HomeMy WebLinkAbout03222022 Planning & Zoning Flood Board Joint Work Session PacketJoint Work Session
March 22, 2022
Seward Area Hazards
Planning & Zoning Commission
Seward -Bear Creek Flood Service Area Board
Hazard Type
Earthquake (EQ)
destroyed from the earthquake (EQ) and its aftershocks. The EQ propagated a devastating tsunami from the Pacific Ocean EQ
epicenter. Subsequent seiche waves continued to oscillate from each side of Resurrection Bay that continued to threaten the
population and delay disaster response activities.
Flood (FL)
Snowmelt run-off and rainfall flooding occur during spring thaw and the fall rainy season. Events occur from soil saturation, coastal
(Riverine and/or coastal related floods storm surge and wind scour, and riverine high water flow scour along the area's rivers, streams, and creek embankments.
and resultant erosive scour damages)
Ground Failure (GF) Ground Failure occurs throughout Alaska from avalanches, landslides, melting permafrost, and ground subsidence. Landslides off
(Avalanche, Landslide/ Debris Flow) mountainsides and subsequent debris flow have occurred on numerous occasions in the Seward area.
Tsunami (TS) The 1964 9.2M Earthquake generated a tsunami in the Pacific Ocean impacting many coastal Communities along with the City of
Seward. The same event caused a Resurrection Bay seiche that devastated Seward's waterfront with recurring waves, infrastructure
(Seiche) destruction with fires burning out of control.
Volcano generated ash periodically impacts the community from volcanos located along the Aleutian Chain. The closest of five
Volcanic Ash (VA) volcanoes is Mt. Redoubt located approximately 116 miles, and the furthest is Mt. Novarupta, approximately 239 miles, from the
Seward area.
Severe Weather (WX) Severe weather impacts the community with climate change influences such as changing El Nino/La Nina Southern Oscillation
(ENSO) patterns generating increasingly severe weather events such as winter storms, heavy or freezing rain, thunderstorms and
(Cold, Drought, Rain, Snow,Wind, with subsequent secondary hazards such as riverine or coastal storm surge floods, landslides and avalanches, heavy snow, and high
etc.) wind, and extreme cold temperatures.
The community and the surrounding forest area become dry in summer months with weather (such as drought and lightening),
Wildland Fire (WF) human caused incidents igniting dry vegetation in the adjacent area (burning trash outside their landfill's burn box, camp fires, etc.),
and increasing pine bark beetle infestations killing black spruce exacerbating the area's fire fuels threat.
Hazardous Materials (HM) The Seward area has diesel fuels and fish processing plants that handle hazardous materials that is tracked through by the Alaska
Department of Environmental Conservation and the EPA.
Active & potentially active faults In Alaska
Age of most recent displaceme ii
Historic time
Past 10,000 years
Past 2 million years
Possibly past 2 million years
Bering
3X r,..
Earthquake
Seward has experienced 993
earthquakes since 2010 with
an average M2.9 seismicity
(2018).
Recurrence is "Highly
Likely" and the severity of
earthquake impacts are
considered "Critical" with
possible injuries and
complete shutdown of
facilities.
34, r�. :. „«
One year of earthquake activity in Alaska (DGGS 2018). O
Flood / Erosion
• Rainfall Runoff
• Snowmelt
• Coastal Storm Surge
• Riverine Scour
• Coastal Scour
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Seward Flood Eve n t" -'2 018.
https:Z/www.youtu be.com/watch?v=hsNCOjTUwSA
Flood
Erosion
The extent of flooding and
resulting damages are
considered "Critical" with
possible injuries and
complete shutdown of
facilities.
Nationwide, floods result in
more deaths than any other
natural hazard.
FEMA Flood Insurance & Coastal Studies O USACE Lowell Water Diversion System Inundation Study
Ground Failure
Avalanche
,.m Landslide
e
e
Debris Flows
Subsidence
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r.
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-
Ground Failure
Recurrence is considered
"Highly Likely" and though
impact threats are considered
"Limited", the extent of
damages could range from
minor to catastrophic.
Climate change scenarios
project increased average
temperatures and
precipitation and could
increase the occurrence of
landslide -type events.
Recent landslides on Mt. Alice & Lowell Point Road (i)
Sunami
Seiche,
Potential Tsunami Inundation Dar,
m`ages ,
p
Tsunami & Seiche
The catastrophic 1964 Good Friday
Earthquake induced distant and locally
generated tsunamis.
Though it is not possible to predict,
future distant tsunami events are
"Highly Likely" and the extent of
damages considered "Catastrophic"
with the potential for multiple deaths,
complete shutdown, and severely
damaged property and infrastructure.
COMMUNITY NAME W TOTAL ESTIMATE�F IMPROVED PARCELW TOTAL NUMBER OF TOTALNUMBEROF PERCENTAGE OF IMPROVED
VALUE OF IMPROVED VALUE IN TSUNAMI IMPROVED PARCELS IMPROVED PARCELS PARCELS IN TSUNAMI ZONE
PARCE' ZONE 016 IN TSUNAMI ZONE
.- '=_�4 Good Friday Tsunami amages (upper)
10 <.
