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Warren County Hazard Mitigation Plan August 2011
Section 3 28
SECTION 3- Risk Assessment
Requirement §201.6(c)(2): [The plan shall include] A risk assessment that provides the factual basis for activities proposed in the strategy to reduce losses from identified hazards. Local risk assessments must provide sufficient information to enable the jurisdiction to identify and prioritize appropriate mitigation actions to reduce losses from identified hazards.
The risk assessment process identifies and profiles relevant hazards and assesses the
exposure of lives, property, and infrastructure to these hazards. The goal of risk assessment is
to estimate the potential losses in Warren County, including loss of life, personal injury, property
damage, and economic loss, from a hazard event. The risk assessment process allows
communities in Warren County to better understand their potential risk from natural hazards and
provides a framework for developing and prioritizing mitigation actions to reduce risk from future
hazard events.
The risk assessment for Warren County and its jurisdictions followed the methodology
described in the FEMA publication 386-2, Understanding Your Risks: Identifying Hazards and
Estimating Losses (2002), which includes a four-step process:
Identify Hazards
Profile hazard Events
Inventory Assets
Estimate Losses
This section is further divided into three parts: hazard identification, hazard profiles, and
vulnerability assessment:
Section 3.1 Hazard Identification identifies the hazards that threaten the entire
county and describes why some hazards have been omitted from further
consideration.
Section 3.2 Hazard Profiles discusses the threat to the planning area and
describes previous occurrences of hazard events and the probability of future
occurrence.
Section 3.3 Vulnerability Assessment assesses the County’s total exposure to
natural hazards, considering critical facilities and other community assets at risk, and
assessing growth and development trends.
Warren County Hazard Mitigation Plan August 2011
Section 3 29
Multi-Jurisdictional Risk Assessment
For this multi-jurisdictional plan, the risk assessment assesses each jurisdiction’s risks where
they deviate from the risks facing the entire Warren County. Warren County is not a large
county (431 square miles) and is fairly uniform in terms of climate and topography as well as
construction characteristics and development trends. Accordingly, overall hazards and
vulnerability do not vary greatly across the planning area for most hazards.
3.1 Hazard Identification
Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the type…of all natural hazards that can affect the jurisdiction.
3.1.1 Methodology
All the hazards from the 2004 plan and the State Plan are included in this 2009 update except
that severe winter weather and tornadoes/severe thunderstorms are broken down into four
different hazards- hailstorm, severe winter weather, thunderstorm & high winds, and tornadoes.
The reason for discussing them separately is that there is significant increase of these hazards
in Warren County.
Based on the data limitations within the county, through the guidance provided by the State
Hazard Mitigation Plan and through the discussions with County Emergency Management
Director and the participating jurisdictions, this plan update also addresses in brief the two
natural hazards- land subsidence and levee failure. Levee failure is included with floods as it
falls within the scope of potential flooding events.
Considering the updated Missouri State Hazard Mitigation Plan 2007 and the updated
Emergency Operations Plan, there has been a gradual increase in manmade incidents, which
can be just as devastating as natural disasters in Warren County. Therefore, the following man-
made hazards are included as part of the plan update process: nuclear power plants, hazardous
materials, transportation, utility interruptions and power failures, and terrorism. The hazard
analysis provided for these hazards in this section is based on the 2004 Hazard Mitigation Plan
and the County Emergency Operations Plan.
The following natural hazards are not included in this analysis because they do not threaten
Warren County Hazard Mitigation Plan August 2011
Section 3 30
Missouri: avalanches, coastal erosion, coastal storms, hurricanes, tsunamis, and volcanoes.
While expansive soils, landslides, and rock falls are recognized as hazards in Missouri, they
occur infrequently and their impacts are minimal; so they will not be profiled further in this
document.
Table 3.1 Summary of Hazard Identification Lists (2004 and 2010 Plan)
2004 Plan Hazard List 2010 Plan Hazard List
Dam failure
Drought
Earthquakes
Floods
Heat wave
Severe Winter Weather (Snow, Ice and Extreme Cold)
Tornadoes/Severe Thunderstorms
Wildfires
Dam
Drought
Earthquake
Extreme Heat
Flood/Levee Failure
Hailstorm
Severe winter weather
Thunderstorm and high winds
Tornado
Wildfire
Hazardous materials
Terrorism
Transportation
Utility Interruption & Power failure
Data on past impacts and future probability of these hazards in the Warren County planning
area was collected from following sources:
Missouri Hazard Mitigation Plan (May 2007)
Information on past hazard events from the Spatial Hazard Event and Loss Database
(SHELDUS), a component of the University of South Carolina Hazards Research Lab
that compiles county-level hazard data for 18 different natural hazard event types.
Information on past extreme weather and climate events from the National Oceanic and
Atmospheric Administration’s (NOAA) National Climatic Data Center.
Federal Disaster Declarations from the Federal Emergency Management Agency
(FEMA)
The U.S. Geological Survey (USGS) and the Center for Earthquake Research and
Information (CERI) were major sources for earthquake information.
The Dam Safety Division of Missouri (DNR) provided major information concerning
dams.
Warren County Hazard Mitigation Plan August 2011
Section 3 31
Other sources included Missouri Department of Natural Resources (MDNR), Missouri
Department of Conservation (MDC), county officials; existing county, regional and state
plans; reports on the floods of 1993 and 1995; position papers on transportation issues;
and information from local residents (sources are indicated where data is cited).
3.1.2 Disaster Declaration History
One method used by the HMPC to prioritize hazards was to examine events that triggered
federal and/ or state disaster declarations. Federal and/or state declarations may be granted
when the severity and magnitude of an event surpasses the ability of the local government to
respond and recover. Disaster assistance is supplemental and sequential. When the local
government’s capacity has been surpassed, a state disaster declaration may be issued,
allowing for the provision of state assistance. Should the disaster be so severe that both the
local and state governments’ capacities are exceeded; a federal emergency or disaster
declaration may be issued allowing for the provision of federal assistance.
The federal government may issue a disaster declaration through FEMA, the U.S. Department
of Agriculture (USDA), and/or the Small Business Administration. FEMA also issues emergency
declarations, which are more limited in scope and do not include the long-term federal recovery
programs of major disaster declarations. Determinations for declaration type are based on scale
and type of damages and institutions or industrial sectors affected.
A USDA disaster declaration certifies that the affected county has suffered at least a 30 percent
loss in one or more crop or livestock areas and provides affected producers with access to low-
interest loans and other programs to help mitigate disaster impacts. In accordance with the
Consolidated Farm and Rural Development Act, counties neighboring those receiving disaster
declarations are named as contiguous disaster counties and are eligible for the same
assistance. Table below lists federal disaster declarations received by Warren County. Each of
the disaster events affected multiple counties; estimated damages reflect total losses to all
counties.
Table 3.2
Declaration Number
Declaration Date Disaster Description Counties included Estimated damage
FEMA-1676-DR January 14, 2007 Severe Winter Storms and Flooding
Barry, Barton, Callaway, Camden , Christian, Cole, Crawford, Dade, Dallas , Dent, Franklin , Gasconade, Greene, Hickory , Jasper, Laclede, Lawrence , Lincoln , Maries, McDonald, Miller, Montgomery , Newton , Osage, Phelps,
$35 million
Warren County Hazard Mitigation Plan August 2011
Section 3 32
Declaration Number
Declaration Date Disaster Description Counties included Estimated damage
Polk, Pulaski, St. Charles , St. Clair, St. Louis , Stone, Warren , Webster, Wright, and the independent City of St. Louis for debris removal and emergency protective measures (Categories A and B), including direct Federal assistance.
FEMA-3281-DR December 12, 2007
Severe Winter Storms All 114 Missouri Counties and the Independent City of St.Louis
NA
FEMA-1736-DR December 27, 2007
Severe Winter Storms Adair, Andrew, Atchison, Audrain, Barton, Benton, Boone, Buchanan, Caldwell, Callaway, Camden, Cedar, Clinton, Cole, Dade, Daviess, DeKalb, Gentry, Grundy, Harrison, Hickory, Holt, Jasper, Lincoln, Linn, McDonald, Mercer, Miller, Moniteau, Montgomery, Morgan, Newton, Nodaway, Osage, Pike, Putnam, St. Clair, Schuyler, Scotland, Sullivan, Warren, and Worth Counties. Direct Federal assistance is authorized.
$28,931,081
FEMA-1749-DR March 19, 2008 Severe Storms and Flooding
Audrain, Barry, Barton, Boone, Bollinger, Butler, Callaway, Camden, Cape Girardeau, Carter, Cedar, Christian, Cole, Cooper, Crawford, Dade, Dallas, Dent, Douglas, Dunklin, Franklin, Gasconade, Greene, Hickory, Howard, Howell, Iron, Jasper, Jefferson, Laclede, Lawrence, Lincoln, Madison, Maries, McDonald, Miller, Mississippi, Montgomery, Moniteau, Morgan, New Madrid, Newton, Oregon, Osage, Ozark, Pemiscot, Perry, Phelps, Pike, Polk, Pulaski, Reynolds, Ripley, St. Charles, St. Clair, St. Francois, St. Louis, Ste. Genevieve, Shannon, Scott, Stoddard, Stone, Taney, Texas, Vernon, Warren, Washington, Wayne, Webster, and Wright Counties and the Independent City of St. Louis for emergency protective measures (Category B), limited to direct Federal assistance under the Public Assistance program.
$68,000,000
FEMA-3303-DR January 30, 2009 Severe Winter Storms, All 114 Missouri Counties and the Independent City of St.Louis
NA
Source: FEMA
Warren County Hazard Mitigation Plan August 2011
Section 3 33
Table below lists U.S. Department of Agriculture disaster declarations for Warren County (2005-
2007).
Table 3.3 USDA Disaster No. Start Date Drought Tornadoes
Severe Storms
Below Normal Temperatures
Winter Storms
Excessive Moisture
S2119 01/01/2005 X
M1631 11/03/2006
X X
X
S2407 01/01/2006 X
M1676 12/01/2007
X X
N1736 12/06/2007
X
N873 01/12/2007
X
S2532 03/30/2007
X X
Source: USDA Farm Service Agency.
3.2 Hazard Profiles
Requirement §201.6(c)(2)(i): [The risk assessment shall include a] description of the…location and extent of all natural hazards that can affect the jurisdiction. The plan shall include information on previous occurrences of hazard events and on the probability of future hazard events.
