Chapter 1 - Caltrans - State of California

Chapter 3 Comments and Coordination
quantified due to the inherent deficiencies of current models. When a highway is
widened and, as a result, moves closer to receptors, the localized effect of a given amount
of MSAT emissions for the BUILD alternatives may be higher relative to the NO BUILD
alternative, but this should be offset due to increases in speeds and reductions in
congestion. Also, MSATs would be lower in other locations when traffic shifts away
from them. On a regional basis, the EPA and California vehicle fuel regulations and fleet
turnover, would cause substantial reductions over time and in almost all cases, would
cause region-wide MSAT levels to be significantly lower than today.
Construction/Temporary Impacts
Construction activities associated with the proposed project would be temporary and
would last the duration of project construction. Currently, project construction is
scheduled to start in early 2011 and the anticipated date of completion is 2015. The
discussion below has concluded that project construction would not create adverse
pollutant emissions for any of the alternatives under consideration. Short-term impacts to
air quality would occur during minor grading/trenching, new pavement construction and
the re-striping phase.
During construction, short-term degradation of air quality may occur due to the release of
particulate emissions (airborne dust) generated by excavation, grading, hauling, and
various other activities. Emissions from construction equipment also are anticipated and
would include CO, nitrogen oxides (NOx), volatile organic compounds (VOCs), directlyemitted
particulate matter (PM10 and PM2.5), and toxic air contaminants such as diesel
exhaust particulate matter. Ozone is a regional pollutant that is derived from NOx and
VOCs in the presence of sunlight and heat.
Site preparation and roadway construction would involve clearing, cut-and-fill activities,
grading, removing or improving existing roadways, and paving roadway surfaces.
Construction-related effects on air quality from most highway projects would be greatest
during the site preparation phase because most engine emissions are associated with the
excavation, handling, and transport of soils to and from the site. If not properly
controlled, these activities would temporarily generate PM10, PM2.5, and small amounts of
CO, SO2, NOx, and VOCs. Sources of fugitive dust would include disturbed soils at the
construction site and trucks carrying uncovered loads of soils. Unless properly controlled,
vehicles leaving the site would deposit mud on local streets, which could be an additional
source of airborne dust after it dries. PM10 emissions would vary from day to day,
depending on the nature and magnitude of construction activity and local weather
conditions. PM10 emissions would depend on soil moisture, silt content of soil, wind
speed, and the amount of equipment operating. Larger dust particles would settle near the
156 IS/EA VEN-SB US101 HOV Project