Overlay on 2012 Imagery (lower)
Average Monthly Precipitation for Seward. Alaska
l ." .. 1-1 PRISM .-0 5-Moclrl Aver..U,.rt 2krn trnnErma..... - ff<CP a,5)
1961-1990 2010-2019 .-$��"- 2040-2049 = 2060-2069 = 2090-2099
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Average Monthly Temperature for Seward, Alaska
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1961.1990 2010-2019 W 2040-2049 = 2060-2069 2090-2099
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Severe Weather
1
Seward small boat harbor - emergency declaration 2017 12
Seward has experienced a
severe weather event (coastal
storm surge, ice storm, heavy
snow, high winds, etc.) most
years in the last three
decades.
Recurrence is "Highly
Likely" and "Limited"
impacts are possible
across the entire
community.
Hazardous Materials
Hazardous substances can be
found nearly everywhere in our
society.
There are various potentially hazardous materials within the Seward area. They include fuel storage
facilities, explosives storage, and hazardous materials shipped into the city by marine vessel, truck,
or train cargo. One of the most prevalent is anhydrous ammonia that is used in local fish
processing plant chilling facilities.
EPA Regulated Facilities within the Seward Area (2017). 15
Hazard Type
Earthquake3
Riverine Flood4
Flood
Coastal Flood
Ground Failure
Tsunami Seiche
Volcanic Ash
Weather
Wildland Fire
Potential Hazard Exposure Analysis Overview - Residential
Buildings
Hazard Area
Methodology
Residential Non
-Residential
Number
Value ($)2 Number
Value ($)2
Strong
9-20% (g)
0
0
Very strong
20-40% (g)
0
-- 0
--
Severe
>40-60% (g)
783
222,174,087 269
302,085,377
Moderate
500-year floodplain
0
-- 1
219,2190
High
100-year floodplain
2
601,221 2
2,487,872
Coastal VE Flood
High
0
-- 1
220,508
High
Within Max inundation Area
Low to Moderate Ash
Severe
Low
Moderate
High
Zone
Within 100 ft of
slopes >20
degrees
descriptive
descriptive
descriptive
Low fuel rank
Moderate fuel rank
High fuel rank
47 14,873,719 3
71 33,826,700 117
783
222,174,087
269
783
222,174,087
269
603
167,946,749
223
179
53,983,582
36
1
243,754
0
10,061,513
105,605,512
302,085,377
302,085,377
251,935,410
50,149,966
Goal/
Action ID Description
From: 2013 SBCFSA:
The City of Seward should continue improving its
NAP Community Rating System, under the
Federal Insurance Administration's Community
MH 2.5 Rating System (CRS) by exceeding the required
standards to obtain further flood insurance
premium reductions for policyholders within
communities while simultaneously reducing
flood losses.
Priority Responsible Potential
(High,
,
Office or Funding
Medium
Low) Agency Source(s)
City Office,
High Tribal Council City, Tribe
Office, or KPB
2010 HMP Brought Forward:
City, Tribe, HMA,
Identify avalanche areas within the city and
City Office, NOAA, AFG,
MH 2.6 generate GIS Hazard Maps. Coordinate with
Low Tribal Council FP&S, SAFER,
Community Development Office on locations of
Office, or KPB ANA, EFSP,
areas for any zoning issues.
NRCS
Timeframe
(1-3 Years Benefit -Costs (BC) /
2-4 Years Technical Feasibility (T/F)
3-5 Years)
B/C: NFIP participation while one of FEMA's highest priorities
also enables communities with an effective program focus on
repetitive flood loss properties and other priority flood
1-3 years locations and projects.
TF: City is currently a member and residents enjoy lower cost
insurance. Continuation is relatively simple.
B/C: Identifying threatened infrastructure proximity to natural
hazards is vital to their sustainability. Providing advanced
warning of pending disasters further reduces life loss and
potentially can reduce damage if quick action is possible to
Ongoing mitigate the impact.
2010 HMP Brought Forward:
Develop and implement programs to coordinate City Office,
CityTribe, NOAA,
MH 2.7 maintenance, mitigation and response activities Medium Tribal Council NWS, Ongoing
as indicated in the City's Emergency Operations Office, or KPB
Plan.
TF: The project is technically feasible as the community has
staff and resources they have used to relocate and elevate
buildings.
B/C: Sustained emergency warning, communication, and
response activity capabilities enable communities to warn and
protect their hazard threatened populations. This project will
help build and support community capacity enabling the
public to prepare for, respond to, and recover from disasters.
TF: This project is technically feasible using existing City staff
For More Information
Local Hazard Mitigation Plans
l
City of Seward
www.cityofseward.us/home/showpubiisheddocument?id=2148
f Seward -Bear Creek Flood Service Area
www.kpb.us/images/KPB/Service Areas/sbcfsa/documents/SBCFSA LHMP2013.pdf
www.kpb.us/images/KPB/Service Areas/sbcfsa/documents/Appendix K Maps.pdf