(05) 2035 LQ GP - CERTIFIED EIR - Section IV (2013)Terra Nova/La Quinta General Plan EIR
Section IV. Unavoidable Significant Impacts
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LA QUINTA GENERAL PLAN
ENVIRONMENTAL IMPACT REPORT
IV. UNAVOIDABLE SIGNIFICANT IMPACTS
An assessment of potential environmental impacts associated with implementation and build out
of the La Quinta General Plan Update was provided in Section III of this EIR. The analysis led to
a determination of the level of impact on each environmental resource, including no impact, less
than significant impact, less than significant with mitigation, or potentially unavoidable
significant impact as a result of build out of the General Plan. This section summarizes those
impacts that are potentially unavoidable. Even with the imposition of mitigation measures,
impacts to the following categories will remain significant and are unavoidable.
Air Quality
Implementation of the General Plan Update will result in significant air quality impacts in the La
Quinta Planning Area. Air pollutants will be generated from a variety of activities, including
grading and construction, vehicle emissions, and daily operations. Emissions generated by
vehicular traffic are projected to be the greatest source of air pollutants. The use of natural gas
and electricity for operation of existing and new buildings and structures will also result in the
emission of air pollutants.
Construction Emissions
Air quality emissions from construction activities will occur as a result of new development
within the City limits and Sphere of Influence. As discussed in Section III of this EIR, emissions
from construction within the City are projected to remain below established thresholds for all
criteria pollutants expect for NOx and ROG. As shown in Section III, approximately 122 pounds
per day of NOx and 818 pounds per day of ROG are expected even with the implementation of
mitigation measures. This is well above the 75 pound per day threshold established by
SCAQMD. As such air quality emissions from NOx and ROG’s during construction activities
within City limits have the potential to result in significant and unavoidable impacts.
Construction related air quality emissions from the development of lands within the Sphere of
Influence are projected to exceed established daily thresholds for NOx and ROG, even with
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implementation of mitigation measures. As shown in Section III of this EIR, approximately 104
pounds per day of NOx, and 697 pounds per day of ROG have the potential to occur during
construction activities. This is above the SCAQMD thresholds of 100 pounds per day for NOx,
and 75 pound per day for ROG. Air quality emissions from NOx and ROG during construction
activities within the Sphere of Influence have the potential to result in significant and
unavoidable impacts.
Air pollutant emissions from construction activities are temporary and will end once construction
is complete. Nonetheless, during construction activities and assuming simultaneous construction
of vacant lands within the Planning Area, the proposed General Plan Update has the potential to
result in a cumulatively considerable net increase of NOx and ROG. Should construction
activities in the City and Sphere occur simultaneously at the rates assumed in Section III,
emissions of PM2.5 and PM10 will also exceed thresholds of significance, at 261 and 58 pounds
per day, respectively. Projections of these criteria pollutants exceed established daily thresholds
and have the potential to result in significant and unavoidable impacts for these criteria
pollutants.
Operation Emissions
For operation of the General Plan Update, air quality emissions have the potential to result in a
cumulatively considerable net increase of all six criteria pollutants, including CO, NOx, SOx,
PM10, PM2.5, and ROG, as well as greenhouse gas emissions. Emissions of air quality pollutants
from operation include the use of electricity and natural gas, as well as area source and moving
source emissions. Projections of these pollutants exceed established daily thresholds and have
the potential to result in significant and unavoidable impacts.
Emission from the consumption of electricity will primarily occur offsite, where electricity is
generated. As such, the Planning Area will be indirectly impacted by these emissions.
Nonetheless, the Planning Area is responsible for generating the electricity demand. While it is
expected that the electricity grid mix will incorporate more renewables in future years, the use of
coal and natural gas fired power plant will contribute significant emissions generated by the
onsite energy demand.
Natural gas generation facilities and onsite use of natural gas for cooking, heating, and other uses
will result in significant impacts. Although some of these emissions may not occur within the
Planning Area, as no such generating facilities exist within the planning area, the emission
projections result in a considerable increase, with significant impacts.
