Stormwater regulations and their relationship to tmd ls
Spring Green 2008 Flooding and Flood Control Options
1. Spring Green 2008 Flooding
and Flood Control Options
Jon Lefers, PE
Montgomery Associates: Resource Solutions, LLC
WAFSCM 2010 Conference
November 4, 2010
2. Introduction
• Why did the flood occur?
• What happened?
• Can something be done about future
damages from flooding?
4. Why did the flood occur?
• Wetter than normal late summer/fall in 2007
• Record winter snowfall
• June 7-8 and June 12 storms
• No outlet for flood waters
10. What happened?
• 4,400 acres flooded
• Crops destroyed • Sanitary sewer failures
• Homes and businesses • Culvert failures
damaged or destroyed • Roads flooded
• Families evacuated & • Health and safety
displaced from homes problems
15. Can something be done about
future damages from flooding?
FEMA Buyouts
• 28 substantially damaged homes were acquired
and demolished or removed from flood hazard
areas at a total cost of $5.4 million.
Flooding Reduction
• Developed a rainfall-runoff-routing model
• Evaluated several scenarios for performance
– Key factors: Depth, area, and duration of flooding
• Evaluated impacts and costs for various
solutions
16. Hydrologic Analysis
• Runoff Volumes
– SCS Curve
Number
Methodology
• Soils runoff
potential
• Land use runoff
potential
– Antecedent
moisture conditions
accounted for
17. Runoff Volumes (Acre-Feet)
100 year
June 7-8 June 12 Storm Current
Big Hollow 1,013 1,740 1,442
Runoff
Central Basin 560 546 725
Pattern
East Basin 360 350 479
West Basin 1,182 1,153 1,516
Total Volume 3,116 3,790 4,162
18. Model Water Table Map
Groundwater moves from high to low elevations
Wisconsin River
Source: WGNHS model
19. Modeled Increase in Water Table (ft) when
Recharge is Increased by 1 inch
1.5 ft
1.0 ft
26. Permits, Coordination, & Design
Standards
• DNR
• US Army Corps
• Lower Wisconsin State Riverway Board
• DOT (Highways and railroad)
• Wisconsin & Southern RR
• DATCP & NRCS
• Town of Spring Green
• Sauk County
• Above and below ground utilities
• Local landowners (irrigation and land impacts)
27. Conclusions
• Flooding in Spring Green was a combination of
flash flooding and groundwater-driven extended
flooding
• Allowing for flooding of agricultural fields lasting
a few days is critical to implementing a feasible
drainage system.
• Several drainage outlets would need to be
constructed.
• Multiple permitting and design challenges exist
for constructing drainage outlets to the
Wisconsin River