HomeMy WebLinkAboutX-A-02 - Spring Flood Preparation City Council Memorandum
To: Mayor Fasbender & City Councilmembers
From: Nick Egger – Public Works Director
Date: March 13, 2019
Item: Update on Flood Forecast & Response Planning Steps
Council Action Requested:
Council is requested to approve a similar flood fighting policy as adopted in 2011. City forces would
provide sand, sandbags, logistical support, and hauling of filled sandbags to curbside locations, but City
forces will not be used to fill sandbags or to build barriers on private property. After the flood, City
forces will haul away all sandbags that are brought back out to the curb.
Background Information:
Early National Weather Service forecasts are predicting that by early to mid-April there is up to a 75%-
90% chance of the Mississippi River reaching a flood stage of about 20 feet, and a 50%-75% chance of
reaching a stage of 21.5 feet. Right now, the prediction shows that there is a lesser chance of a stage
higher than this. Please see the chart below for the NWS projections as of March 4th. A more current
projection may be available by the time the Council meets on March 18th and I will present the latest
known information at the meeting.
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At 21.5 feet, the stage is about ½ ft. lower than the 2001 flood, which was the third highest flood on
record at 22 feet. This forecast needs to be qualified – many variables can significantly change the
forecast higher or lower, including how rapidly the snowmelt occurs, and additional snowfall or rainfall
events. Over the next few weeks, the forecast can and will change. It is also important to note that the
NWS’s forecasts do lean conservative, and our observations over the years are that actual flood stage
has ended up being slightly below the forecasted figure made closest to the crest.
Physical Impact
At flood stages such as those currently predicted, about 10 homes on the north side of 1st Street in East
Hastings can be directly impacted by flooding. In 2001, only three or four of these homes requested
sandbagging to protect against that year’s flooding. In 1997, with a flood stage of ¾ ft. lower than 2001,
about half a dozen homes sandbagged. In 2011 and under a similar forecast as this year, a handful of
homes sandbagged, but the projection was later downgraded and the crest ultimately came to just
below 18 feet, making little to no use of the barriers. In 2014, we reached a stage of just below 19 feet,
and none of the homes sandbagged despite this having about 1 foot of impact on the lowest of the
homes.
There are also a number of public infrastructure impacts that would occur based on the current
forecast, including closure of several segments of City roadways, closure of spaces within Jaycee, Lake
Rebecca, River Flats, and Levee Parks. I have attached a two-page summary covering notable City and
private property locations where impacts may be observed, and will provide a brief presentation that
features some photos taken during past flood events that give points of reference.
City Response
As flood levels rise, Public Works, Parks, Police and Fire will coordinate efforts and close roadways, trails
and parks as appropriate. We will monitor river levels and flood forecasts.
City staff has engaged in preliminary discussions with the Bless Hastings group which in 2011 played an
integral role in our response efforts by recruiting and coordinating volunteer efforts that were used to
sandbag homes where that was requested. As in the past, City staff proposes to support those efforts
by supplying sand, sandbags, and poly sheeting needed to sandbag homes, and to haul sandbags filled
by volunteers to curbside locations where they can be accessed by volunteers to construct barriers on
private property. In addition, flood update and planning meetings will be scheduled, with the frequency
of the meetings dictated by flood forecasts and planning flood fighting needs.
Financial Impact:
The financial impact of flood fighting activities is unknown; dependent on level of flooding experienced
and the demand for sandbags by the aforementioned property owners. A very rough guess would be
$20,000 to $30,000, which would include any overtime that may be needed to support volunteer
sandbagging activities. With spring flooding being on the State Legislature’s, Governor’s, and our
Congressional Representative’s radars, there is a good possibility that emergency declarations could be
made and that certain flood response efforts and public infrastructure damage would be eligible for
State and/or Federal reimbursement.