3.2.1 Methodology
Each hazard identified in Section 3.1, Hazard Identification, is profiled individually in this section
in alphabetical order for easier reference. The level of information presented in the profiles
varies by hazard based on the information available. With each update of this plan, new
information will be incorporated to provide for better evaluation and prioritization of the hazards
that affect Warren County.
The sources used to collect information for these profiles include those mentioned in Section
3.1.1 as well as those cited individually in each hazard section. Detailed profiles for each of the
identified hazards include information on the following characteristics of the hazard:
Hazard Description
This section consists of a general description of the hazard and the types of impacts it may have
on a community. It also includes a ranking to indicate typical warning times and duration of
hazard events. Definitions for these rankings are included in Table 3.4.
Warren County Hazard Mitigation Plan August 2011
Section 3 34
Historical Statistics
This section describes the geographic extent or location of the hazard in the planning area and
includes the information on historic incidents and their impacts based upon the sources
described in Section 3.1 hazard Identification and the information provided by the HMPC.
Where available, maps are utilized to indicate the areas of the planning area that are vulnerable
to the subject hazard.
Probability of Future Occurrence
The frequency of past events is used to gauge the likelihood of future occurrences. Where
possible, the probability and severity of occurrence was calculated based on historical data.
Probability was determined by dividing the number of events observed by the number of years
and multiplying by 100. This gives the percent chance of the event happening in any given year.
An example would be three droughts occurring over a 30-year period, which suggests a 10
percent chance of a drought occurring in any given year. The probability was assigned a rank as
defined in Table 3.4.
Magnitude/Severity
The magnitude of the impact of a hazard event (past and perceived) is related directly to the
vulnerability of the people, property, and the environment it affects. This is a function of when
the event occurs, the location affected the resilience of the community, and the effectiveness of
the emergency response and disaster recovery efforts.
Hazard Summary
To maintain a consistent reporting format, prioritization was based on four elements of risk:
probability, magnitude/severity, warning time, and duration. Table 3.4 defines the rankings for
each element of risk. Table 3.5 lists different hazards in the county with their respective risk
criteria.
Table 3.4 Ratings for each hazard
Element/ Level Characteristics
Probability The likelihood that the hazard will occur.
4- Highly Likely Event is probable within the calendar year. Event has up to 1 in 1 year chance of occurring (1/1=100%) History of events is greater than 33% likely per year. Event is "Highly Likely" to occur
3- Likely Event is probable within the next three years.
Warren County Hazard Mitigation Plan August 2011
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Event has up to 1 in 3 years chance of occurring (1/3=33%) History of events is greater than 20% but less than or equal to 33% likely per year Event is "Likely" to occur
2- Occasional Event is probable within the next five years. Event has up to 1 in 5 years chance of occurring (1/5=20%) History of events is greater than 10% but less than or equal to 20% likely per year Event could "Possibly" occur
1-Unlikely Event is possible within the next 10 years Event has up to 1 in 10 years chance of occurring (1/10=10%) History of events is less than or equal to 10% likely per year Event is "Unlikely" but is possible of occurring
Magnitude / Severity The deaths, injuries, or damage (property or environmental) that could result from the hazard.
4- Catastrophic Multiple deaths Complete shutdown of facilities for 30 or more days More than 50 percent of property is severely damaged
3- Critical Injuries and/or illnesses result in permanent disability Complete shutdown of critical facilities for at least two weeks 25–50 percent of property is severely damaged
2- Limited Injuries and/or illnesses do not result in permanent disability Complete shutdown of critical facilities for more than one week 10–25 percent of property is severely damaged
1-Negligible Injuries and/or illnesses are treatable with first aid Minor quality of life lost Shutdown of critical facilities and services for 24 hours or less Less than 10 percent of property is severely damaged
Warning Time
4 Minimal (or no) warning
3 6-12 Hours
2 12-24 Hours
1 24 + Hours
Duration
4 More than 1 Week
3 Less than 1 Week
2 Less than 1 Day
1 Less than 6 Hours
Warren County Hazard Mitigation Plan August 2011
Section 3 36
Table 3.5 lists the identified hazards for each participating jurisdiction for Warren County
Table 3.5 Hazards Identified for each participating jurisdiction
Hazard Warren County
Innsbrook Marthasville Pendleton Warrenton Wright City
Truesdale Warren school
Wright city school
Washington school
Gasconade school
Dam X X X -- -- -- -- -- -- X --
Drought X X X X X X X X X X X
Earthquake X X X X X X X X X X X
Extreme Heat X X X X X X X X X X X
Floods/ Levee failure X X
X *
-- X X X X X X --
Hailstorms X X X X X X X X X X X
Severe winter weather X X X X X X X X X X X
Thunderstorms & High Winds X X X X X X X X X X X
Tornadoes X X X X X X X X X X X
Wild Fire -- -- X -- X -- X X -- -- --
Hazardous Materials X X X X X X X X X X X
Terrorism X X X X X X X X X X X
Transportation X X X X X X X X X X X
Utility interruptions/power failure
X X X X X X X X X X X
X Jurisdictions susceptible to a specific hazard -- Jurisdictions not susceptible to a specific hazard * jurisdictions susceptible to levee failure
Warren County Hazard Mitigation Plan August 2011
Section 3 37
Table 3.6 Warren County Hazard Profile Summary
Natural hazards
Hazard Probability Magnitude/ Severity
Warning Time
Duration Total score Prioritization
Dam Occassional-2 Critical-3 1 1 7 Low
Drought Likely-3 Critical-3 1 4 11 Low
Earthquake Likely-3 Critical-3 4 1 11 Medium
Extreme Heat Likely-3 Critical-3 1 3 10 Medium
Floods/ Levee failure Likely-3 Critical-3 2 2 10 Medium
Hail Likely- 3 Limited- 2 3 1 9 Low
Severe winter weather Likely-3 Critical-3 3 3 12 High
Thunderstorms & High winds
Highly Likely-4 Limited-2 4 1 11 High
Tornadoes Highly Likely-4 Limited-2 4 1 11 High
Wild Fire Occassional-2 Limited-2 1 1 6 Low
Man made hazards
Hazardous Materials Likely-3 Limited-2 4 2 11 High
Terrorism Unlikely-1 Limited-2 4 3 10 Low
Transportation Likely-3 Critical-3 4 2 12 Medium
Utility Interruption & Power failure
Highly Likely-4 Limited-2 4 3 13 High
Note: a) Measures for Probability and Magnitude were determined by BRPC using the Warren County Hazard Mitigation Plan 2004- hazard work sheets, Missouri State Hazard Mitigation Plan, and other relevant sources. b) Hazard prioritization exercise was accomplished during the kickoff meeting. The rankings in this table were based on the committee’s own experience, their needs, and capabilities. This prioritization exercise was used as a basis for further analysis by the individual jurisdictions for prioritizing the goals and action plans. c) The total score of all the elements of risk - probability, magnitude/severity, warning time and duration were considered for prioritizing the hazards. A total score of 10, 11 and 12 received medium and high priority and scores of 6 to 9 received a low priority. d) However, lows were ranked differently from the total scores depending on the type of hazard. Drought has a total score of 11 but it received a low priority due to few major noted occurrences in the jurisdictions and it is not anticipated to damage structures. e) Terrorism has a total score of 10 and received a low priority as there were no occurrences in the County.
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Section 3 38
3.2.2 Dam Failure
Hazard Description
A dam is defined by the National Dam Safety Act as an artificial barrier that impounds or diverts
water and (1) is at least 6 feet high and stores at least 50 acre-feet of water, or (2) is at least 25
feet high and stores at least 15 acre-feet.
Missouri’s DNR regulates the design, construction and maintenance of 4,100 non-federal, non-
agricultural dams that are at least 35 feet high. Dam owners have primary responsibility for the
safe design, operation and maintenance of their dams. They are responsible for providing early
warning of problems at the dam, for developing an effective emergency action plan, and for
coordinating that plan with local officials. The state has ultimate responsibility for public safety
and many states regulate construction, modification, maintenance, and operation of dams.
DNR’s Dam Safety Division maintains a database of all dams regardless of federal, state, local
or private ownership.
The failure of dams or levees can result in injuries, loss of life, and damage to property and the
environment. While levees are built solely for flood protection, dams often serve multiple
purposes, one of which may be flood control. Severe flooding and other storms can increase the
potential that dams and levees will be damaged and fail as a result of the physical force of the
flood waters or overtopping.
Dams and levees are usually engineered to withstand a flood with a computed risk of
occurrence. If a larger flood occurs, then that structure will likely be overtopped. If during the
overtopping, the dam fails or is washed out, the water behind is released as a flash flood. Failed
dams can create floods that are catastrophic to life and property, in part because of the
tremendous energy of the released water.
The problem of unsafe dams in Missouri was underscored by dam failures at Lawrenceton in
1968, Washington County in 1975, Fredericktown in 1977, and a near failure in Franklin County
in 1978.
Oversight is extremely valuable to the owners as well as those people living downstream of the
dam who could be flooded in the event the dam should fail. Dams can fail for many reasons.
The most common are:
Piping: internal erosion caused by embankment leakage, foundation leakage and
deterioration of pertinent structures appended to the dam.
Warren County Hazard Mitigation Plan August 2011
Section 3 39
Erosion: inadequate spillway capacity causing overtopping of the dam, flow erosion, and
inadequate slope protection.
Structure Failure: caused by an earthquake, slope instability or faulty construction.
These failure types often are interrelated. For example, erosion, either on the surface or
internal, may weaken the dam or lead to structural failure. Additionally, a structural failure may
shorten the seepage path and lead to a piping failure.
Missouri DNR has defined three levels of hazard potential – high, significant, and low - as
accepted by the Interagency Committee on Dam Safety. The definitions are:
High: Failure or mis-operation will probably cause loss of human life.
Significant: Failure or mis-operation results in no probable loss of human life but can
cause economic loss, environmental damage, disruption of lifeline facilities, or impact
other concerns. Significant hazard potential classification dams are often located in
predominantly rural or agricultural areas but could be located in areas with population
and significant infrastructure.
Low: Failure or mis-operation results in no probable loss of human life and low
economic and/or environmental losses. Losses are principally limited to the owner’s
property.
Warning Time: Level 1 ─24+ Hours
Duration: Level 1─ Less than 6 hours
Historical Statistics
According to Missouri DNR’s Dam Safety Division in Rolla, Warren County now has 128 dams.
