2.0 hazard identification and risk assessment

Transcription

2.0
HAZARD IDENTIFICATION AND RISK ASSESSMENT
2.1
HAZARD IDENTIFICATION
Based on historical occurrences specific to Clinton County, the Hazard Mitigation
Planning Team developed a listing of known natural hazards to be addressed in this
plan. These known natural hazards were identified through a process that involved the
following:
•
input from the individual Hazard Mitigation Planning Team
members, local officials, and the public;
•
coordination with various federal, state, and local agencies;
•
a review of past disaster declarations at the federal and state level
specific to Clinton County (see Table 2-1);
•
analysis of hazard identification and risk assessment publications at
the state and local level;
•
limited field reconnaissance; and
•
Internet research.
TABLE 2-1
CLINTON COUNTY DISASTER HISTORY
DATE
HAZARD EVENT
ACTION
January 1966
Heavy Snow
Governor’s Proclamation
February 1972
Heavy Snow
June 1972
Flood (Agnes)
Governor’s Proclamation & President’s Declaration of Major Disaster
February 1974
Truckers Strike
September 1975
Flood (Eloise)
January 1978
Heavy Snow
February 1978
Blizzard
July 1991
Drought
March 1993
Blizzard
Governor’s Proclamation & President’s Declaration of Emergency
Clinton County Hazard Mitigation Plan
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TABLE 2-1
(CONTINUED)
DATE
January 1994
September 1995
January 1996
HAZARD EVENT
ACTION
Severe Winter Storms Governor’s Proclamation & President’s Declaration of Major Disaster
Drought
Severe Winter Storms Governor’s Proclamation & President’s Declaration of Major Disaster
January 1996
Flooding
December 1998
Drought
July 1999
Drought
September 1999
Hurricane Floyd
February 2003
Severe Winter Storm
September 2003 Hurricane Isabel/Henri Governor’s Proclamation & President’s Declaration of Major Disaster
September 2004
Tropical Depression
Ivan
Additionally, Clinton County’s Geographic Information System (GIS) Department
was used as an important resource in identifying and mapping the County’s
infrastructure, critical facilities, and land uses.
Data from this source was used to
determine those hazards that present the greatest risk to Clinton County. Table 2-2
summarizes the identification of these hazards.
Due to the perceived infrequency of some natural hazards such as avalanches,
coastal storms, coastal erosion, tsunamis, and volcanoes these natural hazards are not
addressed in this plan. Additionally, Research conducted by the Pennsylvania Bureau
of Topographic and Geologic Survey indicates that earthquake damage, expansive
soils, and land subsidence are rare occurrences in Clinton County, causing no injury or
severe property damage to date. With that in mind the Hazard Mitigation Planning
Team has decided not to address earthquake events in this plan at this time. Also the
Hazard Mitigation team decided not to address drought, extreme heat, wildfire, or
hailstorms in this plan as well due to the fact that historically they have had little or not
impact on Clinton County.
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TABLE 2-2
CLINTON COUNTY HAZARD IDENTIFICATION SUMMARY TABLE
HAZARD
HOW IDENTIFIED
WHY IDENTIFIED
Analysis
of
the
County’s
Vulnerability Assessment
Potential impact of Sayers and Bush Dams
on Clinton County
Review
of
Past
Disaster
Declarations
Identification of NFIP Repetitive
Loss Properties
Severity and Frequency of Past Events
Locally Acknowledged as the Most
Prevalent Potentially Devastating Natural
Hazard Event
Presence of the Susquehanna River and its
Many Tributary Streams
Review
of
Declarations
Disaster
Severity of the Flood-Related Damages
Caused by the 1972 (Agnes) and 2004
(Ivan) Events
Landslides
Local Knowledge / Public Input
Review of Data Harvested from
County’s 911 CAD System
Mountainous Topography Within the County
Known Landslide Locations Within the
County
Severe Storms
(Thunderstorms
and blizzards)
Review
of
Past
Disaster
Declarations
Severity and frequency of past events
Severity and Frequency of Past Events
Dam Failure
Flooding
Hurricanes/
Tropical Storms
Tornadoes
2.2
Past
HAZARD EVENT PROFILES
In Table 2-2 the Hazard Mitigation Team identified 6 hazards that have the
potential to impact Clinton County. Table 2-2A further defines the probability of these
hazards occurring by municipality.
2.2.1 Dam Failure
Dam failures can produce an extremely dangerous flood situation due to the
large volume of high-velocity water that is released and the minimal amount of time (if
any) for conducting warning and evacuation procedures. Breaching often occurs within
hours after the first visible signs of a failure. As such, three of the top four killer floods in
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TABLE 2 – 2A – INSERT HERE
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the Country (including the 1889 Johnstown flood in Pennsylvania) were the result of
dam failures. Dam failures typically occur for one of three reasons.
•
•
•
The foundation fails due to seepage, settling, or earthquake.
The design, construction, materials, or operation were deficient.
Flooding exceeds the capacity of the dam’s spillway.
Proper design, regular maintenance and routine inspection can go a long way in
preventing a dam failure.
Dam failure presents a potential flooding hazard for Clinton County due to the
presence of several dams within the county and one within 2 miles of the county line.
Kettle Creek Lake (Alvin R. Bush Reservoir) on Kettle Creek in Leidy Township (see
Figure 2-1), the Foster Joseph Sayers Dam on Bald Eagle Creek in Centre County, and
three (3) smaller dams or impoundments could affect the county if breached. Both F.J.
Sayers Dam and A.R. Bush Dam are operated and maintained by the U.S. Army Corps
of Engineers (U.S. ACE), Baltimore District.
The City of Lock Haven owns Warren H. Ohl Dam in Greene Township and the
Boyd R. Keller Reservoir Dam in Wayne Township, both of which are located along
McElhattan Creek. Both dams/reservoirs are used to provide a water supply for a large
portion of Clinton County. The Ohl Dam is a 58-foot high 98-foot long earthen
embankment dam including a spillway, maintaining a normal pool of 1,720 acre-feet of
water with a maximum pool capacity of 2,520-feet. The Keller Dam located south of the
Ohl Dam on McElhattan Creek is 53-foot high 590-foot long earthen embankment dam,
including spillway, maintaining a normal pool of 278 acre-feet of water with a maximum
pool capacity of 546 acre-feet. In addition to the Ohl and Keller Dams the City of Lock
Haven also owns a third reservoir/dam, the Upper Castanea Reservoir/Dam located in
Castanea Township on the headwaters of Harvey’s Run. The Castanea Reservoir/Dam
is a 30-foot high, 274-foot long earthen embankment dam, including spillway,
maintaining a normal pool of 33 acre-feet of water with a maximum pool capacity of 51
acre-feet. The Castanea Reservoir Dam is used to supplement the water supply for the
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FIGURE 2-1 - INSERT HERE
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central portion of Clinton County. These smaller dams/impoundments do not represent
a significant hazard due to their small capacities and inundation areas and were not
analyzed in detail. Alvin R. Bush Dam/Kettle Creek Lake is located in Western Clinton
County in Leidy Township approximately one (1) mile from Sugar Camp Run, and
approximately 8.5 miles upstream from the confluence of Kettle Creek and the West
Branch Susquehanna at Westport. The reservoir is formed by an earth fill embankment,
rock faced, with an un-gated concrete spillway. At ordinary minimum pool elevation,
Kettle Creek Lake is 840.000 ft., with a capacity of 1,590 acre-ft. of water.
