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P a g e C S - 1
Community Safety
Element

a Puentes urban environment contains a variety of hazards, both
natural and related to human activity that can potentially endanger
community safety. Residents and businesses look to City and
County agencies to protect the community from threats to public safety.
People recognize that a low crime rate, fire prevention, and reliable
emergency response services contribute to the overall livability of La
Puente. Equally important contributors to community safety are the safe
handling, transport, and disposal of hazardous materials, and reduction
of excessive noise. As described in the Community Vision, residents feel
that creating and maintaining a safe environment is one of the Citys most
important objectives.

Scope and Content

The Community Safety Element addresses hazards in La Puente and
presents goals and policies to reduce the potential risks of death, injuries,
property damage, and economic and social disruption associated with
hazards. Hazards affecting La Puente include earthquakes; excessive
noise; hazardous materials associated with commercial, industrial and
residential uses; criminal activity; and urban fires.

Within this chapter, community safety issues are organized into four
broad themes:


Hazard Mitigation. Addresses seismic hazards, flooding, and
human activity hazards, such as the use, transport and disposal of
hazardous materials.


Emergency Response. Emergency response efforts are essential to
prevent or minimize potential loss of life or property damage and
to respond effectively to safety hazards, accidents and natural
disasters.


Noise. Noise affects our health and quality of life.


Safety Services. Police and fire protection services create a safe
community for residents and businesses. Low crime, foresight in
the development process, and adequate enforcement lead to a safe
environment.
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Hazard Mitigation


Seismic Activity

Southern California lies on the edge of the Pacific Plate, one of the many
jigsaw puzzle pieces that fit together to comprise the Earths crust. The
constant shifting, pushing, and shoving of these crustal plates - together
with the complex interfacing of many varied geological structures
creates ruptures and crustal weaknesses known as faults. Movement
along a fault releases stored energy and tension, thereby producing
earthquakes. Powerful and widespread rupture or shaking ground can
cause buildings to move off their foundations or collapse; damage
buildings and other structures, roads and other public infrastructure;
damage utility lines and set off fires; and threaten the lives of people and
animals. The damage to structures presents the greatest risk to life and
property. Issues relevant to La Puente include the potential for
earthquakes and secondary hazards related to earthquakes that may
occur in the region.


Fault rupture is potentially the
most destructive, but the least
likely, form of earthquake damage
to structures.

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Earthquakes

La Puente lies within a region of several active faults and therefore is
subject to the risks and hazards associated with earthquakes. Eleven
major faults impact the Los Angeles region. The California Geological
Survey classifies seven of these faults as active. Several major faults
within a 50-mile radius of La Puente are capable of producing substantial
effects from ground shaking. These faults include the San Andreas,
Whittier-Elsinore, Chino, Sierra Madre-Cucamonga, and San Fernando
faults. A major earthquake produced along any of these faults has the
potential to produce strong ground shaking in La Puente.

Faults
Discovered in 2003, the Puente
Hills fault system is comprised
of three sections that run under
downtown Los Angeles,
through La Puente, and into the
Coyote Hills of north Orange
County. Research continues to
examine whether this fault also
extends into the San Jose Hills
area. Figure CS-1 shows the
geographic relationship of the
City to immediately surrounding active and potentially active faults.
No active faults have been identified at the ground surface within
the city limits, nor have any Alquist-Priolo Earthquake Fault zones
been designated. However, the City overlies the Puente Hills
segment of the Elysian Park blind thrust fault. The fault is referred
to as blind because it does not intercept the ground surface and
therefore cannot be detected visually. These faults are all capable of
movement that could produce substantial ground shaking.

Expansive Soil
As in much of California, expansive type soils are prevalent in La Puente.
Expansive soils act much like a sponge. As they absorb water, they swell
and as they lose water, they shrink. Expansive soils may become
unstable during ground shaking, and are one of the most prevalent
causes of earthquake damage to buildings. Damage caused by expansive
soils includes disfiguring and structural damage due to cracking walls,
ceilings, driveways, sidewalks and basement floors. Minor damage to
doors and windows may cause them to function erratically. To minimize
damage to wood frame structures foundations can be made more flexible,
through the use of reinforced or post-tensioned slabs.
The newly discovered Puente
Hills Fault has been credited
with causing the 1987 Whittier
Narrows Earthquake.
The Alquist-Priolo Earthquake
Fault Zoning Act (Public
Resources Code, Section 2621,
et seq.) was adopted by the
State legislature following the
1971 San Fernando
Earthquake to establish a
statewide program to map
surface traces of known active
faults, and to restrict
development in areas adjacent
to faults, known as Alquist-
Priolo Earthquake Fault Zones.

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Figure CS-1: Earthquake Faults Map
(8.5 x 11)


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Site preparation may include prewetting, removal of the expansive soil
and replacement with non-expanding soils, chemical treatments of the
soil or other methods. Grading and drainage should be designed so that
excess surface water is collected and safely discharged off the building
pad. Structural design of new buildings should consider the potential
effects of expansive soils on selected building materials. If for instance,
the structure contains masonry walls, which are intolerant to even small
movements, a rigid foundation or one that will isolate the structure
should be used.

During an earthquake, the ground can shake violently. Rapid back-and-
forth motion can cause buildings to fall off foundations, resulting in
major structural damage and sometimes total collapse of buildings.
Seismic risk associated with the regional fault system, expansive soils,
and the blind thrust fault underlying La Puente emphasizes the need to
ensure that all development projects and the retrofit of existing
structures incorporate appropriate design features to guard against
widespread property damage and loss of life in the event of an
earthquake.

Seismic Retrofitting
Residential seismic retrofitting strategies focus on strengthening house-
to-foundation connections using specially designed hardware and
construction methods. Retrofitting allows a structure to withstand
greater earthquake force with less structural damage. Older houses are
especially susceptible to earthquake damage, and therefore prime
candidates for retrofitting, because they were built before homes were
required by law to be earthquake-resistant. Seismic retrofitting of an
older home typically deals with four components of the structure: cripple
walls, shear walls, connections, and foundation. Retrofitting reinforces
each of these elements to strengthen the force-resisting strength of a
building. However, the most beneficial efforts focus on strengthening
cripple walls because seismic forces in a building accumulate all the way
down to the ground, and they are greatest at the base of the building.












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Design of new seismic retrofit systems, whether hidden or exposed,
should respect the character and integrity of the building being
retrofitted, as well as buildings in the surrounding area. The City will
continue to encourage earthquake preparedness in newer homes through
simple home protection such as bolting furniture and water heaters and
creating emergency supply kits.

A cripple wall is less than a full story high, usually
found between the first floor and the foundation of a
structure. It is generally the weakest part of older
buildings.