Potential Visibility Effects at Grand Canyon National Park from Power Plants in Northwest New Mexico

1
Potential Visibility Effects at Grand Canyon
National Park from Power Plants in Northwest New
Mexico

• Carl Bowman
• Air Quality Specialist
• Grand Canyon National Park
• December 9, 2004

2
Visibility in Grand Canyon

• Visibility, our ability to see and appreciate the
  Grand Canyon, is a critical resource.
• Congress hereby declares as a national goal the
  prevention of any future, and the remedy of any
  existing, impairment of visibility that results
  from manmade air pollution.
• (Clean Air Act 169A (a)(1)

3
Analysis Methods

• Conducted by NPS Air Resources Division
• Photographs of existing impairment from actual
  2001 episode
• Modeling analysis showing transport from
  northwest New Mexico
• Maps summarize modeling analysis of proposed
  facility
• Photographic depiction of potential impacts under
  different conditions

4
Layered Haze, Morning
5
Uniform Haze, Midday
6
The field of view of the monitoring camera
located at Desert View.
Visibility Monitoring Photos
7
A Clear Day in the Grand Canyon
1/14/01 245
Airmass stagnation over the Four Corner region
allows for emissions from power plants to
accumulate
8
Clouds and Plumes Move into the Colorado River
Valley
1/15/01 845
High pressure system breaks down, storm
circulation allows plumes to move toward Grand
Canyon.
9
Clouds and Plumes Move into the Colorado River
Valley
1/15/01 1200
Power plant emissions continue to travel down the
Colorado River drainage.
10
Clouds and Plumes Move into the Colorado River
Valley
1/16/01 1200
Emissions continue to circulate west and disperse
over a wider area, reaching Grand Canyon.
11
Clouds Evaporate but Plumes Remain as Layered Haze
1/17/01 245
After storm clouds evaporate, sulfate particles
from the plumes remain suspended in the Grand
Canyon, creating haze.
12
Next Day, the Haze is Gone
1/18/01 245
Haze-causing sulfate particles shrink, deposit,
and/or disperse enough that haze is no longer
visible.
13
Potential Impacts from the Proposed Source

• Sources in northwest New Mexico have the
  potential to cause a layered haze within the
  Grand Canyon or contribute to a uniform haze
• Effects are demonstrated using photographic
  depictions
• Based on the estimated concentrations of
  pollutants from a power plant in northwestern New
  Mexico, and the radiative transfer properties of
  the pollutants

14
Conclusions

• A new power plant in northwest New Mexico has the
  potential to impact the visibility at Grand
  Canyon National Park (as well as other national
  parks in the region)
• These effects must be adequately analyzed in the
  EIS, and will require
• High-resolution dynamic meteorological model runs
  
• A transport and dispersion model capable of
  simulating complex flow
• Radiative transfer modeling of the visibility
  effects