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CNAPTERFOUR Environmental Consequences ' • Impact to the Flat Tops Wilderness Area must be addressed in the construction permit application. • Visibility and acid deposition to sensitive lakes must be addressed as AQRV~;. • The visibility impact threshold is 0.5 deciview. • The acid deposition impact threshold is a ] 0 percent change in acid neutralizing capacity (ANC) at the sensitive lakes. • The Mt. Zirkel background visibility data should be used in the visibility analysis, and the U5FS would provide methodologies and background data on lake chemistry for use in the acid deposition analysis. Several factors contributed to making this a conservative analysis: • The Piceance facility and Pazachute facility were modeled at maximum operating condition for this analysis. • Receptor locations were selected based on the closest proximity of Yankee Gulch sources to the Class I azea boundaries. • At each receptor both the minimum and maximum elevations occurring anywhere in the Class I azea were assigned, resulting in six receptors for the Class I area grid. • The more conservative "highest" short-term concentrations were used. • The significant impact levels proposed as part of the NSR reform were used, which are significantly lower than the impact levels currently in effect. Table 4.5-5 presents the results from the Class I increment analysis. The combined impacts from both the Piceance and Pazachute facilities aze less than the Class I significant impact levels. Impacts predicted below the significant and impact level aze by definition detern;.ined to not significantly effect the air quality at the Class I azea. TABLE 4.5-5 CLASS I SIGNIFICANT IMPACT ANALYSIS ,: - :;;hFSRRefurin.Pra ....:.:..d :::.:: ::.:: ::::::-::-.::::::1VLa~€mEEitt.;::;:,:::;;:::::::: ` :: Ciass:;~::: n6eaut :::::::: ::: ::::::::.::Prti`ec#'Taat ::::'::;!::::: • Av rs :.::. ::.::::::::.::::::.Iiir t:'' vel.::';::"':'::':: ::: :: <,::::.::;:?°Y:.::.:.:: e:::.:...:::':.;:.;:: ~ouQt;ant :.:: :: ::.: ~.::... .::::::.:..:::..::::::.: ~rttCR,',8t :... . :..::...:::::.:.:: .... . . ::..:...:: ~: ~: jEg~.....~1~:~:`:;~::~::;:::~:::~::~:~ :.~. :~~:..;: :.:>~~~:~~:::: ~~ ~ ~ ~~~:y~:~:::~:::::' ~~~~~~~~~~ N02 Annual 0.1 0.010 PM 10 24-Hour 0.3 0.040 Annual 0.2 0.005 'The short-term design concentration for the Class 1 significant impact analysis is the highest concentration. Source: RTP 1998a,b 4-26 Meteorology and Air Quality LJ 1 1 1 LJ 1 1 1 1 1 1