HomeMy WebLinkAbout77-47B 6rd 111r tr-i7uvr
7011CALUATip1v
Mnitimunf Larthqunk4 irriclalli ed _
Fauna Il li,Ialor Magnlludn) in County Intensity Esllmatnd liodruck
tRedltilo+� lL_ rrl. Acceleration lrr Count Distance
Cleveland Hill Mnxlmunt 11v-, or N�axlmum ultra nY Fram jaunty
10 Milos Lon Rf n 4 0, '� "^ --,fL Dom County Q Strike 511 Ndr i, I 4 *-Y+, . Rom
Midland - SvO(ror ' Vlll VIl a,45 -0,6g + O,i
0 Miles Long � C,l vorasrlko Slip 7,7 6,0.6.9 VIII -ix Vill 0.1.0:2� F 40 MIn usty Active Fault
Heyward - „ 0,1 0, a7 s
160 Miles Lon , U Souln Sauthwast Active Fcult
S 5.rlka Slip 7,0 �; 7.0
San Andreas Fault Zane N, Vil V1 0.09"0. * 70 Mlles
200 Miles Lan r section 1f1 �' tl.Otig 'saulfrwest
iX-'irlka Slip 0 3 0 9 Active Fault
Unit CK-Jhce • llenoy Lake Vii VI -Vit 0,05 4 95 MUos
CNt, 100 M11es Long S - 0.Ohq Southwest
7,0 Activa. Fault
Russell Valley 5.0-5,9 VI11 VJI+ 50 Miles
10 Miles Long O,i-0,2g + O,t Cast
615 Active Pauit
Foothills Shoe Zorro 6''S Vil VI 0 50 Miles
, 069 a.0rlg East
Active Faul}
1'10 M1105 Long - Wends
S. of 113 Ix
5`7 VllfSo c Into f?btentiali
yliilows 0•6.0.90 0. 25-0. 4g Southth Count
+ 40 M40 Long y Active
Unnamed Fruit Near Dunnlgnn 7.9 $.0.5, 9 VIII VU -Vitt
# 18 Miles long g 6 ?Alteg West Potentially Active
I -i 6,7 4.0-4,4 Vill
hl Sutter, Butte VI O,tl5-0.15g + O t
i G Sn1all Faults, 2.4 Miles Luny 5 i _ i g ^ 70 Mile's South Potentially Active
! 5,0 4,Ou4.G VI
,A Co'"' Rtingt+ Thrust Zano V -VI O.iIS-O,tlg �. 0,2
" 700 Miles Long g 5-0 Miles South Potentially Active
Big Bend Fault Zona a+25 4,0-r1,� IkrX VIiI
0,2.0,259 0.1-0.12cJ + 95 Allies tarsi
9a Nilies Long Potentially 7.1 + 6,01 ix -x y Active
Camef3 peak. VIII. -IX 0,5-0.Bg 0.2-0,39 1rt Count
132 Miles Long y Potentially Active
7,1 f 6,01 �xwx
Moloney - Dagwoad peak ' VIII*I?C 0,5-0.ag 0.2-0,91 Borders gaunt
} 200 idile% Long 0;3 610 y potentially Active
Hawkins Valley " X..Xil Ix -x
0,5+0,559 0.
170 Miles Lang 15 + 7-12 Mlles Enst .. Potentially Active
7.6 6,0 IX VIII
'See Appendix B for deiinition. 0.2-0,38 0' 15-0,2g ± 25 Miles East Potentially Active
4 t Ieidar, Ro rzr, j
Geology, g 1972. Afa�imum Fxpnctor! t?adronk dccalarattons from Earthquakes fn C
alt/ornla, California Division of Mines and
llousner, G. W, 1955,. Intensity of Earthquake Ground Shakia 4 g ,
Earthquake tnDtncertn9, ,Vow Zealand, Volume i,
g Near the Causative Fault, Pro eedtn a 3rd World
No%"ll, B. F. and Schultz T, Y I COnjrrnncc on
R, 1975, AHonuatlon of Atodiffed Atercaiti Intanstt ivtth b7stancc o
Se(nanoloytcal Soctety of Amertea, Vol. 55, Na, 3 r
Jenkins, 0. P. 1962, i pp. G r1�Gfi3, from tiro Epicenter, Buliettn of the
Ci,otogto Alap of Caltfcrnia Chico Shoot, California Division of Minas and Geology,
Jennings, Charles, 1975,
F'oult Atap of California, California Division of Mines and Ceology;
5chnatiei p. f3., I�Seed,
Research Center July 1972. Aacelarattons to Rook for Earthquakes to Western tlr,'.t
s. Department of Commerce, National Oceanic and Atmos ed States; Earthquake Engineering
Terrestrial Rata Center, Earthquake Data Pae. Atmospheric Administration, Environmental Data service, National Geophysical and. Solar-
of ground shaking in Butte County are probably the Hayward-
Calavoras faults, the San. Andreas fault, tho Midland-Sweitzer
favltt the Last Chance -Honey Lake fault zones, and small
unmapped faults at scattered locations in the. foothills and
mountains of Butte County and tba surrounding area, The
Hayward --Calaveras and San Andreas faults have recurrence
intervals such that seismic activity of magnitude 7 and 8
can be anticipated every 100 to 500 years, However, the
long distance of these fault systems from Butte County
should attenuate the ground motion and produce only moderate
intensity ground shaking in the County.
The recurrence interval of earthquakes on the Midland-
Sweitzer fault is not documented. However, large magnitude
earthquakes generated by this fault can be anticipated and
could result in moderate to intense ground shaking in the
county. The degree of ground shaking can be expected to
vary with the type of soil; however, a Modified Miercalli
intensity of VIII could be expected in much of Butte County.
The recurrence interval of the Last Chance -Roney Lake fault
zones is also not known. Ground shaking from these faults
could vary from moderate to severe depending upon the typeq
of soil in the area. The maximum credible earthquake in
this fault zone is considered to be 7.8 Richter and could
result in slight -to moderate ground motion in Butte County.
Local earthquakes ' could result from movement on small faults
similar to those of the Cleveland Hill fault, Geologic and
seismic data indicate tlrtit small faults can. exist throughout
the foothills and mountains Of Butte County. Assuming these
small faults exist, and applying the "floating earthquake"
concept,earthquakes could result in moderate to severe
ground shaki ng similar to the ground shaking from the 1975
oroville earthquake,
ff. PREDICTED 2VPL-CTS OV EARTUQUAXE-53
Large earthquakes are historically associated with surface
ruptures localized along the Main surface traces of striko-
slip or thrust faults. Geologic data indicates the general
displacement of the ground surface along a fault in Butte
county may be horizontal along with some vertical movement.
The break pattern is typically expressed by an echelon
pattern of ground fractures that trend obliquely to the
overall trace of the fault (this was observed at the Cleveland
Hill fault in 1975). The fractures normally displace from a
few inches to several feet, and the surface zone of major
faults ranges in width from a few feet to several hundred
feet or more.
Based upon geologic evidence and seismicity data, the
estimated length of surface rupture for a typical Butte
County fault may range from 6 to 25 miles. Locally, branch
faults may also move, but movement on these lesser faults
would be much more difficult to predict.
There is insufficient historical( geologic, and seismological
data available to make a realistic estimate of the ground
notion resulting from potentially active faults.
1. Ground shaking
The character of ground shaking from a postulated earthquake
is dependent on many factors. 1-4ost important is the character
o I f the earthquake source (type of off8ett,magnitude, location,
size,of rupture, and stress drop). A second important
factor is the distance from the associated rupture surface
or earthquake to the area affected by the earthquake. The
third important factor is the: type of local geologic Material.
(Housnert Strong Ground Motion in Earthquake Engineering.)
11-16
To predict ground shaking in butte Coljnty the fin't stop is
to estimate the b0drOOk motion at var'" 5
locations In the
County. The bedrock shaking amplitude :dor Butte County was
approximated by usjnq data proposed by Greensfel.der fcr the
continuation of bedrock motion versus distances from the
fsault. An essential consideration is the effect of geological
Conditions in -the near surface amplification of the shock -
waves as they travel; up '.through the layered ro2k and soil.
There are not enough g' geologic and seismic data available in
Butte County to accurately estimate seismic: or ground
response at a particular site. Therefore, estimates are
based upon data obtained from other localities in California:
The anticipated maximum ground shaking intensity across all
Of Butte County is vlll on -the- Modified Mercalli scale;
however, the intensity could vary locally from v1I to IX,
depending on the type and location of the fault (see
Table 11-1).
2. Liquefaction
Liquefaction is defined as the transformation of a granular
material from .a solid state into a liquified state as a
consequence of increasedore--water
p pressure (1'oud Lique-
faction, Flow, and Associated Ground Fai.lare),. Liquefaction
occurs when there is a sudden but temporary increase in the
fluid pressure between -the soil grains caused when the
weight of the overlying 'soil or structure is temporarily
supported by the water and not the soil grains.
The method commonly used for estimating liquefaction poten-
tial is based upon the E% ified procedure for Evalu pt#g
$O l�Liquefaction Potential, by Seed and Idris, Journal, of'
Soil Mechanics and Foundations Division, (ASCE 1971j, This
11-17
a�
procedure was developed for ol,f, .in sandy soils w4th rel,ativ
densities lass than 40 pe,rOent deposited in relatively Level
areas. Because the slope of the alluvial plains surrounding
the Sacramento Valley is small., this method can be applied
to most of the valley area. It cannot, however, be applied .
to sloping ground of mountainous terrain..
Us'inq assumel soil parameters and a moderato intensity
earthquake, it is concluded that granular soils with relative
densities less than 65 percent that are located beneath the
free -water surface have a high potential, for liquefaction
during moderate or strong ground shaking. The liquefaction
potv-ntial of the Sacramento Valley can be generally summarized
as follows:
Clean, granular sediment (particularly sands)
below the water table with a relative density of
less -than 65 percent should be considered to have
high liquefaction potential during moderate or
strong ground motion.
* Clean, granular sediment with relative densities
greater than 90 percent should have low lique-
faction potential even in strong ground motion.
i Clean, granular sediment with relative densities
between 65 to 90 percent should have moderate
liquefaction potential, depending upon intensity
and duration of the ground shaking, site conditions,
and the textural properties of the sediments.