All Warren County dams are earthen construction. The mean dam height is 34 feet. The mean
maximum storage capacity is 429 acre-feet. (An acre-foot is one acre of water that is one foot
deep. For example, a 10-acre lake that is 10 feet deep would have a maximum storage
capacity of 100 acre-feet.) Many are less than 35 feet high and not regulated by Missouri DNR.
Therefore, people living downstream of these smaller unregulated dams are virtually at the
mercy of the dam owner’s construction and maintenance practices.
Of 125 dams, 28 are rated by Missouri DNR as ―high‖ risk. Only seven are regulated by the
State. High-hazard dams exhibit one or more characteristics: more than 30 years old; high ratio
of maximum storage to dam height; and/or high population density downstream. Below is a
summary table of the county’s high-hazard dams.
Warren County Hazard Mitigation Plan August 2011
Section 3 40
Table 3.7 Warren County High-Hazard Dams
Official Name Year Built Length Ht. (ft.)
LAKE SHERWOOD DAM 1967 1000 67
OUR COUNTRY PLACE DAM 1965 760 64
WOODRIDGE LAKE DAM 1975 485 64
INNSBROOK #4 DAM 1975 700 46
DEER HOLLOW LAKE DAM 1972 500 78
ISLEY LAKE DAM 1983 400 65
MARTHASVILLE MV-5 DAM 2004 1,000 36
BROCKFELD DAM 2006 292 51
CARDINAL LAKE DAM 2001 370 44
DOGWOOD LAKE DAM 1970 430 42
DUNN LAKE DAM 1970 490 38
KOEPKE LAKE DAM 1967 650 40
LAKE ASPEN DAM 1979 650 53
LAKE KITZBUEHL DAM 2004 400 58
LAKE KONSTANZ DAM 1999 525 90
LAKE ST. GALLEN DAM 1979 410 57
LAKE WANDERFERN DAM 1976 410 54
MILLER LAKE DAM 1977 200 46
NINE ACRE LAKE DAM 1976 310 37
OWL CREEK ESTATES DAM #1 1970 480 41
OWL CREEK ESTATES DAM #2 1974 400 54
OWL CREEK ESTATES DAM #3 1974 380 49
SEABROOK DAM 1986 340 41
STARK LAKE DAM 1968 470 39
SUGAR HOLLOW LAKE DAM 1968 420 43
SUNNY MOUNT CHURCH DAM 1970 400 40
TRINITY LAKE DAM 1986 400 44
ALPINE LAKE DAM 2000 1279 118
The most recent earthen dam failure in Warren County occurred on May 27, 2008 at Innsbrook
on Lake Alpine which tore a section of pipe from the dam. Alpine lake is the largest private,
man-made lake in the State of Missouri. The lake is about 11 miles around its perimeter and
reaches a depth of 90 feet. The incident occurred after a period of heavy rainfall which caused a
large diameter pipe used to lower the lake failed. Part of a 36-inch spillway pipe was expelled
from the dam of the 236-acre lake. The pipe feeds an overflow spillway at the center of a
quarter-mile earthen dam at the south end of the lake.
Warren County Hazard Mitigation Plan August 2011
Section 3 41
When the force of the water literally tore the section of pipe from the dam, it created an opening
in the dam which measured approximately 40 feet across.
At the time of this incident, emergency officials estimated that the water level of the lake was at
least 3 feet above the drainage pipe. Emergency personnel and officials from DNR took steps to
prevent a possible breach in the dam. The spillway and broken pipe were sealed off with a
mixture of rocks and concrete to prevent further seepage.
Location
Map 3.1 shows Warren County dams along with critical facilities
§̈¦I-70 §̈¦I-70
¬«47
¬«94
¬«94
¬«47
¬«47
¬«47
¬«94
¬«94
Innsbrook
Warrenton
Foristell
Wright City
Truesdale
Marthasville
82018201
UVU
UVB
UVW
UVO
UVY
UVA
UVEE
UVD
UVN
UVM
UVAA
UVCC
UVJ
UVTT
UVF
UVH
UVOO
UVMM
UVWWUVNN
UVA
Daniel Boone SchoolRebecca Boone SchoolBlack Hawk Middle SchoolWarren County High SchoolHoly Rosary Catholic SchoolWarrenton Christian SchoolJolly TotsReach Out Adult Day CreWarrenton Area Child Care CenterKiddie KampusLittle Lambs Lutheran PreschoolWarrenton ManorBristol ManorCountry Cove WestWhispering Pines Assisted Living
Wright City ElementaryWright City Middle SchoolWright City High SchoolGood Shepherd Lutheran Day CareUnion Basic Child Care Center
Marthasville Elementary School
Ü
0 2 4 61Miles
County boundary
Incorporated Areas
Roads
Dams
Source: Boonslick Regional Planning Commission
Warren County Hazard Mitigation Plan August 2011
Section 3 42
Missouri DNR’s Division of Dam Safety completed the dam inundation maps for the high hazard
dams in Warren County. DNR employed LiDAR data extracted from ArcView using HEC-
GeoRAS, hydraulic analysis using HEC-RAS, and mapping using ArcView. DNR conducted the
analysis using the Rapid Assessment Method, and the Detailed Method. Both these methods
employ several standard assumptions about the nature of the breach and flow conditions.
The jurisdiction specific maps provided below were developed using the DNR dam inundation
maps. It can be seen from the maps that the major inundation areas are located in the
unincorporated parts of the county, Innsbrook and Marthasville.
Map 3.2 shows dams & inundation areas in Marthasville
UVD
UVO
¬«47
¬«94
¬«47
Ü
0 0.4 0.8 1.20.2Miles
Warren County boundary
Marthasville
Roads
Dam
Inundation area
Ü
Marthasville MV.5 Dam
Warren County Hazard Mitigation Plan August 2011
Section 3 43
Map 3.3 shows dams & inundation areas in Village of Innsbrook
UVO
UVD
UVM
UVN
UVCC
UVTT
UVF
UVU
UVOO
UVMM
UVH
UVAA
UVT
UVT
¬«47
¬«94
¬«47
¬«47
¬«47
¬«94
0 1 2 30.5Miles
Warren County boundary
Innsbrook
Roads
Dams
Inundation zone
Ü
Warren County Hazard Mitigation Plan August 2011
Section 3 44
Map 3.4 shows dams & inundation areas in the unincorporated area along with
population density
0 2 4 61Miles
Inundation Zone
Dams
Warren County boundary
Population density
1 Dot = 10
POP00
Ü
Warren County Hazard Mitigation Plan August 2011
Section 3 45
Probability of Future Occurrence
No records were found to indicate any major dam failures in Warren County. The probability of
occurrence of dam failure is ―occasional‖.
Occasional- Event is probable within the next five years.
Magnitude/Severity
Marthasville, Washington School District (Marthasville elementary school) - ―Critical‖.
As per the maps, the unincorporated area as 14 dams. The magnitude/severity for the
unincorporated area is considered to be limited considering the population density.
Also, the Village of Innsbrook has 13 dams identified. Most of the homes located in this Village
are considered as secondary homes. Therefore, the magnitude/severity has been ranked as
limited.
Innsbrook, unincorporated areas - ―Limited‖.
Critical ─ 25–50 percent of property is severely damaged; Injuries and/or illnesses result in
permanent disability; Complete shutdown of critical facilities for at least two weeks.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
3.2.3 Drought
Hazard Description
The National Weather Service defines drought as ―a deficiency in precipitation over an extended
period, usually a season or more, resulting in a water shortage causing adverse impacts on
vegetation, animals, and/or people. The Missouri Drought Response Plan distinguishes
between five categories of drought, as follows:
Agricultural drought, defined by soil moisture deficiencies;
Hydrological drought, defined by declining surface water and groundwater
supplies;
Meteorological drought, defined by precipitation deficiencies;
Hydrological drought and land use, defined as a meteorological drought on one
area that has hydrological impacts in another area, i.e. a drought in the Rocky
Mountains may be significant in Missouri because the Missouri River is in part
dependent upon upstream precipitation and snow pack; and
Warren County Hazard Mitigation Plan August 2011
Section 3 46
Socioeconomic drought, defined as drought impacting supply and demand of
some economic commodity.
Figure 3.1 shows the Palmer Drought Index published jointly by NOAA and the United States
Department of Agriculture (USDA).
Figure 3.1
Source: National Climatic Data Center.
The most commonly used indicator of drought and drought severity is the Palmer Drought
Severity Index (PDSI) published jointly by NOAA and the United States Department of
Agriculture. The PDSI measures the departure of water supply (in terms of precipitation and
stored soil moisture) from demand (the amount of water required to recharge soil and keep
rivers, lakes and reservoirs at normal levels). The result is a scale from +4 to -4, ranging from an
extremely moist spell to extreme drought. By relating the PDSI number to a regional index, one
can compile data that reflects long-term wet or dry tendencies.
Regional indicators such as the PDSI are limited in that they respond slowly to deteriorating
conditions. On the other hand, observing surface conditions and groundwater measurements
may provide only a snapshot of a very small area. Therefore, the use of a variety of drought
indicators is essential for effective assessment of drought conditions, with the PDSI being the
primary drought severity indicator.
Warning Time: Level 1- 24+ hours
Warren County Hazard Mitigation Plan August 2011
Section 3 47
Duration: Level 4- More than 1 Week
Historical Statistics
Drought in Warren County is primarily a problem of rural water supply, especially those supplied
by small water structures. When good water becomes a scarce commodity and people must
compete for the available supply, the importance of drought severity and duration increases
dramatically.
According to the Climate Prediction Center, average annual precipitation for the St. Louis
regional area is 39 inches and the state rates Warren County for moderate drought
susceptibility. Precipitation-related impacts on time scales ranging from a few days to a few
months can include effects on wildfire danger, non-irrigated agriculture, topsoil moisture,
pasture conditions, and unregulated stream flows. Lack of precipitation over a period of several
months or years adversely affects reservoir stores, irrigated agriculture, groundwater levels, and
well water depth.
Montgomery County PWSD #1, and St. Charles County PWSD #2 are the two systems that
serve Warren County. Groundwater resources in the county are adequate to meet domestic and
municipal water needs, but due to required well depths, irrigation wells are very expensive. In
addition, the abundance of steep-slope topography generally is unsuitable for row-crop
irrigation.
Warren County lies in an area of Ordovician and Cambrian dolomites and sandstones (light blue
areas on the map) that can yield 15-500 gallons per minute depending on depth and the
producing formations. Wells in alluvial soils along the Missouri River (shown in beige) typically
yield more than 1,000 gallons per minute and the water is suitable for irrigation.
