HomeMy WebLinkAbout12072020 City Council Work Session Packet - Lowell Creek Feasibility Study Seward City Council
Work Session Packet
Topic: Lowell Canyon Feasibility Study with the
US Army Corps of Engineers
December 7, 2020
City Council Chambers Beginning at 6:00 p.m.
Instructions For
CITIZEN INVOLVEMENT
DURING CITY COUNCIL Virtual WORK SESSIONS
Due to COVID-19, alternate methods for citizen involvement during City Council work sessions
have been created to allow public interaction while keeping everyone safe and healthy. Although
there is no in person public attendance allowed, council wants to encourage citizen participation.
If you wish to participate in a work session, please follow these simple steps:
STEP 1: Sign up on the city clerk's contact list. Send an email to clerk2cityofseward.net
and request to be included on the contact list AND provide your phone number.
Sign up by 5:00 p.m. on the day of the work session. You'll receive a
confirmation email from the city clerk that you're on the list; if you don't receive
the confirmation,please call 224-4045 to confirm.
STEP 2: Keep your phone handy throughout the work session. When answering your
phone, please mute any background noise so you can be heard by council clearly.
How it will work:
During regular intervals throughout the work session, the proceedings will be halted and the city
clerk will call citizens who have signed up. After all citizens have been contacted, council will
continue the work session.
Citizens sign up one time per work session, and will be contacted at every interval during the
work session. Each time you are called, the city clerk will ask if you wish to be contacted at the
next interval during that work session.
How to watch or listen to a work session:
1. Watch Live Streaming on the city's YouTube page. Log onto YouTube and type "City of
Seward Alaska" into the search bar or go to:
2. htlps://www.youtube.com/channel/IJCWzsXcDwdyklHKGgvYS_UNQ
3. Listen on the radio. Tune to KIBH-FM 91.7
4. Watch on television. Tune into GCI Cable Channel 9. Note: GCI has recently been
experiencing technical difficulties with the sound; they are working diligently to fix the
problem.
LOWELL CREEK FLOOD
DIVERSION .
FEASIBILITY STUDY '
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SEWARD CITY COUNCIL
MEETING
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B. Steven Howard, '
Chief of Project Management
Alaska District_
U.S. Army Corps of Engineers
07 December 2020
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US Army Corps
of Engineers u
AGENDA
Anchorage
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• Overview of the Tentatively Selected Plan (TSP) .
• Location of tunnel/outfall Seward .
• How the length of the Outfall was determined
• Water intakes (fresh and sea water) in the vicinity of ,.
the project
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® TENTATIVELY SELECTED PLAN
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Alternative 4A selected as the Tentatively
Selected Plan (TSP)
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• Significantly reduces risk to life safety ." MewMver5ionDam
• $124.6m implementation cost Existing Diversion Dam
Alternative 4A. =r
• New 18 ft Diameter Tunnel and Diversion Dam
w. Raturbish Existing 7Wnnal
• 150 ft outfall extension ..-- � l ,o'oiar
• Refurbish existing tunnel
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• Canopy to protect tunnel inlet from landslide
• Select tree removal -=-�
• Earl warningsystem Cnnstrer M :` '
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Extend Uvtfall
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® 150-FT OUTFALL PRELIMINARY DESIGN
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Existing Tunnel
t.EXISTING LOWE L L POINT ROAD
TPUCK SHOWN IS 16'TALL
ROAD ALIGNMENT RUNS
EL-yl SY I BETWEEN PILES PN AND P05
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Ai_ EL 57AV
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;A7 1� IIII III.,. C r
tunnel "
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Proposed a
Extended Outfall >e
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Locations are approximate and H �
for graphical purposes only "
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® TUNNEL ALIGNMENT
' South Tunnel Alignment considered, but not carried
Proposed Tunnel ' a forward
Maintaining an adequate grade for the length of the
} tunnel places outfall elevation at sea level.
Existing Tunnel
South Alignment&
Proposed Tunnel
Not carried forward primarily due to.
• ; `+ " Outfall elevation causes tunnel to be susceptible to
blockages, causing the tunnel be inoperable or
reduced capacity/efficiency
- 444 ziiiihr� ' Additional concern of how a blockage would be cleared
• during an event
ON
South Alignment(Not Proposed)
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® OUTFALL MEASURE
• 150 ft outfall
o Except for no extension, least cost to construct and maintain
o Benefits of potentially keeping Lowell Point Rd. open and differing removal of debris to after
flood events
• <150ft outfall would be cost more to construct due to road realignment
• >150ft outfall:
o Cost more to construct and maintain(500 ft outfall)
• Requires dredging of debris, would be more costly than current debris removal methods
o Cost more to construct to achieve no debris removal(750 ft outfall)
Outfall Discharge Point Estimated Maintenance Benefit Comments
Length Construction Costs
Cost
Limited Base of mountain Sediment would continue to be deposited in the current location damaging or
No Extension west of road $4,000,000 $556,000/year destroying the bridge during events and threatening community infrastructure
100-ft West of road $14,200,000 $556,000/year Would require realignment of the road to prevent damage to the bridge
Would eliminate flood-fighting during events and damage to the bridge.More
Fluvial fan west frequent dredging than longer options,but similar effort compared to the shorter
150-ft of road $13,900,000 $556,000/ ear outfall.
Deep water west Sediment would be deposited into the Bay,but periodic dredging would be
500-ft of road $36,900,000 $754,000/ ear I required approximately every 5 years
Deep Water in
750-ft Resurrection Bay -$56,000,000 No dredging Sediment deposited directly into deep water.No dredging would be required.
U.S.RRMY
WATER INTAKES
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Coordinates •
asmlmg provided by
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Cla 2 -
15'East of Terminus �-.,,,
?� Line B f lamp 1 �'
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-.c '7 SeaLife Center
Freshwater intake P
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QUESTIONS?
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B.Steven Howard, Chief Project Management
Alaska District
U.S.Army Corps of Engineers
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