Analysis of the Alvin R. Bush Dam/Kettle Creek Lake Emergency Action Plan
and review of Internet based data indicated that the inundation area from a sudden
break of Bush Dam on Kettle Creek would be bounded on its east and west banks by
steep mountainous terrain of the Appalachian Plateau region to the Susquehanna River
for a total distance of approximately 8.5 miles (topographic mapping of this estimated
inundation area is contained in the A.R. Bush Dam Flood Emergency Plan of
September 1988, which is available for inspection at the Clinton County Office of
Emergency Management).
Analysis of the A.R. Bush Dam Flood Emergency Plan (1988) indicated that
those Clinton County municipalities located along the Susquehanna River south of the
Kettle Creek confluence and west on Bald Eagle Creek to Blanchard would experience
significant over bank flooding to an elevation roughly equal to that of a 100 year flood
event.
The Foster Joseph Sayers Dam is a unit of a comprehensive flood control project
for the protection of communities in the West Branch Susquehanna River Basin. Foster
Joseph Sayers Dam is located on Route 150 in Centre County, Pa., on Bald Eagle
Creek about 1 mile upstream from Blanchard and 14 miles above the confluence of
Bald Eagle Creek and the West Branch Susquehanna at Lock Haven. Foster Joseph
Sayers Reservoir, completed in 1969, is the focal point for water-based recreation at
Bald Eagle State Park. The reservoir is formed by an earth fill dam with an un-gauged
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concrete ogee weir, abutting concrete walls and a partially unpaved exit channel. Foster
Joseph Sayers Lake’s ordinary minimum pool elevation is 610.0 ft. with a capacity of
6,300 acre-ft. of water. Further more, analysis of the Foster Joseph Sayers Dam Flood
Emergency Plan indicated that the inundation area from a sudden break of Sayers Dam
on Bald Eagle Creek would be bound on the south by Bald Eagle Mountain and on the
north by uplands of the Appalachian Plateau. Topographic mapping of this estimated
inundation area is contained in the Foster Joseph Sayers Dam Flood Emergency Plan
of September 1988, which is available for inspection at the Clinton County Office of
Emergency Management. Based on a review of the Foster Joseph Sayers Dam Flood
Emergency Plan by the Hazard Mitigation Planning Team, a failure of Foster Joseph
Sayers Dam would have an impact the same or greater than a 100 year flood event for
those communities along the West Branch Susquehanna River below the City of Lock
Haven and along the entire path of Bald Eagle Creek from the F.J. Sayers
impoundment to the confluence with the West Branch Susquehanna at Lock Haven.
2.2.2 Flooding
Like communities along the Susquehanna River, Clinton County is susceptible to
the problems and hazards associated with flooding.
Within Clinton County, most
flooding typically occurs when a channel (i.e., a river, creek, stream, or ditch) receives
too much water and the excess flows over its banks onto the adjacent floodplain. This
type of flooding is known as riverine (or over bank) flooding and is generally a problem
only where there has been development in the floodplain.
Riverine flooding in an
undisturbed floodplain is a natural process that has been occurring for millennia with
little or no adverse consequences. It is only in recent history that natural floodplains
have been altered by human encroachment, giving rise to flooding as a potentially
devastating natural hazard. Within Clinton County, there are numerous places where
homes, businesses, and even industries have been constructed in a floodplain. As
such, flooding is arguably the most geographically/topographically influenced and
potentially devastating natural hazard that Clinton County may face.
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In addition to basic riverine and over bank flooding (such as occurs on the
Susquehanna River, Bald Eagle Creek, and Fishing Creek), Clinton County is also
susceptible to a modified form of riverine over bank flooding known as flash flooding.
Unlike the Susquehanna River, which may take up to two or more days to rise and
crest, many of the County’s inland streams and watercourses are subject to flash
flooding. Flash floods occur in hilly and mountainous areas where surface water runoff
enters a drainage channel during and/or immediately following a significant storm event
or in urban areas where pavement and drainage improvements speed runoff to a
stream. As such, flash flooding is characterized by a rapid rise in water levels and
higher velocity flows. Within Clinton County, flash floods occur in rural areas on such
streams as Bald Eagle Creek and Fishing Creek, while recently there has also been a
noticeable increase in the occurrence of flash flooding in the more urbanized area
around Clinton County. Flash floods tend to be particularly dangerous and destructive
because there is typically little or no warning time and people are caught unaware. All
flash floods strike quickly and end swiftly.
Floods caused by ice jams are of little or no concern in Clinton County. All
though there is a documented history of ice jam flooding early in the 20th century, there
have been no such situations documented over the past fifty years. Ice jam flooding is
comparable to flash flooding in that the formation of an ice jam causes water upstream
to rise rapidly. When the jam releases, sudden flooding occurs downstream. Ice jams
can occur during fall freeze-up when ice begins to form, during midwinter when
channels freeze solid and form anchor ice, and during spring melt when the breakup of
surface ice results in large, floating masses of ice. The force of impact from ice carried
by floodwaters typically causes more damage to buildings, bridges, and other structures
than open-water flooding.
Figure 2-2 indicates that Clinton County has a well-developed drainage network
consisting of numerous first-, second-, and third-order streams. Several larger
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FIGURE 2.2 – INSERT HERE
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watercourses (e.g., Young Woman’s Creek, Beech Creek, Fishing Creek, Bald Eagle
Creek, Pine Creek, Kettle Creek and the West Branch Susquehanna River) also
traverse the County. As evidenced by Figure 2-2, most of these watercourses have
delineated floodplains established by FEMA through the National Flood Insurance
Program (NFIP). These delineated floodplains show the estimated area of inundation
associated with the 100 year storm event.
For most communities that participate in the NFIP (see Table 2-3), FEMA has
prepared a detailed Flood Insurance Study (FIS).
The FIS presents water surface
elevations for floods of various magnitudes, including the flood that has a 1-percent
probability of being equaled or exceeded in any given year (also called the 100-year
flood or base flood) and the flood that has a 0.2-percent probability of being equaled or
exceeded in any given year (also called the 500-year flood).
The water surface
elevation of the 100-year flood event is called the base flood elevation (BFE). BFE’s
and the boundaries of the 100- and 500-year floodplains are shown on the participating
community’s Flood Insurance Rate Mapping (FIRM).
For participation in the NFIP,
FEMA has established the 100-year floodplain as the regulatory standard for local
floodplain management purposes.
As such, the Hazard Mitigation Planning Team
selected the 100-year flood (see Figure 2-2) as the maximum magnitude of flood hazard
for study in this plan.