Map I1-2,del,ineates zones estimated to have low, moderate,
or high liquefaction potential.. The zones were derived from
geologic investigations of the unconsolidated sediments of
the Sacramento V'al,ley. The liquefaction potential of granular
xl:-"18
layers was estimated from the available literature at the
University of California BaxthquaXe 'ngineeri.ng Research
Center regarding relative density, water table, lithology
and seismicity.
,areas paralleling the Sacramento River containing cleat sand
layers were estimated to have a generally high I'quefaotion
potential. Granular layers underlying the most of the
Sacramento Valley have a slightly higher relative density
and are thought to have a somewhat~ lower liquefaction poten-
tial and are classed as moderate risk. Clean layers of
granular material of Pleistocene or older age are of even
higher relative density and therefore are esitmated to have
a low potential for liquefaction. Areas of bedrock throughout.
the Sierra Nevada are assumed to have no liquefaction poten-
tial; however, localized areas of valley fiU consisting of
Recent sand and gravel alluvium can have moderate to high
liquefaction potential.
The zones delineated in this investigation as havit: lique-
faction potential indicate only general areas in wi the
liquefaction may occur in clean, saturated, granular layers.
current data are not adequate for accurate mapping and do
not provide an indication of the extent of ground failure
that night follow liquefatatiov The 'estimated liquefaction
potential of each of these tiones is based upon limited soil
and geologic data generalized to include an entire map unit.
Thereforer Map 11-2 must be considered approximate and
invalid for direct determination, of liquefaction potential
on a`specific site. The map does, however, indicate areas
where the probability of liquefaction exists during a major*
earthquake
IT -19
3. Seiches
A seiehe is a periodic oscillation of a body of water such
as a river, lake, harbor, or bay resulting from seismic or
other causes. The period of the oscillation may vary from a
few minutes to several hours. Seiche effects have not been
recorded ipF any of th4 reservoirs in Butte County t~ha.t are
within the jurisdiction of the state of California Division
of Safety of Dams.
The assessment of hazards from water waves is very difficult
due to the limited historical data, and geological knowledge
of the areas surrounding the reservoirs in Butte county.
Crude methods are presently available for assessing the
amplifying effect of the coastal. topography and for mapping
potential areas of inundation from dam and reservoir failure
or from landslide-genora.ted waves that may overtop a dam
crest. It appears, however, that water waves resulting from
a large landslide are a much greater seismic hazard in Butte
County than a seiche.. According ,to the TJ.S. Geological:
Survey, the near failure of the Van Norman Reservoir was ,due
to liquefactica and landslides during the 1967 San Fernando
earthquake, requiring the evacur.tion of 80,000 people below
the dam;
4. Landslides
Zn earthquake a.n Butte County ,with a postulated Richter
magnitude of,6 or larger could cause landslides it the area
of intense g ound motion near the fault. may- Landslides
be ek -tile
could if the postulated earthquake were to happen
during the wet season and in areas of high ground water
levels,or saturated soils, particularlyin areas of moderate
or high landslide potential (see Safety Element; Section
III). It is likely that existing Landslides would lrj�ve
11-20
renewed or increased movement and that new landslides- would
occur around Lake Oroville. If- the postulated earthquake
were to occur during ca dry season and in areas of low ground
water levels, the amount of landsliding would probably be
much less. No landslides wore noted in reports regatding
the 1975 Oroville earthquake, which occurred during a dry
neason in an area of moderate landslide potential.
5, Dam Safety
There are 26 dams in Butte County which are under California
Division of Safety of Dams jurisdiction. Of these, 18 are
earthfill embankments, three are gravity concretei three are
variable rad;us concrete arch, one is rock embankment, and
one is hydraulic fill. All of these dams are inspected each
year by Division personnel. The Division of Safety of Dams
has no knowledge of any dam within the County that could
presently'be considered a safety hazard under the Division's
seismic evaluation criteria.
1'aulp II_7. SrXSMlt3 SAL'BTY 1ZLrMLN
VINDINGu
--
POLICY
1, Butte County is in an area of known
faults and recent seismic
1, zr,Foriir klre public of current
IMPLEMGNmA'Y'ION
activity,
Xwttm�Ith of seismic curren in
1. Approve and publish this plan
all parts of the County.
clement. Y,eep the information:
2i Tile only known ncti.ve fault in
2.
up-to-date.
Butte County is LIAO Cleveland
Hill fault near Oroville. A
Take into account all .known
seismic inPnrmation Jn making
2a Consider the most recent 3rifox�
number
of faults in or near the County
land use decisions. Avoid
ma ion on seismic racers in all
zoning
should be considered potent
locating schools, hospitals,
and subdivision decisions.
Active. The prow ,9.ty of the San
e Sall
and similar user to known fault
Andreas fault sl' ,esti is generally
significant in oValuaUng
ureas,
seismic
risk in the County.
H
I -I
I
b Require appropriate detailed
N
seismic investigations for all
public and, private projects in
3. xhc� area around the Cleveland Hill
3,
locations of known ,seismic risk.
fault has been designated as a S e-
tial Studies Zone under the Alquist-
Follow the polici6a and criteria
established by the State Mining,
3. Exercise a l�ProVai authority whit
Prialo Act, effective January 1, 1977.
(Chapter 7, 5, bi�rsion
and Ce,ylogy Board within the
Speciti;l Studies zone,
respect to all real estate devta-
lccupan and
2, California
Code,)
thinstruct,ures.eci human
occupancy within. the Specie]
Studies Zone, as provided by
a. Portions of the Sacramento Valle
4.
State law.
have a generally high potential y
:for liquefaction sarong
Consider liquefaction potential
irs making laird use decisions..
4' Require appropriate design of
a tnejoa
earthquake.
structures susceptible to the
effects of liquefaction.
- N
Rte Section XXX
SAF-M)t ELEMENT
5 CONVONT$
Title
'age
A4 GENERAL
IIl-1
le
State Requirements
IlI-1
2.
Planning Relationships
a. LaAd use Element
111-2
b. Circulation Element
111-u2
c. Housing Element
111-2
d. Conservation and Open Space Elements
1:11-2
B. GEOLOGIC HAZARDS
121-3
1' .
Objectives
111;-3
2.
Landslides
111-3
a. Characteristics
111-3
rD. Distribution
III -6
3.
Subsidence
III -7
a, Characteristics
111--7
b. Distribution
111-9
Erosion
IIT --9
a. Characteristics
111:'-9
b. Distribution,
1:11-10
5.
Expansive Soils
III -11
a.. Characteristics
I11--11
b. Distributinn
111-12
6.
'Vol.canics
115-13
7.
Policies
111:-13
C. FIRt
HAZARDS
1II-15
1.
Objectives
III -15
2,
Hazards
IIT -15
3.
Fire Protection Services
111•-17
4,
Policies
111-19
TABLES
Title
iia e
.9 ITT -1
Geologic ,Hazards stab -Element (Findings,
Policies, and. Implementation),
IxI-1'
111-2
Adequacy pl Fire Protection in Butte
Counter Unincorporated Areas
111-21
111-3
Eire Hazard Sub -Element (Findings,
Pot icier, arad implementation,
11i- 22
sy
Wes,
UlmSection III
$Anny Pmr.,MENS,
A. GENERAL
1. State Requirements
Section 65302.1 of the Government Code requires county general
plans to include a Safety Element "...for the protection
of the community from fires and geologic hazards including
features necessary for such protection as evacuation routes,
peak load water Supply requirements, minimum road widths,
clearances around structures, and geologic hazard mapping
in areas of known geologic hazards,"
The Council on Intergovernmental Relations 1973 General Plan
Guidelines advise that the Safety Element should include
an identification and evaluation of safety hazards and a
general policy statement which establishes measures to abate
and protect from the effects of recognized hazards.
2i Planning Relationships
From the standpoint of hazardsp some of the bounty's lands
are more suited for certain activities than others. . Policies
and ordinances can be developed to make sensible use of our
economic and land. resources while :ecognizing known hazards,
The Safety Blement ela es to 1
of ger General Plan elements,
the
Land Use Element, thp Circulation Element, the Housing tlement,
and the Conservation and open Space Elements.
a. Land Use Elemont
Hazardous conditiotSt a prime determinant of .and use oapabil3-
ties, are considered in the LatdUse Blement, The Land Use
Element designates appropriate uses for lands determined
unfit for development and human occupancy because of natural
hazards and the sod to respect those hazards. The Land
Use 9lement can also advocate that development within areas
of high risk consider all aspeo+!3 of the hazard, including
safeguarding structures and natural resources.
The identification of natural hazards cr.n contribute to the
development of standard*,/"an
�dyp�,Iicie8,r regulating the typet
location$ and intensity of land use in relation to the hazards.
Land use controls can also prohibit come types of activities
and developments that may obstruct access or endanger life
and property.
b. Circulation Element
Pe-ten-.t-i-al,ly--ha,za-r-da,us-,n.a,tu,r,,ala,cond�t,ions affect the location
and design of circulation facilities.— In case of a 'major
A -
emergency or di8astert evacuation rout's and major transports-
for
tion systems must be located, designed, and maintained _ for
---t--
mo)aility and safety. ,%'~ standards and safety, measures
an be es:�)::;rii�ed f or,_alj--c rcul ation systems in hazardous
areasAs—Opposed
repairs- or T.,e--QOas trut., t ion
should be considered- when- new, road-.proj ect-s-laT, e- -proposed.
C, Housing Element
The presence Of natural hazards will limit housing type,
cost, and density. I Depending on the degree,of hazard#,new
housing developments will need to incorporate within their
design any special hazard abatement or control methods and
111-2
incur the costs of doing so. Development of land considered
"acceptable risk" should be encouraged, while land, unfit for
structures for human occupancy should remain: undeveloped.
d. Conservation and Open Space Elements
. The identification and recognition of hazardous areas can
lead to policies aiding in the development of open space
and the conservation of natural. resources, Land determined
unfit for human occupancy can be preserved fox agriculture,
for the enjoyment of scenic beauty, for recreation,, and for
the development of natural resources.
