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HomeMy WebLinkAbout20110307 - VIII-A-1To: Mayor Hicks and City Councilmembers From: Tom Montgomery Date: March 2, 2011 Re: Preliminary Flood Forecast and Recommended City Response Council Action Requested: Council is requested to approve a similar flood fighting policy as adopted in 2010; City forces will provide sand, sandbags, logistical support, and hauling of filled sandbags to curbside locations, but City forces will not be used to fill sandbags or place sandbags to protect private property. After the flood, City forces will haul away all sandbags that are brought out to the curb. Background Information: Early National Weather Service forecasts are predicting a 50% chance of the Mississippi River reaching a flood stage of 22.5 ft. by the first week in April. This flood stage is about 1 /2 ft. higher than the 2001 flood, which would be the 3rd highest flood on record. 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. Based on our 2001 flood experience, about 10 homes on the north side of 1 St Street in East Hastings will be directly impacted by flooding. In 2001, only three or four of these homes sandbagged to protect against flooding. In 1997, with a flood stage of 3 /4 ft. lower than 2oo1, about half a dozen homes sandbagged. There are two to three other homes that may be impacted by flooding — along Lake Isabel or East loth St. /CSAH #54; as well as the City's park property — Levee Park, Jaycee Park, Lake Rebecca, and the Mississippi River Flats. The 1St St. underpass will flood, East 4th Street through the DNR property will flood, and when the river reaches a stage of 19 ft., the Lock and Dam Road will flood and need to be closed. At 19 ft., the support beams for the East 4th St. bridge will start to go underwater and the bridge will need to be closed. 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. Aside from some park structures in Lake Rebecca Park, no City structures are expected to be impacted by flooding. Cft� df Hastkts + 101 FdwM Street East + Har ngs, MN 45033 -1965 * P:6614B#23 + f-651d437-443 + 41ww uhasUngs mus City staff has begun preliminary discussions with the Bless Hastings group which has volunteered to recruit and coordinate volunteer efforts that may be needed to sandbag homes. 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 sandbag dikes. In addition, flood update and planning meetings will be scheduled, with the frequency of the meetings dictated by flood forecasts and planning and flood fighting needs. Financial Impact: The financial impact of flood fighting activities is unknown; dependant on level of flooding experienced and demand for sandbags. 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. Attachments: • General Flood Information Notes • NWS Flood Forecast Graphs • 2ooi and 1997 flood pictures at crest elevations General Flood Information Notes: National Weather Service Flood Information Website: htlp:H water. weather. gov / /ahps2 /weekly.php ?wfo =mpx &gage =hstm5 &view =1,1,1 1 1,1,1,1,1 &toggles= 10,7,8,2,9,15,6 USACE Lock & Dam 2 Web Page for Pool, TW & Flow Information: htlp://www.mvp-wc.usace.army.mil/projects/Lock2.shtml Important Elevations: STAGE ELEVATION 15.00 685.65 15.35 686 15.95 686.6 16.90 687.55 17.35 688 18.43 689.08 18.85 689.5 19.35 690 19.35 690 19.85 690.5 22.35 693 23.45 694.1 DESCRIPTION Top of Steps - Levee Pk Low Point - Missippi River Trail by Levee Pk steps Low Point - 1 st St/RR Bridge Underpass — Water on Rd Low Point E 4 th St. — Water on Road Top of Riprap - Jaycee Pk Low Point - L/D Road Low Beam — E 4" St. Bridge Low Point - 1st St & Franklin Boat Ramp Parking Lot Front Deck Hydropower Plant Top of Deck — E 4" St. Bridge Top of Lock Wall - Hydro Access Estimated Flood Impact on 1 St St. Homes from GIS Contours: Needs Field Verification! STAGE ELEVATION 18.35 689 607 1 st St. E 19.35 690 613 1 st St. E 16.35 687 623 1 st St. E 18.35 689 707 1 st St. E 18.35 689 801 1 st St. E 18.35 689 803 1 st St. E 18.35 689 817 1 st St. E 22.35 693 901 1 st St. E 23.35 694 1001 1 st St. E 18.35 689 1015 1 st St. E 18.35 689 1021 1 st St. E DESCRIPTION 17.35 688 1111 1st St. E - newer home 1st floor above 693 16.35 687 1115 1 st St. E Historical 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) 18.90 ft on 06/28/1993 (8) 18.90 ft on 04/18/1951 (9) 17.22 ft on 03/25/2010 (10) 17.10 ft on 05/04/1975 (11) 16.90 ft on 04/07/1986 (12) 16.60 ft on 06/30/1957 (13) 15.50 ft on 05/11/1950 (14) 15.10 ft on 07/29/1972 2 � � c � & 2 4 � & U 2 O LL @ U c & � @ U x W @ � & � $ F / \ & / t ± q \ §} xa Q =0 (� §\ %_{ § C \ -j00 \ 2r \ -0 �\ \��� & # \} e�qa \ �\ j % \ Q ) , 5 , ( S ± 4 4 * l oom . . . . 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