The DNR’s drought response system has four phases. Phase 1 begins when water monitoring
analysis indicates anticipated drought consequences. The situation moves into Phase 2 when
the PDSI reads -10 to -20. At the same time, stream flow, reservoir levels and groundwater
levels are below normal over a period of several months. Phase 3 is based on a PDSI between
-2 to -4 and various other factors. Phase 4, or activation of drought emergency procedures,
generally begins when the PSDI exceeds -4. Table below shows the existing water systems in
Warren County.
Table 3.8
Water System Name Type Status Source Water Type
Cedar Grove Village SUBD C A Ground Water
Dogwood lake campground Intern NC A Ground Water Emmaus Homes Inc C A Ground Water
Warren County Hazard Mitigation Plan August 2011
Section 3 48
Water System Name Type Status Source Water Type
Flying J Travel Plaza NTNC A Ground Water Glenbrook Estates C A Ground Water Innsbrook C A Ground Water Lake Sherwood SUBD C A Ground Water Maple Ridge MHP C A Ground Water Marthasville C A Ground Water Midway Trailer Park C A Ground Water Montgomery CO PWSD #1 C A Ground Water Oakview Estates SUBD C A Ground Water Pleasant Oak MHP C A Ground Water St. Charles Co PWSD #2 Dutzow C A Ground Water St. Charles Co PWSD #2 Warren C A Ground Water St. Ignatius Loyola School NTNC A Ground Water Truesdale C A Ground Water Valley Lake Estates C A Ground Water Warco Manufacturing Co NTNC A Ground Water Warren County Water & Sewer Co C A Ground Water Warrenton C A Ground Water Washington Airport NC A Ground Water Wright City C A Ground Water Child Evangelism Fellowship NC I Ground Water Gateway refrigerated warehouses NTNC I Ground Water Truesdale Packaging NTNC I Ground Water
C- Community- Serves at least 15 service connections used by year-round residents or regularly serves 25 year-round residents.
NTNC- Non-Transient Non-Community- Serves at least the same 25 non-residential individuals during 6 months of the year.
NC- Transient Community- Regularly serves at least 25 non-residential individuals (transient) during 60 or more days per year.
Source: DNR, Drinking Water Watch
Location
While, no records were found to indicate any droughts in Warren County, no parts of the county
are exempt from this hazard. The hazard might affect countywide.
Probability of Future Occurrence
Overall, it is possible for Warren County to experience drought in any given year. The probability
of future occurrence of a drought is ―likely‖.
Likely- Event is probable within the next three years.
Magnitude/Severity
Drought impacts are wide-reaching and may be economic, environmental, and/or societal.
Drought conditions can also cause soil to compact and not absorb water well, potentially making
Warren County Hazard Mitigation Plan August 2011
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an area more susceptible to flooding. An ongoing drought may also leave an area more prone to
wildfires. Water supply can also be of concern during periods of prolonged drought. The
magnitude/severity of drought is ―critical‖.
Critical ─ 25–50 percent of property is severely damaged; Injuries and/or illnesses result in
permanent disability; Complete shutdown of critical facilities for at least two weeks.
3.2.4 Earthquake
Hazard Description
According to SEMA, earthquakes can be defined as shifts in the Earth’s crust causing the
surface to become unstable. This instability can manifest itself in intensity from slight tremors to
large shocks. The Earth’s crust is made up of gigantic plates, commonly referred to as tectonic
plates. These plates form what is known as lithosphere and vary in thickness from 6.5 miles
(beneath oceans) to 40 miles (beneath mountain ranges) with an average thickness of 20 miles.
These plates ―float‖ over a partly melted layer of crust called the athenosphere. The plates are
in motion and where one plate joins another, they form boundaries. Pressures on the North
Atlantic ridge affecting the eastern side of the North American plate and movements along the
San Andreas Fault by the Pacific plate have reactivated the subterranean faults in the
Mississippi embayment.
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 1- Less than 6 Hours.
Historical Statistics
Three earthquake zones -- the New Madrid Fault, the Wabash Valley Fault and the Illinois Basin
-- could affect Warren County because of their close proximity. Of these three, the New Madrid
poses the greatest threat. During the winter of 1811-1812 three earthquakes estimated to have
been magnitude 7.5 or greater were centered in the New Madrid fault in southeast Missouri.
Thousands of aftershocks continued for years.
Significant earthquakes, each about magnitude 6, occurred in 1843 near Marked Tree,
Arkansas, and on October 31, 1895 near Charleston, Missouri. In November 1968 a magnitude
5.5 earthquake centered in southeastern Illinois caused moderate damage to chimneys and
walls at Hermann, St. Charles, St. Louis, and Sikeston, Missouri. The felt areas include all or
portions of 23 states. Other earthquakes have occurred throughout southeastern parts of
Warren County Hazard Mitigation Plan August 2011
Section 3 50
Missouri. Smaller, but still destructive, earthquakes are even more likely, according to the
Missouri Seismic Safety Commission.
Location
While, no records were found to indicate any earthquake events in Warren County, no parts of
the county are exempt from this hazard. The hazard might affect county wide.
Probability of Future Occurrence
Based on the history of the New Madrid Fault and the January 2003 estimates, Warren County
stands a 20-33% chance of experiencing an earthquake of magnitude 6.0 or greater within the
next 50 years. Since Warren County lies within a good distance from the New Madrid Fault,
small earthquakes usually are not noticeable. The more severe threat stems from an
earthquake producing Modified Mercalli impact levels of VII-XIII. According to SEMA, a major
earthquake affecting Warren County definitely is expected. The probability of future occurrence
of an earthquake is ―likely‖.
Likely- Event is probable within the next three years.
Magnitude/Severity
The amount of energy released during an earthquake is most commonly expressed on the
moment magnitude scale and is measured directly from energy released from the fault or
epicenter as recorded on seismographs. Another measure of earthquake magnitude is intensity.
Intensity is an expression of the amount of shaking at any given location on the surface as felt
by humans and defined by the Modified Mercalli Intensity Scale. It is typically the greatest cause
of losses to structures during earthquakes and is determined by many factors including distance
from epicenter and soil types.
The magnitudes of the 24 recent earthquakes in the New Madrid fault ranged from 1.1 to 2.4.
None of these quakes impacted Warren County in any way. However, the scientists from the
U.S. Geological Survey (USGS) and the Center for Earthquake Research and Information at the
University of Memphis (CERI) recently updated their forecast.
Figure below shows the projected earthquake intensities map for the State of Missouri.
According to Missouri State Emergency Management Agency, Warren County is at risk for a
Level VI impact on the Modified Mercalli Intensity Scale from a 6.7 earthquake, Level VII from a
7.6 earthquake and Level VIII from a 8.6 earthquake.
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Figure 3.2 Projected Earthquake intensities map
The following list shows the abbreviated description of the 12 levels of Modified Mercalli
intensity.
I. Not felt except by a very few under especially favorable conditions.
II. Felt only by a few persons at rest, especially on upper floors of buildings.
III. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many
people do not recognize it as an earthquake. Standing motor cars may rock slightly.
Vibrations similar to the passing of a truck. Duration estimated.
IV. Felt indoors by many, outdoors by few during the day. At night, some awakened.
Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy
truck striking building. Standing motor cars rocked noticeably.
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V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable
objects overturned. Pendulum clocks may stop.
VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen
plaster. Damage slight.
VII. Damage negligible in buildings of good design and construction; slight to moderate in
well-built ordinary structures; considerable damage in poorly built or badly designed
structures; some chimneys broken.
VIII. Damage slight in specially designed structures; considerable damage in ordinary
substantial buildings with partial collapse. Damage great in poorly built structures. Fall
of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
IX. Damage considerable in specially designed structures; well-designed frame structures
thrown out of plumb. Damage great in substantial buildings, with partial collapse.
Buildings shifted off foundations.
X. Some well-built wooden structures destroyed; most masonry and frame structures
destroyed with foundations. Rails bent.
XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent
greatly.
XII. Damage total. Lines of sight and level are distorted. Objects thrown into the air.
Abridged from The Severity of an Earthquake, a U. S. Geological Survey General Interest Publication.
The magnitude/severity of an earthquake in Warren County is ―critical‖
Critical ─ 25–50 percent of property is severely damaged; Injuries and/or illnesses result in
permanent disability; Complete shutdown of critical facilities for at least two weeks.
3.2.5 Extreme Heat
Hazard Description
According to information provided by FEMA, extreme heat is defined as temperatures that hover
10 degrees or more above the average high temperature for the region and last for several
weeks. Ambient air temperature is one component of heat conditions, with relative humidity
being the other. The relationship of these factors creates what is known as the apparent
temperature.
In addition, the NWS recently has devised a method to warn of advancing heat waves up to
seven days in advance. The new Mean Heat Index is a measure of how hot the temperatures
actually feel to a person over the course of a full 24 hours. It differs from the traditional Heat
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Section 3 53
Index in that it is an average of the Heat Index from the hottest and coldest times of each day.
Figure below shows the NWS Heat index scale. To find the Heat Index from the table, see the
relative humidity along the left side of the table and the air temperature along the top. Where
the two intersect is the Heat Index for any given time of day.
Figure 3.3
Source: NOAA’s National Weather Service Heat Index, January 2009.
From 1995-2006, there were 230 fatalities in the U.S. are attributed to summer heat. According
to the National Weather Service, among natural hazards, no other natural disaster—not
lightning, hurricanes, tornadoes, floods, or earthquakes—takes a greater toll. The levels of
severity, by Heat Index apparent temperature are shown in the table below.
Table 3.9 Levels of Severity by Heat Index apparent temperature
Category Heat Index Health Hazards
Extreme Danger 130°F - Higher Heat Stroke/ Sunstroke is likely with continued exposure.
Danger 105°F - 129°F Sunstroke, muscle cramps, and/or heat exhaustion possible with prolonged exposure and /or physical activity.
Extreme Caution 90°F - 105°F Sunstroke, muscle cramps, and/or heat exhaustion possible with prolonged exposure and /or physical activity.
Caution 80°F - 90°F Fatigue possible with prolonged exposure and/or physical activity.
Source: National Weather Service Heat Index Program
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Section 3 54
The National Weather Service has a system in place to initiate alert procedures (advisories or
warnings) when the Heat Index is expected to have a significant impact on public safety. The
expected severity of the heat determines whether advisories or warnings are issued. A common
guideline for issuing excessive heat alerts is when the maximum daytime Heat Index is
expected to equal or exceed 105 degrees Fahrenheit (°F) and the night time minimum Heat
Index is 80°F or above for two or more consecutive days.