TABLE 2-3
CLINTON COUNTY NFIP PARTICIPATION STATUS BY MUNICIPALITY
COMMUNITY
ID
DATE OF
ENTRY
CURRENT
EFFECTIVE
MAP
POLICIES
IN FORCE*
INSURANCE
IN FORCE ($)*
TOTAL
PREMIUM
PAID ($)*
Allison Township
421534
9/3/80
7/6/98
1
500,000
2,900
Avis Borough
420318
1/16/80
1/16/80
20
1,184,900
9,186
Bald Eagle Township
420319
2/4/81
2/4/81
62
6,972,000
49,612
Beech Creek Borough
420320
8/2/90
8/2/90
11
552,600
4,248
Beech Creek Township
420321
9/5/90
9/5/90
10
733,600
5,046
Castanea Township
420322
2/2/77
1/21/98
12
748,800
5,700
Chapman Township
420323
12/18/79
12/18/79
10
660,000
3,045
Colebrook Township
420324
6/15/81
6/15/81
10
856,300
5,919
MUNICIPALITY
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TABLE 2-3
(CONTINUED)
COMMUNITY
ID
DATE OF
ENTRY
CURRENT
EFFECTIVE
MAP
POLICIES
IN FORCE*
INSURANCE
IN FORCE ($)*
TOTAL
PREMIUM
PAID ($)*
Crawford Township
421535
9/1/86
9/1/86
1
38,000
162
Dunnstable Township
420325
3/1/77
3/1/77
17
1,273,200
8,929
Flemington Borough
420326
2/2/77
1/17/97
2
90,000
568
Gallagher Township
421537
9/1/86
9/1/86
0
0
0
Greene Township
421538
9/1/86
9/1/86
53
4,025,700
24,312
Grugan Township
421539
12/1/86
12/1/86
0
0
0
East Keating Township
421536
10/1/86
10/1/86
4
213,500
1,106
West Keating Township
42542
10/1/86
10/1/86
0
0
0
Lamar Township
420327
3/16/88
3/16/88
70
4,683,100
35,287
Leidy Township
421540
9/1/86
9/1/86
14
1,185,000
6,412
Lock Haven City
420328
2/2/77
9/17/97
104
6,822,500
48,505
Logan Township
421541
5/1/86
5/1/86
62
5,894,000
25,187
Loganton Borough
421533
9/1/86
9/1/86
2
201,000
756
Mill Hall Borough
420330
2/16/77
9/5/84
126
6,255,700
57,594
Noyes Township
420331
11/5/80
11/5/80
25
902,300
9,491
Pine Creek Township
420332
4/1/77
4/1/77
116
10,448,600
70,527
Porter Township
420333
7/15/88
7/15/88
110
8,505,700
54,286
Renovo Borough
420334
12/28/76
12/28/76
73
4,295,800
34,836
South Renovo Borough
420335
2/2/77
2/2/77
6
215,700
2,286
Wayne Township
420336
11/1/79
11/1/79
61
4,076,400
23,905
Woodward Township
420337
1/16/80
9/17/97
49
4,562,100
31,795
N/A
N/A
N/A
1,031
75,896,500
521,600
MUNICIPALITY
TOTAL
*Data current through 10/28/04
Definitions:
M = Minimally Flood Prone, no elevation on map
NSFHA = No Special Flood Hazard Area
N/A = Not Applicable
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November 2004
Clinton County has experienced its worst flooding as a result of tropical
storms/hurricanes and snowmelt events. Tropical storms and hurricanes occur between
the months of June and November, with the peak season being September to October.
These storms bring torrential rains and high winds and often cause flash flooding as
well as over bank flooding of inland streams and rivers. Some of the most notable
floods (e.g., June 1972 and September 2004) were the result of tropical storms (Agnes
and Ivan, respectively). Photographs 1 - 3 depict some of the devastating effects felt by
tropical depression Ivan.
Snowmelt events typically occur between the months of
January and April. Because the ground often remains frozen under snow, it cannot
absorb the water from the melt, and large volumes of surface water runoff are produced.
Extreme flooding events can occur during snowmelts when additional rainfall combines
with the snowmelt runoff such as the flood of January 20th, 1996.
The Clinton County Department of Emergency Services monitors three
automated gauging stations. These are operated by the U.S. Geological Survey
(U.S.G.S.) and are located on the Susquehanna River at Renovo (Station No.
01545500), Lock Haven (Station No. 0154800), and on Bald Eagle Creek at Beech
Creek Station (Station No. 01548005). Table 2-4 lists the peak annual discharge and
stage values of the Susquehanna River from 1901 to 2004 as measured at the Renovo
U.S.G.S. gauging station. Table 2-5 lists the peak annual discharge and stage values
for the Susquehanna River from 1975 to 2004 as measured at the Lock Haven U.S.G.S.
gauging station. Table 2-6 lists stage values for Bald Eagle Creek at Beech Creek
Station (Station No.0154885) from 1911 through 2004.
Figures 2-3 and 2-4 graphically show these annual peak river stages at Renovo
on the West Branch of the Susquehanna. Analysis of this data indicates that major
flood events with a peak river stage greater than 16 feet at the Renovo gage have
occurred on 10 different occasions since 1901. A brief synopsis of some of the more
notable events are provided below.
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TABLE 2-4
PEAK ANNUAL SUSQUEHANNA RIVER DISCHARGE AND STAGE
RECORDED AT RENOVO, PENNSYLVANIA (1901-2004)
(PAGE 1)
Discharge
Stage
Water Year
Date
(cubic feet/second)
(feet)
1901
4/22/1901
53,201
11.10
1902
12/15/1901
79,100
13.52
1903
3/1/1903
73,400
13.00
1906
12/4/1905
59,000
11.70
1907
1/21/1907
43,700
10.00
1908
2/16/1908
71,100
13.50
1909
4/30/1909
88,100
15.50
1911
1/15/1911
62,300
13.10
1912
10/2/1912
67,900
11.15
1913
1/9/1913
83,000
14.90
1914
3/28/1914
63,100
12.54
1915
1/8/1915
67,100
13.00
1916
3/28/1916
87,000
15.80
1917
3/17/1917
32,800
8.82
1918
2/20/1918
75,300
14.50
1919
5/22/1919
69,400
13.80
1920
3/13/1920
81,300
15.00
1921
3/18/1921
28,600
7.97
1922
11/29/1921
50,700
11.20
1923
3/5/1923
65,800
13.06
1924
4/7/1924
65,000
13.00
1925
2/12/1925
77,000
14.50
1926
9/6/1926
50,000
11.10
1927
1/23/1927
55,400
11.80
1928
6/6/1928
56,200
11.90
1929
3/15/1929
59,400
12.30
1930
2/27/1930
42,200
9.80
1931
4/5/1931
36,400
8.97
1932
4/1/1932
42,200
9.80
1933
3/15/1933
52,000
11.09
1934
4/12/1934
21,500
6.85
1935
5/8/1935
33,600
9.13
1936
3/18/1936
236,000
29.39
1937
4/28/1937
63,800
13.21
1938
12/18/1937
57,400
12.83
1939
2/16/1939
27,900
8.65
1940
4/1/1940
92,900
16.51
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TABLE 2-4
PAGE 2
Discharge
Stage
Water Year
Date
(cubic feet/second)
(feet)
1941
4/6/1941
43,800
10.79
1942
7/18/1942
117,000
18.92
1943
12/30/1942
105,000
17.74
1944
3/17/1944
47,000
11.16
1945
3/7/1945
71,700
14.18
1946
5/28/1946
130,000
20.11
1947
4/6/1947
28,000
8.48
1948
4/15/1948
79,800
15.07
1949
1/29/1949
29,800
8.75
1950
3/29/1950
63,000
13.21
1951
11/26/1950
151,000
21.96
1952
1/27/1952
63,800
13.33
1953
5/26/1953
59,000
12.74
1954
3/2/1954
77,100
14.79
1955
12/31/1954
43,000
10.74
1956
3/8/1956
82,500
15.40
1957
4/7/1957
41,400
10.48
1958
4/7/1958
39,800
10.31
1960
3/31/1960
71,700
14.24
1961
2/26/1961
87,000
15.91
1962
4/1/1962
43,800
10.84
1964
3/10/1964
143,000
21.28
1966
2/14/1966
48,700
11.41
1967
9/29/1967
53,000
11.95
1969
4/6/1969