Attachments:
• General Flood Information Notes
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General Flood Information Notes
UPDATED March 2019
National Weather Service Flood Information Website:
http://water.weather.gov/ahps2/hydrograph.php?wfo=mpx&gage=hstm5
Important Elevations – City Infrastructure
Base Elevation of River is 670.65’
STAGE ELEVATION DESCRIPTION
15.00 685.65 Top of Steps & Veterans Memorial - Levee Park
15.35 686.00 Low Point - Mississippi River Trail by Levee Park steps
15.54 686.19 Low Point – Spiral View Loop Road (north side of river beneath Highway 61 Bridge)
15.80 686.45 Low Point – E 10th Street/County Road 54 (just east of 18th Street intersection)
15.95 686.60 Low Point - 1st St/RR Bridge Underpass – Water on Rd
16.90 687.55 Low Point E 4th St. – Water on Road
17.05 687.70 Low Point – E 10th Street – ½ way between Vermillion River bridge and E 18th Street
17.25 687.90 Low Point – E 10th Street just west of E 18th Street
17.35 688.00 Top of Riprap - Jaycee Park
18.43 689.08 Low Point - L/D Road
18.55 689.20 Bottom of Flood Columns – Levee Park
18.85 689.50 Low Beam – E 4th St. Bridge
19.35 690.00 Low Point – E 1st St & Franklin
19.35 690.00 Lake Isabel Boat Ramp Parking Lot (lowest areas)
19.85 690.50 Front Deck Hydropower Plant
20.95 691.60 Floor of Musical Playground
21.15 691.80 Floor of Rotary Pavilion
22.35 693.00 Top of Deck – E 4th St. Bridge, and HASTINGS Sign – Levee Park
22.45 693.10 Labyrinth slab – Levee Park
23.00 693.65 Patio/Fireplace – Levee Park
23.45 694.10 Top of Lock Wall – Hydro-electric Plant Access
Estimated Flood Impact on 1st St. Homes from GIS Contours:
Based on 2013 GIS Elevation Data and 6/23/2014 Field Surveys - * indicates approximate elevations
STAGE (FEET) ADDRESS/OWNER LAST NAME LOWEST STRUCTURE OPENING ELEVATION
17.70 623 1st Street East - Mollick 688.35 – Door on NE side of home
18.19 607 1st Street East - Latch 688.84 – Rear door
18.09 613 1st Street East – Whelan 688.74 – rear door
18.50 1115 1st Street East – Plan 689.15 – Cellar Door at rear of home
18.96 801 1st Street East – Biscoe/Wiegele 689.61
18.86/19.1 707 1st Street East - Heselton 689.51 – Garage/Outbuilding, 689.75 - House
20.07 1021 1st Street East – Leslie 690.72 – Chimney flue door
20.47 1015 1st Street East – Carl 691.12 – E side entry door
20.56/21.38 803 1st Street East - Wiegele 691.21 – Garage, 692.03 - House
21.35 817 1st Street East – Machinery Consultants 692*
22.35 1111 1st Street East – Plan 693*
23.35 1001 1st Street East – Reuter 694*
23.55 803 1st Street E – Flaten 694.2
24.35 901 1st Street East - Gear 695*
24.35+ Properties at E end of E 4th Street 695+
**There are also a couple of low areas in yard spaces on the south side of 1st Street E which can
become inundated by way of the City’s storm sewer connection. These are located at the properties
of 914 E 1st Street and 109 Washington Street.
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General Flood Information Notes
UPDATED March 2019
Recent Crests
(1) 16.60 ft on 07/01/2018 (P)
(2) 17.50 ft on 05/01/2018 (P)
(3) 15.19 ft on 10/13/2017
(4) 15.22 ft on 05/27/2017
(5) 15.85 ft on 07/18/2016
(6) 12.87 ft on 05/23/2015
(7) 18.95 ft on 06/27/2014
(8) 14.35 ft on 07/02/2013
(9) 15.07 ft on 06/02/2012
(10) 17.76 ft on 04/13/2011
(11) 17.42 ft on 03/30/2011
(12) 16.22 ft on 10/04/2010
(13) 17.22 ft on 03/25/2010 (P)
(14) 22.00 ft on 04/29/2001
(15) 21.60 ft on 04/17/2001
(16) 21.30 ft on 04/13/1997
(17) 18.90 ft on 06/28/1993
(18) 16.90 ft on 04/07/1986
(19) 17.10 ft on 05/04/1975
(20) 15.10 ft on 07/29/1972
(P): Preliminary values subject to further review.
Historic Crests
(1) 25.90 ft on 04/17/1965
(2) 24.30 ft on 04/16/1969
(3) 22.00 ft on 04/29/2001
(4) 21.60 ft on 04/17/2001
(5) 21.30 ft on 04/13/1997
(6) 20.90 ft on 04/16/1952
(7) 18.95 ft on 06/27/2014
(8) 18.90 ft on 06/28/1993
(9) 18.90 ft on 04/18/1951
(10) 17.76 ft on 04/13/2011
(11) 17.50 ft on 05/01/2018 (P)
(12) 17.42 ft on 03/30/2011
(13) 17.22 ft on 03/25/2010 (P)
(14) 17.10 ft on 05/04/1975
(15) 16.90 ft on 04/07/1986
(16) 16.60 ft on 07/01/2018 (P)
(17) 16.60 ft on 06/30/1957
(18) 16.22 ft on 10/04/2010
(19) 15.85 ft on 07/18/2016
(20) 15.50 ft on 05/11/1950
(26) 12.87 ft on 05/23/2015
(P): Preliminary values subject to further review.
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