Warning Time: Level 1- 24+ Hours
Duration: Level 3- Less than 1 week
Historical Statistics
Of the 24 heat waves to hit St. Louis region between 1994 and 2007, 18 produced heat indices
within the ―Danger‖ range. These heat waves resulted in the following impacts:
91 deaths (no deaths reported within Warren County);
1859 injuries; and
property damage valued at $5.09 million
crop damage valued at $875,000
Table 3.10 List of Heat Waves across the Region (1994-2009)
Date Heat Index Deaths Injuries Property Damage
06/12/1994 100+ 4 55 0
07/17/1995 120 20 225 $75,000
07/28/1995 N/A 0 120 $15,000
08/01/1995 110-120 9 230 0
07/18/1998 110 0 137 0
07/18/1999 105-115 42 397 0
07/07/2001 105-110 5 61 0
07/17/2001 110-115 0 19 0
07/29/2001 105-110 0 4 0
08/01/2001 105 0 34 0
08/07/2001 102-110 1 10 0
08/21/2001 105-110 0 14 0
07/08/2002 105-110 1 26 0
07/20/2002 105-115 0 47 0
07/26/2002 105-115 0 185 0
08/01/2002 N/A 1 59 0
08/15/2003 100-105 2 54 0
08/24/2003 105-110 0 0 0
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Date Heat Index Deaths Injuries Property Damage
07/20/2004 105-110 0 25 0
07/20/2005 105-120 4 65 0
07/17/2006 105-110 0 12 0
07/29/2006 105-110 0 0 0
08/01/2006 100 0 59 0
08/05/2007 100-105 0 0
Totals 91 1859 $90,000
Source: National Climatic Data Center.
Location
Based on the statistics, extreme heat frequently strikes Warren County during its seasonal
pattern. No parts of the county are exempt from this hazard.
Probability of Future Occurrence
Although periods of extreme heat generally occur on an annual basis, events that cause
significant health impacts occur less frequently. Based on patterns of previous occurrences,
probability of future occurrence is considered ―likely‖.
Likely- Event is probable within the next three years.
Magnitude/Severity
The magnitude/severity of extreme heat for Warren County is considered as being ―critical‖.
Critical ─ 25–50 percent of property is severely damaged; Injuries and/or illnesses result in
permanent disability; Complete shutdown of critical facilities for at least two weeks.
3.2.6 Flood/Levee failure
Hazard Description
A flood is a partial or complete inundation of normally dry land areas. Riverine flooding is
defined as the overflow of rivers, streams, drains, and lakes due to excessive rainfall, rapid
snowmelt or ice. There are several types of riverine floods including headwater, backwater,
interior drainage, and flash flooding.
Flash flooding is characterized by rapid accumulation or runoff of surface waters from any
source. This type of flooding can occur within six hours of a rain event, after a dam or levee
failure, or following a sudden release of water held by an ice or debris jam. Flash floods can
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Section 3 56
catch people unprepared. Because flash floods can develop in just a matter of hours, most
flood-related deaths result from this type of flooding event.
Several factors contribute to flooding. Two key elements are rainfall intensity and duration.
Intensity is the rate of rainfall and duration is how long the rain lasts. Topography, soil
conditions, and ground cover also play important roles. Most flash flooding is caused by slow-
moving thunderstorms or heavy rains. Floods, on the other hand, can be fast-rising, but
generally develop over a period of hours or days.
Urbanization further aggravates the flooding potential by increasing runoff two to six times over
what would occur on natural terrain. As land is converted from fields or woodlands to buildings
and pavement, it loses its ability to efficiently absorb rainfall. During periods of urban flooding,
streets can become swift moving rivers, while basements and viaducts can become death traps
as they fill with water.
The areas adjacent to rivers and stream banks that serve to carry excess floodwater during
rapid runoff are called floodplains. A floodplain is defined as the lowlands and relatively flat
areas adjoining rivers and streams. The term ―base flood,‖ or 100-year flood, is the area in the
floodplain that is subject to a one percent or greater chance of flooding in any given year, based
upon historical records.
Warning Time: Level 2- 12-24 Hours
Duration: Level 2- Less than a Day
Historical Statistics
The largest disaster to impact Warren County in recent years was the flood of 1993. Flash
flooding was responsible for a woman’s death as her home was swept downstream. Loss of
agricultural lands, homes, businesses, and infrastructure, as well as the temporary closing of
some local businesses, contributed to economic losses. Areas hardest hit by the flooding were
along the Missouri River in southern Warren County. Table below shows the flood events in
Warren County.
Table 3.11 Warren County flood events (1994-2008)
Date Type Deaths Injury Property
damage($) Crop damage($)
4/11/1994 River Flood 0 0 5,000,000 5,000,000
5/16/1995 Flash Flood 0 0 0 0
5/16/1995 Flash Flood 0 0 1,000 0
5/27/1995 Flash Flood 0 0 0 0
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Section 3 57
Date Type Deaths Injury Property
damage($) Crop damage($)
4/28/1996 Flash Flood 0 0 0 0
5/1/1996 Flood 0 0 0 0
6/22/1997 Flash Flood 0 0 0 0
3/20/1998 Urban/sml Stream Fld 0 0 0 0
10/6/1998 Flood 0 0 0 0
7/6/1999 Urban/sml Stream Fld 0 0 0 0
6/20/2000 Urban/sml Stream Fld 0 0 0 0
6/24/2000 Flash Flood 0 0 0 0
12/4/2001 Flood 0 0 0 0
5/7/2002 Flash Flood 0 0 0 0
5/12/2002 Flash Flood 0 0 0 0
5/12/2002 Flash Flood 0 0 0 0
6/25/2003 Flash Flood 0 0 0 0
12/7/2004 Flash Flood 0 0 0 0
5/8/2007 Flood 0 0 0 5,000
2/5/2008 Flash Flood 0 0 0 0
Source: National Climatic data Center.
According to the National Mapping System, major rivers in Warren County include Missouri
River, Charrette Creek, Tuque Creek, North Fork Charrette Creek, Peruque Creek, Camp
Creek, Hickory Lick Creek, Lost Creek, Massie Creek, Little Lost Creek, Cullum Branch, Loutre
Slough, Clear Branch, Smith creek, Peers Slough, Wolf Creek, Indjan Camp Creek, Dry Creek,
Engemann Spring.
Table 3.12 Historical statistics of flash floods in Warren County (2000-2009) Date Time Description
24 June 2000 01:30 AM Rainfall up to 6 inches caused widespread flash flooding across the area. Sandbagging had to be done off Highway F in the Harvest Acres subdivision due to a flooded creek.
07 May 2002 03:30 AM Numerous creeks and small streams flooded making roads impassable.
12 May 2002 05:00 AM Rainfall of 2-4 inches caused flash flooding across the area.
25 June 2003 10:30 PM Heavy rain caused flash flooding across much of Warren County. Interstate 70 became virtually impassable in several places due to high water.
07 Dec 2004 12:45 AM Moderate to heavy rain brought several creeks out of their banks across Warren County.
08 May 2007 11:00 AM The Missouri river flooded parts of the southern border of Warren County. The flooding was limited to farmland along the river and to a few roads in the Marthasville area.
08 Feb 2008 04:15 PM 2 to 4 inches of rain fell over portions of Warren county during the afternoon and noon hours.
15 Jun 2009 07:10 AM In excess of three inches fell in a short amount of time over portions of Warren County. Hwy U at Booneslick Road was flooded and Hwy 47 was flooded in spots south of Warrenton. Also, Interstate 70 and adjacent access roads were flooded in spots near the Warren/Montgomery county line.
Warren County Hazard Mitigation Plan August 2011
Section 3 58
Location
The flash flooding for Warren County is mostly confined to the 100-year floodplain and no data
suggests that it occurs outside the 100-year floodplain. An action plan has been proposed to
improve drainage of roadways in flash flood areas (Goal #1, Action Plan 1.2.6). HAZUS was
used to generate a one percent annual flood, or 100-year flood, event for major rivers and
creeks in the County. The software produces a flood polygon and flood depth grid that
represents the 100-year flood. While not as accurate as official flood maps these floodplain
boundaries are for use in GIS-based loss estimation.
Map 3.5 shows Innsbrook flood boundary
Innsbrook
Warrenton
Ü
Map showing Innsbrook floodboundary
Warren County Incorporated Areas
Interstate 70
Roads
Rivers
100 year flood boundary
A
0 0.7 1.40.35Miles
Warren County Hazard Mitigation Plan August 2011
Section 3 59
Map 3.6 shows Marthasville flood boundary
¬«47
¬«94
¬«47
Marthasville
Ü
Map showing Marthasville floodboundary
Warren County Incorporated Areas
Interstate 70
Roads
Rivers
100 year flood boundary
A
0 0.2 0.40.1Miles
Warren County Hazard Mitigation Plan August 2011
Section 3 60
Map 3.7 shows Warrenton & Truesdale flood boundary
¬«47
¬«47
§̈¦70§̈¦70
Warrenton
Truesdale
8201
8201
Ü
Map showing Warrenton & Truesdale floodboundary
Warren County Incorporated Areas
Interstate 70
Roads
Rivers
100 yr floodboundary
0 0.5 1 1.50.25Miles
Warren County Hazard Mitigation Plan August 2011
Section 3 61
Map 3.8 shows Wright City flood boundary
§̈¦70 §̈¦70Wright City
Foristell
Ü
Map showing Wright City floodboundary
Warren County Incorporated Areas
Interstate 70
Roads
Rivers
100 year flood boundary
A
0 0.5 10.25Miles
Warren County Hazard Mitigation Plan August 2011
Section 3 62
Map 3.9 shows Warren County 100-year floodplain along with critical facilities
Innsbrook
Warrenton
Foristell
Wright City
Truesdale
Marthasville
82018201
§̈¦I-70 §̈¦I-70
Daniel Boone SchoolRebecca Boone SchoolBlack Hawk Middle SchoolWarren County High SchoolHoly Rosary Catholic SchoolWarrenton Christian SchoolJolly TotsReach Out Adult Day CreWarrenton Area Child Care CenterKiddie KampusLittle Lambs Lutheran PreschoolWarrenton ManorBristol ManorCountry Cove WestWhispering Pines Assisted Living
Wright City ElementaryWright City Middle SchoolWright City High SchoolGood Shepherd Lutheran Day CareUnion Basic Child Care Center
Marthasville Elementary
Ü
0 2 4 61Miles
County boundary
Incorporated Areas
Interstate 70
Roads
Lakes
100 yr floodplain
Warren County Hazard Mitigation Plan August 2011
Section 3 63
Probability of Future Occurrence
Warren County faces two major risk factors for flooding. The land that forms Warren County is
included in the Missouri River basin that drains most of the northern and central part of the
state. The Missouri River flows east along the county’s southern boundary and joins the
Mississippi River some 50 miles east of the county. The southern rim of the county lies directly
in the Missouri River floodplain where most the 1993 flood damage occurred. According to the
federal government’s Flood Insurance Rating Maps (FIRM), for Warren County 15% of the land
lies within the 100-year floodplain. The majority of that 15% lies directly adjacent to Missouri
River levees.