B. GEOLOGIC HAZARDS
1, Ob,'ectives
The primary objective of the Geologic Hazards sub -element
is to prescribe policies to reduce loss of life, injuries, O
property damage, and to deal effectively with the socio-economic
disorder which could result from, geologic hazards in
Butte County, Secondary objectives are to:
Map and evaluate known geologic hazards.
Provide general criteria for the development of
other General. Plan elements.
s Heighten public awareness of geologic hazards.
Landslides
a. Characteristics
Landslides are a downward and outward movement of slope -farming
materials composed of rock, soil; artificial fill,, or combinations
TTI_3
thereof. A similar but slower movement is called "creep."
Landslides, in the strict: sense, do not creep;however, creep
io related to slope Astability and the potential for land-
slides to develop. A landslide may move rapidly as in a
soil or rock.avalanche, or it may more very slowly for hours
or even weeks. The volume of material may vary from millions
of cubic yards to ;Less than 1 cubic yard. The landslide
movement normally results in the development of cracks, ridges
scarps, and faults, all of which may not exist or be easily
identified in a specific landslide
Landslides are classified by the U. S . Geological Survey :into
several groups ('U.S. Geological Survey; MF 493). See Appendix C
for a description of four of the more common landslide groups.
The formation of landslides is affected byr
Type of material. (Unconsolidated soil,, soft rock
or surface deposits generally move downslope easier
than consolidated soil or hard bedrock.
Structural and physical properties of earth materials.
(The orientation of layeringr structure, and zones
of weakness of most rook and sediment relative
to slope direction will greatly affect landslide
potential.)
Steepness of slopes. (Landslides usually occur
on moderate to steep slopes.)
Water. (Areas of moderate or steep slopes with
a high ground --water table or seasonally high rainfall
have frequent landslides because water commonly
decreases the resistance to sliding. water decreases
the cohesive forces that bindclay minerals together,
lubricates surfaces along which slippage may occur,
1l~l-4
adds weight to surface deposits and bedrock, can
cause volume changes in the material, and mixes
with fine-grained unconsolidated materials to produce
wet( unstable slurries.)
Amount of vegetation. (abundant 'vegetation with
deep roots tends to hold bedrock and surface deposits
together, thereby increasing ground stability.)
Proximity to areas undergoi;lg active erosion or
man-made cuts and f Ills . (Aapid erosion along
stream courses and reservoir shorelines makes slopes
in these areas particularly susceptible to landslidi,ng.)
° Earthquake generated ground motion. (Strong ground
motion can trigger movement of marginally stable
earth slopes and loosen hillside materials for
future failure.
Factors in the identification of potential landslide areas
include degree of slope, type of bedrocks type of sail, amount
of rainfall and previous landslide activity (mostnew landslides
occur in,aress of previous landsliding),. One of the most
important parameters is the degree of slope. An examination
Of slopes and known landslide areas in the County ind-icates
that•most landslides occur on slopes greater than . 15
percent
with very fete on slopes of 5 to 15 percent or less.
Because of their Physical and chemical character,_ certain'
bedrock units are more susceptible to l.andsliding than others.
Also important are the types and thickness of soils that
tenni to develop over these bedrock units As a consequence,
two: adjacent areas may appear to be similar in most resi'sects
but may differ greatly'in landslide Potential 'because of
bedrock or soil conditions.
111-5
The prediction of landslJdes at a Specific site reqUires
analysis Of the complex iAterrelation$hipa of all of the
above factors as Well as a detailed Onsite investigation.
Because such detailed 5,nCormatiou is- not available in Butte
Countyt the identification of potential landslide areas is
preliminary and delineates only relative slope stabilitie'
bi Distributlon
There are landslides in Butte County, but they do not appear
to commonly occur. T here is, however, a potential for land-
slides in some areas.. These areas, shown in Map 111-1, are
described below.
The areas of lowest landslide potential in Butte, County are
the generally flat lands of the Sacramento Valley; however,
there appears to be some landslide hazard due to the potential
for liquefaction of soils bordering the Sacramento River
and its tributaries (see map 11-2 in the Seismic Element:
of the General Plan). An area of generally low landslide
potential lies in the hills south of Oroville and in the
generally flat uplands north Of Oroville such as the Paradise
area, The slopes bordering the flat uplands, such as the
slopes around Table Mountain, are highly susceptible to land -
sliding.
The areas of apparent highest landslide potential lie in
a north -south belt through the mountainous central area of
the'CoUnty. In this area, fairly well developed soils overlie
impervious bedrock on steepi slopes which at times undergo
very heavy rainfall. The slopes most susceptible to landslildes-
are underlain by older metavolcanic rocks which have undergone
,extensive deformation and deep weathering.
Areas of granitic rocks and Tertiary sediments in the central
region of the County also have a high potential for landslides.
A
rto;f�n though the granitic rocks are of an age and nature that
normally result In stable slopes, some steeper areas have
been extensively deformed and weakened. The Tertiary sediments
subject to landoliding consist mostly of sandstone, claystone,
siltstone with minor conglomerate shale, and. lignite. This
rock groupi found predominantly north of Oroville and known
as the lone Formatione is generally overlain with older basalt
flows and is exposed only where the basalt flows have been
eroded, such as around Table Mountain.
3. Subsidence
a, Characteristics
Subsidence is a sinking of a large area of surface materials
in which there is no free side and the material is displaced
verticall; with little or no ho.-Ji,zontal component. Subsidence,
usually as a result of man's activities, is fairly common
in California.
Generally, there are two potential causes of subsidence in
Butte Coun,tyt ground -water withdrawale and oil and gas withdrawal*
Ground -Water withdrawal subsidence is the most extensive
and the most damaging in California. This type of su ' bsidetce
has been found in large areas of the San Joaquin Valley and
in some areas of the Sacramento Valley. Generally,. subsidence
is a greater hazard in confined ground -water basins and particu-
larly in those that, contain compressible layers of silt and
clay. 'Subsidence hazard is also greater in areas where initial
lowering of the water table is occurring in valley fill alluviums
with layers of silt and clay such as those in the Sacramento
valley. in the paste irrigation demands in the Sacramento
Valley have been mostly supplied by surface waters. . Now,
ground --water pampage, is increasing and there are extensive
long-term declines in ground -water levels in a few areas,
There are recent and on-going studies of subsidence in the
Sacramento V'al.ley. Thence studies, by the California Department
of Water Resources, the U.S. Geological. Survey r and the U.S. Bur-
eau of aeol.amation, show that measurable land subsidence
has probably occurred in areas of intensive ground-water
Pumping cOmPrising approximately 100 square miles north of
Willows and possibly a third of the valley floor south of
the Sutter Buttes (Lofgren and Ireland, Prelims nary Inyes�ticra-
tion of Land Subsidence in the Sacramento Valle ). As much
as 2 feet of subsidence apparently Yas been caused by heavy
ground-water pumping east of Zamorr•,,. At several locatior4s
between Davis and Zamora subsidence exceeds 0.5 foot. A
U-S. Geological Survey report states that localized subsidence,
possibly caused by natural gas withdrawal, has occurred near
Corning and Arbuckle, in most of the valley, elevation data
are inadequate to positively determine if subsidence has
occurred, f
The amount ofVround-water withdrawal ,sem -'�-�� depends
primarily upon six factors: 1) the magnitude of water level
decline; 2) the thlckness of the water bearing strata tapped;
3) the thickness and compressibility of the silt--clay layers
within the verta.(*,,al sections of ground-water withdrawal;
4) the duration of maintained water level decline; 5) the
number of water withdrawals in a given area, and 6) the geologic
structure and general geology of the ground-water basin.
The damaging effects of ground--water withdrawal subsidence
include gradient changes in roads, streams, canals, drains,
sewers, and dikes; damage to water wells result.%ng from sediment
compaction; and flooding of low-lying, areas. These effects
should be of serious concern.
Many of the public facili,ti:es
and systems constructed with slight gradients could be signifi-
cantly damaged by even very small elevation changes.
There has been subsidence at 22 oi'l and gas fields in California,
Even though most of these sire in the Los Angeles basin, the
potential for subsidence from oil and gas withdrawal- exists
in Other areas of the state as well, Differential subsidence,
a common form of subsidence from oil and gas withdrawa).,
generally extends beyond the producing area in the form of
a shallow bowl* The subsidence takes place in much the game
way as that of ground -water withdrawal and the effects are
also much the same. Subsidence caused by gas withdrawal
alone does not usually reach magnitudes comparable to subsidence
caused by oil or ground -water withdrawal.
b. Distribution
Land subsidence is a potential hazard in Butte County. Areas
of Potential subsidence in the county are confined to the
Sacramento Valley and include local areas of heavy ground-
water withdrawal and the six producing gas fields shown in
Map TTI -'1 * According to investigations by the U.S. Geologic
Survey, the areas of heaviest ground -water withdrawal extend
about 2 miles north and south from Chico and in a 1 -mile
radius around Gridley. The amount of subsidence that could
take place in the County will depend primarily on the amount
,of ground -water withdrawal. The likelihood of subsidence
resulting from large ground -water drawdowns during droughts
should be a major concern to all agencies responsible for
'I'le COUnty's water resources, public facilities and economic
Ll -being.
Erosion
a. Characteristics
Erosion generally involves two distinct activitess wear and
removal ofearth or rock material and transport from one
,site to another, Theerosion, process includes weathering,
111-9
solution, abra,si.on, and movement. The level of erosion depends
upon the soil texture and structure slope, vegetative cover,
and type and amount of water runoff.
Longtermdamage carp result from sheet and gully erasionr ti
wind erosion, erosion of stream courses, and erosion of lakeshores,
Depositional damages can occur on flood plains, rivers, lakes,
and strum channels and drainage ditches, The construction
of roads, reservoirs, and subdivisions, farming, and logging
frequently accelerate the erosion process and exacerbate
the damage
b; Distribution
Map IXI-2 shows the degree of erosionn that may be expected
in Butte County where the protective vegetation is removed
by construction, fire, or cultivation. Using information
from the united States Department of Agriculture Soil Conserva-
tion Service Rend General Soil Maty of Butte Count,
California, 1967,£ thele are five classes of erosion hazard.
x None, Slopes less than 2 percent, with subsoil
permeability ranging from moderately rapid to rapid.