21,900
7.34
1970
4/3/1970
58,500
12.77
1971
2/28/1971
38,400
10.92
1972
6/23/1972
181,000
26.56
1973
2/3/1973
40,700
11.62
1974
3/10/1974
35,800
10.79
1975
9/26/1975
70,900
15.93
1976
2/17/1976
45,800
12.43
1977
4/3/1977
46,800
12.61
1978
5/15/1978
37,800
11.14
1979
3/5/1979
61,500
14.71
1980
11/27/1979
38,300
10.96
1981
2/20/1981
51,400
13.07
1982
10/28/1981
44,000
12.93
1983
6/29/1983
32,200
9.91
1984
2/15/1984
69,200
15.40
1985
4/1/1985
34,100
10.25
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November 2004
TABLE 2-4
PAGE 3
Discharge
Stage
Water Year
Date
(cubic feet/second)
(feet)
1986
11/17/1985
45,800
12.17
1987
11/27/1986
40,400
11.31
1988
2/3/1988
31,200
9.73
1990
7/13/1990
32,000
9.88
1991
3/4/1991
45,200
12.07
1992
7/16/1992
31,400
9.76
1993
4/1/1993
54,000
13.36
1994
3/25/1994
55,700
13.60
1995
1/21/1995
28,000
9.13
1996
1/20/1996
86,000
21.87
1997
11/9/1996
43,800
11.86
1998
1/8/1998
39,600
11.19
1999
1/24/1999
38,700
11.03
2000
4/23/2000
26,000
8.73
2001
3/22/2001
20,400
7.53
2002
5/14/2002
40,100
11.26
2003
3/19/2003
39,900
11.24
2004
9/18/2004
110,000
21.00
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TABLE 2-5
PEAK ANNUAL SUSQUEHANNA RIVER DISCHARGE AND STAGE
RECOREDED AT LOCK HAVEN, PENNSYLVANIA (1975-2004)
Water
Gage
Stream-
Year
Date
Height
(feet)
flow
(cfs)
1975
Sep. 26, 1975
22.92
91,500
1976
Feb. 18, 1976
15.91
44,500
1977
Apr. 03, 1977
16.2
46,200
1978
May. 15, 1978
14.52
42,900
1979
Mar. 06, 1979
19.85
68,900
1980
Nov. 27, 1979
14.59
43,300
1981
Feb. 21, 1981
16.82
55,500
1982
Oct. 28, 1981
14.83
44,800
1983
Jun. 29, 1983
13
32,800
1984
Feb. 15, 1984
22.38
79,000
1985
Apr. 01, 1985
13.36
35,300
1986
Nov. 17, 1985
15.33
47,600
1987
Nov. 27, 1986
14.74
43,700
1988
May. 20, 1988
13.69
37,800
1989
Jun. 21, 1989
15.43
47,200
1990
Jul. 13, 1990
13.07
33,800
1991
Mar. 05, 1991
15.72
48,900
1992
Jul. 16, 1992
13
33,000
1993
Apr. 01, 1993
18.6
64,000
1994
Nov. 28, 1993
18.3
60,700
1995
Jan. 21, 1995
12.89
32,500
1996
Jan. 20, 1996
25.76
93,900
1997
Nov. 09, 1996
16.94
55,100
1998
Jan. 09, 1998
15.4
47,200
1999
Jan. 25, 1999
14.87
44,400
2000
Apr. 23, 2000
12.53
30,000
2001
Mar. 23, 2001
11.67
23,300
2002
May. 14, 2002
15.21
46,200
2003
Mar. 19, 2003
14.91
44,600
2004
Sep. 19, 2004
28.1
120,000 Estimated
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November 2004
TABLE 2-6
PEAK ANNUAL BALD EAGLE CREEK DISCHARGE AND STAGE
RECOREDED AT BEECH CREEK STATION, PENNSYLVANIA (1911-2004)
Water
Year
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
Date
Sep. 09, 1911
Oct. 02, 1911
Mar. 27, 1913
Mar. 28, 1914
Feb. 25, 1915
Jun. 17, 1916
Mar. 12, 1917
Feb. 26, 1918
May. 22, 1919
Mar. 13, 1920
May. 5, 1921
Nov. 29, 1921
Mar. 04, 1923
Apr. 06, 1924
Feb. 12, 1925
Feb. 26, 1926
Nov. 16, 1926
Apr. 30, 1928
Mar. 14, 1929
Feb. 26, 1930
May. 23, 1931
Apr. 01, 1932
Mar. 15, 1933
Apr. 12, 1934
Jan. 10, 1935
Mar. 18, 1936
Apr. 28, 1937
Dec. 19, 1937
Feb. 15, 1939
Mar. 31, 1940
Apr. 06, 1941
May. 22, 1942
Dec. 30, 1942
May. 7 1944
Mar. 22, 1945
May. 27, 1946
Jun. 08, 1947
Apr. 15, 1948
Dec. 30, 1948
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29
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Gage
Stream-
Height
flow
(feet)
(cfs)
8.8
10.9
9.4
9.3
9
13.2
6.6
9.5
9.4
10.2
7.3
9.5
8.9
11
9.25
7.6
7.8
8.1
7.42
6.16
8.71
7.53
6.69
6.37
6
14.42
8.88
7.34
6.17
11.06
6.33
9
10.94
9.38
9.02
12.48
5.6
9.65
7.91
10,800
15,700
12,000
11,800
11,100
22,000
6,550
12,300
12,000
13,900
8,120
12,300
10,700
15,900
11,600
8,840
9,330
10,100
8,360
5,720
11,500
8,600
6,760
6,120
5,350
25,600
10,900
7,560
5,520
16,200
5,970
11,100
15,700
12,000
11,100
20,000
4,610
12,500
8,810
November 2004
TABLE 2-6
PAGE 2
Water
Year
1950
1951
1952
1953
1954
1955
1956
1957
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
Date
Mar. 29, 1950
Nov. 25, 1950
Mar. 11, 1952
May. 26, 1953
Mar. 02, 1954
Mar. 22, 1955
Oct. 15, 1955
Apr. 09, 1957
Jan. 22, 1959
Mar. 31, 1960
Feb. 26, 1961
Apr. 08, 1962
Mar. 18, 1963
Mar. 10, 1964
Mar. 24, 1965
Feb. 14, 1966
Mar. 15, 1967
Oct. 26, 1967
Nov. 18, 1968
Apr. 02, 1970
Mar. 01, 1971
Jun. 23, 1972
Feb. 03, 1973
Apr. 04, 1974
Sep. 26, 1975
Jun. 21, 1976
Apr. 06, 1977
May. 17, 1978
Mar. 06, 1979
Nov. 26, 1979
Feb. 24, 1981
Jun. 05, 1982
Jun. 28, 1983
Feb. 15, 1984
Mar. 31, 1985
Mar. 15, 1986
Nov. 26, 1986
May. 19, 1988
May. 17, 1989
May. 16, 1990
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Gage
Stream-
Height
flow
(feet)
(cfs)
7.94
12.96
9.52
10.3
9.24
6.53
8.58
7.96
7.6
9.24
10.92
7.61
6.6
12.41
4.44
9.22
7.67
6.81
4.9
6.23
6.66
12.29
6.05
5.99
9.75
5.72
6.52
6.03
7.89
6.49
6.87
6.42
6.16
10.7
10.47
11.98
10.62
11.46
11.2
10.94
8,810
21,400
12,300
14,200
11,600
6,140
10,300
9,010
8,210
11,600
15,700
8,210
6,320
19,700
2,760
11,600
8,350
6,700
3,450
5,650
6,430
19,400
5,340
5,230
12,800
4,720
6,180
5,290
8,790
5,780
6,490
5,660
5,190
15,600
4,200
5,830
3,920
5,060
4,690
4,340
November 2004
TABLE 2-6
PAGE 3
Water
Year
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Date
Mar. 04, 1991
Apr. 01, 1992
Apr. 16, 1993
Nov. 28, 1993
Jan. 20, 1995
Jan. 19, 1996
Nov. 09, 1996
Jan. 08, 1998
Mar. 04, 1999
Apr. 19, 2000
Mar. 22, 2001
May. 13, 2002
Mar. 21, 2003
Sept. 18, 2004
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Gage
Stream-
Height
flow
(feet)
(cfs)
10.75
9.82
12.76
14.3
10.71
15.62
12.29
10.8
10.09
10.02
9.49
10.87
10.83
15.9
4,090
2,970
6,420
9,960
4,140
12,600
6,470
4,260
3,380
3,410
2,820
4,250
4,200
13,000
November 2004
FIGURE 2-3 DISCHARGE IN CFS AT RENOVO, WEST BRANCH OF SUSQUEHANNA
Discharge
2003
2000
1997
1994
1991
1987
1984
1981
Discharge
1978
1975
1972
1969
1964
1960
1956
1953
Water Year
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
Discharge
1948
1945
1942
1939
1936
1933
1930
1927
Discharge
1924
1921
1918
1915
1912
1908
1903
Water Year
0
50000
100000
150000
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200000
250000
November 2004
FIGURE 2-4 RIVER STAGE AT RENOVO, WEST BRANCH OF THE SUSQUEHANNA
Stage
2003
2000
1997
1994
1991
1987
1984
1981
1978
1975
1972
1969
1964
1960
1956
1953
Water Year
0.00
5.00
10.00
15.00
20.00
25.00
30.00
Stage
1948
1945
1942
1939
1936
1933
1930
1927
1924
1921
1918
1915
1912
1908
1903
Water Year
0.00
5.00
10.00
15.00
20.00
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25.00
30.00
35.00
November 2004
PHOTOGRAPH NOS. 1 & 2
Photograph No. 1: Aerial view of Hogan Boulevard and Camelot Estates in
Bald Eagle Township during the 2004 Hurricane Ivan Flood.