Flood Event by Month, 1993-2008
Month # of Events
September 2
June 5
May 8
April 2
July 1
October 1
December 1
Out of 20 total floods, fourteen are flash floods, three are floods, one is a river flood, and two are
stream floods.
The probability of future occurrence of a flood in Warren County is ―likely‖.
Likely- Event is probable within the next three years.
Magnitude/Severity
Past flood events in Warren County have caused significant damage to property and agriculture,
endangered lives, and shut down critical facilities, and agriculture.
Marthasville, Washington School District (Marthasville elementary school) - ―critical‖.
Unincorporated areas, Innsbrook, Warrenton, Wright City, Truesdale, Warren School District,
Wright City School District - ―limited‖.
Critical: 25-50 percent of property severely damaged; shutdown of facilities for at least two
weeks; and/or injuries and/or illnesses result in permanent disability.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
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Section 3 64
Levee Failure: Associated with the riverine flooding hazard are floods caused by breaching or
failure of levees. Levees are human made structures designed to contain, control or deflect the
flow of water to provide protection from temporary flooding. Levees usually protect seasonal
flooding, and may be subject to water loading for periods of only a few days or weeks each
year.
Based on a 2007 database of levees known by the Corps, there are 66 levees in Missouri.
Twenty nine of these are considered to provide 100-year flood protection. FEMA, as part of its
floodplain map modernization effort, has identified 41 levees in Missouri as provisionally
accredited levees (PAL). It is expected that additional data on levees will become available in
upcoming years with FEMA’s efforts to certify levees nationwide for flood protection. Warren
County is categorized under the tri-county levee district along with Montgomery and Gasconade
Counties.
Location
The levee failure is confined to the south of the county where the Missouri River flows east and
joins Mississippi Rivers 50 miles east of the county. Although levees protect Route 47 from
Missouri River flooding, Charrette Creek, Toque Creek near Marthasville, and Lake Creek near
Dutzow occasionally cause flooding and road closures.
Map 3.10 shows the location of the creeks near the southern border of the county
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Section 3 65
A one-day closure in 1990 resulted from flash flooding of Toque Creek. The road has been
closed three times since 1990 (twice in 1993 and once in 1995) when the Missouri River levees
failed. Both Toque Creek and Lake Creek are tributaries to Charrette Creek, which lies between
Route 47 and the Missouri River. Toque Creek and Lake Creek join with Charrette Creek so
near the Missouri River they are susceptible to combined backwater effects during Missouri
River and other significant flooding events. The jurisdiction close to the Missouri river is the City
of Marthasville.
Map 3.11 shows the levee districts in the county
Marthasville
DU
TZ
OW
LD
TUQ
UE C
REEK
SEC 2
TUQUE CREEK
HOLTMEIER
ST J
OH
NS
BO
TTO
M A
SS
N
CHARRETTE BOTTOMS SEC 4
ÜWarren County Boundary
Warren County Incorporated Areas
Missouri river levees
Flood zone
AE
A 0 0.5 10.25Miles
Warren County Hazard Mitigation Plan August 2011
Section 3 66
It has been noted that in case of any major flood events, there could be a major economic loss
to Warren County majorly to the City of Warrenton and Wright City. The reasons are that Hwy
47 serves as a connection between Warren County and Franklin County. Many people who
work in Warren County live in Franklin County and vice-versa. Therefore, any levee failure in
case of flood event would cause an effect on Warren County’s economy.
Probability of Future Occurrence
The probability of future occurrence of a levee failure in Warren County is ―likely‖.
Likely- Event is probable within the next three years.
Magnitude/Severity
City of Marthasville, Washington School District (Marthasville elementary school) -―critical‖.
Critical: 25-50 percent of property severely damaged; shutdown of facilities for at least two
weeks; and/or injuries and/or illnesses result in permanent disability.
3.2.7 Hail
Hazard Description
Hail develops in strong thunderstorms when rapidly rising currents of air, called updrafts, carry
raindrops to a height where they freeze. Other droplets of super cooled water will continue to
freeze onto the hailstones. Stronger updrafts will produce larger hailstones and they will
eventually fall out of the sky when the updraft can no longer support them.
Hailstorms cause damage to property, crops, and the environment, and harm livestock.
Vehicles, roofs of buildings and homes, and landscaping are the other things most commonly
damaged by hail. Hail has been known to cause injury and the occasional fatality to humans,
often associated with traffic accidents.
Based on information provided by the Tornado and Storm Research Organization, Table below
describes typical damage impacts of the various sizes of hail.
Table 3.13 Tornado and Storm Research Organization Hailstorm Intensity Scale
Intensity Category
Diameter (mm) Typical Damage Impacts
Hard Hail 5 No damage
Potentially Damaging
5-15 Slight general damage to plants, crops
Significant 10-20 Significant damage to fruit, crops, vegetation
Severe 20-30 Severe damage to fruit and crops, damage to glass and plastic structures
Warren County Hazard Mitigation Plan August 2011
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Intensity Category
Diameter (mm) Typical Damage Impacts
Severe 25-40 Widespread glass damage, vehicle bodywork damage
Destructive 30-50 Wholesale destruction of glass, damage to tiled roofs, significant risk of injuries
Destructive 40-60 Bodywork of grounded aircraft dented, brick walls pitted
Destructive 50-75 Severe roof damage, risk of serious injuries
Destructive 60-90 Severe damage to aircraft bodywork
Super Hailstorms
75-100 Extensive structural damage. Risk of severe or even fatal injuries to persons caught in the open
Super Hailstorms
>100 Extensive structural damage. Risk of severe or even fatal injuries to persons caught in the open.
Source: Tornado & Storm research organization
Warning Time: Level 3- 6-12 Hours
Duration: Level 1- Less than 6 hours
Historical Statistics
The NCDC reported 23 hail events in Warren County between 1994 and March 2009. Table
below shows the number of hail events by the size of the hail. These events didn’t cause any
reported crop damages or property damages.
Table 3.14 Warren County Hail Events, 1994- March 2009
Hail Size (inches) Number of Events (1994 - March 2009)
0.75 8
0.88 3
1.00 6
1.50 1
1.75 5
Total 23
Location
Hailstorms frequently strike all of Warren County during its seasonal pattern. No parts of the
county are exempt from this hazard.
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Probability of Future Occurrence
Based on NCDC data, there were 23 hail events in Warren County from 1994- March 2009, an
average of 1.54 each year. Hail events producing hail 1.00 inches and larger occurred 17 times
over the same 15 year period.
The probability of future occurrence is ―likely‖.
Likely- Event is probable within the next three years. History of events is greater than 20% but
less than or equal to 33% likely per year.
Magnitude/Severity
On an average, Missourians experience hail 2-3 times a year; most of the time it is smaller than
a pea (1/4") and will cause little or no damage. The magnitude/severity of a hail storm in Warren
County is ―limited‖.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
3.2.8 Severe Winter Weather (Snow, Ice and Extreme Cold)
Hazard Description
Winter storms in Missouri typically involve snow, extreme cold, and/or freezing rain (ice storms).
According to SEMA, severe winter weather events can cause various injuries, deaths and
property damage. Causes of death range from traffic accidents during adverse driving
conditions to heart attacks caused by overexertion while shoveling snow. Hypothermia or
frostbite may be considered the most direct cause of death and injury attributed to winter
weather.
Economic costs are difficult to measure. Heavy ice can bring down trees, power lines, telephone
lines, and communications towers. Power outages create an increased risk of fire as residents
seek alternative fuel sources (wood or kerosene for heat and fuel-burning lanterns or candles
for emergency lighting). Crops, trees, and livestock can be killed or injured due to deep snow,
ice or severe cold. Buildings and automobiles may be damaged from falling tree limbs, power
lines and poles. Local governments, homeowners, business owners, and power companies can
be faced with spending millions of dollars to restore services and remove debris.
According to the National Center for Health Statistics, approximately 600 adults die from
hypothermia each year, with the isolated elderly being most at risk. Also at risk are those
without shelter or live in a home that is poorly insulated or without heat. Other potential health
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and safety threats include toxic fumes from emergency heaters, household fires caused by
fireplaces or emergency heaters, and driving in treacherous conditions.
The National Weather Service describes different types of winter storm conditions as follows:
- Blizzard: Winds of 35mph or more with snow and blowing snow reducing visibility to
less than ¼ mile for at least three hours.
- Blowing Snow: Wind-driven snow that reduces visibility. Blowing snow may be falling
snow and/or snow on the ground picked up by the wind.
- Snow Squalls: Brief, intense snow showers accompanied by strong, gusty winds.
Accumulation may be significant.
- Snow Showers: Snow falling at varying intensities for brief periods of time. Some
accumulation is possible.
- Freezing Rain: Measurable rain that falls onto a surface whose temperature is below
freezing. This causes the rain to freeze on surfaces, such as trees, cars, and roads, forming
a coating or glaze of ice. Most freezing-rain events are short loved and occur near sunrise
between the months of December and March.
- Sleet: Rain drops that freeze into ice pellets before reaching the ground. Sleet usually
bounces when hitting a surface and does not stick to objects.
Provided by the National Weather Service, Figure below shows the relationship of wind
speed to apparent temperature and typical time periods for the onset of frostbite.
Figure 3.4 Wind Chill Chart
Source: http://www.weather.gov/os/windchill/index.shtml
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Warning Time: Level 3- 6-12 Hours
Duration: Level 3- Less than 1 week
Historical Statistics
Warren County received 5 presidential major disaster declarations, and 4 USDA declarations for
this hazard, listed in the table below.