Slight -- Slopes of 2"-9 percent with permeability
ranging from moderate to moderately rapid with
weak soil profiledevelopment.
Moderate - Slopes of 5-30 percent with soils of
no profile development to weak profile development
and slopes of 9.15 percent, wit1r .moderate profile
development
High Slopes of 30-50 peroent in soils with no
profile development to wear profile development
Ili -7
and slopes of 15-30 percent on soils with moderiA,te
to strong profile development.
Very High - Slopes in excess of 5Q percent on soils
with no profile development and slopes over 30
percent with moderate to strong soil profile development,
Typically, the areas of high erosion hazard are underlain
by volcanic and metavolcanic rocks, The areas of very high
erosion hazai:"I are- typically underlain by granitic rocks,,
The areas of high to very high erosion hazard typically have
a moderate to high annual rainfall (approximately 30-60 inches).
Soils of the Sacrament.o Valley arc, typically of the slight
erosion class with slight to high erosion classes along major
streams and drainages. The areas northwest and south, of
Oroville are typically in the moderate erosion class but
contain isolated areas of high erosion potential. The eastern
two-thirds of the County is typically in the high to very
high erosion class* The areas surrounding Lake Oroville
and extending south to Bangor and Ifurleton and.north to Richard-
son Springs and Stirling City are typically in the high to
very high classes, The tops of the basalt flow plateaus
and the volcanic areas near Butte Meadows and L7onesville
are generally in the slight to moderate erosion class.
5, Expansive Soils
a. Characteristics
Expansive soils are soils which have a potential for shrinking
and swelling with changes in moisture content. Extensive
damage to structures and roads can result from the shrinking
and swelling process.
The volume change of the soil is influenced by thea moisture
content and the percentage and type of clay minerals in the
toil. The three classes of expansive: soil generally recognized
are:
m LOW -- These soils range from sand to ;gilt with
varying amounts of clay mineraiz. The soils include
sc,ndy clay if the clay is kaolinitic and generally
ha,=e a shrinkage: index of less than 5 (sand and
gravel al,.luvial deposits and dredge tailings mak,;.
up a fourth shrink -swell class which has no potential
for volume change due to moisture change. This y
soil group is commonly placed in the low class.)
Moderate - This class includes the si.l*v clay to
clay textured soils if the clay is kao4initic and
also includes heavy silt, light sandy clays', and
silty clay with mixed clay minerals. The shrinkage
index is generally between 5 and 7.
0 High - This shrink -swell classification includes
clay and clay with mixed montmox:illonite. The
shrinkage index of these soils is generally greater
than 7
b. Distribution
As Map 111-3 shows, expansive soils exist over most of Butte
County. ;Soils with no or low: expansion potentialarefound;
generally along stream valleys and on steep mountain slopes.
Soils of high expansion potential are found in the nearly
level areas of the Sacramento Valley around the popul=ation,
centers of Chico, oroVillet Biggs, and Gridley.
--7
G. Voloanics
Mount Lassen, considered to be one of the few active Volcaroes
in the continental United States, is located about 23 miloE,
north of Butte County. The last series of volcanic erupti�jns
at Mt., Lassen between 1914 and 1917 deposited volcanic ash aver
a fairly wide,area surrounding the cone. Localized mudfloi�s
were also deposited in stream valleys around the volcanic
cone. There is no record of any significant ash or mud
deposit reaching Butte County within historic time.
While geologic hazards do exist in the Lassen
Park area, the possibility of mudflows, flowing avalatchee, or
volcanic ash endangering the people of Butte County appearst
from historical and geological data, very remote.
Lassen volcano is being studied and monitored by the U.S. Geological
survey for seismic and, volcanic activity. According to Professor
4. H. Williams of the University of California at BerkeleV,p
the monitoring system can provide an early warning of a
potential volcanic eruption,
7. Policies
Table III -1 summarizes the Geologic Hazards findings discussed
above', states the County's policy in response 'z -o the firid,:ngs,
and outlines implementation measures.
TAbld XT1-l. GEOLOUC ITAZARD SU113-1=3MLTNT
FINDINGS
pQt�IC�
T,M(?L MGNTJI'TCt N
tLTA.�,,ON
1.
,`Fre idanfi.f'iration of 9"logic
hazards is in the public in--
1.
,rarotm the public of 0010 is
harzrxds..
1 I.
J.-�..._.,
Approve and publish the hazard
tere;st.
maps in this plan element. Keep
the •inP.oa.�mat3or� up to �iatr.,
2.
Geologic hazards limit land
development capabilities.
2.
Consider geologic hazards in
2.
theI)etOInfor
de'valopnlona at Land trst�,
!lousing, Ciroolatian Causer-
a ppropriate uses for high
hazard `teas. establish limit;
va"On and Open Space VlamentA,
on the density and type of dove-
lopment permitted in
high hazard
a.
The risk of landslides is
greatest in areas with
3
Consider landslide pa tent.ial in
3.
areas.:
Require investigation of landslider.ovirw
Slakes c,vrsr 15%, weak rock;
or private development.
and public FdOl Citic+s in
Potential for prcposed development.
and high rainfall.
areas
rated 4 and s on Na xrx-2.
p
review findings is environmental
4
'Thr removal
,
review and subdivision review.
H
" of surl'acc�
zein and wGtt6x
4.
Consider orasion i�att�ntial in
r
4.
Roquire investigation of erosion
�
'
va�•c.es yt3y
varies b slops:, soil,
vegetation, prooipi,tationpres"L
.evic�w at
.and publicprivate
r vat a osetnrmz�us
taotential for p
proposed development.
findings in environmental
and development. it is
Mrated hid), and vary ��iqh an
M+7� ill -2,
review and subdivision review.
greateat tri areas of
granitic rock.
5.
Ground surfs singe and
cause sivnifica can
l thane damage �n,
$,
.Protect a ainst subsidence
Pram
5.
Monitor sinking as necessary.
areas wF.yre there is e;r-
tonsi,ve withdrawal of
ground -water �vitltdra wal
and ail and gas withdrawal..
Consider subsidence potential
in review of
ground
water, oil and gas.
proposed withdrawals.
Many valley areas with clay
soil ;ave a high potential
6,
nrobact development in valley
Ca '
shoes
6«
Monitor shrinking and swelling
for SLruotural damage from
with ex a nsivo seeds.
as necessary. Require litigation
soil shrinking and ,swelling
measures for.large developments
and major facilities when there
is a high potential for damage.
C. VIRE HAZARDS
1. Objectives
The primary objective of the Fire Hazards sub -element is to
prescribe policies to reduce ices of life, injuries, property
damage r destructi On of natural resources, and to deal effec-
tively with the socio--economi C disorder which ooul.d. result
from fires in the unincorporated areas of Butte -Jounty.
secondary LInj ectives are to
Map and oval.uate fire hazards
Provide general criteria for the development of
other General plan elements
Heighten public awareness of fare hazards
2. Hazards
The immediate impacts of a wildland fire i.nolude Loss of
valuable forests, wildlife, watersheds, and scenic resources
along with the destruction of homes and other property
There may also be injury or loss of life. secondary impacts
include a reduction in the value :of land and the further
degradation of natural resources. Brosi.on, for example►
results in siltation of lakes and rives, increased flooding
Potential, poor, water quality, and a reduction in desirable
F aquatic population.
In recent years, fires have been more frequent in the valley"
than in the mountainous areas of the County. From 1971
through 1975, an average of 679 fires per year occurred in
the valley compared to 306 in the foothills and mountains
(see Appendix Table C-1). Most of the valley fires have
been grass hires near the more populated areas of Chico,
1XI-15
Durham, Richval of Biggs, Gridley, and Orovil.le, and along
the main roads connecting these communities,
Although there have been Newer fires in the foothill and
mountain areas than in the valley, there has been a dispro-
portionately higher number of fires per unit of papulation
in the foothills and mountains. This condition is probably
Y
due to the more hazardous natural combination of dense
vege-tatiori, dry woather, and steep topography which encourages
rapid fire spread, (The critical factor contributing to
fire spread and in -tensity is the density and distribution of
vegetative fuel, especially brush and forests..) The number
of fire incidences in the foothill and mountain areas can be
expected to increase along with an increase in recreational
activities and residential uses.
Map I11-4 shows the areas of varying fire hazard severity in
the non -urban and unirrigated areas of the County. The fire
hazard classes were identified according to the State
Division of Forestry procedure described in the April 1973
report, A Fire Nazard Severity Classification system for
California's Wildlands. The procedure allows delineation of
areas of moderate, high, or extreme fare hazard based on
natural factors in wildl.and areas (mostly those undeveloped
areas in the foothills and mountains of eastern Butte County.)
The Division of Forestry procedure is discussed in Appendix C.
A significant hazard to life and structures from wildland
fire does not exist until a wildl.and area is developed and ,
occupied, Not only does the introduction of .human activity
into wildlands increase fire occurrences`, it also increases
the demand for rapid response and control of those fires.
The rapid population growth of the State's urban areas,
accompanied by an increase in affluence and leisure time,
ha.., resulted in a.dramatic increase in the number of people
111-16
visiting and enjoying the recreation opportunities of Butte
County, For much the same reason, the County's permanent
population hag also grown steadilrt. The problems of yrotecting
life and property from fire hazards have increased signifi-
oantly with the growing numbers of residents and visitors in
the mountain and foothill areas. This trend has been somewhat
accelerated by the development of take Oroville, which not
only attracts large numbers of viM.tors to the areat but has
also created intense pressures to develop nearby wIldlands
for year --round residential and commercial uses.
3. Protection Services
Information on existing fire protection services, responsi-
bilities, and adequacy of protection was derived from the
Butte County Local Agency Formation Commission (LAFCO)
report, Fire Protection in the tinincor2orated Areas of Butte
Count, (July 1975), and from interviews with the staffs of
local fire control agencies.
Fire protection for the unincorporated areas of Butte County
is provided by several agencies. Two unincorporated areas,
Paradise and El Medic, have formed fire protection distric#s.
The foothill and mountain areas (State Zone) are protected
primarily by the State Division of Forestry and the U.S.
