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Home My WebLink About13.C.2. Spring Flooding Mitigation EffortsTO: FROM: SUBJECT: DATE: INTRODUCTION: BACKGROUND: City of Shakopee Memorandum Honorable Mayor and City Council Mark McNeill, City Administrator Craig Robson, Captain 6 ■ ( ° Spring Flooding Mitigation Efforts March 1, 2011 The Police Department is requesting Council direction to determine what level of support the City should provide to public and private interests likely to be impacted by anticipated spring flooding. Recently the National Weather Service (NWS) released projections related to spring flooding in Shakopee. Despite the NWS projection of major flooding, a major impact on the City's population is not typical. Transportation issues are the most impactful and road closures are a certainty this spring. The typical impact of flooding in Shakopee is the closure of CR 101, the flooding of a local restaurant, and the encroachment of flood waters on a small portion of the housing at Valley Haven. To mitigate the effects of flooding some communities supply materials like sand and sandbags and individuals are responsible to protect their property. In larger flood fights the local jurisdiction coordinates volunteer efforts to construct dikes and flood walls. Although seemingly inexpensive, the costs and logistical concerns related to volunteer coordination cannot be overlooked. Some of these considerations are: under state law the City has the obligation to provide volunteers with liability and workers compensation coverage, volunteers must be supplied with personal protective equipment, consideration must be given to sustaining or feeding them, and volunteers must be supervised while working. During the 2010 spring flood City of Shakopee provided sand and sandbags and staff were involved in coordinating a sandbagging effort at Valley Haven. Approximately $3,221.28 was spent in this effort. These costs account for labor, material, supervision and miscellaneous expenses. Additional expenses were incurred for the removal and disposal of the sandbags. Also City owned equipment was supplied to one local business 13.c.2. to protect it from flooding. The City recovered a large portion of its expenses under a disaster declaration during the 2010 spring flood. It should be noted that a disaster declaration is not automatic with flooding and Scott County did not qualify for one during the fall flooding of 2010. Alternatives: 1. Provide direction to staff related to the level of City support to public and private interests likely to be impacted by projected flooding. 2. Table and provide staff with additional direction. RECOMMENDATION: Staff recommends Alternative #1. BUDGET IMPACT: There is no specific line item in the police department budget for flood mitigation efforts and City funds would have to be secured from the general fund. Staff is seeking direction related to the level of resources Council is willing to commit ACTION REQUESTED: If the Council concurs, they should, by motion, authorize appropriate city officials to purchase and use City materials, equipment and staff to conduct Spring flooding mitigation efforts in Shakopee. CITY OF SHAKOPEE Memorandum TO: Jeff Tate, Police Chief FROM: Bruce Loney, Public Works Director SUBJECT: 2011 Flood Preparations by Public Works DATE: February 24, 2011 INTRODUCTION: This memo is intended to address the 2011 flood preparation that has been done and to be done this year by the Public Works Department. BACKGROUND: The flood predictions for the Minnesota River indicated a high probability of a spring flood. Last year the City experienced two flood events during the spring and in the fall. From the floods of last year, the Public Works Department did repair two manholes at Levee Drive and Bluff Avenue, respectively, and one pipe failure east of L -16. These areas were fairly major Infiltration/Inflow (I/I) areas. Attached to this memo are the historical crests in the City of Shakopee from the National Weather Service. Last year's floods were both around the 716 elevation. In preparation for a flood, the Public Works Department does the following: 1. Monitor L -16 sewer flows and the dikes around L -16. The elevation of the dike is at 722. 