Table 3.15 Disaster Declarations in Warren County Involving Winter Storm
Declaration Date Description Declaration Type Disaster Number
January 30, 2009 Severe Winter Storms Presidential- Major Disaster Declaration
FEMA 3303-DR
March 19, 2008 Severe Winter Storms Presidential- Major Disaster Declaration
FEMA 1749-DR
December 27, 2007 Severe Winter Storms Presidential- Major Disaster Declaration
FEMA 1736-DR
December 12, 2007 Severe Winter Storms Presidential- Major Disaster Declaration
FEMA 3281-DR
January 14, 2007 Severe Winter Storms Presidential- Major Disaster Declaration
FEMA 1676-DR
December 1, 2007 Winter Storms USDA M1676
December 6, 2007 Winter Storms USDA N1736
January 12, 2007 Winter Storms USDA N873
March 30, 2007 Winter Storms USDA S2532
The NCDC reported 38 events from 1994 to March 2009. The total property damage was
estimated at $3.2M and crop damage at $2,000. Also, 15 injuries and 2 deaths were reported
during this time period.
January 14, 2007 FEMA 1676-DR: An arctic boundary settled south of the area on the 12th and
13th of January bringing subfreezing temperatures to the northwestern half of the county
warning area. Three rounds of precipitation occurred during this period, with the first being the
most destructive of all. Significant tree and limb damage was reported as a result of this storm,
together with widespread power outages.
Location
Severe winter weather events frequently strike all of Warren County during its seasonal pattern.
No parts of the county are exempt from this hazard.
Low levels of traffic allow snow or ice to accumulate on unpaved roads making it difficult to
plow. This hazard may have a lesser effect on city residents where most roads are paved and
city road crews can clear roads more frequently. On the other hand, the cities and towns can be
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strongly affected during severe winter weather because greater numbers of people travel within
its boundaries for work, shopping, and education.
Probability of Future Occurrence
During the 15-year period from 1994-March 2009, there were 38 recorded winter storm events
in Warren county. The probability of future occurrence of a winter storm in Warren County is
―likely‖
Likely- History of events is greater than 20% but less than or equal to 33% likely per year.
Magnitude/Severity
The magnitude/severity of a severe winter storm is ―critical‖
Critical- 25-50 percent of property severely damaged; shutdown of facilities for at least two
weeks; and/or injuries and/or illnesses result in permanent disability.
3.2.9 Thunderstorms and High winds
Hazard Description
Thunderstorms can produce a strong rush of wind known as a downburst, or straight-line winds
which may exceed 120 miles per hour. These storms can overturn mobile homes, tear roofs off
of houses and topple trees. Approximately 10 percent of the thunderstorms that occur each year
in the United States are classified as severe. A thunderstorm is classified as severe when it
contains one or more of the following phenomena: (1) Hail, three-quarters inch or greater; (2)
Winds gusting in excess of 50 knots (57.5 mph); or (3) A tornado.
High winds often accompany thunderstorms. High winds can result in property damage and
injury. Strong gusts can rip roofs from buildings, snap power lines, shatter windows, down trees,
and sandblast paint from cars. Other associated hazards include utility outages, arcing power
lines, debris blocking streets, dust storms, and an occasional structure fire from this natural
hazard.
Figure below shows wind zones in the United States. Missouri State comes under Zone IV with
a wind rate of 250 mph.
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Figure 3.5
Source: FEMA
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 1- Less than 6 Hours
Historical Statistics
During the 15-year period from 1994 - March 2009, there were 59 thunderstorms and high wind
events recorded by NCDC. 53 were reported as thunderstorms and 6 as high wind events.
Table 3.14 shows the magnitude and number of thunderstorm and high wind events in Warren
County from 1994 – March 2009.
Table 3.16 Warren County Thunderstorm and High wind events
Magnitude No. of Thunderstorms & high winds
0 Knots 7
40-50 Knots 9
51-55 Knots 26
56-65 Knots 17
Location
Thunderstorms and high wind events frequently strike all of Warren County during its seasonal
pattern. No parts of the county are exempt from this hazard.
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Probability of Future Occurrence
The probability of future occurrence of thunderstorms and high winds in Warren County is
―highly likely‖.
Highly Likely- History of events is greater than 33% likely per year.
Magnitude/Severity
The magnitude/severity of thunderstorms and high winds in Warren County is ―limited‖
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
3.2.10 Tornadoes
Hazard Description
Tornadoes are cyclical windstorms or a violently rotating column of air. The average forward
speed of a tornado is about 30 m.p.h., but may vary from nearly stationary to 70 m.p.h. The
average pathway may vary in any direction, but the average tornado moves from southwest to
northeast. Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but may ensue at any
hour of the day. Any person or structure at any location could be damaged by a tornado. The
amount of damage depends on 1) the strength of the tornado, 2) the tornado’s proximity to the
person/structure, 3) the strength of the structure, 4) how well a person is sheltered, etc.
Damage can range from very slight to total.
The Fujita Scale (F-Scale) is the standard measurement for rating the strength of a tornado. The
National Weather Service (NWS) bases this scale on an analysis of damage after a tornado to
infer wind speeds. On February 1, 2007, the NWS transitioned from the F-Scale to the
Enhanced Fujita scale (EF-Scale). The EF-Scale is considerably more complex and enables
surveyors to assess tornado severity with greater precision. Table below details both the scales.
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Table 3.17
Source: National Weather Service.
*** IMPORTANT NOTE ABOUT ENHANCED F-SCALE WINDS: The Enhanced F-scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage based on a judgment of 8 levels of damage to the 28 indicators listed below. These estimates vary with height and exposure. Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, "one minute mile" speed.
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 1- Less than 6 Hours
Historical Statistics
Of the reported 3 tornadoes, the most impacted in Warren County were in the vicinity of
Warrenton and Wright City.
Figure below illustrates the number of F3, F4, F5 tornadoes recorded in the United States per
3,700 square miles between 1950 and 1998.
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Figure 3.6 Tornado activity in the United States
The historical data since 1994 – March 2009 is shown in the table below.
Table 3.18 Warren County Tornado events: 1994- March 2009 Location or County
Date F-Scale Death Injury Property Damage
Warrenton 04/13/1998 F0 0 0 1K
Wright City 04/10/2001 F0 0 0 20K
Warrenton 03/13/2006 F0 0 0 0
Source: National Climatic Data Center.
Location
Tornado events are likely to occur countywide. No parts of the county are exempt from this
hazard.
Probability of Future Occurrence
The location of Warren County in Wind Zone IV makes the probability of a tornado in any given
year ―highly likely‖.
Highly Likely- History of events is greater than 33% likely per year.
Magnitude/Severity
The magnitude/severity of thunderstorms and high winds in Warren County is ―limited‖
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
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3.2.11 Wildfires
Hazard Description
The majority of the fires, however, and the greatest acreage loss will occur during the spring fire
season, which is normally between February 15 and May 10. The length and severity of this
burning period depends on weather conditions. Spring in Missouri is noted for its low humidity
and high winds. In addition, spring is the time of the year when rural residents normally burn
their garden spots, brush piles, etc. Many landowners also still believe it is necessary to burn
the woods in the spring of the year in order to get more grass, kill ticks, and get rid of the brush.
These conditions, together with below normal precipitation and high temperatures, result in
extremely high fire danger. Depending on weather conditions, a sizable number of fires also
can occur between mid-October and late November.
Warning Time: Level 1- 24+ Hours
Duration: Level 1- Less than 6 Hours
Historical Statistics
According to SEMA’s 2000 Hazard Analysis, wildfires are most common in the southern districts
of the state. However, it is possible for wildfires to occur in Warren County due to drought,
debris burning, and incendiary fires. Debris burning is consistently the number one cause of
wildfires. Incendiary fires, willfully set on another person’s property, continue to rank second in
the number of wildfires each year. Fires caused by natural ignition, like lightning, are rare
despite 50 to 70 thunderstorm days per year.
According to the Missouri Department of Conservation Forest Fire Reporting, in Warren County
the total number of acres burnt was 603.94. One of the residential areas near Wright city were
threatened by fire in 2004, and one other residential area in New Truxton was threatened in
2006. The reasons for the above fire incidents were either debris or unknown fire.
Location
An increased risk of wildfire occurs in areas called the WUI (Wildland Urban Interface) in
addition to the risk faced by the forested areas within the county. The 2000 Wildland-Urban
Interface in the U.S. defines a WUI as ―the area where houses meet wildland vegetation
(interface WUI) or where houses and vegetation or mixed together (intermix WUI)‖.
Within the WUI the three defined Community types that are vulnerable to Wildfire are:
- Interface Community
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Structures directly abut wildland fuels. There is a clear line of demarcation between
wildland fuels and residential, business, and public structures. Wildland fuels do not
generally continue into the developed area. The development density for an interface
community is usually three or more structures per acre, with shared municipal services.
- Intermix Community
Structures are scattered throughout a wildland area. There is no clear line of
demarcation; wildland fuels are continuous outside of and within the developed area.
The development density in the intermix ranges from structures very close together to
one structure per 40 acres.
- Occluded Community
Often found within a city, structures abut an island of wildland fuels (e.g. park or open
space). There is a clear line of demarcation between structures and wildland fuels. The
development density is usually similar to those found in the interface community, but the
occluded area is usually less than 1,000 acres in size.
The maps below show the wildland-urban interface for Warren County. Both Interface and
Intermix communities exist in Warren County.
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Section 3 78
Map 3.11 shows the wildland-urban interface for Warren County
§̈¦70
§̈¦70
¬«47
¬«94
¬«94
¬«47
¬«47
¬«47
¬«94
¬«94
Innsbrook
Warrenton
Foristell
Wright City
Truesdale
Marthasville
82018201
Incorporated Areas
State highway
Interstate 70
County boundary
Wildland Urban Interface
High_Dens_Interface
High_Dens_Intermix
Med_Dens_Interface
Med_Dens_Intermix
Low_Dens_Interface
Low_Dens_Intermix
High_Dens_NoVeg 0 2.5 51.25MilesÜ
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Marthasville has a mix of high density interface, medium density interface, medium density
intermix, and low density interface.
Map 3.12 shows the wildland-urban interface for the City of Marthasville
Marthasville
¬«47
¬«94
¬«47
Incorporated Areas
State highway
Interstate 70
Wildland Urban Interface
High_Dens_Interface
Med_Dens_Interface
Med_Dens_Intermix
Low_Dens_Interface
Ü0 0.1 0.2 0.30.05
Miles
Warren County Hazard Mitigation Plan August 2011
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Innsbrook has a mix of medium density interface and medium density intermix.
Warrenton has a mix of high density interface, medium density interface, medium density
intermix, low density interface, and low density intermix.
Wright City has medium density intermix.
