1 / 18

Impact Area

Impact Area. 1-hour standards. when a proposed source’s ambient impacts warrant a comprehensive (cumulative) source impact analysis the size of the impact area within which the air quality analysis is completed

samantha-kelly
Download Presentation

Impact Area

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Impact Area 1-hour standards

  2. when a proposed source’s ambient impacts warrant a comprehensive (cumulative) source impact analysis • the size of the impact area within which the air quality analysis is completed • whether the emissions increase from a proposed new major stationary source or major modification is considered to cause or contribute to a violation of any NAAQS SILs used to determine

  3. Is there a 1-hour standard or is it a three year standard whose metric is the 98th or 99th percentile of the distribution of 1-hour concentrations averaged over the 3-year period? • Can there technically be more than one violation at a receptor over a given time period under the metric for the standard? Misnomer?

  4. The sum of n distributions of any type is approximately normal • Its mean is equal to the sum of the means of the components • The standard deviations add like the law of cosines. Distribution Sums

  5. 99% of the data is below 2.3 standard deviations above the mean • 98% of the data is below 2.06 standard deviations above the mean Normal Distribution

  6. NO2 • 1st highest daily 1-hour value averaged over 5 years • 7.52 ug/m3 • 4 ppb • 4% of the probabilistic standard • SO2 • 1st highest daily 1-hour value averaged over 5 years • 7.8 ug/m3 • 3 ppb • 4% of the probabilistic standard EPA Proposed 1-hour SILS

  7. SIL as Percentage

  8. AEGL-1is the airborne concentration, expressed as parts per million or milligrams per cubic meter (ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. • NO2 – 0.5 ppm (4% = 37.6 ug/m3) • SO2 – 0.2 ppm (4% = 20.8 ug/m3) Acute Exposure Guideline Levels

  9. 24-Hour <75 ug/m3 3-hour <8760 ug/m3 Annual Typical Impact Area

  10. Possible OccurrenceOutside Historical Impact Areas

  11. Evaluate maximum 1-hour emissions against: • Annual – 1 ug/m3 • 24-hour – 5 ug/m3 • 1-hour – 25 ug/m3 • If exceeded, culpability is determined by the difference in the design value with and without the project compared to EPA proposed SIL • If not exceeded the project is considered insignificant.

More Related