2. Monitor I/I flow from Dangerfield's and the Valley Haven Trailer Park. These private service lines can be high infiltration lines when the river comes up. Inspection of these lines prior to a flood is necessary and possible temporary flow monitoring may be done to determine the amount of I/I during a flood event. 3. Huber Park flood proofing — The main items is to turn off the power to the amphitheater and to monitor the elevation to the playground. Depending on the flood levels, it may be necessary to construct a small sandbag wall to protect the playground rubber chips. (Attached is a map of Huber Park and flood elevations) 4. Canterbury RV Park — Close valves on their sewer system to City's sewer. 5. River District Line — Inspect the sealed manholes and inspect sewer services cleanouts prior to flood. Repair any items found to be defective. 6. Support any sandbag operations, as directed by Council and the Police Department. 7. Assist County and State in road closures, if necessary. 8. Monitor Holmes Street bridge which is currently under construction. The floods impacts in the City of Shakopee are usually the flooded highways over the Minnesota River and sanitary sewer I/I. The river crossings will probably close this spring when C.R. 101 starts flooding at elevation 710 and T.H. 41 starts flooding at 714. The sanitary sewer I/I is an extra cost to the sanitary sewer system and prior to the replacement of the River District line was significant. There still is some I/I in this area and staff has repaired two manholes and one pipe that were found to be major leaks. Attached are drawings showing the 720 contour line from 2003 aerials and the major area of concern during a flooding event of the Minnesota River. ACTION REQUESTED: Provide staff any direction or comments on spring flooding. ENGR/2011- PROJECTS /2011 - COUNCIL/FLOOD- PREPARATION Bruce Loney, P Public Works Director Historical Crests for Minnesota River at Shakopee Page 1 of 1 Historical Crests for Minnesota River at Shakopee (1) 721.80 ft on 04/15/1965 (2) 719.70 ft on 04/15/1969 (3) 719.29 ft on 06/25/1993 (4) 718.10 ft on 04/19/2001 (5) 717.86 ft on 04/13/1997 (6) 717.40 ft on 04/29/2001 (7) 716.20 ft on 04/16/1952 (8) 715.10 ft on 03/24/2010 (9) 714.38 ft on 04/14/1951 (10) 709.70 ft on 06/22/2001 (11) 708.40 ft on 04/07/1998 (12) 708.00 ft on 04/28/1995 (13) 707.92 ft on 03/27/1936 (14) 707.40 ft on 06/25/1996 (15) 706.80 ft on 04/18/1999 (16) 706.20 ft on 05/25/1999 (17) 705.60 ft on 06/09/1995 (18) 705.50 ft on 07/30/1997 (19) 704.92 ft on 05/22/2005 (20) 704.80 ft on 04/07/1996 (21) 704.00 ft on 06/18/1999 (22) 703.81 ft on 04/10/1941 http: // water. weather .gov /ahps2 /crests.php ?wfo =mpx &gage =skpm5 2/23/2011 735 ENTRY PLAZA 732 ENTRY SIDE PLAZAS 730 ENTRY WALK 728.5 500 YEAR 723 RESTROOMS 722.2 100 YEAR 720.4 MID - AMPHITHEATER PLATFORM 719.5 PLAYGROUND 719 50 YEAR 716 -719 PARKING 714.3 PERFORMANCE AREA STAGE 712 10 YEAR 712 PERFORMANCE AREA PLAZA 710 5 YEAR 708 WOOD STRUCTURE OVERLOOK 707 OVERLOOK TERRACE 705.4 2 YEAR 695 RIVER TERRACE 693 FISHING PLATFORM 692 1 YEAR MAY -SEPT MEDIAN 689.3 ANNUAL MEDIAN HUBER PARK FLOOD ELEVATIONS /40 735 730 /25 • 4241 - i /15 710 /05 /00 09. 090 585 D80 735 ENTRY PLAZA 732 ENTRY SIDE PLAZAS 730 ENTRY WALK 728.5 500 YEAR 723 RESTROOMS 722.2 100 YEAR 720.4 MID - AMPHITHEATER PLATFORM 719.5 PLAYGROUND 719 50 YEAR 716 -719 PARKING 714.3 PERFORMANCE AREA STAGE 712 10 YEAR 712 PERFORMANCE AREA PLAZA 710 5 YEAR 708 WOOD STRUCTURE OVERLOOK 707 OVERLOOK TERRACE 705.4 2 YEAR 695 RIVER TERRACE 693 FISHING PLATFORM 692 1 YEAR MAY -SEPT MEDIAN 689.3 ANNUAL MEDIAN HUBER PARK FLOOD ELEVATIONS KEY 500 YEAR FLOOD ELEVATION 728.5 (0.2 % CHANCE) 100 YEAR FLOOD ELEVATION 722.2 (1% CHANCE) 50 YEAR FLOOD ELEVATION 719.0 (2% CHANCE) 10 YEAR FLOOD ELEVATION 712.0 (10% CHANCE) 5 YEAR FLOOD ELEVATION 710.0 (20% CHANCE) 2 YEAR FLOOD ELEVATION 705.4 (50% CHANCE) 1 YEAR MAY -SEPT MEDIAN 692.0 (100% CHANCE) CHECK RIVER 'DISTRICT MANHOLES & SERVICE CLEANOUTS ECK RIVER: TRICT MANHOL & SERVICE EANOUTS .; LMES S DGE UN NSTRUC USER PAM( ,GROUND A VATION = 71 --CHECK RIVER`S TRICT MANHO1 & SERVICE CLEANOUTS OR K WITH :SCO I UNTY ON WY- FLOODING