Section 5.7
Geology and Seismic Hazards
SECTION 5.7
GEOLOGY AND SEISMIC HAZARDS
This section describes the City of Buena Park’s existing geologic, seismic, and soil conditions, and
the existing Federal, State, and local regulations with which development must comply. Geologic
and seismic impacts that could result from implementation of the proposed General Plan Update
are identified, and where appropriate, mitigation measures are recommended to avoid or lessen
impacts.
5.7.1
EXISTING SETTING
This section identifies existing earth resources, and seismic and geologic hazards within the City.
Earth resources in this context include geologic and soil conditions.
GEOLOGY
Regional Conditions
The City of Buena Park is located in the southeastern section of the coastal plain of Los Angeles
and Orange counties. Specifically, Buena Park is located within the central lowland coastal plain
of Orange County, which stretches northeasterly from the vicinity of Irvine, beyond Santa Ana
and Garden Grove, and into Los Angeles County. The central lowland comprises the Downey
and Tustin Plains, an approximately 300 square mile area.
The coastal plain of Los Angeles and Orange counties is bounded by the Santa Ana Mountains,
and the areas of Elysian, Repetto, and Puente Hills to the northeast; the Santa Ana Mountains to
the southeast; the San Joaquin Hills to the south; and the Pacific Ocean on the west. The primary
rivers traversing this coastal plain include the Los Angeles, San Gabriel, Rio Hondo, and Santa
Ana rivers. The Rio Hondo River flows in a southwest direction across the coastal plain and
merges with the Los Angeles River. The San Gabriel River flows south on the eastern portion of
the coastal plain generally parallel to the Los Angeles River. The Santa Ana River stretches
approximately 75 miles and has a total drainage of approximately 3,200 square miles. The Santa
Ana River originates in the San Bernardino Mountains and traverses San Bernardino, Riverside,
and Orange counties.
The coastal plain of Los Angeles and Orange counties was formed from recent (Holocene)
alluvial deposits. The alluvial fans of the Los Angeles, San Gabriel, Rio Hondo, and Santa Ana
rivers resulted from the formation of a gently sloping plain through stream deposition. The
portion of the coastal plain within Orange County is underlain by deep structural depression
containing primarily sedimentary rocks. The subsurface of the County varies in thickness and
lithology due to the rapid rate of deposition of rock units, folding, and faulting. The sedimentary
deposits of the coastal plain are a hybrid of marine and continental sediment. A significant
amount of the sedimentary deposits have been removed over time due to erosion, resulting in
numerous discontinuities in the land surface.
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Local Conditions
The City of Buena Park consists of urbanized land on generally flat topography with a slope of
less than 20 feet per mile. Buena Park consists of two different geomorphic areas: the Coyotes
Hills and the Downey Plain. The Coyotes Hills form the northeast portion of the City and have
an elevation ranging from approximately 400 to 600 feet. The Coyotes Hills were formed
through earth movement and local faulting. The Downey Plain comprises the majority of the
City’s land area and is characterized by nearly level topography. This plain was formed through a
series of stream deposits from the Los Angeles, San Gabriel, Rio Hondo, and Santa Ana rivers and
consists of weathered unconsolidated and semi-consolidated alluvial soils.
The City is underlain by the Talbert Aquifer, and sedimentary deposits from recent time (15,000
years ago) and the Pleistocene period (one million years ago). The composition of these deposits
is described below.
RECENT TIME (15,000 YEARS AGO) SURFICIAL DEPOSITS
Young Alluvial Channel Deposits (Qya)
Locally young alluvial channel deposits include elements of late Holocene (approximately 11,000
years ago) alluvial. Young alluvium of Recent Time is found on or near the surface of the City
and much of Orange County at a depth of approximately 175 feet. The top layer of young
alluvium consists of recent stream channel deposits, including sand, silt, clay, and gravel,
unconsolidated and semi-consolidated alluvial fan, and flood stream sediments. Alluvial deposits
are typically poorly sorted and permeable. Lenses of fine sand and gravel along the coast and in
scattered sections of the main portion of the groundwater basin contain perched and semiperched water. Perched groundwater is a zone of saturation in a formation that is discontinuous
from the water table (main body of groundwater) and the unsaturated zones surrounding this
formation.
Pleistocene Period (1 million years ago) Deposits
Lower layers of soil composition in Buena Park consist of Pleistocene Period Stream Terrace and
Older Alluvium, La Habra Formation, Lakewood Formation, Coyote Hills Formation, and San
Pedro Formation.
Stream Terrace and Older Alluvium
The Stream Terrace and Older Alluvium are separated from Recent Time soils by unconformities
in sedimentation. Older Alluvium and terrace deposits are composed of reddish brown, semiconsolidated silt, sand, gravel, and rubble. Older Alluvium deposits are generally above the water
table. These deposits are generally permeable enough to transmit precipitation to underlying
sediments.
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La Habra Formation 1
The La Habra Formation is found in the Coyote Hills and along the southern flank of the Puente
Hills. It is a non-marine deposit and appears to have been an old flood plain. This formation
consists of siltstone, thick-bedded friable sandstone, pebbly sandstone, and pebble-cobble
conglomerate; locally abundant clasts of platy white siltstone.
Lakewood Formation
The Lakewood Formation ranges in thickness from 10 to 500 feet or more in the northern
portion of Orange County. This formation consists of interbedded clay, silt, sand, and gravel that
transmit water slowly. The Lakewood Formation merges with the La Habra Formation near the
City of La Habra.
Coyote Hills Formation
The Coyote Hills Formation lies below the Lakewood and La Habra Formations. The Coyote
Hills Formation has a maximum thickness of approximately 500 feet. This formation is
composed of nonmarine sandstone and mudstone. The lower sandstone lies atop the San Pedro
Formation and is approximately 250 feet thick. The upper mudstone has a maximum thickness
of approximately 500 feet. According to the Department of Water Resources, sandstone deposits
are permeable and mudstone deposits appear to be non-permeable.
San Pedro Formation
The San Pedro Formation contains deposits of marine sands, gravel, silts, and clays. Marine
mollusks are locally abundant within this deposit. The San Pedro Formation ranges in thickness
of approximately 275 feet in the Santa Ana Gap to approximately 800 feet in the northern portion
of Orange County. There is a coarse sequence of sand and gravel interbedded with silt and clay
lenses near the base of the San Pedro Formation. This unit is designated as the principal aquifers
used for domestic water in the Orange County and Los Angeles areas.
The Upper San Pedro Formation comprises the lower aquifer system below the San Pedro
Formation and the Main aquifer. Local nonconformities and changes in the lithology of deposits
within the Orange County Coastal Plain reflect varying degrees of tectonic movement around the
end of the Pliocene Time. These deposits are composed of pebble conglomerates, conglomeratic
sandstones, siltstones, and in some places abundant marine mollusks. The maximum thickness
of the Upper San Pedro Formation ranges between approximately 900 feet at the eastern end of
the East Coyotes Hills and approximately 1,400 feet north of Yorba Linda East Coyotes.
SOILS
The City of Buena Park is urbanized and primarily built-out. Surface soils in the City may no
longer reflect the natural soil associations and characteristics identified below, since topsoil in the
City has been predominately developed. Fill material of unknown origin and varying
composition currently cover most of the City’s developed area.
1
Explanation for the Geologic Map of the Long Beach 30’ X 60’ Quadrangle, California, California
Department of Conservation Geological Survey, 2003, http://www.conservation.ca.gov/cgs/rghm/rgm/
Pages/preliminary_geologic_maps.aspx, Accessed March 9, 2009.
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Soil Associations
A soil association is an overarching classification of similar soil types occurring on similar
material or on a combination of rocks and soil types that have similar profiles, arrangements,
sequence of layers, or other characteristics. The following soil associations underlie Buena Park:2

Chino-Omi Association. The Chino-Omi association is characterized by nearly level,
somewhat poorly drained, calcareous silt loams to clays on alluvial fans, flood plains, and
basins.