Map 3.13 shows the wildland-urban interface for the City of Warrenton, Innsbrook & Wright City
Innsbrook
Warrenton
Foristell
Wright City
Truesdale
8201
8201
§̈¦70
§̈¦70
¬«47
¬«47
County boundary
Incorporated Areas
State highway
Interstate 70
<all other values>
Wildland Urban Interface
High_Dens_Interface
Med_Dens_Interface
Med_Dens_Intermix
Low_Dens_Interface
Low_Dens_Intermix
High_Dens_NoVeg
0 0.8 1.60.4Miles Ü
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Probability of Future Occurrence
Judging from the amount and location of the county’s forests, a disastrous wildfire is not likely.
Therefore, the probability of future occurrence of a wildfire is ―occasional‖.
Occasional- History of events is greater than 10% but less than or equal to 20% likely per year.
Magnitude/Severity
Although only a third of the county is forested, a wildfire in the grass and crop-covered plains of
the northern areas could produce significant crop losses. Grass grows back quickly with little
damage, but fires in forests and croplands are costly.
Marthasville, Warrenton, Warren School district - ―Critical‖
Truesdale - ―limited‖.
Critical- 25-50 percent of property severely damaged; shutdown of facilities for at least two
weeks; and/or injuries and/or illnesses result in permanent disability.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
Manmade and Other Hazards
3.2.12 Hazardous Materials
Hazard Description
A hazardous material is any substance or material in a quantity or form that may pose a
reasonable risk to health, the environment, or property. As per the updated State Hazard
Mitigation Plan, the hazardous materials included are substances such as toxic chemicals,
fuels, nuclear wastes and /or products, and other radiological and biological or chemical agents.
In this section, hazardous materials incidents from fixed facilities and transportation accidents
are addressed.
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 2- Less than 1 Day
Historical Statistics
Three major highways cross the county: I-70 (East-West), Hwy 47 North/South) and Hwy 94
(East -West along the Missouri River). One active railroad runs also East-West (Norfolk and
Southern). Several facilities in Warren County manufacture, store and use hazardous
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substances. Three pipelines run through the county; one carries ammonia, the other two carry
petroleum products. There are a number of fixed facilities in Warren County that use or store
hazardous substances. The Southern parts of the county, including Hwy 47 & 94, are located
within flood plains. Flooding in the past has resulted in run-off of agricultural chemicals and
petroleum products into the Missouri River.
In the event of a serious hazardous materials incident in Warren County, most likely it will be a
transportation-related accident. Hazardous materials are also transported daily over highways,
rail, barge traffic, air, etc. A hazardous material incident would mostly likely occur on Interstate
70 or along the Norfolk Southern Railroad. Highway 47 and 94 could also be the site of a
potential hazardous material incident, but to a lesser extent due to a lighter volume of truck
traffic.
Fixed facility accidents
The most recent earthen dam failure occurred on May 27, 2008 at Innsbrook on Lake Alpine.
Alpine lake is the largest private, man-made lake in the State of Missouri. The lake is about 11
miles around its perimeter and reaches a depth of 90 feet. The incident occurred after a period
of heavy rainfall which caused a large diameter pipe used to lower the lake failed. Part of a 36-
inch spillway pipe was expelled from the dam of the 236-acre lake. The pipe feeds an overflow
spillway at the center of a quarter-mile earthen dam at the south end of the lake. When the force
of the water literally tore the section of pipe from the dam, it created an opening in the dam
which measured approximately 40 feet across. At the time of the incident, emergency officials
estimated the water level of the lake was at least 3 feet above the drainage pipe. Emergency
personnel and officials from DNR took steps to prevent a possible breach in the dam. The
spillway and broken pipe were sealed off with a mixture of rocks and concrete to prevent further
seepage (EMissourian.com). The main concerns during the incident as outlined by the
Emergency Director Michael Daniels are as follows:
Establishing a unified command structure and developing an incident action plan.
Stopping or slowing down the flow of water from Alpine lake into the remaining
pipe that was still in place.
Identifying residential structures downstream of the dam that were impacted in
the event total dam failure occurred.
Developing contingency plans for search and rescue in the event the dam failed.
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Transportation accidents
According to the Missouri State Highway Patrol crash report, Warren County experienced
604 accidents (fatal, personal injury, property damage) in 2008, 658 in 2007, and 763 in 2006.
Figure 3.19 shows the major roads where the accidents occurred. Most of them have been
occurring I -70 and on the intersection of HWY 19 and HWY 161.
Figure 3.7 Major Roads prone to accidents in Warren County
Source: http://www.mshp.dps.mo.gov
Probability of Future Occurrence
The probability of future occurrence of fixed facility accidents is ―likely‖.
Likely- History of events is greater than 20% but less than or equal to 33% likely per year.
Magnitude/Severity
The magnitude/severity is ―limited‖.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
3.2.13 Terrorism
Hazard Description
Federal Bureau of Investigation (FBI) defines Terrorism as ―the unlawful use of force or violence
against persons or property to intimidate or coerce a government, the civilian population, or any
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segment thereof, in furtherance of political or social objectives.‖ Terrorism causes loss of life,
injuries to people and properties, and disruptions in services. According to the State Hazard
Mitigation Plan, potential terrorist actions include the following:
Bombings, airline attacks, weapons of mass destruction (WMD) attacks, infrastructure
attacks, cyberterrorism, agroterrorism, arson, kidnappings, and assassinations.
Domestic terrorism is another form of threat which comes from white supremacists, black
separatists, animal rights/environmental terrorists, anarchists, antiabortion extremists, and self-
styled militia. According to FBI, international terrorism has been a major challenge for the United
States. This threat can be categorized into three: loosely affiliated extremists operating under
the radical jihad movement, formal terrorist organizations, and state sponsors of terrorism. The
different types of foreign terrorist organizations are listed in the State Hazard Mitigation Plan
2007.
After the attacks on September 11, 2001, parts of 22 domestic agencies were consolidated into
one department, the U.S. Department of Homeland Security (DHS), to protect the nation against
future terrorist threats. Depending on the necessity communities may receive assistance from
state and federal agencies operating within the existing Integrated Emergency Management
System. FEMA is responsible for supporting state and local response to the consequences of
terrorist attacks.
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 3- Less than 1 week
Historical Statistics
Warren County has potential targets for terrorist activities. These may include, but are not
limited to:
Federal, state, county and municipal government facilities and structures.
Military installations.
HAZMAT Facilities.
Medical facilities.
Religious facilities.
Businesses and manufacturing centers.
Airports, railroads, highways and navigable rivers.
Pipelines; power plants; public utilities; landmarks; and large public gatherings.
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Agriculture.
There are twenty eight Homeland Security Response Teams that operate throughout the State
of Missouri. Warren County is under Region C There are no terrorism incidents identified within
the county.
Probability of Future Occurrence
Since, there haven’t been any incidents taken place in the county; the probability of future
occurrence is ―unlikely‖
Unlikely- History of events is less than or equal to 10% likely per year.
Magnitude/Severity
The severity of a terrorist attack could vary from high to low depending on the attack. If the
attack is on a building, it would destroy the lives of those inside the building. But if the attack is
on a large urban area such as contaminating large area’s water supply, it would affect large
number of people. Therefore, the magnitude/severity is considered to be as being ―limited‖ to
―catastrophic‖ depending on the attack.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.
Catastrophic- Multiple deaths; Complete shutdown of facilities for 30 or more days; More than
50 percent of property is severely damaged.
3.2.14 Transportation
Hazard Description
As per the State Hazard Mitigation Plan, for the purpose of this study, transportation is defined
as the means, or system, that transfers large groups of individuals from one place to another.
This hazard addresses only those accidents that involve passenger air or rail travel that results
in accident death or injury.
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 2- Less than 1 day
Historical Statistics
Table 3.17 shows the fatality Rates by Mode of Travel, 2001–2003 (Average Deaths per 100
Million Passenger Miles) Highway Vehicle Occupants and Transit Passengers. There were
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about 148 fatal accidents in the State involving commercial vehicles. An action plan has been
added which proposes to maintain an inventory of traffic incidents within the county.
Table 3.19 National Fatality Rates by mode of travel
Type of Vehicle Death Rate
Airlines 0.02
Automobiles 0.77
Vans, SUVs, Pickup Trucks 0.76
Heavy, Light, and Other Rail Vehicles
Not reported
Intercity and Commuter Railroads 0.03
Intercity Buses 0.02
Transit Buses 0.03
Source: State Hazard Mitigation Plan 2007
Probability of Future Occurrence
The probability of future occurrence is ―likely‖.
Likely- History of events is greater than 20% but less than or equal to 33% likely per year.
Magnitude/Severity
The magnitude/severity is ―critical‖
Critical- 25-50 percent of property severely damaged; shutdown of facilities for at least two
weeks; and/or injuries and/or illnesses result in permanent disability.
3.2.15 Utility Interruptions and Power failures
Hazard Description
This hazard may include electrical power, natural gas, public water supplies, and
communications systems. Utility systems exist everywhere and are subject to damage from
digging, fire, traffic accidents, and severe weather, including flooding, earthquake, and other
day-to-day events.
Warning Time: Level 4- Minimal (or no) warning
Duration: Level 3- Less than 1 Week
Historical Statistics
On January 30, 2002, a severe ice storm struck portions of western and northern Missouri. This
hazard was referred as the worst in Missouri’s history which left devastated and darkened
homes and businesses. Ice accumulations were over an inch and covered all the objects that
were at or below freezing. Further, the weight of the ice broke utility poles, conductors, tree
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limbs and other objects that could not withstand the weight of the ice. The ice storm of 2005 with
2-6 inches snow caused 2 deaths.
Utility failures could be localized. These failures impact generally on the very young or elderly,
who are more prone to health risks that are associated with resultant loss of heating/cooling
systems and with the loss of medical equipment that requires a power source.
The threat of earthquakes has been of greatest concern to the County which obstructs the
operability of the existing utilities.
Probability of Future Occurrence
Since, utilities exist throughout the County and are vulnerable to interruptions or failures, there
is a high probability that this hazard may occur at anytime or anyplace throughout the state. The
probability of future occurrence is ―highly likely‖
Highly Likely- History of events is greater than 33% likely per year.
Magnitude/Severity
The degree of severity of these day-to-day events may be considered low. Therefore, the
magnitude/severity is ―limited‖.
Limited- 10-25 percent of property severely damaged; shutdown of facilities for more than a
week; and/or injuries/illnesses treatable do not result in permanent disability.