Photograph No. 2: Flooding in Renovo Borough during the 2004 Hurricane Ivan Flood.
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PHOTOGRAPH NO. 3
Photograph No. 3: Rescuers aiding victims to safety during the 2004 Hurricane Ivan Flood.
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For the purpose of this study, we have chosen the flood of June 1972 as our
storm of record for Clinton County. The St. Patrick’s Day flood of 1936 actually caused
a higher crest at Lock Haven than the flood of 1972 (see Photograph No. 4), however
for the purpose of comparison in regard to monetary damage totals as well as tying
events to a reasonable historic reference, the Agnes event of 1972 will be used as our
event of record.
Tropical Storm Agnes occurred in June 1972 just after an earlier rainfall event
had saturated the ground in much of Pennsylvania. Agnes brought as much as 18
inches of rain to some places in Pennsylvania, with Clinton County receiving 10 to 12
inches. This event produced severe surface water runoff conditions which caused
abnormally high flows in local streams and tributaries. Most communities along the
Susquehanna River, including Clinton County experienced severe flooding. The
U.S.G.S. gage at Lock Haven recorded a peak river stage of 31.3 feet. Numerous other
streams in Clinton County reached historical crests causing flooding in nearly all
communities within the county. It was estimated that Pennsylvania incurred over $2
billion (1972) in damages and was so severely impacted that President Richard Nixon
declared the entire state a disaster area (Miller, 1974; Gannett Fleming, 1974).
Photographs 5 & 6 illustrate some of the devastating effects this flood had on Clinton
County.
In January 1996, snowmelt combined with heavy rainfall, led to a large-scale
flash flooding event across Pennsylvania. Early in January, a blizzard occurred freezing
the ground and leaving up to seven feet of snow base (see Photograph No. 7). On
January 19th, temperatures climbed quickly into the 60’s causing rapid snowmelt. In
addition, heavy rains averaging between 1.2 and 3 inches fell over the area during a 6hour period. The frozen ground could not absorb the water from the snow melt or the
rainfall and large amounts of surface water runoff were produced. To further compound
the problem, large floating masses of ice accumulated at the various river crossings
(see Photographs No. 8 & 9 of similar events), creating obstructions to the flood flow.
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Photograph No. 4: Flooding in Lock Haven During 1936 Flood.
PHOTOGRAPH NO. 5: 1972 AGNES FLOOD
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November 2004
Photograph No. 6: 1972 Agnes Flood - Main Street, downtown Lock Haven
Photograph No. 7
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Photograph No. 8: Ice accumulation on Pine Creek in Pine Creek Township
Photograph No. 9: Flooding in Clinton County During 1964 Ice Jam.
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November 2004
On January 20th, 1996 the U.S.G.S. gage at Lock Haven recorded a peak stage of
25.07 feet. This crest was the third highest crest recorded at Lock Haven. No damage
was reported in the City of Lock Haven, as this was the first flooding event to occur
since the completion of the Dike / Levee system (see Photographs 10 & 11). However,
numerous other communities within Clinton County reported considerable damage
totals. Damage estimates for the entire Susquehanna River basin as a result of this
flood event were in the range of $600,000,000 (NWS, 1998).
2.2.3 Hurricanes/Tropical Storms
As previously mentioned, Clinton County experienced some of its worst flooding
as the result of hurricanes/tropical storms. Although Clinton County is located too far
inland to be impacted by all of the common hazards associated with a hurricane/tropical
storm event (i.e., severe winds and coastal storm surge), it is susceptible to the
significant rainfall and associated flooding that can sometimes occur.
Analysis of
Clinton County’s disaster history (see Table 2-1) indicates that there have been five
disaster declarations since 1958 due to flooding associated with hurricane/tropical storm
events. These events occurred in 1972 (Agnes), 1975 (Eloise), 1999 (Floyd), 2003
(Isabel), and 2004 (Ivan). As previously mentioned, the June 1972 Hurricane Agnes
event resulted in the flood of record for the central and eastern portions of the
Susquehanna River basin with the Susquehanna River reaching a peak stage of 31.3
feet at Lock Haven.
More detailed information on hurricane/tropical storm-related
flooding can be found in Section 2.2.2.
2.2.4 Landslides
As defined by FEMA, a landslide is the downward and outward movement of
earth materials reacting under the force of gravity. As such, “landslide” can be used to
describe a number of different types of events displaying different movement
characteristics and involving different materials.
Rockslides, rock falls, mudflows,
mudslides, debris flows, and debris avalanches are all types of landslide events that
involve different materials moving in a different manner. Landslides typically occur
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40
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November 2004
PHOTOGRAPHS OF DIKE LEVEE SYSTEM CONSTRUCTED TO PROTECT THE CITY OF LOCK
HAVEN FROM FLOODING HAZARDS. LOCK HAVEN IS ALSO THE COUNTY SEAT (COUNTY
COURTHOUSE SHOWN ABOVE).
Photograph No. 10
Photograph No. 11
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November 2004
when some factor (e.g., increased water content or change in load) causes the force of
gravity to outweigh the forces working to hold material in place, resulting in the
downslope movement of the subject material. Several natural and human factors may
contribute to or influence landslides.
These factors include topography, geology,
precipitation, steepness of cut and fill slopes, and cut-slope stability. Figure 2.5 shows
Clinton County’s geologic formations.
According to the PA DCNR, “landslides cause damage to transportation routes,
utilities, and buildings and create travel delays and other side effects.” Fortunately,
deaths and injuries due to landslides are rare in Pennsylvania. Almost all of the known
deaths due to landslides have occurred when rock falls or other slides along highways
have involved vehicles. Storm induced debris flows are the only other type of landslide
likely to cause death and injuries. These occurrences as a whole are known as mass
wasting events.