Hueneme-Bolsa Association. The Hueneme-Bolsa association is characterized by nearly
level, poorly drained and somewhat poorly drained, calcareous fine sandy loams, silt
loams, and silty clay loams on alluvial fans and flood plains.

Metz-San Emigdio Association. The Metz-San Emigdio association is characterized by
nearly level, somewhat excessively drained and well drained, calcareous loamy sands and
fine sandy loams on alluvial fans and flood plains.

Sorrento-Mocho Association. The Sorrento-Mocho association is characterized by nearly
level to moderately sloping, well drained sandy loams, loams, and clay loams on alluvial
fans and flood plains.

Myford Association. The Myford association is characterized by nearly moderately steep,
moderately well drained sandy loams that have strongly developed subsoil, on terraces.

Alo-Bosanko Association. The Alo-Bosanko association is characterized by strong sloping
to steep, well drained clays on coastal foothills.

The Cieneba-Anaheim-Soper association is
Cieneba-Anaheim-Soper Association.
characterized by strong sloping to very steep, somewhat excessively drained and well
drained sandy loams, loams, clay loams, gravelly loam, and cobbly loams on coastal
foothills.
Soil Types and Characteristics
According to the United States Department of Agriculture Soil Conservation Service, soil types
and characteristics within Buena Park include the following:3

Bolsa silt loam, drained. This nearly level soil generally occurs on large alluvial fans. If the
soil is bare, runoff is slow and the erosion hazard is slight. The water capacity of this soil
is 11.5 to 12.5 inches, which is the range of available water that can be stored in soil and
available for growing crops.
2
United States Department of Agriculture Soil Conservation Service, Soil Survey of Orange County and
Western Part of Riverside County, California, Sheets 1, 3, and 4, 1974.
3
Ibid.
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
Metz loamy sand. This nearly level to gently sloping soil generally occurs on large fans
and on flood plains. If the soil is bare, runoff is slow and the erosion hazard is slight. It
has a water capacity of 4.0 to 6.0 inches.

Metz loamy sand, moderate fine substratum. This nearly level to gently sloping soil
generally occurs on large fans and on flood plains. If the soil is bare, runoff is slow and
the erosion hazard is slight. It has a water capacity of 4.0 to 6.0 inches.

San Emigdio fine sandy loam, 0 to 2 percent slopes. This nearly level soil generally occupies
alluvial fans on flood plains and along stream channels. If the soil is bare, runoff is slow
and the erosion hazard is slight. The soil has an available water capacity of 7.0 to 9.0
inches.

San Emigdio fine sandy loam, moderately fine substratum, 0 to 2 percent slopes. This nearly
level soil generally occurs on alluvial fans on flood plains and along stream channels.
Permeability is moderately slow in the underlying material. Runoff is slow and the
erosion hazard is slight. Available water capacity for this soil is 7.0 to 10.0 inches.

Mocho Loam, 0 to 2 percent slopes. This nearly level soil generally occurs on fans or flood
plains. If the soil is bare, runoff is slow and the erosion hazard is slight. The soil has an
available water capacity of 9.5 to 12.0 inches.

Chino-Silty Clay Loam, drained. This nearly level soil generally occurs on large alluvial
fans. If the soil is bare, runoff is slow and the erosion hazard is slight. This soil type is
drained and the water table is more than 60 inches below the surface.

