significant issue which have been raised by stakeholders relate to the use (or lack thereof) of future emiss ion inventories as opposed to the MANE-VU 2002 base year inventory. Another issue raised by stakeholders re lates to the use of the CALPUFF dispersion model fo r distances

over 300 kilometers where the model’s characterizat ion of diffusion may cause results to be overestima ted for sources beyond this distance. Finally, stakeholder s are eager to learn whether MANE-VU intends to ado pt an alternative method for calculating reconstructed ex tinction or use the default approach included in cu rrent U.S. EPA guidance.

With regard to the emission base year, the intentio n of the contribution assessment is primarily to id entify source that are contributing to our present visibil ity problems. MANE-VU does intend to conduct addit ional modeling work using many of these same platforms, a s well as the Community Multi-scale Air Quality (CM AQ) model, for the 2018 projection inventories that are still being developed by the RPO. The results of these analyses will be published in a pollution apportionment tech nical memorandum and will serve as the primary basi s for setting reasonable progress goals for MANE-VU class I areas. That, however, was not the intent of th is document.

MANE-VU recognizes the limitation of the CALPUFF mo del and its treatment of dispersion. We also recognize the limitations of the REMSAD model with respect to its ability to accurately simulate oxida nt fields and photochemistry. Clearly the data analysis techniqu es like Q/d have their own limitations and it is wi th exactly this spirit (“all models are wrong, some are useful”) th at we have presented results from multiple methods to demonstrate the degree of agreement between them. That is, despite the fact that each platform has it s strengthsResponse to comments on MANE-VU Contribution Assessment

-2- and weaknesses, the agreement between them in appor tioning contributions to sulfate observed in MANE-V U class I areas gives us confidence that none of these appr oaches is too far from the truth. While we agree w ith

commenters that the CALPUFF results for sources ove r 300 kilometers should not be presented as a stand -alone work product, we feel that they do add to a weight of evidence demonstration that these sources do app ear to have significant combined influence on observed sulfate concentrations in all MANE-VU Class I areas.

Estimated natural background and current baseline v isibility conditions must be used together to provi de information on the uniform rate of progress that se rves as a path of comparison for the process of set ting reasonable progress goals. While we have included information on the implications of utilizing the IMPROVE steer ing

committee recommendation for an alternative method to calculate baseline visibility conditions, we are not aware of a similar procedure that has been approved by th e IMPROVE steering committee for the calculation of natural background conditions. As our statement on natural background conditions from June of 2004 states, “t he Board supports the MANE-VU Class I states’ use of these [ U.S. EPA] defaults, and recommends these defaults b e refined

if and when scientific data and alternative methods warrant a change in one or more of the default par ameters and such a change would be economical and practical to implement, result in a significant change in the na tural background goal, and not create inconsistencies els ewhere.” This continues to be true and MANE-VU wi ll revisit this issue when the IMPROVE steering committee prov ides a consensus approved alternative method for th e estimation of natural background visibility conditi ons for the MANE-VU region.

We appreciate all of the stakeholders review and pa rticipation in the review of this document. We are sure that it stands as an improved document as a result. Than k you for your interest in our technical work.

Sincerely,

Gary Kleiman, Project Director Mid-Atlantic/Northeast Visibility Union Contributio n Assessment