Forest 'Service. Fire protection for the unincorpovated
areas of the valley (Local Zone) is provided primarily by
the Butte County Fire Department (BCPD). BCFD is also
primarily responsible fot suppressing non -forest fires
(structures, vehicles, etc) and for the protection of life
in the State Zone,
BCFD is operated through a cooperative fire protection
agreement between the county and the State Division of
Forestry. The agreement places responsibility for the
administration and operation of the Butte County Fire
Department with tho Division of Porestry, while the county
maintains policy and fiscal control. The State -County
organization operates 23 firs stations, five lookouts, and
33 forest and structural fire trucks. The headquarters,
maintenance shops, warehousing, and central fixe dispatching;
faci,litleo are in Crovill,e. The State also maintains an air
tanker base at the Chico Airport and a Forestry Conservation Y
Camp near Maga.lia, All, fixe agencies in the County are tied
together by a well operated and sophisticated communication
system.
The areas receiving fire protection, from BCI" -'D units, State
units, and/or volunteer fire companies are shown ,in Figure 13:1-1.
The valley axoa, which is protracted. by 11 fire stations
(including cities) ane! eight volunteer fire companies, is
divided into three; protection units by the LAVCb report,
The Local -State Zone: boundary and the area :served by the
U.S. Forest Service are also shown in Figure XTI-1.
The butte County Department of public works reviews proposed
developments for compliance with design standards and regulates
street construction to provide for safe circulation. To
provide for safe ai4d quick _access for fire service and for
evacuation, the Public works Department sets standards for
maximum cul -de --sacs length, maximum street grade, minimum
road turning radii, and identification of reads and buildings.
even with these recluir-ements, problems of road acc(:ssr
street naming, and house numbering have hampered responses
to,fire by control agencies,,
subdivisions, land divisions, and use permits are subject to
review and approval by the ,County Fire Department for
conformance to fire safety standalrds*L I New buildings must
conform tothe Uniform Building Code (UHC) requirements for
fire: protection systems and minimum fire resistance of
materials The County has not adopted the Unirorm Fire
x�x�1s
Code, a complementary coda to the 'SBC. The Uniform Fire
Cade regulates the mointef ante of projZ trty and certain
dangerous and hazarai-iu-• activities.
Fire protection service is adequate in the two special fire.
',ection districts of Paradise ,and El Medio-. The duality
service in the remaining unincorporated areas is described
in the LAVCO report.
a'Qual,ity of service is fair for areas within a 5 mile
radius of the 11 fire stations, and where there is an
adequate water supply and few exposure problems For,
the most part this included area within the valley.
Several key areas without adequate fire protection
include the west side of Chico, Southgate Industrial
Park, the community of Hono t, and scattered residences
in the outlying areas. structural fire protection for
the mountainous communities is either marginal or non-
existent. Areas receiving marginal, protection include
the Upper Ridge, Cohasset, Clipper Mills, Forest Ranch,
and Stirling City. Areas with no strucutral fire
protection include Bald Rock/Berry Creek, Feather
'palls, Forbestown, Garbo Gap/CQncow/Yankee Hilit and
pentz/Cherokee/ Butte College."
Table 111:-2 summarizes the adequacy of protection based on
:dire company equipment and manpower, response time, and
water supply. Table 111-2 also 'includes the fire hazard
classification for each area.
4. Policies
Table 111-�3 summarizes the Fire Hazard findings discussed
above, states Lhe County's policy in ,response to the findings,
and outlines implementation Measures,
Y
Y'AI Yli °.r i'1'I
11
l
I � �
1
• naY
��q•4'w\kk
DE SAEIILA� .,.
VOLUNTEER CO. U.S. FOR CST SERVICE
�� �� a��y�.Y�`ti`�``�+" `
,r Y
COHASSET !;
„« VOLUNTEER CO. �' � r N I
CNlCC4/67UR.t AM RANCH r';� �` .7
FOREST �- i STERLING -CITY z
PROTECYION ,*' r,.
UNITi
.� '- � • ..7 rA ;IWC
U.S. FOREST SERVICE
p nA 'fl
PARADISE FIRE
{: red t w.n.iA a •✓,•,.PROTECTION DISTRICT
a ; * w •♦ w �.:+ r p`"�h JARBO GAP%CONCOWI
WEST YANKEE HILI. '3
CHICO ��, Y I nY
PENirz/CHEROKEI[/
so � `r, u { y tlr � "'' r40-1
6rE COLLEGEINDUSTPIALY+,.;,0PARK ,BALD ROCK/
` L, BERRY CREEK H
r 1 i , �, R •,p r, „r a k;�,j"i.�6r9 "L U.S. FOREST
wz.tk A� s" x4� p b�RVICE
e ,
t r 1 a r t `ax rcarnek raw �`f'
FEATNEft
kt y ern FALLS z
', - 'h J.tt 1� r,� F,JRpF�YbNH R MILLS
} tg tk fi revL r ' O lii f 7w J . IL.._J LIPPER MILLS
yA '.rt r
p VOLUNTEER CO'."
r`' 34'x' n,ar r7ca ,,1 I
`rr t r w r, r v.agt rF iPr FOReESTOWN I
RICHVALF/EIGGS/ r t r
GRIC1LE1t PROTECTICIN r A„r r d , x : y EL MEDIC
UNITS ' alG � ta+ r' Ful rr� PROTECTION DISTRICT
OROVILLE/PALERMO/BANGOR
An'--., G llulit'� r r J: F a PROTECTION UNIT r
t -ri7,,r t,,ky t
HONCUT
FIGL URE 191.1
NOTES I, BUTTE COUNTY FIRE [DEPARTMENT AND FIRE POTE vTIll�,
VOLUNTEER, COMPANIES REAS
2, VOLUNTEERS AND STATE QIVISION OF FORCS'T`RY
_.
SAFETY ELEMENT
3. STATE DIVISION OF FORESTRY BUTTE COUNTY GENERAL PLAN
SOURCE, [;BUTTE COUNTY LOCAL AGENCY FORMATION ",
COMMISSION. JULY 1975. FIRE PROTECTION 1N PI ANNiNG &1?'AJKA
THE UNINCORPORATE[ AREAS OF EIUTE SCALES a. „ .La
�E:PARTAtENTrN
COUNTY. �` 1r'a 8 MI..
Totfiu 111.2. ADEQUACY OP FRO! PROTI CTJON IN 6010, COUNTY UNiNCO11110HATO ARt; S
ARCA
PRIAIARY 5V -_I CC
R17511t7NSC TOW
WATER SUPPLY sYq*ms.
FiRIi HAZARD
5FVFi11TY2
Af)rOUACY 411
ROTCf 1"IANj
County Pint
Wit. ��:�s•
1, Chino/Durlt m
4 UCFt) stations +
Milority of ar+;a
Chico urea. « gond
Mostly low West of
N. Chico C Durham -
2 Volunteer Co.
within t0 wiflutes
Ourh.im « Olt fife simple
Hwy 99, Moderategood.
Remainder
for first en+Jine -
firmNo others
to extreme efist
OK far simply fires
adequaw.
only,
2, Richval4/
3 OCIT) smtlons +
Soma as Above
Richvalo - Inadequate.
Mostly low
Rlehvale =hood nrcar
plggs/CrtdWy
2 Volunteer Co.
No others, Extensive
hydrants. Remaindor -
irrigation
OK for simple fires
only,
3. Oroviilo/
4 BCP0 statlons +
Same as Alcove
Goan systems In Oroville
Mugtiy moderate
Adecluata near hydrants,
Palermo/
4 Volunteer Co.
urban area. Several
with areas of high
Other areas - OK foe
Bangor
other $mail systems.
6 extreme.
simple flros only.
Volunteer Fire
Company Areas
4, Cohasset
1 Volunteer Co,
Some as Arrive
None - 2 storage. tanks.
High 6 extreme
Marginal
S. Do Sabia
2 Volunteer Co.
Same as above
Paradise Pines - good,
Mostly high
Marglnal
No others.
6, Clipper Mills
1 Volunteer Co,
Varies - generally
Merry Mtn. Village -
Mostly high
Marglnal beyond
adequate
good. No others.
village area.
Independent Protection
Districts
r. Paradise
3 stations +
All areas within
Good
Varies
Very good
Volunteers
4-7 minutes for
3 engines
txeelient.
1, El Media
1 staUor, +
All areas within
Good
Low
Fair to good
Volunteers
2-10 niiriutes for
3 enginas - good.
Mountafri Communities
9. Forest Ranch
state +
Varies
Several small systems,
'High 6 extreme,
Marginal
1 Volunteer' Co.
10. StIrling City
state +
Varies
System In town.
High c extreme
Marginal
I Volunteer Co.
11,, Janata Gap/
Side only
None
None
High & extreme
None
Yankee Hill
12, Pentz/
State + Durham
1525 minutes tram
Butte College - good,
Moderate to extreme.,
Marginal
Cherokee/
F Oroville Station,
Durham 6 Orovilie
No others.
Butte, College �,
nearby'
stations.
13, Bald Rack/
State only
None
Lake Madrone - system
High 6 extreme.
None`
Berry Creek
in towr. No others.
14. Feather
state +
N.D. A.4
System In town.
High s extreme,
N,D,A,
Fags
t Volunteer Co.
It, Forbestown
State only
Nona
System in town.
High
None
.Other Mountain Area S.
State Div. of
Varies
Insignitteant
High r extreme
None to -marginal
Forestry 6
(Primarily Wildland
U. S, Forest
Piro Control)
service
See Figure 111-1.
2Classltieation according to the State Division of
Forestry roianrt, A'Fire Hazard snverity Classification System for .Callfoenla,s Wifdlands, April 1973.
See hazard ClaSsds on
Map 111.4.
3Defined by LAMO,
4 N data avatlobte:
Source: Commission. Firs, Pralectinty in the Unincorpnratcd' Areas of Flullo County, July
Fathisrr
� ns
1975, Recommendations for
nBeuttt rtCounty
� s t
arc from loon
111-21
meevla XXX' -X. 1`l1tk." HAZARDtailrl,i!F;MLN2'
I'tNC►TNG
POLICY
lt�[kx.t:M1 N't~A�!ICtN
1.
