Problem Identification Meeting (50% Deliverable)

1. Problem Identification Meeting (50% Deliverable) February 10, 2009 AECOM, Inc. and A.D.A. Engineering, Inc.

2. Agenda • Review flood profiles • Review flows in the Brooks area • Summarize bridge overtopping and flooding • Peak stage and flow results • Flooding maps • What if we had 1995 rainfall today • Compare the SLCWP flows to 100-year simulation results • Summarize problems and challenges

3. I-75 Sanctuary Rd Corkscrew Rd Three Oaks Estero River South 25yr DS Water Surface Profile Confluence w/ North Branch

4. Three Oaks I-75 Rivers Ford Bridge Estero River 25yr DS Water Surface Profile Sandy Lane Rookery Bridge

5. Halfway Creek 25yr DS Water Surface Profile Three Oaks RR Crossing US 41 FPL Crossing Via Villagio

6. Fairway Estates Weir Spring Creek 25yr DS Water Surface Profile Old US 41 FPL Crossing US 41 Railroad

7. Halfway Creek 10-Year Design Storm Flows Into the Brooks and Diversion Flows to the Estero River

8. Halfway Creek 10-year Design Storm Flows West of the Brooks

9. Bridge Over-topping Potential Flooding in the Brooks

10. Comparison of Stages from the 1999 Study to this Study • The table below compares stages for 5-, 10-, 25-, and 100-year design storms for the 1999 and the 2009 South Lee County studies • Differences are large for Halfway Creek at US 41, Spring Creek at Strike Lane, Srping Creek South at Old U.S. 41 (USGS gage), and the Imperial River at Matheson Street

11. Comparison of Flows from the 1999 Study to this Study • The table below compares flows for 5-, 10-, 25-, and 100-year design storms for the 1999 and the 2009 South Lee County studies • Differences are large for Halfway Creek at US 41, Spring Creek at Strike Lane, Spring Creek South at Old U.S. 41 (USGS gage), and the Imperial River at Matheson Street

12. Inundation Maps • Switch to ArcGIS

13. Comparison of actual 1995 vs what would happen if we had 1995 rainfall today

14. Brooks Agreement from 1999 SLCWP • 2009 simulated 100-year peak flow for Halfway Creek at U.S. 41 is 340 cfs • Brooks diversion simulated 100-year flow to the Estero River is 14 cfs, less than 10% of the planned diversion • Peak stages in the Brooks will result in flooding of some buildings during the 100-year event, while peak flows into the Brooks under I-75 are 400 cfs, less than half of planned flows • Flows to the South Branch of the Estero River are less than half of planned flows p. 6 of Amendment 1

15. Definition of Existing Problems • Water levels appear to be higher than desired in the Brooks while predicted peak flows through the Brooks are less than one half of design levels • Water levels appear to be very high in San Carlos Estates (see Spring Creek at Strike Lane), however modifications to the model files are being made to adjust this. Flooding of San Carlos Estates is expected to persist in spite of the model changes. This condition will have to be considered before any proposal to divert Halfway Creek flows through Spring Creek. • Flows in the South Branch of the Estero River do not cause flooding problems • Flows in the North Branch of the Estero River appear to result in road flooding in Country Creek Estates, however model instabilities may be the problem • If rainfall conditions observed in 1995 occurred today, flows might be less than before, however model results files are still under review