While implementation of the proposed mitigation measures and Greenhouse Gas Reduction Plan
may be effective in substantially reducing emissions to levels below significance for certain
sectors, emissions from moving sources will remain significant and are unavoidable.
The City has varying levels of control over the avoidance of emissions. Although the EIR sets
forth all feasible mitigation measures and a comprehensive Greenhouse Gas Reduction Plan has
been prepared, air quality emissions may remain significant and unavoidable. Regardless of
mitigation measures, development of the General Plan will contribute to cumulative air quality
impacts locally and regionally. Although emissions can be mitigated to a certain degree,
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significant and unavoidable impacts to air quality, including greenhouse gas emissions, will
occur as a result of development of the General Plan.
The implementation of mitigation measures for project-specific proposals is an effective means
to reducing air quality impacts for the entire General Plan area. Design features that result in
minimal trip generation, increase the use of green building design and technologies, provide
alternative transportation options and onsite features such as electric charging station, and
incorporate the use of alternative energy sources both locally and regionally through
technologies such as individual and region-wide solar roof installation projects and region-wide
wind farm development, will reduce the emissions associated with build out of the Planning
Area. These measures will not only reduce emissions of criteria pollutants, but will also reduce
emissions of greenhouse gases.
Traffic
The consequences of General Plan build out have been evaluated for the 63 major roadway
segments and 37 intersections. Based on this analysis, the proposed General Plan is projected to
generate a total of approximately 635,905 average daily trips. Of these, 449,489 ADT would be
generated within the City's corporate limits and 186,416 would be generated in the City Sphere-
of-Influence.
Within the City's corporate limits, the proposed Land Use Plan will generate about 3.6% more
traffic than build out of the 2002 General Plan. Within the City's Sphere, the proposed Land Use
Plan will generate about 34% more traffic than build out of the 2002 General Plan land use
designations.
The majority of the roadway segments are forecast to operate at acceptable levels of service (V/C
ratios less than or equal to 0.90 or LOS D or better). Three segments are projected to operate at
LOS E and three at LOD F at 2035 build out.
Washington Street segments between Avenue 42 and Miles Avenue and between Highway
111 and Eisenhower Drive (6-lane Major Arterial) are forecast to exceed theoretical
maximum carrying capacity by up to 3,000 VPD with the most problematic segment between
Fred Waring Drive and Miles Avenue. LOS D service volumes are exceeded by over 9,000
VPD.
Madison Street between Avenue 54 and Airport Boulevard (4-lane Primary Arterial) is
forecast to exceed theoretical maximum carrying capacity by approximately 4,900 VPD.
LOS D service volumes are exceeded by over 9,000 VPD.
Harrison Street between Airport Boulevard and Avenue 58 (8-lane Augmented Major) is
forecast to exceed theoretical maximum carrying capacity by approximately 3,800 VPD.
Although the capacity of Harrison Street was assumed to be that of an Augmented Major
Road (76,000 vehicles per day), it would likely operate as an Expressway due to limited
accessibility compared to an Augmented Major Road, thus carrying a larger capacity. Prior
study by the County raised the potential of grade-separated intersections to further enhance
capacity.
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Of the 37 intersections analyzed, the following four are not expected to be able to accommodate
all the required build out improvements and therefore have the potential to be operating at
unacceptable levels of service by 2035 General Plan build out:
Washington Street @ Fred Waring Drive;
Adams Street @ Miles Avenue;
Jefferson Street @ Highway 111;
Madison Street @ Avenue 50.
It should also be noted that three of the four impacted intersections are shared between more than
one jurisdiction. For instance, the Washington Street/Fred Waring Drive intersection is located
within the corporate boundaries of the cities of La Quinta, Palm Desert and Indian Wells. In
these cases, close and on-going coordination between cities will be necessary to provide
optimum intersection improvements and to otherwise address forecast operational deficiencies.
However, even with the implementation of feasible mitigation measures, impacts will be
significant and unavoidable.
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