Mast of the County has a
1.
Wo protection ,from fire
1.
Consider fire hazards in all
natural fire hazard of
hazards a consideration in
land use anti zoning decisions,
at lcaat moderate severity.
all , planning, regul a torts
environmental review, sub -
Nearly all of tho foothill
and Capital improveillant
divioton review and the pro -
and mountain areas have
hazards of high or extreme
Programs, with 8poula.1, Concern
tar "high"
Virion of Public services
area., of and
severity,
"extreme" biro hazard.
2.
The number of fire e occurrc+nces
2.'
»rrevide adeyuake fire pro-
Z.
Identify present and future
is increasing along with the
inoreasinU numbers of visitors
tection services in all areas
limiLs of adequate Eire pro-
and residents in the county.
of population growth and high
recreation use
tection services. culde de -
ve10011011t trr
those areas through
zoning, and development review
processes.
M 3..
Rcssialantial developmetat is
3.
Limit development where natural;
3.
Zone high and extreme natural
occurring in the mountainous
the
fire hazard's are high or extrema
fire ftazarrirs areata which are
t
rarOUG of County whore
until adequate Firer protection
inadequately protected for
I
natarni fire hazards are
high or extreme and W11:3 o
i, provided.
low residential densities only.
tare prat eotion £aciliL•ies
Provide no new public facilities
that
are mostly inadeclttt o and
encourage growth in ,these
difficult to provide.,,
areas except -those essential to
public uafraLy.
A.
vegetation is the critical
factrar in fire sproad.
4.
U:;r. Fuelbrakes along the
4.
Require fuelbre,aks where
edge of 0,evelo,ping areas and
feasible with', "bi h" and
In high and ' oxtrame" fire
"ext=rrme'r fire hazard areas.
hazard areas.
a.
Fire protection facilities
5.
Provide adequate f1ra
5.
. Construct fire stations as
are lacking or margined in
protection in ali areas where
required to protect areas of
some areas of the County,
service levels are deficient.
greatest need, promote the
formation of volunteer fire
companies in rural communities.
G,
Development in reservoir
G.
Limit development in
6.
Prepare zoning plans for critical
watersheds leads to fires
which threaten cotnmuni,ty
reservoir watersheds.
watershed areas. Consider possible
water supplies.
damages to watershed inenviron-
mental review.
ravtt3 rT-3, PTR9 tll►7.ARb RLLMENT
(Cantinued)
7»
Y'.t,a;e control and nlipprea8ion
in restricted by
7. snsure that water suppijon
7•
Develop
inadequate
inadequate water sut�plies
for naw development are
adequate for fire
fare protection standards
for individual and
prr>tact�o»
purposa=,
community Water
systems serving new development.
Apply these standards to sub-
divisions, land divisions, and
A.
Access to fires by emergencyuse
$•
permits.
Inadequat it often limited by
Inadequate roads,
rrsure that road access for
new deve2oprnent iv adequate
8.
Develop standards for widths,
Fat fire protection purposes.
purposes.
and curves of new roads to
permit
passage and maneuvering of
emergency vehicles. Require multi -
Ple
9.
Piro report and response times
y
accezrs whore feasible.
are often delayed by incon�-
sist'onuies and deficiencies
nhquire or pramattt tlra easy
nddO:ticatid of streets
8.
Develop grtd implement a eon-
-i
in street naming and house
and davoloped prcypurt.to�s.
sistent Street naming and -house
numbering system
num
for t
he entirenumbering.County. 110quire all
' w
names and
numbers to be clearly visible.
14.
Some human activities ?nd
land uses have a high
10. Re uiata�
q as necessary those
1Q.
Hold
Potential for causing fires.
aetivitio-s and uses with a
hlyh fire
hearings to adopt the
Uniform Pi;re
potential.
Code or modi-
fications thereof.
Section IV
VIM NOISE BU,14 Nor
CON"14NTS
w
Titla
Ru e
,A.
crNVRAL
xV-1
le
,Stage Requirements
IV -1
2,
Planning Relationships
IV -2
F
3.
How Noise Is Measured
TV -3
B.
OBJECTIVE'S
iv -4
C.
THE
COUNTY NOISE ENVIRONMENT
IV -6
1.
Complaints
IV -6
'
a, Butte County
IV -6
b, State Dr,+„oartm,ent of Parks and
Recrel ion
IV -7
c. city of Z=hico
IV -7
2.
T.raff io
IV -8
3.
Railroads
4.
Airports
xVw1 e,
5.
Noise -Sensitive Areas
TV --2'
6.
Noise Survey
xV2.
7.
Summary
TV --2
D.
POLICZE'S
IV -2.:
TABLES
Title
IV' -1
Estimated :Annual Traffic Xnarease Rates
on state Highways
IV -8
IV -2
Traffic Volumes and Estimated Noise
Levels for State Highways
IV -9
IV -3
County Roads Witk� 1975 and. Estimated
1907 Traffic Volunta:s of 5, 000 ADT
xV`--
or Greaten
CNE,L Worksheet . for Line Operations
7V=-11
IV -15
.s IV -5
Ambient Noise Monitoring Sites
IV -23
IV -6
Noise Element , (Findings, Pali.cies o and
,p�ementatinnj
SV -25
Section xV
NOISE ZMEMBNT
A. GENERAI,
w 1. Stage Requirements
California Government Code Section 65302 (5)r as amended
by Senate Bill 860 (effective January 1, 1976), r-equine$
the County to prepare a Noise Element which:
"...,shall recognize guidelines adopted by the
Office of Noise Castrol pursuant to Section 39850.1
of the Health and Safety Code, and which quantifies
the oomm"AitY noise environment in terms of noise
exposure contours for both near and song-term
levels of growth and traffic activity. Such noise
exposure information shall become a guideline
for use in development of the land use element
to achieve noise compatible Land use and also,
to provide baseline levels and noise source identifi-
cation for local noise ordinance enforcement."'
Section 65302 (g) also states that the adopted Noise Element
shall.
„...become the guidelines for determining oompli
s ance with the State's Noise insulation Standards as
contained' in Section 10.52 of: Title 25 of the Cali-
i fornia Administrative Code,"
This Noise Element was prepared generally in accordance with
the State Office of Nolse Control's Guidelines for the pre-
araton and Content of Noise Elements of the General plan
dated February76`. These
A19`� guidelines outline the.,. procedures
to be used to OOnfOrm with Cal:ifOrnia Government Code Section
65302 (g) Accor41ng to tlae Guidelines, the Noise Element
should guantify the oommunity noise environment in terms of
nOi,sc eXposure contours for bath near and long-term Levels
of growth and traffic activity,. noise exposure information
guides the development of the Land Use Element, the Circulation
Element, and noise ordinances. Noise sources considered by
the element include highways, railroadsr airports, industrial
Plants, and Cather stationary noise sources identified
by the
local agency as contributing to the Community noise environment,
The Guidelines also state that noise contours are to be
expressed in community n0iae equivalent levels (CN8L) or
day -night average levels (Ldn)and be shown in 5 decibel
increments down to 60 d.B. Noise exposure should be determined
by monitoring in noise sensitive areas, The Noise Element
M
should, also identify the number of people exposed to various
noise levels. Finally, the Noise Element ;should recommend
Mitigating measures and solutions to existing and foreseeable
noise problems.
Public and private agencies conducting activities identified
as significant noise sources are required by law to provide
specific data o,y Present and projected activity levels
as well as noise contours or a detailed Methodology for
developing noise contours
2 Planning Relationship
The Noise Element is a "source" document to be used in formulat-
ing Policies for rather elements of the General. Paan including
the Land and Use Element and the Circulation Element; The Noise
Element also
ontains policies regarding noise and noise
abatement which will influence other public policy documents
relating to the location of public facilities health and
safety standards, construction standards, and community
noise ordinances.
IV -2
This Noise Element primarily addresses noise in the unincorpor-
ated areas of Butte County. The analysis shows, however,,
that . W of the siVnificant noise problems are within the
incorporated areas of the county. These incorporated areas
9
are required to prepare their orcin general plans and noise
elements. The Noise Element recognizes City -county noise
problems because responsibility for abating noise in the urban
ixiag areas should be shared.
3. Hoer Noise Is Measured
The noise environment of a community has a base of steady back-
ground noise made up of many sources.. The noise of individual
nearby events such as a car or train, an aircraft or a lawrnmover
is superimposed on this background.
Describing a noise environment and assessing its impact requires
selecting a measurement that correlates well with human
response to loudness or to annoying characteristics of a
particular noise. The A --weighted frequency scale of ,a standard
sound level meter has such a response characteristic. A -
scale noise levels are expressed in decibels --A or dBA.
The measuring unit "decibel." (written dB) is used to express
t
he relative loudness of a sound. each time the intensity
I a sound is doubled, there is an increase of 3 decibels,
and each time the intensity is multiplied by 10, there is
an increase of 10_ decibels. Masa people judge each, increase
of 10 dB to be twice as loud.
Ldn or CNDL are descriptions of, diurnal noise levels. They
'
are a weighted average of daytime and nighttime sound levels,
al1AL ITATIVE SOUND LEVEL
DESCRip,rIONS DECIBELS
OU'I'oOOR LOCATIONS
._.
LOS ANGELES —Srd FLOOR APARTMENT NRXTTO
FREEWAY
LOS ANGELI«S -- 3/4 MILT" FROM TOUCH DOWN AT
MAJOR AIRPORT
CITY NOISE 't7
FHAt�iLEM
(DOWNTOWN MAJOR GELI a DOWNTOWN WITH SOME
METROPOLIS) CONSTRUCTION ACTIVITY
— 2nd FLOOR APARTMENT
VERYNOISY —78
_, BOSTdN ROW HOUSING ON MAJOR AVENUE
.J OISY URBAN
WAS S MILES FROM TOUCH DOWN AT MAJOR
o AIRPORT
URBAN _. NEWPORT �- u,
*�F30..�, 5 MILES FROM TAKEOFF AT SMALL
in AIRPORT
LOS ANGELES — OLD RESIDENTIAL AREA
SUBURBAN
SMALL TOWN, A 50" �s Fes_ `I...LLMOfiE w• SMALL TOWN CUL--de-"SAG
QUIET, SUBURBAN `eaAN DIEGO - WQODED RESIDENTIAL
C ALIPORNIA--TOMATO FIELD ON FARM
OUTDOOR DAY -NIGHT SOUND LEVEL IN db (re 20 MI
IV-
aitPort. Thera are no residences hear either tram and
trhera have been no compl.ai.nts
The auto race track at the fairgrounds in Chico is very noisy
t t
x
imes. Races have been hold during summer evenings. once
a year there are boat races on the Thermalito Afterbay which
produce noise heard in Thermalito.