We have included landslides in this document for the simple fact that mass
wasting events occurring in Clinton County have the potential to significantly disrupt
critical transportation routes from one section of the county to another. Delivery of
critical services such as police and other emergency response can be delayed or even
completely prohibited by a slide or slump. A survey of geologic hazards within proximity
to roadways was conducted for Clinton County Government by a team comprised of
individuals from the Lock Haven University Department of Geology and Physics and the
Clinton County GIS Department. Findings of this study have been utilized to identify
problem areas throughout the county. A map of these areas has been included in this
document (see figures 2.6 & 2.7). The study identified geologic formations with known
rock unit instability, areas of steep slopes, unconsolidated surficial cover and areas
within close proximity to roadways. Formations with known problems were identified
then selected within a buffer of each roadway. The resulting points identify areas that
have potential risk for mass wasting.
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42
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November 2004
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43
-
November 2004
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44
-
November 2004
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45
-
November 2004
While some sites identified in this document have produced no significant mass
wasting events to date, others were clearly identified sites that have a long history of
producing significant events. One in particular has been the subject of a mitigation
project implemented by the Pennsylvania Department of Transportation. This site is
located in a steep cut of the Susquehanna River above SR 120 known as the Ice Mine
Cut (see Photographs 12 & 13). The Ice Mine Cut project was performed in 1997 to
move a potential hazard back away from SR 120 in Bald Eagle Township. This site had
for years deposited debris onto SR 120. The mitigation project cut the hillside back a
reasonably safe distance from the roadway and deposited all the material excavated
from the site up and out of the potential slide area. While this area continues to deposit
material down slope, a buffer was created back from the roadway, drastically reducing
the risk to motorists. This site is also significant due to the fact that it is the primary
maintained roadway access to the western portion of Clinton County. A population of
nearly 10, 000 people resides north of the site, so a road closure at this location would
effectively isolate the Renovo area from State Police and Advanced Life Support
coverage. The Hazard Mitigation Planning Team identified the potential landslide
hazard areas shown on figures 2.6 and 2.7 along with the one known landslide hazard
area (Ice Mine Cut), as the maximum physical extent of landslide hazard for study in
this plan.
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November 2004
Photographs of Ice Mine Cut Project which involved excavation of mountainside and creation of
retention wall to eliminate landslide hazards on roadway.
Photograph No. 12
Photograph No. 13
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November 2004
2.2.5 Severe Storms
Severe storms include thunderstorms, hailstorms, and blizzards. Thunderstorms
and hailstorms are generated when a warm, moist air mass rises rapidly into the
atmosphere as a result of some lifting force (e.g., colliding weather fronts, sea breezes,
or orographically due to mountains). As the warm, moist air rises, it cools, and the
moisture condenses, forming towering cumulonimbus clouds, thunder, and lightning.
When compared to hurricanes/tropical storms and winter storms, thunderstorms affect
relatively small areas. The typical thunderstorm is only 15 miles in diameter and lasts
an average of 30 minutes.
However, despite their small size, every thunderstorm
should be considered dangerous. Every thunderstorm produces lightning, which kills
more people each year than tornadoes. Heavy rain from thunderstorms can lead to
flash flooding. Strong winds, hail, and tornadoes are also dangers associated with
some thunderstorms. Of the estimated 100,000 thunderstorms that occur each year in
the United States, only about 10 percent are classified as severe. A thunderstorm is
considered to be severe if it produces hail at least ¾ inch in diameter, winds of 58 miles
per hour (mph) or higher, or tornadoes.
Hailstorms are an outgrowth of severe
thunderstorms and cause nearly $1 billion in damage to property and crops on an
annual basis in the United States.
Coordination with the NWS indicated that, since 1950, Clinton County reported
122 occurrences of thunderstorm-related wind damage and 12 occurrences of
thunderstorm-related hail in excess of ¾ inch in diameter. 4 hail events were reported
in Clinton County resulting in hail of one inch in diameter and with one storm in Renovo
depositing hail measuring from nickel to quarter size. The most damaging thunderstorm
Clinton County has ever experienced occurred in June 1998.
Thunderstorm
downbursts crossed the Flemington and Lock Haven areas, taking down at least 100
trees in Flemington and western parts of Lock Haven. The path of damage was about 4
miles long and 3/4-mile wide, touching down initially about 3 miles west-northwest of
Lock Haven and traveling southeast into the city. Two microbursts occurred on the
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November 2004
south edge of the path. The first microburst uprooted about 100 trees with winds of
about 80 mph. No structures were damaged, but numerous cars were struck by falling
trees. The second microburst, of lesser intensity, snapped a dozen trees. One tree
damaged a car and another a building. Hail of 5/8 inch diameter or slightly less than
dime size was also reported. In December of 2000 a less severe storm resulted in a
fatality due to a tree falling on a residence in Westport. As such, the Hazard Mitigation
Planning Team selected these thunderstorm events as the maximum magnitude severe
storm hazards to be studied in this plan.
Clinton County is also susceptible to blizzards and other severe winter storms
(i.e., heavy snows and ice storms). Blizzards are severe winter storms that pack a
combination of blowing snow and wind resulting in very low visibilities. While heavy
snowfalls and severe cold often accompany blizzards, they are not required.
Sometimes strong winds pick up snow that has already fallen, creating a blizzard.
Officially, the NWS defines a blizzard as large amounts of falling or blowing snow with
winds in excess of 35 mph and visibilities of less than ¼ mile for an extended period of
time (greater than 3 hours). Blizzards and other severe winter storms can create a
variety of dangerous conditions. Traveling by automobile can become difficult or even
impossible due to “whiteout” conditions and drifting snow.
Power outages are a
common occurrence during heavy snow, wind, or ice events that may cause personal or
economic hardships. The strong winds and cold temperatures accompanying these
storms can be dangerous if people are exposed for any length of time.
Analysis of Clinton County’s disaster history (see Table 2-1) indicates that there
have been eight disaster declarations since 1966 due to severe winter storms (heavy
snow and blizzards). Coordination with the NWS indicated that Clinton County has
experienced 47 significant winter storms involving snow and/or ice accumulations since
1966. During January 6th through the 8th in 1996 the Blizzard of ’96 impacted Clinton
County resulting in two Federal Disaster Declarations.
Prior to the blizzard which
yielded 12” – 24” of snow accumulation, an additional 6” to 10” of snow fell on Clinton
County on January 2, 1996. Following the blizzard on January 19th and 20th 1996, the
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November 2004
combination of over two feet of melting snow and unseasonably warm temperatures and
drenching rain unleashed a devastating flooding event which also resulted in a Federal
Disaster Declaration.
As a result of these declarations, Clinton County received
$1,657,344 in federal aid to assist in recovery efforts. The allocation of funds to Clinton
County from disaster declarations follow:
•
$571,339 in FEMA assistance to state agencies, local governments and some
private, nonprofit organizations to help repair storm-damaged public
infrastructure. This aid covers emergency services, debris removal and the repair
or replacement of public facilities such as roads, bridges, buildings and utilities.
•
$94,077 in individual assistance funds, including $999,745 to individuals for
temporary housing assistance, and $92,384 to 74 applicants for individual and
family grants.
•
$86,260, the federal share of funding for road and bridge repairs in Sproul State
Forest, on a section of Young Woman’s Creek Road.
As such, the Clinton County Hazard Mitigation Planning Team selected this winter storm
event as the maximum magnitude severe winter storm hazard for study in this plan.
