1 FEMA Flood Insurance Rate Map Update FEMA Public Meeting
October 22, 2009
Slide 2
FEMA Initiates Levee Reaccreditation Every 5 Years Heritage
Levee (City) Pole Crk Debris Basin (WPD) Pole Crk Channel
(WPD)
Slide 3
Accredited: Non Accredited: Heritage Levee (City) Pole Crk
Debris Basin (WPD) Non accredited levees cause Flood Zone A Levees
Expected to be Accredited by November 2009 Pole Crk Channel
(wpd)
Slide 4
Slide 5
Accredited: Non Accredited: Years to Accreditation Future
Heritage Levee (City) 3 to 10 1 to 6 Pole Crk Debris Basin (WPD)
Pole Crk Channel (WPD) 4 to10 6 to 12
Slide 6
HISTORY OF SESPE CREEK LEVEE 1978: Los Serenos Flood 1979:
Q-100 = 98,000 CFS 1983: COE Sespe Levee - 121,000 CFS 1979 to
2009: 6 Large Flood Flows 2006: Q-100 = 135,000 CFS
Slide 7
T E C H N I C A L S T U D I E S Los Serenos 1978 Flood
(pre-levee) 7
Slide 8
Improved Hydraulic Analysis Since 1979 1979: HEC 2 One
Dimensional Flow Analysis 2009: HEC RAS + Flow 2 D Two Dimensional
Flow Analysis Better projection of flow from island crossover
Slide 9
Main Channel Shifts from West to East (1938 2008) 193819752005
9 T E C H N I C A L S T U D I E S
Slide 10
Scour and Aggradation T E C H N I C A L S T U D I E S 10
(1970s, 2004, & 2005 topography)
Raise levee 1 to 6 feet Preliminary initial cost $6,500,000
Deepen Foundation?+3X$ A L T E R N A T I V E S A N A L Y S I S 12
Preliminary Plan Retrofit the USACE Levee 6 1
Slide 13
A L T E R N A T I V E S A N A L Y S I S Possible
Modification/Replacement of Hwy 126 Bridge Extension/replacement of
exist. structure Options: 90 extension; Raise existing structure
Cost: $13,000,000 or or$44,000,000 Possibly Non effective
Slide 14
T E C H N I C A L S T U D I E S Summary of Key Sespe Issues
Increase in estimated peak flow rates based on additional stream
gage data (+35% compared to 1979 analysis) Shift of dominant
channel from west to east fork Active channel changes with major
storm events Lower reach of USACE levee does not meet Federal
requirements Long-term sediment deposition and local erosion Levee
foundation must be checked for adequacy for the new 100 year flow
14
Slide 15
T E C H N I C A L S T U D I E S Next Steps on Sespe Creek Levee
Ventura County Watershed Protection District reaches consensus with
FEMA and Army Corps of Engineers on the retrofit work necessary to
restore Q-100 capacity. Prepare Environmental Impact Report, Plans
and Specifications. Locate funds and construct improvements. Obtain
Letter of Map Revision from FEMA which removes Flood Zone A and
requirements for flood insurance. Accreditation: 3 to 10 years ALL
CONCEPTS AND COSTS PRESENTED TONIGHT ARE PRELIMINARY AND SUBJECT TO
SIGNIFICANT CHANGE 15
Slide 16
Heritage Levee (City) Heritage Levee Issues LOMR going to FEMA
this month: October 2009. If approved by FEMA, Heritage area could
be removed from Flood Zone A as early as Spring 2010.
Accreditation: 6 months to 6 years
Slide 17
Pole Crk Debris Basin (WPD) Pole Creek Debris Basin Issues
Construction of permanent basin on hold until Heritage Bridges
project moves forward. Once approved by FEMA El Dorado should be
removed from Flood Zone A Accreditation: 4 to 10 years
Slide 18
Pole Creek Channel Issues Pole Crk Channel (wpd) VCWPD is
planning to increase capacity from Q-50 to Q-100. Schedule and
funding for this work is uncertain due to issues over Steelhead
Trout passage. Accreditation: 5 to 15 years Next FEMA map update
(2012) may put some homes in east Fillmore into Flood Zone A until
channel improvements are complete.
Slide 19
Accredited: Non Accredited: Heritage Levee (City) Pole Crk
Debris Basin (WPD) QUESTIONS ? Pole Crk Channel (wpd)