Corralitos, loamy sand. This nearly level to gently sloping soil generally occurs as long
narrow areas along stream channels. If the soil is bare, runoff is slow and the erosion
hazard is slight. The soil has an available water capacity of 4.0 to 5.5 inches.
FAULTS AND SEISMICITY
According to the California Geological Survey, faults are planes of weakness in the earth’s crust
where one side has moved relative to the other. They are recognized and mapped by sheared and
displaced rock units and by the distinctive landforms created by repeated rupture of the earth’s
surface. An active fault is defined in California Code of Regulations (CCR) Section 3601(a) as a
fault that has had surface displacement within Holocene time (about the last 11,000 years), hence
constituting a potential hazard to structures that might be located across it. A fault that has
ruptured during the last 1.8 million years (Quaternary time), but is not proven by direct evidence
to have moved or not moved within the Holocene, is considered to be potentially active. Any
fault older than Pleistocene (1.8 million years) is considered inactive. A fault zone consists of a
zone of related faults that commonly are braided and subparallel, but may be branching and
divergent.
California is a seismically active region, with numerous faults located throughout. Exhibit 5.7-1,
Regional Faults, depicts the locations of the regional faults. Table 5.7-1, Fault Location and
Probability, lists local and regional faults that have the potential to affect the City and their
potential probable earthquake magnitude. As illustrated on Exhibit 5.7-1, the Norwalk Fault
traverses the northeast portion of Buena Park. The Los Coyotes Fault is identified in the City of
Buena Park General Plan Final Environmental Impact Report (June 28, 1995) as being located
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near the City’s northern boundary.4 Additionally, faults located within 5 miles of the City include
Whittier-Elsinore, Newport-Inglewood, and Los Alamitos Faults.
Table 5.7-1
Fault Location and Probability
Fault
Location/Closest Distance
From Buena Park1
Los Coyotes Fault
North and northeast portion of the
Buena Park
North of the City boundary
Whittier-Elsinore Fault
4.5 to 6 miles north
Newport-Inglewood Fault
Los Alamitos Fault
San Andreas Fault
Sierra Madre Fault
San Jacinto Fault
Palos Verdes Hills Fault
San Pedro Basin Fault
San Gabriel Fault
Raymond Fault
Elysian Park Fold and Thrust Belt
5 to 8 miles southwest
3 miles southwest
35 miles northeast
20 to 25 miles north
35 to 40 miles northeast
15 to 20 miles southwest
30 to 40 miles southwest
20 to 25 miles north
18 to 20 miles north
12 miles northwest
Norwalk Fault
1
2
Potential Probable Earthquake Magnitude2
6.3
Not reported
6.0 to 7.2 for the Whittier Fault segment and
6.5 to 7.5 for the Elsinore Fault segment
6.0 to 7.2 or greater
Not reported
6.8 to 8.0
6.0 to 7.0
6.5 to 7.5
6.0 to 7.0 or greater
7.0
7.8
6.0 to 7.0
Not reported
City of Buena Park General Plan Final Environmental Impact Report, David Evans and Associates, Inc., June 28, 1995.
Southern California Earthquake Data Center, supported by the U.S. Geological Survey, Seismological Laboratory, California Institute of
Technology, and SCEC, http://www.data.scec.org/fault_index/alphadex.html, (Accessed March 5 and 6, 2009).
Faults that have the potential to affect the City of Buena Park are discussed below.
Norwalk Fault. The Norwalk Fault traverses the north and northeast portion of Buena Park.
This fault extends approximately 16 miles from Norwalk to Coyote Hills. The fault is noted as
the possible source of a Magnitude 4.7 earthquake occurring on July 8, 1929, which caused
significant damage in Whittier and Norwalk. Microseismic activity along the Norwalk Fault is
high; the fault may be capable of generating a magnitude 6.3 earthquake on the Richter scale.
The Norwalk Fault is the only fault located within the City; however no surface faulting has been
associated with this fault.
Whittier-Elsinore Fault. The Whittier-Elsinore Fault is located approximately 4.5 miles north
of the City at its closest point. The fault extends northwest trending approximately 150 miles
from the Mexican border to the northern edge of the Santa Ana Mountains. The Whittier section
of the Elsinore Fault Zone extends over 20 miles from the Whittier Narrows southeasterly to the
Santa Ana River where it merges with the southeasterly trending Elsinore fault and other smaller
faults. Movement on this fault occurs as a right-lateral strike-slip (movement is parallel to the
direction or trend of the fault plane) with some reverse slip. The Whittier Fault and Elsinore
Fault segments are considered capable of generating earthquakes with a magnitude of 6.0 to 7.2
and 6.5 to 7.5, respectively, on the Richter scale. This fault is considered active by the State of
California and an Alquist-Priolo Special Study Zone has been established around this fault.
4
David Evans and Associates, Inc., City of Buena Park General Plan Final Environmental Impact Report,
Table 3-24, Page 3-39, June 28, 1995.
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Sources: Fault lines were obtained from the California Geological Survey, USGS online database, and NASA.
ENVIRONMENTAL IMPACT REPORT
BUENA PARK GENERAL PLAN UPDATE
Regional Faults
09/10 • JN 10-105872
Exhibit 5.7-1
Geology and Seismic Hazards
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Newport-Inglewood Fault Zone. The Newport-Inglewood Fault Zone is located approximately
five miles southwest of the City of Buena Park at its closest point. The Newport-Inglewood Fault
Zone is a series of echelon northwest-trending and vertically-dipping faults extending
approximately 47 miles from the southern edge of the Santa Monica Mountains southeastward to
the offshore area near Newport Beach, the fault zone continues offshore southeasterly past
Oceanside and is known as the Offshore Zone of Deformation. This fault has right-lateral
movement, with a local reverse slip associated with fault steps. The zone is seismically active with
a number of recorded earthquakes, including the historic 6.4 magnitude Long Beach Earthquake.
This fault zone could generate a magnitude 6.0 to 7.2 on the Richter scale or greater credible
earthquake.
Los Alamitos Fault. The Los Alamitos Fault is located approximately three miles southwest of
Buena Park at its closest point. This fault extends approximately eight miles in a northwest and
southeast direction. Cities close to the Los Alamitos Fault include Los Alamitos, Lakewood, and
Bellflower. According to the southern California earthquake data center, the age of the fault is
uncertain and the fault is indistinct. The fault may be part of the larger Compton-Los Alamitos
fault system.
San Andreas Fault. The San Andreas Fault is located approximately 35 miles northeast of Buena
Park at its closest point. The San Andreas Fault extends more than 745 miles over the length of
California. The fault is divided into segments. The San Andreas Fault has a right-lateral strikeslip movement. An earthquake along the San Andreas Fault could affect most of southern
California. Several earthquakes have been historically attributed to this fault. It is estimated by
geologists that this fault may be capable of generating an earthquake of magnitude 6.8 to 8.0 on
the Richter scale, which is the estimated maximum credible earthquake potential.
Sierra Madre Fault. The Sierra Madre Fault is located approximately 20 miles north of Buena
Park at its closest point. The Sierra Madre Fault is classified as a “master” fault and consists of
five primary segments and thousands of feet of vertical and significant left-lateral offsets located
along the base of the San Gabriel Mountains and southward up and over the San Gabriel
Mountains. The fault extends for approximately 47 miles, west to east, from San Fernando to
San Dimas-Claremont. The Sierra Madre Fault Zone segments consist of north-dipping reverse
thrust faults. The slip rate is between approximately 0.36 and 4.0 millimeters per year (mm/yr)
and may be greater at its western terminus of the fault. The Sierra Madre Fault has an expected
magnitude of 6.0 to 7.0 on the Richter scale.
San Jacinto Fault Zone. The San Jacinto Fault is located approximately 35 miles northeast of
Buena Park at its closest point. Segments of this fault extend from San Bernardino southeast
approximately 135 miles through the Imperial Valley, and into northern Baja California. At the
northern end of this fault, a right-lateral strike-slip fault appears to merge with the San Andreas
Fault. Over the past century, the San Jacinto Fault has produced at least ten earthquakes, all with
approximate magnitudes of 6.5 or greater on the Richter scale. Geologic, geodetic, and
seismologic observations generally point to an average slip rate of eight to 12 mm/yr during
Quaternary time. This fault is considered capable of generating earthquakes in the magnitude of
6.5 to 7.5 on the Richter scale.
Palos Verdes Hills Fault. The Palos Verdes Hills Fault is located approximately 15 miles
southwest of Buena Park at its closest point. The fault extends approximately 50 miles in a
northwest and southeast direction. Cities located in proximity to the Palos Verdes Hills Fault
include San Pedro, Palos Verdes Estates, Torrance, and Redondo Beach. This fault is considered
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capable of generating earthquakes with magnitudes of 6.0 to 7.0 on the Richter scale or greater.
Fault geometries may allow only partial rupture during an earthquake event.
San Pedro Fault. The San Pedro Fault is located approximately 30 miles offshore to the
southwest of Buena Park at its closest point. The San Pedro Fault is a nearly vertical fault, which