2.2.6 Tornadoes
A tornado is a rapidly rotating column of air extending from a thunderstorm to the
ground that has the potential to cause significant damage to anything in its path.
Although tornadoes occur in many parts of the world, these destructive forces of nature
are found most frequently in the United States east of the Rocky Mountains during the
spring and summer months.
In an average year, 800 tornadoes are reported
nationwide, resulting in 80 deaths and over 1,500 injuries. With wind speeds in excess
of 250 mph, tornadoes are considered nature’s most violent storms. Damage paths can
be as wide as 1 mile and over 50 miles long.
Tornadoes are related to larger vortex formations and often form in convective
cells such as thunderstorms or in the right forward quadrant of a hurricane, far from the
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November 2004
hurricane eye.
Tornadoes in the winter and early spring are often associated with
strong frontal systems that form in the central states and move east. Occasionally,
large outbreaks of tornadoes occur with this type of weather pattern. Several states
may be affected by numerous severe thunderstorms and tornadoes. It is interesting to
note that tornadoes may appear nearly transparent until dust and debris are picked up
or a cloud forms in the funnel.
Tornados have been identified in Clinton County on radar, by observers, and
while on the ground. However, historically there has been little to no damage that can
be directly attributed to a tornado. In 1984, an F4 tornado tore through unpopulated
portions of western Clinton County but no damage was reported other than fallen trees.
On May 19, 1997 near Renovo An F1 tornado (73-112 mph) moved through the town
between 6:45 p.m. and 6:50 p.m. Hundreds of trees were downed, the roofs of a hotel,
a supermarket, a home and several other structures were damaged. A tin roof was
peeled off a railroad car maintenance building now being used as an industrial
development center. Eyewitnesses reported seeing the funnel cloud and people talked
of seeing rotation in the debris. Sporadic damage associated with the storm extended
along a path of nearly 15 miles beginning near Bitumen west of Renovo, continuing
through Renovo east to Farwell. Width of the damage was up to 1/4 mile in spots, but
the tornado damage was probably confined to only a small portion of the path. Damage
was confined to the lower elevations of the river valley from the north facing slopes of
the mountains into the valley floor. Unlike some hazards, tornadoes are not specific to
select parts of the County. Rather, a tornado could strike in any part of the County at
any time, and could cause as much or as little damage as possible for the given
magnitude event. As such, it is not appropriate to map tornado occurrence as a method
of profiling the hazard. Clinton County is certainly susceptible to tornados however
none have had significant monetary damages.
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November 2004
2.3
VULNERABILITY ASSESSMENT: IDENTIFYING ASSETS
Asset identification is a critical step in the hazard mitigation planning process.
Inventorying existing structures and identifying critical facilities provide insight into the
County’s vulnerability to select hazards and the magnitude of the potential damages of
those hazards. As such, asset identification was conducted as a phased process that
involved municipal coordination, public input, GIS data analysis, Internet research,
review of local emergency management plans, and limited field reconnaissance.
The first task of the asset identification focused on the identification and mapping
of critical facilities throughout the County.
Documentation of this critical facilities
inventory is included in the appendices. Critical facilities are structures in which vital
community operations are performed.
If these facilities are impacted by a natural
hazard, there could be severe consequences to public health and safety. Therefore, it
is imperative that critical facilities be adequately protected from natural hazards. Critical
facilities are not strictly defined by FEMA. Rather, communities are encouraged to
evaluate their own facilities and determine which would be necessary during an
emergency event. As such, critical facilities fall into two general categories:
buildings or locations vital to the hazard response effort (i.e.,
Emergency Operations Centers, police, fire and EMS stations,
hospitals/mass care centers, evacuation centers/emergency
shelters, communications facilities, schools, etc.); and
buildings or locations that, if impacted, would create secondary
disasters (i.e., hazardous materials facilities, water/wastewater
treatment plants, etc.).
After the critical facilities were identified and mapped, the focus of the asset
identification shifted to assessing vulnerability on a per-hazard basis. Based on the
hazard event profiling that was described in the previous section, GIS data analysis was
used to inventory the total number of structures as well as the critical facilities that are
potentially vulnerable to the identified hazards.
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As previously mentioned, natural
November 2004
hazards such as hurricanes/tropical storms, tornadoes, and severe storms are not
appropriate to be mapped at the county level as they are likely to impact the entire
County or undefined locations within the County. As such, the entire County must be
considered vulnerable to these hazards. In regard to the other identified hazards (i.e.,
dam failure, flooding, and landslides), Table 2-7 lists the total number of vulnerable
structures. Table 2-8 lists vulnerable critical facilities by municipality for the profiled
hazard event, which would be a 100 year or greater flood event. Information reported in
Table 2-7 was used to estimate potential losses from the profiled hazard events (see
next section).
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November 2004
TABLE 2-7
CLINTON COUNTY VUNERABLE STRUCTURES
BY MUNICIPALITY
NUMBER OF STRUCTURES WITHIN 100 FLOOD BY MUNICIPALITY
MUNICIPALITY
COUNT
ALLISON TWP
2
AVIS BORO
3
BALD EAGLE TWP
383
BEECH CREEK BORO
29
BEECH CREEK TWP
94
CASTANEA TWP
43
CHAPMAN TWP
301
COLEBROOK TWP
43
DUNNSTABLE TWP
91
EAST KEATING TWP
55
FLEMINGTON BORO
4
GALLAGHER TWP
2
GREENE TWP
1
GRUGAN TWP
85
LAMAR TWP
391
LEIDY TWP
150
LOCK HAVEN CITY
1
LOGAN TWP
50
MILL HALL BORO
242
NOYES TWP
169
PINE CREEK TWP
297
PORTER TWP
356
RENOVO BORO
212
SOUTH RENOVO BORO
46
WAYNE TWP
7
WEST KEATING TWP
7
WOODWARD TWP
152
TOTAL
3216
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November 2004
TABLE 2-8
CLINTON COUNTY CRITICAL FACILITIES
BY MUNICIPALITY
CRITICAL FACILITIES WITHIN 100 YEAR FLOOD BY MUNICIPALITY
ADDRESS
MUNICIPALITY
FACILITY NAME
SERVICE TYPE
34 E END MTN RD
LAMAR
BEECH CREEK
BOROUGH
LAMAR TWP ELEMENTARY
BEECH CREEK MUNICIPAL AUTHORITY
PINE CREEK TOWNSHIP
PINE CREEK MUNICIPAL AUTHORITY
SCHOOL
WASTEWATER
TREATMENT
WASTEWATER
TREATMENT
PINE CREEK TOWNSHIP
JERSEY SHORE AREA JOINT AUTHORITY
WATER TREATMENT
MILL HALL BOROUGH
MILL HALL POLICE
POLICE
PORTER TOWNSHIP
NITTANY VALLEY FIRE CO.
FIRE
151 MILL ST
429 EIGHTH ST
TIADAGHTON & FIFTH
AVE
215 BEECH CREEK AVE
5101 NITTANY VALLEY
DR
230 11TH ST
RENOVO BOROUGH
RENOVO FIRE DEPT.
FIRE
9 E PEALE AVE
MILL HALL BOROUGH
MILL HALL VOLUNTEER FIRE CO.
FIRE
79 PARK AVE
CHAPMAN TOWNSHIP
CHAPMAN TOWNSHIP FIRE CO.
FIRE
144 HOGAN BLVD
BALD EAGLE TOWNSHIP
TOMORROWS HOPE CHILD CARE
CARE CENTER
7 GIRARD ST
MILL HALL BOROUGH
FAMILY DAY CARE CENTER
CARE CENTER
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November 2004
In regard to long-term asset identification, the Clinton County Planning
Commission indicated that Clinton County is expected to experience moderate growth
over the next 20 years.
