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