parallels the Palos Verdes Hills Fault and extends approximately 53 miles in a northwest to
southeast direction. This fault is considered capable of generating earthquakes with magnitudes
of 7.0 on the Richter scale.
San Gabriel Fault. The San Gabriel Fault is located approximately 20 miles north of Buena Park
at its closest point. This fault extends approximately 87 miles in a northwest and southeast
direction from Frazier Park to Mount Baldy Village. Due to the length of the San Gabriel Fault
and its relationship with the San Andreas Fault System, it is considered potentially active. This
fault consists of a zone of echelon strands striking 45 to 65 degrees west of north with dips
between 50 to 80 degrees towards the north. Movement on this fault occurs primarily as a rightlateral strike-slip. The slip rate is approximately one to five mm/yr and recurrence interval
probably varies significantly along the length of the San Gabriel fault zone. The western half of
this fault is probably much more active than the eastern half. The San Gabriel Fault is considered
capable of generating earthquakes with a magnitude of 7.8.
Raymond Fault. The Raymond Fault is located approximately 18 miles north of Buena Park at
its closest point. The Raymond Fault is a north-facing fault, approximately 16 miles in length.
This fault consists of one to three strands that diverge from the foothills of the San Gabriel
Mountains in Sierra Madre to the Adams Hills area of Glendale. Movement on this fault occurs
as a left-lateral, with only minor reverse slip. The Raymond Fault is linked to the Sierra Madre
Fault system. This fault dips at about 75 degrees to the north. There is evidence that at least eight
surface-rupturing events have occurred along this fault in the last 36,000 years. The fault was the
site of the Pasadena Earthquake in 1988. This fault is considered capable of generating
earthquakes in the magnitude of 6.0 to 7.0 on the Richter scale.
Puente Hills Fault. The Puente Hills Fault is a recently discovered blind thrust fault that runs
from northern Orange County to downtown Los Angeles. Specifically, it runs approximately 25
miles from the La Puente Hills region in the southeast to just south of Griffith Park in the
northwest. The fault is referred to as a blind thrust fault due to a lack of superficial ground
features normally associated with thrust faults that have recently experienced seismic activity.
The fault is considered the source of the 1987 Whittier Narrows earthquake. Studies indicate that
the fault has experienced four major earthquakes ranging in magnitude from 7.2 to 7.5 in the past
11,000 years, but that the recurrence interval for these large events is on the order of several
thousand years.
SEISMIC HAZARDS
Hazards associated with earthquake events that could potentially occur within the City of Buena
Park include fault rupture, strong seismic ground shaking, seismic-related ground failure (i.e.,
liquefaction, lateral spreading, and differential settlement), and earthquake-induced landslides
and slope failures.
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Fault Rupture
Only one fault, the Norwalk Fault traverses Buena Park (the north and northeast portions). No
surface faulting has been associated with the Norwalk Fault. Furthermore, the Norwalk Fault is
not a State designated Alquist-Priolo Earthquake Fault Zone; refer to the Regulatory Setting
discussion below. The Los Coyotes Fault is located near, however, outside of the City’s northern
boundary. Therefore, the potential for fault rupture in the City is considered low.
Strong Seismic Ground Shaking
Buena Park is subject to seismic ground shaking due to the close proximity and potential
earthquake magnitude of nearby faults; refer to Exhibit 5.7-1. The extent of ground shaking
depends on the magnitude of the earthquake and the distance between the City and the
earthquake epicenter. Earthquake shaking hazards are calculated considering earthquake
magnitudes and rates, the decrease in earthquake shaking with distance, and amplification of
shaking by soils. The result is expressed as the level of ground shaking (as a percentage of gravity)
that on average occurs every 500 years.
While the Norwalk Fault has the greatest potential of causing the greatest extent of ground
shaking in the City, the Whittier-Elsinore Fault and Newport-Inglewood Fault could also result
in significant ground shaking. The northeastern areas of the City are most susceptible to damage
resulting from an earthquake.5
Seismic-Related Ground Failure
Liquefaction
Liquefaction can be defined as the loss of soil strength or stiffness due to a buildup of pore-water
pressure during a seismic event and is associated primarily with relatively loose, saturated fine- to
medium-grained unconsolidated soils. Seismic ground shaking of relatively loose, granular soils
that are saturated or submerged can cause the soils to liquefy and temporarily behave as a dense
fluid. Liquefaction is caused by a sudden temporary increase in pore-water pressure due to
seismic densification or other displacement of submerged granular soils. Liquefiable soil
conditions are not uncommon in alluvial deposits in moderate to large canyons and could also be
present in other areas of alluvial soils where the groundwater level is shallow (i.e., 50 feet below
the surface). Bedrock units, due to their dense nature, are unlikely to present a liquefaction
hazard. The California Geological Survey maintains a Seismic Hazards Zone Map that depicts
seismic hazards such as liquefaction. According to the Seismic Hazards Zone Map (Los Alamitos,
Anaheim, Whittier, and La Habra Quadrangles)6 liquefaction susceptibility is considered high
throughout the majority of the City; refer to Exhibit 5.7-2, Liquefaction/Landslide Potential. Areas
of potential liquefaction are delineated based on areas of historic occurrence of liquefaction, or
local geological, geotechnical, and groundwater conditions that indicate a potential for
permanent ground displacement. The northeastern portion of the City is generally not mapped
as susceptible to liquefaction, except for those areas adjoining Coyote Creek.
5
Ibid, Page 3-39.
6
State of California Department of Conservation, California Geological Survey Seismic Hazard Zones
Map, http://gmw.consrv.ca.gov/shmp/html/pdf_maps_so.html, Accessed February 22, 2010.
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Lateral Spreading
Lateral spreading is defined as the finite, lateral displacement of gently sloping ground as a result
of pore pressure build-up or liquefaction in a shallow underlying deposit during an earthquake.
The conditions occur when blocks of mostly intact surficial soil are displaced down slope along a
sheer zone that has formed within liquefied sediment. Lateral spreads most commonly occur on
gentle sloping ground, and can have lateral displacement of several feet. Large displacement can
occur if soil conditions have the potential for liquefaction and if seismically induced ground
shaking is of a sufficient duration. According to the California Geological Survey, lateral
spreading is commonly induced by liquefaction of material during an earthquake. Due to the
high susceptibility of liquefaction in the City, the potential similarly exists for lateral spreading;
refer to Exhibit 5.7-2.
Differential Settlement
Differential settlement refers to settlement occurring under conditions of static load, where
subsurface densification occurs by compaction or consolidation of loose cohesionless sediment
due to strong motion. Settlement is characterized by surface cracking and topographic
depressions ranging from a few inches to several feet and horizontal distributed over a few feet to
thousands of feet. Soil conditions subject to settlement include unconsolidated soils or areas
where weak soils of variable thickness overlie firm soil or bedrock. The type of materials that
would most likely experience seismically-induced settlement and differential compaction are
deposits of alluvium, clays, silts, and possibly poorly constructed manmade fills. If structures
were built on such soil conditions, settlement damage could result in the event of strong seismic
shaking. The areas within the City with potential for differential settlement are in the westcentral portion of the City where SR-91 crosses Valley View Street and Orangethorpe Avenue,
and the southern portion of the City along the margins of Carbon Creek; refer to Exhibit 5.7-3,
Differential Settlement and Expansion Potential.
Earthquake-Induced Landslides and Slope Failures
The City is not located within an area identified as having the potential for earthquake-induced
landslides, according to the California Geological Survey Seismic Hazard Zones Map;7 refer also
to Exhibit 5.7-2. However, the areas which are underlain by the Norwalk Fault (northeastern
portion of the City) may be prone to earthquake-induced slope failure.8
GEOLOGIC HAZARDS
The geologic hazards potentially present in the City of Buena Park are landslides and slope
instability and subsidence. Additionally, erosive and expansive soils are potentially present.
7
Ibid.
8
David Evans and Associates, Inc., City of Buena Park General Plan Final Environmental Impact Report,
June 28, 1995, Page 3-42.
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Buena Park General Plan Update
Source: State of California Department of Conservation, Seismic Hazard Zonation Program, Seismic Hazard Zones Map; La Habra, Anaheim, Los Alamitos and Whittier Quadrangels.
ENVIRONMENTAL IMPACT REPORT
BUENA PARK GENERAL PLAN UPDATE
Liquefaction/Landslide Potential
09/10 • JN 10-105872
Exhibit 5.7-2
Geology and Seismic Hazards