The Butte County sanitarian's office has received very few
noise complaints. There are occasional complaints about the
blasting and heavy trucks associated with rock crushing opera-
tions; Most of these operations are in fairly isolated areas.
Other complaints about industrial activities have been about
in -plant noise. No complaints have been received about the
Western Pacifica railroad classi°_ cati.on and switching yard,
though this is a significant noise source. Some complaints
have been received about barking clogs
b. State Department: of Parks and Recreation
The State Department of Parks and Recreation has jurisdiction
over Lake oroviile and the Thermalito Afterbay and Forebay.
Noise has been a minor problem on the lakes, but is expected
to decrease when the Department begins measuring boat noise
to better enforce existing regulations;
co City of Chico
The City of Chico ]Manning Department has 'received numerous_
noise complaints concerning sorority and fraternity parties
at Californiaa.a state Una:ver .
st
x„ y', Ch�.c.n. There are also occasional
Problems with rock concerts which talo place in the 'University's
football stadium or near Big Chico Creek.The ,rock concerts
are not held as often as in the past, so this problem seems
to be diminishing. The southern Pacific ]railroad line through
the City is a major source of noise complaints. state Highway 99
IV --7
In a noise source but not a major noise complaint problem.
Since the Highway 99 :freeway was constructed? several high-
cost residential, areas have devclopod adjacent to it
Complaints have been made about noise from aircraft in the
Chico Airport Traffic pattern. Most of those complaints
are related to -the high peak noise levels from commercial
Jet and air tanker takeoffs and landings.
24 Traffic
Traffic volumes for 1975 are shown in Map XV -1 for the six
State highways within the County. These volumes were obtained
from the Traffic Branch of the California Department of Transpor-
tation (CAL'TRANS) . Estimated traffic increase rates for
-these highways are shown in Table IV -•1.
!,able XV -1. ESTIMATED ANNUAL TRAFFIC INCRLASt
RATES ON STATE HIGHWAYS
From 1975 (as of 11/24/76)
Hiclhway 32 1 %/yr. @ Glenn County .Line
3.5%/yr, West Side of Chico to Highway 99
1%/yr. East of Chico
Highway 70 5%/yr. @'lube County Line
4%/yr. @ Orovil.le North
Highway 99 5%/yr.
Highway 149 _3%/yr:
Highway 163 1%/yr, @'Glenn County Linc
3t/yr. East. of Highway 99
Highway 191 2t/yr.
Source: CALTRANSr Traffic Branch, Marysville District
Table IV -2 shows 1975 and' estimated 1987 traffic volumes
for the State Highways in the County. Table IV -2 also shows
thatonly two State Highway sections will, have traffic volumes
IV--$
7'dblO XV -2-
T'Rl VVIC VOLUMES) AND RS`.lIKATTU) NOTSt; T,I3V1;LS
1"131 S�AT'L i11 C11WI y
Rea I'L
'Section
197 ;
ADT7
1r's1:im�rto�
1987 ADTI
.,.a�..
trom 'xntn
111ghway 32
Glenn Co.
blest side of
6,.800
7,400
" t3,r�h�Siac eil'r
Line
Chico
Wast side
of Chico
Rte. 99
11,600
15,660
"fligh-Speed"
Rte. 99
Tehama ,Co,
2,300
2,530
.._3
Line
Highway 70
puha Co.
Line
O,roville
11,200
16, 800
"lligh-Speed"
droville
PIUMas ca.
Lino
8,300
11,620
'"High- Speed"
Highway 99
Sutter Co.
Skyway
11,900
17,850
"lii.gh-Speed"
Interchange
Skyway
Interchange
col,assest Hw
Interchange y�
19,900
�
29,050
'
dor o
ndories
atod
b
ufrt�d boundaries
cohasset
Rd.. inter-
Tehama Co.
tine
91000
13,500
"high-Speod"
change
Highway 149
Rte, 70
Rte, 99
51000
61500
"High -Speed"
Highway 162
Glenn Co.
Rte. 99
1,200
1,320
__3
Line
Ate.. 99
Rte. 70
7,500
9,750
"High-specd"
Rte. 70
Lower
Wyandotte Rd.
16,900
21,970
Inside incorpor-
Sted boundaries
Lower
Foreman Creek
8,700
11,3.10
"High -Speed"
Wyandotte
Road
Road
(End of Rte.)
Highway 191Pearson
Rte., 70
Paradise4
. •550
51460
"high -Speed"
Rc"ad
Notes;
1. These values
noise
are estimated
as of 11/24/76
from 1975 ADT figures, Estimated
contours
by CALTRANs
are based on
these numbers until more accurate. data are
supplied
2. Maximum
ADT in this roadway
secticn. ADT
is average
daily traffic.
34 Volumes
less than 9,000
ADT.
IV -9
above 20#000 ADT in 1987, These sections are within
itoorporated areas of Chico and Orovilla. The noise contours
for all State Highways with volumes between 5400 alad 20r00O
ADT cannot be predicted using
, the 'State office of Noise Control
methodology which applies only to roadways with volumes above
20,000 ADT. Using an Office of Noise Control "rule-of-thiLimbb
quIdelinot noise levels for State "fligh Speed" highways with
$400 to 20,000 ADT are estimated to be:
L dn - 70 dD within 100 feet of the roadway.
L dn - 65 dB between 100 and 200 feet of the roadway.
Lan - 60 dB or less beyond 1.00 feet of the roadway.
County road sections with traffic volumes greater than 5,000
ADT (1975) are listed in Table 1V-3. A 3 percent annual
growth rate was assumed to estimate 1987 traffic volumes,
Again, using the office of Noise Control. "rule -of -thumb," all
road sections with traffic volumes between 5,000 ADT and
20,000 ADT, have estimated noise contours as shown below
for varying speed zones.
"High-speed" Roadways; L dn 70 dB within 100 feet of
(40-55 MPH) roadway.
L dn 65 dB between 100 and
200 feet of the roadway.
L dn 60 dB or less beyond 200 feet
of the roadway,
"Low. -S -Peed" Roadways- L dn 65 dB within 100 feet of the
(typically 3$ MPH roadway.
maximum)
L dn 60 dB or less beyotLd 100
feet of the roadway,
IV -10
,` ,'`.
� �<
_._ u.. s�
Skyway is 'tho o�ily County road pro jecL,�d to have traf:-to Vol-
umas above 20400 ADT in 1987, Ustima"-ed noise cont otfra for
this section of skyway between Pearson !,load and Wtg-0*a*'f Road
are shown in Viguro IV -2. Those contovro were caloxla-ed
from the state office of Noise ContrO. 46thodology 110'.1mation
of Community Noise Ex2osure in _Terms pi,p4jy7pLiz Average
gh
Level Noise Cop -tours. The contours s�,ow'ri in Figuro
are based on a generalized day -night spli�; in vebiclo
volume of 87 percent day and 13 percent night. A ,tom;'.n,iJ
day and night heavy truck percentage of 4 perc.ant or t,,is
low speed arter.ial was assumed. Nomograms njekl in the ,,-stimates
aveivi"'Ra that the to dway is levol, with the slaellaut terz%"%n.
Peak traffic noise levels will be above the L ., noise levels
disjussed above* For examr�lef automobiles can Create noise
levels of 60 to 70 dBA anJ trucks, busese and pi,crtly-,.,Iuftled
autos can create ;levels of 70-$5 dBA at 80 feet from the
source.
In Summary, there are, no significant noise problems associated
with State or County roads in the unincorporated arias of the
County, Based on the limited data available anal the CNEL/L dn
Descriptors( projected increases in traffic volumes on these
roads should cause no Significant increases in noise levels.
3. RaiXroad8
The main tracks of Southern Pacific and Western Pacific Rail-
roads have consistently high noise levels,, Both of thesea
,tracks carry heavy freight traffic with as many nighttime as
daytime operations. Rail traffic has not changed in the past
3 years and is not expected to increase sign i ficantly over the
next 10 yearso
For dete!rmininq nois,: levels associated with the typical
operations on these two lines, the methodology presented
in the Wyle Labora.torieu report, Assessment Of Noise Environments
Armed Railrc)ad o era,tions, was used, Table XV -4 shaves the - two main railroad lines with each line divided into categor.4es
according to l,angth, speed, and grade The Composite CNEL
at the fax right of Table XV -4 summarizes the projected CNNL"s
dor each category of track shown in :Figure XV -3.
t
Categories 1 And 2 include the Western pacific line that
runs North of Oroville through the Feather River Canyon on
ascending and descending grades. Categories 3 through 6
include the other sections of both the Western and Southern
Pacific lines. Column 15 in 'fable IV- shows the
r predicted
CNEL at the distance specified for ,each category taking into
account traffic mix (supplied by the railroads) and other
train -related variables that affect noise levels. The Wyle.
method assumes that there its nig noise attenuation by topography
or buildings
Figures IV -4 and IV -5 depict the CNEL noise contours for
the railroad section categories.
4, Airports
Airports,a:re significant noise sources and careful land use
planning around them is required. Both the Chico and the
Orov'4e airports are within city limits, but 'the _lands around
them are unincorporated.. A.ircraft:, operations at these two
airo
p its produce significant noise levels that impact surround:-
Ing Properties
The orovil.le Airport has no scheduled air carrier service,
but it is suitable for that use in the future. The City
of oroville has been requested to provide noize contour Projections
for the airport (see Appendixri) The contours will be incorporated
into the Noise Element when they aro'received.
