Kansas Levee Certifications Assessments, Findings and ...Introductions Presenters Doug Danaher, PE,...
Transcript of Kansas Levee Certifications Assessments, Findings and ...Introductions Presenters Doug Danaher, PE,...
Kansas Levee Certifications –
Assessments, Findings and Challenges
APWA Congress – Denver, Co - Sept 18, 2011
Introductions
Presenters
Doug Danaher, PE, CFM – Wilson and Company
Joe File, PE, CFM – AMEC
Brian Clennan, PE – City of Hutchinson
Kansas Municipal Levee Owners Consortium
Augusta, Dodge City, El Dorado, Florence, Gypsum,
Hutchinson, Manhattan, Marion, Osawatomie, Ottawa,
Salina, Topeka, Wichita
Presentation Outline
Background & Importance of Certification
Assessment Process
Findings
Challenges of Certification (Time and Funding)
History
NFIP Program – 1974
44 CFR 65.10 – 1986
Map Modernization – 2003
Provisionally Accredited Levee Agreements
– 2007
Risk Map – 2010
Background
Background
If the levee is certified by a professional engineer as meeting the criteria in 44 CFR 65.10:
The levee is accredited and mapped.
Area behind the levee is mapped as moderate risk (zone X).
If the levee does not meet 65.10 criteria:
Levee shown on effective maps is de-accredited.
Area behind the levee is mapped as high risk (zone AE or A).
Flood Insurance policies will be required for properties with federally backed or insured mortgages.
5
Background – Certification Impacts
FEMA Levee Certification Program
Consultant Certifies
FEMA Accredits
Process is for Flood Insurance Purposes
COE Programs (Other Purposes)
Background
Those Impacted by
Certification:
•Mayor Jones
•Mr. Jones
•Councilman’s Brother
•Senators Mom
•Floodplain Manager
•FEMA Employee
•Retired General
•Your Son’s Kindergarten
Teacher
•Public Works Director
•Your Wife’s Best Friend
•Your Mother-in-Law
Background
Assessment Process
Freeboard
Closures
Seepage and Stability
Settlement
Embankment Protection
Interior Drainage Analysis
Operation & Maintenance Manual
As Built – As Is
Assessment Process
Phase I – Discovery Phase
Phase II – Analysis Phase
Phase III – Construction & Certification
Assessment Process
Freeboard– Requires 3’ throughout; 3.5’ at upstream end; 4’ at constrictions (bridges)
– Updated river hydrology; river hydraulic model / water surface profiles
– Survey current top of levee profiles
– Compare profiles & identify deficiencies
Assessment Process
Closures– Requires closures for all openings that are structural
parts of the system, designed according to sound
engineering practices.
– Road / rail closures (sandbag, stop log, gates, etc.)
– Conduits (gated and un-gated)
– Considers river timing
Assessment Process
Seepage, Stability and Settlement– Requires Engineering analysis to evaluate seepage during loading
conditions and demonstrate that seepage into or through the foundation
and embankment will not jeopardize stability. Engineering analysis to
assess future settlement and demonstrate freeboard will be maintained.
– Geotechnical science evolved in 1970’s
– Borings to characterize soils
– Analyze for seepage, stability and settlement
– Validate with historical performance and top of levee profile
– Considers river timing
Assessment Process
Embankment Protection– Requires Engineering analysis that demonstrates no appreciable erosion
can be expected, and that expected erosion will not result in failure of levee.
– Considers flow depths and velocities from updated river modeling
– Validated with historical performance (review historical photos)
Assessment Process
Interior Drainage Analysis– Requires analysis to identify flooding sources and the extent of the area
flooded and if the avg depth > 1’, determine water surface elevations.
Based on joint probability and capacity of interior drainage facilities.
– Updated hydrology
– Utilize USACE coincidental peak analysis method
– Utilize updated ground surface elevation data (2-ft contours)
– Complete reservoir routing to minimize ponding surface areas
– Likely to be Zone A on updated FEMA maps
Assessment Process
Operation & Maintenance Manual– Requires Operation & maintenance per current manual, under
jurisdiction of federal, state or community in NFIP. Requires
flood warning system; plan of operation; periodic operation
of closures; backup provisions.
– Update USACE O & M manual; develop detailed operation plan
Assessment Process
As-Built (As-Is) Drawings– Requires certified as-built plans of the levee system.
– Update As-Builts to Reflect Current Conditions
– Can Use Current Ground Surface, Aerials, Profiles, BFE’s, Soil
Borings, GIS Data, Utilities, etc.
Findings
Systems Generally Well Maintained– Review Original Agreement & O & M Manual
– Reporting Requirements, Access Control, Modifications (USACE Approval
and update documents), Detailed Operation Plan, Practice Operation,
Video Inspection of Conduits
Findings
Wichita Valley Center Flood Control System– Constructed from 1950 through 1963
– 97 miles earthen levee embankment
– 4 diversion structure
– 14 floodwalls
– 6 pump stations
– 120 interior drainage structures
– 96 ponding areas
– 11 miles training levees
Findings
Developed Phased Assessment Approach– Phase 1
– LiDar
– Historical Documentation
– Visual Assessment
– Phase 2 - Certification Analysis
(COE completed part of hydrology)
– Phase 3 – Design and Construction
Findings
• “Worst First” Approach– Four Projects Identified
– Plans & Specs parallel to
analysis
• Additional Construction Projects
Findings
City of Manhattan Levee Project– Five Mile Levee System
– Two Closures
– Two Pump Stations
– 19 Drainage Structures
Findings
Required Levee Modifications
– Additional freeboard for one mile of levee (BFE’s went up)
– Decommission two interior drainage structures
Shaded Relief Map
Hutchinson
S. Hutchinson
Hutchinson 1929 Flood
Hutchinson Levees
Levee C: Protects
Reno Co.
Levee F: Protects
Willowbrook
Levees A, D, E
Protect Hutch
Levee B: Protects
S. Hutch
Hutchinson: 2011 vs 2007
Hutchinson: 2011 vs 2007
Hutchinson: 2011 vs 2007
Floodplain w/o Levees
Hutchinson
S. Hutch
Floodplain w/ Levees
Hutchinson
S. Hutch
Findings
Hutchinson Levee System– Lacks freeboard in a few areas
– Additional underseepage control needed
– Update operation & maintenance manual; develop detailed operation plan
Findings
Hutchinson Levee System, Cont.– Corroded conduits
– Additional embankment protection needed
– Large interior drainage areas, potential pump station
Findings
Dodge City Levee System– Insufficient freeboard due to sedimentation in river channel
– Operation challenges for sandbag closures
8 closures require 135 people (8 hrs), 22k bags, 200 cu yd sand, 8 trucks
– Embankment protection improvement & alternative analysis
– Update operation & maintenance manual; develop detailed operation plan
Certification Challenges
Each System Differs
Hydrology
Hydraulics
Geography
Geology
Definition of “System”
Lack of Time
Lack of Funding
Certification Challenges
13 Municipalities Throughout Kansas
Populations range from 400 to 400,000
Primary Functions Include:
– Unified Voice to Rule Makers (Federal and State)
– Share Lessons Learned
Kansas Municipal Levee Owners ConsortiumAugusta, Dodge City, El Dorado, Florence, Gypsum, Hutchinson,
Manhattan, Marion, Osawatomie, Ottawa, Salina, Topeka, Wichita