As part of the County Comprehensive Planning process,
municipal population projections to the year 2020 were used to geographically model
anticipated future growth. Analysis of the model product indicated that the majority (95
percent) of the County’s anticipated future growth is to occur in the southern part of the
County. The remainder (5 percent) of the County’s anticipated future growth is to occur
in the northern part of the County. While any future development will be susceptible to
drought, hurricanes/tropical storms, tornadoes, and severe storms, proper enforcement
of local codes and ordinances should minimize vulnerability to flooding and other
hazards.
2.4
VULNERABILITY ASSESSMENT: ESTIMATING POTENTIAL LOSSES
Estimating potential losses/damages from natural hazard events at the county
level can be a very difficult task to complete with limited data. As such, the Mitigation
Planning Team relied on data provided by the County GIS Department and the County
Assessment Office as well as damage estimates from past hazard events. Damage
estimates from past hazard events were used specifically for those natural hazards that
are not applicable to be mapped at the county level (e.g., hurricanes/tropical storms,
tornadoes, and severe storms). For those natural hazards that are specific to certain
parts of the County (e.g., dam failure and flooding), the GIS data analysis that was
conducted for the asset identification and reported in Table 2-7 served as the primary
means for estimating potential losses from the profiled hazard events.
A summary of
the estimated potential losses from the profiled hazard events is provided below. Those
municipalities that may be impacted by a specific event are shown in Table 2.2A.
2.4.1 Potential Dam Failure Losses
Analysis of the A.R. Bush Dam Emergency Action Plan indicated that 1,717
residences would be flooded and 2 highway bridges would be blown out by a “Probable
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November 2004
Maximum Flood” break of the A. R. Bush Dam. GIS data analysis conducted for the
asset identification (see Table 2-7) indicated that there are 1,717 structures in the
profiled A.R. Bush Dam failure hazard area. Based upon a windshield survey, we’ll use
the same averages for structure type for our damage assessment. 45% will be
residential, 45% residential accessory, 8% commercial, and 2% industrial. Based on
assessment data of the representative floodplain structures that were identified from
throughout the County, assuming an average residence value of $55,616 appears to be
reasonably representative of the County’s average house value. Similarly, an average
residential accessory structure value of $3,000 appears to be reasonably representative
of the County’s average residential accessory structure value. Commercial structures
will be given an average value of $200,000, and Industrial structures will be given an
average value of $750,000. As such, the following losses can be estimated for Clinton
County’s A.R. Bush Dam failure hazard.
Residential Accessory = 772 Structures X $3,000 average value per structure X 30% impact* = $694,800
Residential = 772 Structures X $55,616 average value per structure X 30% impact* = $12,880,665
Commercial = 137 Structures X $200,000 average value per structure X 30% impact* =
$8,220,000
Industrial = 34 Structures X $750,000 average value per structure X 30% impact* = $7,650,000
Infrastructure = 2 highway bridges X $250,000 average value per bridge** X 100% impact = $500,000
Total = $29,945,465 (does not include potential content losses)
*30% impact estimate based on location within the impact area but at some distance set back from the stream channel. The estimate
includes some structural damage due to high velocity flood flows.
**Average bridge value based on professional judgment
GIS data analysis conducted for the asset identification indicated that there are
approximately 793 structures in the profiled Foster Joseph Sayers Dam failure hazard
area of Clinton County. Based upon windshield survey of the geographic area, it is
reasonable to assume that 45 percent (357) of these structures are residential
accessory structures (i.e., sheds, garages, etc.), 45 percent (357) are residences, 8
percent (63) are commercial establishments, and 2 percent (16) are industrial buildings.
As such, the following losses can be estimated for Clinton County’s F.J. Sayers Dam
failure hazard.
Residential Accessory = 357 Structures X $3,000 average value per structure X 30% impact* = $321,300
Residential = 357 Structures X $55,616 average value per structure X 30% impact* = $5,956,473
Commercial = 63 Structures X $200,000 average value per structure X 30% impact* = $3,780,000
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November 2004
2.4.2 Potential Flooding Losses
GIS data analysis conducted for the asset identification indicated that there are
approximately 3,216 structures in the 100-year floodplain in Clinton County. Based
upon windshield survey, assuming that 45 percent (1,447) of these structures are
residential accessory structures (i.e., sheds, garages, etc.), 45 percent (1,447) are
residences, 8 percent (257) are commercial establishments, and 2 percent (64) are
industrial buildings, the following losses can be estimated for Clinton County’s flooding
hazard.
Residential Accessory = 1,447 Structures X $3,000 average value per structure X 10% impact* = $434,100
Residential = 1,447 Structures X $55,616 average value per structure X 10% impact* = $8,047,635
Commercial = 257 Structures X $200,000 average value per structure X 10% impact* = $5,140,000
*10% impact is based on average value of flood insurance claims payments through the NFIP and assumes some structural damage due
to high velocity flows and/or depth of floodwaters
2.4.3 Potential Hurricane/Tropical Storm Losses
Damage estimates from the 2004 Tropical Storm Ivan event were reported at
$2,550,304 for Clinton County.
This amount includes residential, commercial, and
infrastructure damages. As of 2/10/2005 Federal Assistance to Clinton County totaled
$339,807.50. The Ivan event produced flooding somewhat less than 100 year event
crests, and as such produced lower damage totals than we indicate in this document for
a 100 year flooding event.
This event will be used for estimating losses, as it is
probably an average or greater storm event and can be expected on a higher rate of
occurrence than a storm of the magnitude of Hurricane Agnes of 1972.
2.4.4 Potential Landslide Losses
Potential damage due to landslides in Clinton County is limited to roadway
closures and the possibility of highway accidents due to debris deposited on the
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November 2004
roadway. No dollar estimates on expenditures by PennDOT for debris removal were
available for inclusion in this document.
2.4.5 Potential Severe Storm Losses
Damage estimates from the June 20, 1998 severe thunderstorm event were
estimated at $50,000 for Clinton County. This included primarily residential, vehicular,
and infrastructure (i.e., utility line) damages.
The Blizzard of January ’96 winter storm event impacted Clinton County resulting
in two separate Federal Disaster Declarations. The first declaration was declared for a
winter storm event and the second declaration was for a flooding event due to 2 feet of
melting snow from the blizzard event in conjunction with a rainfall event. As a result of
these declarations, Clinton County received $1,657,344 in federal aid to assist in
recovery efforts. This included assistance for temporary housing, public facilities repairs
(roads, bridges, buildings and utilities) and emergency services.
2.4.6 Potential Tornado Losses
Damage estimates from the 1997 F1 tornado event near Renovo were not
reported to PEMA. Damage was limited to roofing and downed trees.
2.5
MULTI-JURISDICTIONAL RISK ASSESSMENT
From a natural hazard perspective, none of the County’s municipalities exhibits
special features or unique characteristics that make them noticeably more or less
susceptible to the profiled hazards. As previously mentioned, natural hazards such as
hurricanes/tropical storms, severe storms, and tornadoes are not specific to certain
parts of the County but rather impact the entire County or any location in the County.
Conversely, natural hazards such as dam failures, flooding, and landslides are specific
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November 2004
to certain locations and jurisdictions within the County as shown on Figures 2.1 – 2.2
and Figures 2.5 – 2.7 respectively and as described in the preceding text.
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November 2004

2.0 hazard identification and risk assessment

Transcription

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