611
TAI3L E IV -
------------
L WORKSHEET FOR LINE OPERATIONS
a.a L. ri f op n,
t' F V. qµh 'f4 Mxrr.v iLlkr ,.p -,..� s.•. _ J
J�btMioft frqun t n "do lit r r upr L.. 1+...1 r.11 A41 t71 - ..
N.rn(kahon Y ) y.rrJl Y.;n.nyl }rrr * 'k} ryl x111 m..-•er,.:„�.e...�,a..�
I p71
nbr rp, sP1 Er .Ih I$!
}° r" "rn• N I
Will I m„ t , +'141 Y1(IT CnMpt?SI)C CN[L AT
u, II[il y}IU,N. nrdk�` INonr♦ Yf r, n,tr Isayr. 114 fl ,,.r Ya HrIFe, SVA ii�rU-
mrc��rarrrprrWAI +� Ch.
t i k r r n dA`i' rrm nr 1� rr rtU'• , i ,� t,: t.,t .I ,: ? ri F'.1'![S a� ClitAtiPC IFJf1I[AT
01 it rner,r l� do ", 1 afar„Evr 7 rW Wl1 CYN PcfV�ra.i�y+1{ n
N.
r %•/�.�.u.:+._+ .. K. + nfur Nr Ild? ,1'al f181 rivl «n{
w+rx Y'^' >.»K ._,.�
to how r<.
C.) 'T "arta rw _
YFNa ilstl,t. Ji ,�..,, y, ,. �,.>, � ,� .., -L-�.• Y�] ,y(,i ,� .. .- _ r%,J „guy,.,•.,. +.rwYa •,ra«,
r: a.. yJH, r� r �IAK n .J1 •— j,.v ,+r.�,F-� l A.-/J�. 4� /..�
. _ > t•
)..� ",,•x.a4,X..'.Itr: .��.r... - Y� �” `"""'."Y"". 's''�.F`-. '.:,,:�:.....,�r..„�.. .,. - ..5.... !rlr1'.�� ,r��.��•. y!� �,.,�,�',,.. _ �7
<� +��,. i>. _”" ' .�..,...,. ,' � ._..� >. •; ins /'� �. �.�.�<.,� �
i r „ps. •r,.iY) _r> «: k. .—., . r; . , r , � -� „r,. �'� .�� ,a.6�.I
f
,Mr.
rr .9Y 4.i zi r«,,. .'vNw• �x �• •...� .,.u„ ty �� � �. � .. <=«ra:>..,
44—
r-,,—
f
t'Ni P r t • � ,_. ._„f, ,.,� >+« N L u.swY,F �. w+,fE.b _
.'a I'T:va !;.oah ». ,:y F rryp+;«f ,g. _,�.,Z -Tf
It,c M w .fir
,>
'IrirNt. ink,,
.»
+»..g
aV �5_ }. r ., _..., ... _.. ..-.+...,+.. A
.x
xr•
7"A+ PPAY itug
)€
r,
jL�.
.,r{r.
�1 ,edr
c
r
The Chico Municipal Airport- is a major ,source of noise
The airport is situated north of the city on Cohasset Road
(see Map IV -1). It is a general transportation airport 'serving
conventional and jet general aviation oper4tions, air tankers,
x
and commercial carriers.
The City of Chino's Municipal Airport is the Only airport
in the County with scheduled commercial flights. Considerable
industry is located on the eastern side of the airport property.
The airport is located north of Chico and the flight path
for general aviation takeoffs and landings passes dear resi-
dential areas During the fire season, the airport is used
extensively by fire -fighting tanker planes which are very
noisy. The major noise problems are with takeoffs and landings
of scheduled �r carrier jet aircraft, ,let takeoff and
landing approach procedures are established so that the
planes skirt the northeastern part of the urban area. This
procedure has reduced the noise problem, but reportedly
the aircraft do not always use the prescribed corridor.
Vigure IV -6 shows the 65 dB and 70 dB C&SEL contours for the
Chico Municipal Airport as provided by the Federal Aviation
Administration for the Chico General. Plan dated July 1976.
The 60 dB CNLL :noise contour required by the 1976 amendment
to Government Code section 65302 ,(g) was not required for the
preparation of the Chico General Plan Noise Element. The City
of Chico General Plan says
"The area designated for potential, low density
residential developmeTit in northeast Chico (approxi-
mately 1-1%4 miles from the end of the runway)
thus falls outside,the 65 CNEL contour, that
is, it would be exposed to noise levels less
than CNBL«
lV-19
t
Ile
�a 8
WIM
aft ado
pa
0 s y0�
Ib 3 R i
0
a •
^S r " A
y r a p #
b die U
+ e Y b
HICO
MUNICIPAL
nur wed Kn! eras r¢tr wv «NM n`.M. 1 d
UMM,11 � 70
p sr.1 tttn tt+! aee`Cw. [xv Ksd. �rpe �+�'af ^wr .� 1�
�'` MSR .. ��r��✓ F-
'<
a
EATON'RO.
°
55 CNE1_
,
70 CNBC
MU "i IV -6
. ,
AIRPORT BOUNDARY
CM CO AIRPORT
:•... �•
AREA TO BE ACCIUMED IN
FEE TITLE FOR 04EwAR ZONE
EXCESS LAND -• TAKING AREA TO RE
ACQUIRED IN FITS TITLE
.
MOISEE CONTOURS
Owp {{ yrrn,
NOISE
LTTE COLNTry GENERAL PLAN
SOURCE.
Airleral Aviation port In st ict Office, e, Burlin eme, California,
�
December 9, 1975
t
OCPAP d£xY NO
R V8I Q ]N e
C
..
! z5�sao ..m"uu,..,.,�« e
Ft.N� i
TV -24
...................
"However, in asserilng airport noise., the cnm
methodology( which is essentially a means of
averaging individual noise events, should be
esPecially viewed as a guide rather than as a
precise and definitive assessment of noise impact.
This is particularly true in Chico, where the single
event noise levels associated with the DC -9 aircraft,
and with the larger air tankers,, can and do annoy
residents who live in the airport vicinity, The
CNEL evaluation is particularly limited in situations
such as'Chicolst where there are relatively few
flights in a day. Thereforer recognition must
also be given to the importance of single event
noise levels."
The City of Chico is acquiring property within the airport
clear zone and 65 dB CNEL level to provide limited short-
term protection of future airport operations from encroaching
incompatible residential uses*
5. Noise -Sensitive Areas
Noise -sensitive. sites shown in Map IV -1 include the Butte
Ecology Conservation Center, t tte college, public schools
in unincorporated areas and'411:the edges of cities, public
and pVivato rest homes with occupancies over 1.5 persons
in unincorporated areas, wildlife management areas, and
the,Peather River Hospital in Paradise. These sensitive
receptors need adequate quiet to properly conduct their
activities.
6. Noise Survey
A community noise survey,was Conducted in December 1976
for three purposes; (1) to measure the noise environment
at typical receptors deemed noise -sensitive and located
XV -21
outside of the tdil 60 dD °noise levels 4enarated by major
noioo uourcos (road.ways, airports y railroads) ; (2) to provide
information on mt j=car noise sources where t,)r di.ctive results
are 3 ngertai+n (rai,l,road maintenance and switching yards)
and ,3) to define ambient noise levels in representative
areas of the 0oanty.
The --, representative sites listed in Table IV -5 were monitored
to de." t-_rmi ne Ldn noise levels. Measurements were taken
at each site between 700 a.m. and 10:00 .p.m, , and between
10.00 p.m, and 700 am. A. -scale readings more taken at
each site every 5 seoonds for periods of at Least 10 minutes
with a Gruel. and Kjaer precision Sound Level Meter, using
a 1 -inch condenser microphone with a wizidscreen. The instrument
was chocked for calibration before each monitoring period.
Meteorol.o , oal conditions varied from clear to foggy, with
calm winaii and temperatures from 45 to 66 degrees.
The calculated day -night average: levels which indicate typical
levels to be expected at the sites can be applied to other
similar locations in the County. The measurements taken
at the Western Pacific maintenance and switching yards in
Oroville show high levels at nearby residonees.
7. Summary
There have been few noise comp ,lai.nts in the county and most
of these involve it -city noise problems,. The unincorporated
areas of the county generally have :Low noise levels and
most of the noise producing activities (motoroycl e tracks r
gravel -crushing operations, etc.) are sufficiently remote
from popi.,Iated ares to cause few conpl.aints.
_'Phare are very few persons exposed to toise levels above
ars Ldn of 160 dB in the unincorporated areas of the County.,
Railerbadst high -spored highways, industries, and airports
currently effect few residential areas or other sensitive
receptors,
1VM�
VabI6 SV -5, AMDIENT NPISB MON11PO ING SITES
Facility Namet
Ype of i'ac 1 V:
Measurement i,ocation
Ldn'
M z
SoUrC-01
,9r
1)
Railroad maintenance
Western Pacific Shops in
70 dZ
yard
CrOville; measured at res ,-
dences across the street
2)
Railroad switching
Western pacific switching
62. dys
yard
yards in oroville, measured
at resi0ences across the
'
$t.rea
Sensitive Areas
3)
Rest Horne in a real.-
8dgewood Care Home in Para-
41 dA
dential neighborhood
dise; measured oil front lawn
4)
Community Hospital in
Feather River Hospital
51 dB
a residentla.l neighbor-
Paradiso; measured in
hood
hospital parking lot
5)
outlying school orButte
"allege; measured on
51 4B
other facility in a
student center lawn
rural area
6)
Rural community school
Durham 1, in Durham;
56 c;B
measured in parking lot, near
Highway 99
1.)
Rural community school.
Richvale BlOMOntary in Richvala;
61 i1B
near light industry,
measured in school parking lot
school activities in
near Highway 99
progrosb
Q)
Suburban community
Las Plumas high School in
57 Gg
school., school acti-
Oroville measured in school
vities in progress
par%inq let
0)
Wildlife refuge near
Veather River Wildlife' Manage-
40 dB
an urban community
menu 7�reaj southwest of
CiroVille; measured near
Pacific Heights Road
10)
Wildlife refuge in
Grey s OdgO Wildlife Manage-
40 d1l
rural area
ment.Area southwest of Gridley,;
measured 'near Liberty Road
`i Source:
CR2t,1, HILL,, T Decembor
1976.
IV -23