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Source: Draft EIR for the Buena Park General Plan Update, August 11, 1994.
Note: Boundaries are approximate.
ENVIRONMENTAL IMPACT REPORT
BUENA PARK GENERAL PLAN UPDATE
Differential Settlement and Expansion Potential
09/10 • JN 10-105872
Exhibit 5.7-3
Geology and Seismic Hazards
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Geology and Seismic Hazards
Landslides and Slope Instability
A landslide is the descent of earth and rock down a slope. Landslides often occur along preexisting zones of weakness within bedrock (i.e., previous failure surfaces). Additionally,
landslides have the potential to occur on over-steepened slopes, especially where weak layers,
such as thin clay layers, are present and dip out-of-slope. Landslides can also occur on antidip
slopes, along other planes of weakness such as faults or joints. Local folding of bedrock or
fracturing due to faulting can add to the potential for slope failure. Groundwater is very
important in contributing to slope instability and landsliding. Additionally, other factors that
contribute to slope failure include undercutting by stream action and subsequent erosion, as well
as the mass movement of slopes caused by seepage or cyclical wetting and drying.
Landslide potential in Buena Park is considered low due to the flat topography of the majority of
the City. However, there is the potential for landslides in the Coyote Hills area due to the sloping
topography.9
Subsidence
Subsidence is normally the result of gas, oil, or water extraction, hydrocompaction, peat
oxidation, and not the result of landslide or ground failure. According to the California
Geological Survey, the City of Buena Park is not mapped as an area containing any significant
mineral aggregate resources.10 There are no known ongoing or planned large-scale extractions of
groundwater, gas, oil, or geothermal energy that would cause subsidence within Buena Park.
Soil Erosion
Soil erosion is defined as the detachment and movement of soil particles by the erosive forces of
wind or water. Wind erosion is a common phenomenon occurring mostly in flat, bare areas; dry,
sandy soils; or anywhere the soil is loose and finely granulated. Water erosion occurs due to the
energy of water, as it falls toward the earth and flows over the surface. Surface water runoff
carries away the detached soil, may detach additional soils, and ultimately deposit sediment
elsewhere. Erosion can be controlled, however, cannot be completely avoided. Soil erosion can
occur naturally or can be accelerated through human activity. As discussed above, the erosion
hazard is slight for the soil types present within the City.
Soil Expansion
Expansiveness, or the potential to swell and shrink with repeated cycles of wetting and drying, is a
common feature of fine-grained clayey soils. The change in volume exerts stress on buildings and
other loads placed on these soils. The occurrence of these soils is often associated with geologic
units having marginal stability. The distribution of expansive soils can be widely dispersed, and
they can occur in hillside areas as well as low-lying alluvial basins. Expansive soils are present on
Knott’s Berry Farm; at the western edge of the City, west of Knott Avenue; north of La Palma and
south of Orangethorpe; in the northeastern portion of the City near the intersection of Fullerton
Creek and Interstate 5; and are expected in the Coyote Hills; refer to Exhibit 5.7-3.
9
Ibid., Page 3-40.
10
Ibid.
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Geology and Seismic Hazards
MINERAL RESOURCES
The City does not contain any significant mineral resources, as identified by the California
Geological Survey. There is no evidence of historic gold mining in the vicinity of the planning
area, and no historic presence of benitoite. No areas of aggregate mineral production are located
within the vicinity of Buena Park, as mapped by the California Geological Survey. Although the
Brea, Carbon, Coyote, and Fullerton Creeks are considered to be a fair to good source of sand,
concrete channels now line the river beds. Surrounding communities have been found to
contain pockets of natural gas and oil; however, they are not believed to extend into the City of
Buena Park.11
AGRICULTURAL RESOURCES
In 1993, approximately 86 acres (one percent) of land within the City were utilized for
agricultural purposes.12 However, current aerial views of the City indicate that previous locations
of agricultural land uses are now developed. The Farmland Mapping and Monitoring Program,
under the California Department of Conservation, produces maps and data used to analyze
impacts to agricultural resources within California. Agricultural land is rated based on soil
quality and irrigation status. According to the Department of Conservation, there is no prime
farmland, farmland of statewide importance, or land enrolled in a Williamson Act Contract
within the City. Land within the City is designated by the Department of Conservation as
“Urban and Built-Up Land.” Although several of the soil types within the City are considered to
meet the criteria for prime farmland, as defined by the Department of Conservation, the City
currently maintains little to no land utilized for agricultural production.
5.7.2
REGULATORY FRAMEWORK
Applicable Federal, State, and local regulatory policies and law that apply to geology, soils, and
seismic conditions are discussed below.
FEDERAL SOIL PROTECTION ACT
The purpose of the Federal Soil Protection Act is to protect or restore the functions of the soil on
a permanent sustainable basis. Protection and restoration activities include prevention of
harmful soil changes, rehabilitation of the soil of contaminated sites and of water contaminated
by such sites, and precautions against negative soil impacts. If impacts are made on the soil,
disruptions of its natural functions and of its function as an archive of natural and cultural
history should be avoided as far as practicable.
ALQUIST-PRIOLO EARTHQUAKE FAULT ZONING ACT
The Alquist-Priolo Earthquake Fault Zoning Act was passed in 1972 to mitigate the hazard of
surface faulting to structures for human occupancy. This State law was a direct result of the 1971
San Fernando Earthquake, which was associated with extensive surface fault ruptures that
damaged numerous homes, commercial buildings, and other structures. The Alquist-Priolo
Earthquake Fault Zoning Act’s main purpose is to prevent the construction of buildings used for
11
Ibid., Page 3-97.
12
Ibid., Table 3-1, Page 3-2.
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human occupancy on the surface trace of active faults. The Act only addresses the hazard of
surface fault rupture and is not directed toward other earthquake hazards.
The Alquist-Priolo Earthquake Fault Zoning Act requires the State Geologist to establish
regulatory zones (known as Earthquake Fault Zones) around the surface traces of active faults
and to issue appropriate maps. “Earthquake Fault Zones” were called “Special Studies Zones”
prior to January 1, 1994. Local agencies must regulate most development projects within these
zones. Before a project can be permitted, cities and counties must require a geologic
investigation to demonstrate that proposed buildings would not be constructed across active
faults. An evaluation and written report of a specific site must be prepared by a licensed
geologist. If an active fault is found, a structure for human occupancy cannot be placed over the
trace of the fault and must be set back from the fault (typically 50 foot setbacks are required).
Effective June 1, 1998, the Natural Hazards Disclosure Act requires that sellers of real property
and their agents provide prospective buyers with a “Natural Hazard Disclosure Statement” when
the property is being sold lies within one or more State-mapped hazard areas, including
Earthquake Fault Zones.
The City of Buena Park is not affected by a State-designated Alquist-Priolo Earthquake Fault
Zone.13
SEISMIC HAZARDS MAPPING ACT
The Seismic Hazards Mapping Act (S-H Act) of 1990 provides a statewide seismic hazard
mapping and technical advisory program to assist cities and counties in fulfilling their
responsibilities for protecting the public health and safety from the effects of strong ground
shaking, liquefaction, landslides, or other ground failure and other seismic hazards caused by
earthquakes. Mapping and other information generated pursuant to the S-H Act is to be made
available to local governments for planning and development purposes. The State requires: (1)
local governments to incorporate site-specific geotechnical hazard investigations and associated
hazard mitigation as part of the local construction permit approval process; and (2) the agent for
a property seller or the seller if acting without an agent, must disclose to any prospective buyer if
the property is located within a Seismic Hazard Zone. The State Geologist is responsible for
compiling seismic hazard zone maps. The Seismic Hazards Mapping Act specifies that the lead
agency of a project may withhold development permits until geologic or soils investigations are
conducted for specific sites and mitigation measures are incorporated into plans to reduce
hazards associated with seismicity and unstable soils.
INTERNATIONAL BUILDING CODE
Development standards require projects to comply with appropriate seismic design criteria in the
International Building Code (IBC) (with California Amendments), adequate drainage facility
design and preconstruction soils and grading studies. Seismic design standards have been
established to reduce many of the structural problems occurring because of major earthquakes.
In 1998, the IBC was revised, as follows:


Upgrade the level of ground motion used in the seismic design of buildings;
Add site amplification factors based on local soils conditions; and
13
California Department of Conservation official website, http://www.conservation.ca.gov/cgs/rghm/
ap/Pages/affected.aspx, Accessed March 5, 2009.
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
Improve the way ground motion is applied in detailed design.
CALIFORNIA BUILDING CODE
California building standards are published in the California Code of Regulations, Title 24,
known as the California Building Code (CBC). The California Code of Regulation, Title 24,
applies to all applications for residential building permits. The CBC consists of 11 parts that
contain administrative regulations for the California Building Standards Commission and for all
State agencies that implement or enforce building standards. Local agencies must ensure the
development complies with the guidelines contained in the CBC. Cities and counties have the
ability to adopt additional building standards beyond the CBC.
BUENA PARK MUNICIPAL CODE
Chapter 13.32 - Stormwater Drainage
Buena Park Municipal Code (Municipal Code) Section 13.32.060, Permit Requirements for
Industrial/Commercial and Construction Activities, specifies that each discharger associated with
construction activity shall comply with all requirements of such permit. Each discharger
identified in an individual National Pollution Discharge Elimination System (NPDES)permit
issued by the U.S. Environmental Protection Agency, the State Water Resources Control Board,
or any regional water quality control board shall comply with and undertake all activities
required by such permit. Proof of compliance with any such permit may be required in a form
acceptable to the director, or his/her designated representative, prior to the issuance of any
Grading, Building or Occupancy Permits, or any other type of permit or license issued by the
City.
Title 15 - Building and Construction Safety
Title 15, Building and Construction Safety, of the Municipal Code is the presiding Building Code
for the purposes of regulating the erection, construction, enlargements, alteration, repair,
moving, removal, conversion, demolition, occupancy, use, equipment, height, area, security,
abatement, and maintenance of buildings or structures in the City. The City has adopted as its
“Building Code” the 2007 California Building Code, incorporating the 2006 International
Building Code (Volumes 1 and 2), including all appendices thereto; refer to Municipal Code
Section 15.56.010, California Building Code - Adopted. Additionally, Chapter 15.80, Earthquake
Hazard Reduction in Existing Unreinforced Masonry Buildings, establishes provisions, which are
intended as minimum standards for structural seismic resistance established primarily to reduce
the risk of life, loss, or injury. The provisions of Chapter 15.80 apply to all buildings constructed
or under construction prior to 1934 or for which a building permit was issued prior to 1934,
which on the effective date of the ordinance codified in this chapter have unreinforced masonry
bearing walls.
Title 18 Division I - Subdivisions
The City’s Subdivision Ordinance (Municipal Code, Title 18 Division I, Subdivisions) establishes
regulations, which are intended “to provide for proper grading and erosion control, including the
prevention of sedimentation or damage to off-site properties.” According to Municipal Code
Section 18.32.080.A.9, a Geological and/or Soils Report, if required by the City Engineer, shall be
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prepared by a licensed geologist and/or registered soils engineer, shall be required for each
tentative map, stating the effect of geological or soil conditions on the proposed development.
According to Municipal Code Chapter 18.72, Soils Reports, a Preliminary Soils Report, prepared
by a Soils Engineer registered in this State, and based upon adequate test borings, shall be
required for every subdivision, unless waived by the City Engineer. If the preliminary soils report
indicates the presence of critically expansive soils or other soils problems which, if not corrected,
would lead to structural defect, a soils investigation of each lot in the subdivision may be
required. Such soils investigation shall be done by a soils engineer registered in this State, who
shall recommend the corrective action which is likely to prevent structural damage to each
structure proposed to be constructed in the area where such soils problem exists.
5.7.3
SIGNIFICANCE THRESHOLD CRITERIA
Appendix G of the CEQA Guidelines contains the Initial Study Environmental Checklist, which
was included with the Notice of Preparation to show the areas being analyzed within the EIR;
refer to Appendix A of this EIR. The Initial Study includes questions relating to geology, soils,
and seismicity. The issues presented in the Initial Study Checklist have been utilized as
thresholds of significance in this Section. Accordingly, geology, soils, and seismicity impacts
resulting from the implementation of the proposed General Plan Update may be considered
significant if they would result in the following:

Expose people or structures to potential substantial adverse effects, including the risk of
loss, injury or death involving;
-
Rupture of a known earthquake fault, as delineated on the most recent AlquistPriolo Earthquake Fault Zoning Map issued by the State Geologist for the area or
based on other substantial evidence of a known fault;
-
Strong seismic ground shaking;
-
Seismic-related ground failure, including liquefaction;
-
Landslides;

Result in substantial soil erosion or the loss of topsoil;

Be located on a geologic unit or soil that is unstable, or that would become unstable as a
result of the project, and potentially result in landslides, lateral spreading, subsidence,
liquefaction or collapse;

Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code,
creating substantial risk to life or property; and/or

Have soils incapable of adequately supporting the use of septic tanks or alternative waste
water disposal systems where sewers are not available for the disposal of waste water (refer
to Section 8.0).
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Based on these standards, the proposed project’s effects have been characterized as either a “less
than significant impact” or a “potentially significant impact.” Mitigation measures are
recommended to avoid or lessen impacts. If a potentially significant impact cannot be reduced to
a less than significant impact level through the application of mitigation, it is categorized as a
significant unavoidable impact.
5.7.4
IMPACTS AND MITIGATION MEASURES
STRONG SEISMIC GROUND SHAKING
 IMPLEMENTATION OF THE PROPOSED GENERAL PLAN UPDATE COULD
EXPOSE PEOPLE AND STRUCTURES TO POTENTIAL SUBSTANTIAL ADVERSE
EFFECTS INVOLVING STRONG SEISMIC GROUND SHAKING.
Impact Analysis: The City is located within a seismically active region of southern California.
As illustrated on Exhibit 5.7-1, the Norwalk Fault traverses the north and northeast portions of
Buena Park. Additionally, the Los Coyotes Fault is located near the City’s northern boundary
and several active faults that can generate ground shaking in Buena Park are located within 50
miles of the City. The intensity of ground shaking within the City would depend upon the
magnitude of the earthquake, distance to the epicenter, and the geology of the area between the
epicenter and the City. The possibility of moderate to high ground acceleration or shaking in the
City may be considered as approximately similar to the Southern California region as a whole.
Development under the proposed General Plan Update would result in the addition of
approximately 1,517 dwelling units and the development of approximately 8.3 million square feet
of non-residential uses, thereby exposing a greater number of residents, employees, and patrons
to the effects of strong seismic ground shaking from locally and regionally generated earthquakes.
Potential damage to existing and new structures would be slight to moderate, although severe
damage to vulnerable buildings cannot be precluded.14 Additionally, damage to infrastructure,
including roadways, bridges, water and wastewater lines, gas lines, power poles, storm drainage,
and other public facilities, could occur due to an earthquake event. However, numerous controls
would be imposed on future development through the City’s permitting process that would
lessen impacts associated with strong seismic ground shaking, among other hazards discussed
below. The design, construction, and engineering of structures within the City would be subject
to compliance with Municipal Code Title 15, Building and Construction Safety, which adopts as
the City’s Building Code the 2007 CBC. The effects of strong seismic ground shaking would be
sufficiently mitigated for structures designed and constructed in conformance with the CBC and
industry-accepted engineering standards. Additionally, strong seismic ground shaking could
result in partial to total collapse of existing unreinforced masonry buildings. Structural
vulnerabilities in older buildings that are less earthquake resistant are most likely to contribute to
the largest source of injury and economic loss, as a result of an earthquake. Most of the existing
homes in the City were constructed prior to the adoption of modern building codes, which have
been established to reduce seismic impacts on structures. Any future modifications to buildings
constructed prior to 1934 would be subject to compliance with the CBC and Municipal Code
Chapter 15.80, Earthquake Hazard Reduction in Existing Unreinforced Masonry Buildings, which
establish minimum standards for structural seismic resistance.
14
Ibid., Page 3-42.
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Compliance with the Municipal Code Title 15 (and CBC) would promote public safety and
welfare by reducing the risk of loss, injury, or death that may result from the effects of strong
seismic ground shaking due to earthquakes. Additionally, the City has identified protective
measures within the Policies and Implementation Measures incorporated into the proposed
General Plan Update, which are intended to decrease the potential risk of seismic and geologic
hazards to the community. These acknowledge safety concerns pertaining to strong seismic
ground shaking. Less than significant impacts involving the exposure of people and structures to
potential substantial adverse effects involving strong seismic ground shaking would occur with
implementation of the proposed General Plan Update, following compliance with the CBC,
Municipal Code, and General Plan Update Policies and Implementation Measures specified
below.
Proposed General Plan Update Policies and Implementation Measures:
Policies
SAF-1.1:
Seek to avoid or minimize seismic risk by appropriately designating land uses and
adhering to current building codes.
SAF-1.2:
Enforce the requirements of current building codes relative to seismic design for
all new development or redevelopment.
SAF-1.3:
Require geologic and soils reports for all new development or redevelopment,
especially in identified areas of the Norwalk Fault Zone and areas with high
liquefaction potential.
SAF-1.4:
Require appropriate mitigation measures and/or conditions of approval relative to
terrain, soils, slope stability, and erosion for new development or redevelopment
in order to reduce hazards.
SAF-1.5:
Ensure that schools, hospitals, and critical facilities, such as fire, police, or
emergency service facilities, are constructed with the standards outlined in Title 24
of the California Administrative Code.
Implementation Measures
SAF-1
Maintain the City’s Emergency Operations Plan, which provides a comprehensive
emergency management program for the City.
SAF-2
The City will periodically conduct mock disaster exercises on a department-wide
and City-wide basis to familiarize those City departments participating in the
City’s emergency operations, with the City Emergency Operations Plan, and to
prepare them to respond in an appropriate and timely manner in the event of an
emergency or disaster.
SAF-5
Utilize existing fault zones to guide the location of development and utilities to
safe areas, and enforce use restrictions where necessary. Where development is
proposed within the zone, require study of potential impacts related to fault
movement in the design of all structures, roadways, utility lines, and other
facilities.
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Geology and Seismic Hazards
SAF-17
Using the City’s website, City publications, or other methods (such as pamphlets),
provide public safety education/information, focusing on in-city natural or manmade hazards; the prevention of life or property-threatening events; and the
appropriate preparation for and reaction to local or regional disasters by the
public.
SAF-18
Develop programs that inform and educate the community about potential risks,
resources and roles and responsibilities for addressing safety.
Mitigation Measures: No further mitigation is required beyond compliance with the
proposed General Plan Update Policies and Implementation Measures.
Level of Significance: Less Than Significant Impact.
SEISMIC-RELATED GROUND FAILURE
 IMPLEMENTATION OF THE PROPOSED GENERAL PLAN UPDATE COULD
EXPOSE PEOPLE AND STRUCTURES TO POTENTIAL SUBSTANTIAL ADVERSE
EFFECTS
INVOLVING
SEISMIC-RELATED
GROUND
FAILURE
(I.E.,
LIQUEFACTION AND LATERAL SPREADING, DIFFERENTIAL SETTLEMENT, AND
EARTHQUAKE-INDUCED SLOPE FAILURE).
Impact Analysis: The City would be at risk due to seismic-related ground failure involving
liquefaction and lateral spreading, differential settlement, and earthquake-induced slope failure.
Liquefaction and Lateral Spreading
Liquefaction susceptibility is considered high throughout the majority of the City; refer to Exhibit
5.7-2. The northeastern portion of the City is generally not susceptible to liquefaction, except for
those areas adjoining Coyote Creek. Due to the high susceptibility of liquefaction in the City, the
potential similarly exists for lateral spreading.
Differential Settlement
The areas within the City with potential for differential settlement are in the west central portion
of the City where SR-91 crosses Valley View Street and Orangethorpe Avenue, and the southern
portion of the City along the margins of Carbon Creek; refer to Exhibit 5.7-3.
Earthquake-Induced Slope Failure
There are no areas within the City at risk due to earthquake-induced landslide potential; refer to
Exhibit 5.7-2. The areas underlain by the Norwalk Fault (northeastern portion of the City) may
be prone to earthquake-induced slope failure.
As discussed previously, numerous controls would be imposed on future development through
the City’s permitting process that would lessen potential impacts associated with seismic-related
ground failure involving liquefaction and lateral spreading, differential settlement, and
earthquake-induced slope failure. A Geological and/or Soils Report may be required for each
tentative map, as determined by the City Engineer, stating the effect of geological or soil
conditions on the proposed development; refer to Municipal Code Section 18.32.080.A.9. Also, a
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Preliminary Soils Report may be required for every subdivision, as determined by the City
Engineer; refer to Municipal Code Chapter 18.72, Soils Reports. Development would be evaluated
by the City Engineer on a site-by-site basis, in order to determine potential for seismic-related
ground failure and soil problems. Additionally, the design, construction, and engineering of
structures within the City would be subject to compliance with the CBC pursuant to Municipal
Code Title 15. The potential effects of seismic-related ground failure involving liquefaction and
lateral spreading, differential settlement, and earthquake-induced slope failure, would be
sufficiently mitigated for structures designed and constructed in conformance with corrective
actions recommended in the Geological and/or Soils Report, and CBC and industry-accepted
engineering standards. Additionally, the City has identified protective measures within the
Policies and Implementation Measures incorporated into the proposed General Plan Update,
which are intended to decrease the potential risk of seismic and geologic hazards. Less than
significant impacts involving the exposure of people and structures to potential substantial
adverse effects involving seismic-related ground failure (i.e., liquefaction and lateral spreading,
differential settlement, and earthquake-induced slope failure) would occur with implementation
of the proposed General Plan Update, following compliance with the CBC, Municipal Code, and
proposed General Plan Update Policies and Implementation Measures.
Proposed General Plan Update Policies and Implementation Measures:
Policies and Implementation Measures identified above.
Refer to
Mitigation Measures: No further mitigation is required beyond compliance with the proposed
General Plan Update Policies and Implementation Measures.
Level of Significance: Less Than Significant Impact.
SOIL EROSION
 IMPLEMENTATION OF THE PROPOSED GENERAL PLAN UPDATE COULD
RESULT IN SUBSTANTIAL SOIL EROSION OR THE LOSS OF TOPSOIL.
Impact Analysis: The soil types present within Buena Park are: Bolsa silt loam, drained; Metz
loamy sand; Metz loamy sand, moderate fine substratum; San Emigdio fine sandy loam; San
Emigdio fine sandy loam, moderately fine substratum, Mocho Loam; Chino-Silty Clay Loam,
drained; and Corralitos, loamy sand. For these soil types, runoff is slow and the erosion hazard is
slight, if the soil is bare. However, the City of Buena Park is urbanized and approximately 98
percent built-out. Therefore, surface soils in the City may no longer reflect the natural soil
associations and characteristics described above, since the City’s topsoil has been predominately
replaced through development.
Clearing, excavation, and grading associated with future development could expose soils to
substantial short-term soil erosion or loss of topsoil, since fill material of unknown origin and
varying composition currently covers most of the City. Grading Plans for proposed
developments would include an approved drainage and erosion control plan to minimize the
impacts from erosion and sedimentation during grading. Additionally, development sites that
encompass an area of 1.0 acres or greater would be subject to compliance with the NPDES
program’s General Construction Permit requirements and consequently the development and
implementation of a Storm Water Pollution Prevention Plan (SWPPP); refer to Section 5.8,
Hydrology and Water Quality. Pursuant to Municipal Code section 13.32.060, Permit
Requirements For Industrial/Commercial and Construction Activities, specifies that each discharger
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Geology and Seismic Hazards
identified in an individual NPDES permit shall comply with and undertake all activities required
by such permit. Proof of compliance with any such permit may be required in a form acceptable
to the director, or his/her designated representative, prior to the issuance of any Grading,
Building or Occupancy Permits, or any other type of permit or license issued by the City. Thus,
in compliance with NPDES requirements, the City requires the contractor to submit a SWPPP to
the City for review/approval. The SWPPP would identify Best Management Practices (BMPs) for
control erosion and pollutant transport. During construction, the contractor would implement
the SWPPP. Given future development would be subject to compliance with the City’s
standards, as well as NPDES General Construction Permit (i.e., SWPPP) requirements for
erosion control, grading, and soil remediation, less than significant impacts are anticipated in this
regard.
Additionally, the City has incorporated into the proposed General Plan Update Policies and
Implementation Measures, which are intended to improve water quality resulting from storm
and urban runoff from existing and future development. Less than significant impacts involving
soil erosion would occur with implementation of the proposed General Plan Update, following
compliance with the NPDES requirements and General Plan Update Policies and
Implementation Measures specified below.
Proposed General Plan Update Policies and Implementation Measures:
Policies
CF-6.5:
Continue to participate in the National Pollutant Discharge Elimination System
(NPDES) permit program.
CF-6.6:
Require new development or redevelopment projects to provide a Water Quality
Management Plan in compliance with the Regional Water Quality Control Board
requirements.
CF-7.1:
Cooperate in regional programs to implement the National Pollutant Discharge
Elimination System (NPDES) program.
CF-7.6:
Require new development and significant redevelopment to utilize site
preparation, grading and best management practices that provide erosion and
sediment control to prevent construction-related contaminants from leaving the
site and polluting waterways.
Implementation Measures
CF-32
Continue to require the implementation of adequate erosion control measures for
development or redevelopment of projects in order to minimize sedimentation
damage to drainage facilities.
CF-33
Utilize development fees, redevelopment funds, drainage fees and other funding
sources to assure that development of drainage facilities corresponds with
development within the City.
CF-34
Identify and improve areas experiencing localized storm drainage problems for
storm drain improvements.
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CF-35
Create public education information and outreach materials regarding proper
materials handling practices to assist residents and businesses in complying with
surface water quality regulations and to increase awareness of potential impacts to
the environment resulting from improper containment or disposal practices.
SAF-9
Encourage use of Low Impact Development (LID) methods that capture and treat
water on-site, therefore, reducing flows to storm drain system.
Mitigation Measures: No further mitigation is required beyond compliance with the
proposed General Plan Update Policies and Implementation Measures.
Level of Significance: Less Than Significant Impact.
UNSTABLE GEOLOGIC UNITS AND EXPANSIVE SOILS

IMPLEMENTATION OF THE PROPOSED GENERAL PLAN UPDATE COULD
EXPOSE PEOPLE AND STRUCTURES TO POTENTIAL SUBSTANTIAL ADVERSE
EFFECTS, INCLUDING RISK TO LIFE OR PROPERTY, INVOLVING UNSTABLE
GEOLOGIC UNITS (SLOPES) AND EXPANSIVE SOILS.
Impact Analysis: Landslide potential in Buena Park is considered low due to the flat
topography of the majority of the City. However, there is the potential for landslides in the
Coyote Hills area due to the sloping topography. Additionally, expansive soils are present on
Knott’s Berry Farm; at the western edge of the City, west of Knott Avenue; north of La Palma
Avenue and south of Orangethorpe Avenue; in the northeastern portion of the City near the
intersection of Fullerton Creek and Interstate 5; and are expected in the Coyote Hills; refer to
Exhibit 5.7-3. Given these conditions are known to be present in the City, future development
could be located on unstable geologic units or expansive soils, creating risk to life or property.
Numerous controls would be imposed on future development through the City’s permitting
process that would further lessen potential impacts associated with unstable geologic units and
expansive soils. A Geological and/or Soils Report may be required for future development, as
determined by the City Engineer; refer to Municipal Code Section 18.32.080.A.9 and Municipal
Code Chapter 18.72. Such reports would state the effect of geological or soil conditions on the
proposed development and recommend the corrective action, which is likely to prevent
structural damage to each structure proposed to be constructed in the area where soil problems
exist. Development would be evaluated by the City Engineer on a site-by-site basis, in order to
determine potential hazards associated with unstable geologic units and expansive soils.
Additionally, the design, construction, and engineering of buildings within the City would be
subject to compliance with the CBC pursuant to Municipal Code Title 15. According to the
California Building Code, special foundation design consideration must be employed where
expansion potential exists. The potential effects of unstable geologic units and expansive soils
would be sufficiently mitigated for buildings designed and constructed in conformance with
corrective actions recommended in the Geological and/or Soils Report, and CBC and industryaccepted engineering standards.
Additionally, the City has identified protective measures within the Policies and Implementation
Measures incorporated into the proposed General Plan Update, which are intended to decrease
the potential risk of geologic hazards. Less than significant impacts involving the exposure of
people and structures to potential substantial adverse effects involving unstable geologic units
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Geology and Seismic Hazards
and expansive soils would occur with implementation of the proposed General Plan Update,
following compliance with the CBC, Municipal Code, and proposed General Plan Update
Policies and Implementation Measures.
Proposed General Plan Update Policies and Implementation Measures:
Policies and Implementation Measures identified above.
Refer to
Mitigation Measures: No further mitigation is required beyond compliance with the proposed
General Plan Update Policies and Implementation Measures.
Level of Significance: Less Than Significant Impact.
5.7.5

CUMULATIVE IMPACTS
FUTURE DEVELOPMENT RESULTING FROM IMPLEMENTATION OF THE
PROPOSED GENERAL PLAN UPDATE COULD RESULT IN CUMULATIVE
IMPACTS RELATED TO SEISMIC, GEOLOGIC, AND SOIL CONDITIONS.
Impact Analysis: Although conditions conducive to potential seismic and geologic hazards
occur regionally, the increased exposure of people and structures to these hazards resulting from
buildout of the proposed General Plan Update would be specific to the City of Buena Park.
However, increased growth within the subregion, as a result of the proposed General Plan Update
and other projects, would contribute to the cumulative exposure of people and structures to
geologic and seismic hazards. As concluded above, impacts related to seismic, geologic, and soil
conditions associated with implementation of the proposed General Plan Update would be less
than significant with adherence to the CBC, Municipal Code, and NPDES requirements. Unsafe
seismic, geologic, and soil conditions exist throughout southern California and new development
in such areas could result in potentially significant impacts. These potential impacts would be
evaluated on a project-by-project basis in accordance with CEQA. If a specific site were
determined to create a significant impact that could not be feasibly mitigated, the site would not
be appropriate for development. Individual development projects under the proposed General
Plan Update would undergo site-specific evaluation to determine threat and the cumulative
threat of regional seismic and geologic hazards. This process, along with compliance to Federal
and State laws, local building codes, and public safety standards would result in less than
significant cumulative impacts related to potential seismic, geologic, and soil hazards.
Implementation of the proposed General Plan Update would not result in cumulatively
considerable impacts involving seismic and geologic hazards.
Proposed General Plan Update Policies and Implementation Measures:
Policies and Implementation Measures identified above.
Refer to
Mitigation Measures: No further mitigation is required beyond compliance with the proposed
General Plan Update Policies and Implementation Measures.
Level of Significance: Less Than Significant Impact.
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Geology and Seismic Hazards
5.7.6
SIGNIFICANT UNAVOIDABLE IMPACTS
All impacts related to potential seismic, geologic, and soil hazards associated with
implementation of the proposed General Plan Update for the City of Buena Park would be less
than significant by adherence to and/or compliance with the existing regulatory framework, and
proposed General Plan Update Policies and Implementation Measures. No significant
unavoidable seismic, geologic, or soil impacts would occur as a result of buildout of the proposed
General Plan Update.
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