Experience · Innovation · Results

Drainage Assessment of Tete Bayou

Engineers ∙ Surveyors · Environmental Consultants

PRESENTED TO

IBERIA PARISHGOVERNMENT

CITY OF NEW IBERIA

Organizational ChartDr. Ehab Meselhe,

P.E.Senior Hydraulic

Engineering Consultant

Robert MillerMS, P.E.

Hydraulics Engineer

Justin Shaw M.S., E.I.

Hydraulics Engineer

Jeanne Arceneaux M.S., E.I.

Hydraulics Engineer

Dax Douet, P.E.Engineering Project

ManagerDirector

Ivan Diaz, P.E.Drainage Engineer for City of New

Iberia(33 Years)

Raymond Reaux, P.E.Vice President – Engineering

General Scope of Work

• INVESTIGATE HISTORICAL FLOODING IN UPPER PORTION OF TETE BAYOU

• EXAMINE REPETIVE LOSSES DUE TO OVERBANK FLOODING

• DEVELOP POSSIBLE DRAINAGE IMPROVEMENT SCENARIOS

• PERFORM FIELD SURVEYING• ANALYZE IMPROVEMENT SCENARIOS THROUGH

HYDROLOGIC AND HYDRAULIC MODELS• PRESENT QUANTITATIVE SOLUTIONS ALONG

WITH REPORT

Study Area

4/XX

Project Objectives

• Develop Numerical Models to Study Tete Bayou and Pharr Canal• Examine Four Proposed Drainage Improvement Scenarios:

Scenario No. 1: Cleaning of Tete Bayou and the Pharr Canal;Scenario No. 2: Scenario No. 1 + widening of the Pharr Canal intake, and removing

existing spoil banks along Tete Bayou;Scenario No. 3: Scenario No. 2 + diverting flow from Tete Bayou to Bayou Teche

through a sub-surface box culvert system; and Scenario No. 4: Scenario No. 1 + widening of Pharr Canal.

Analysis Timeline

• Contract Execution Date: January 19, 2011

• Field Survey Collection Start Date: February 8, 2011

• Numerical Model Development Start: February 21, 2011

• Agency Meeting with City and Parish Date: April 5, 2011

• Draft Report to City and Parish Date: July 22, 2011

Data Collected

• Survey Date Collected By C.H. Fenstermaker & Associates, Inc.

• 1,589 Survey Points Collected• Historical Hydrologic Data• Land Use/Land Cover Maps• Soil Type Maps• LiDAR Data• FEMA Flood Zones

FEMA Calibration

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-5

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10

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010,00020,00030,00040,00050,00060,000

Elev

atio

n (f

t)

Main Channel Distance (ft)

Existing 100-year Storm Event

Existing 100-yr WSE

Ground

FEMA BFE

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet Rd

CALIBRATION CHECKS

100-year Rainfall Event1% Chance that a 12.6 inch Rainfall over 24 hours will

Occur in a Given Year

December 2006 Storm Event Calibration

Tete Bayou at Belle Place Olivier Rd Facing South

Tete Bayou at Emile Verret Rd Facing WestTete Bayou at Emile Verret Rd Facing East

Tete Bayou near Candleglow Dr Facing East

Estimated Rainfall Event5.02” Rainfall (24 hours)

Approx. 3-yr., 24-hour Storm

December 2006 Storm Event Calibration

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5

10

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010,00020,00030,00040,00050,00060,000

Elev

atio

n (f

t)

Main Channel Distance (ft)

December 2006 Storm Event

December 2006 WSE

Ground

December 2006 High Water Mark

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet RdTete Bayou at Belle Place Olivier Rd Facing South

Scenario No. 1

11/XX

Definition:Channel Cleaning of Tete Bayou and the Pharr Canal

Scenario No. 1 – Water Surface Elevation Comparison

12/XX-10

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atio

n (f

t)

Main Channel Distance (ft)

Existing - Scenario 1 Comparison

10-yr Existing WSE

10-yr Scenario 1 WSE

Ground

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet Rd

0.6’ Reduction inWater Surface Elevation

10-year Rainfall Event10% Chance that a 7.8 inch Rainfall over 24 hours will

Occur in a Given Year

Scenario No. 1 – Inundation Comparison

13/XX

Scenario No. 1 – Results

Scenario No. 1 Flood Duration Comparison

BridgeWater Surface Elevation > 7’ NAVD 88

Existing Scenario No. 1

Emile Verret Rd 24 hrs 15 hrs (37%)Belle Place Olivier Rd 18 hrs 12 hrs (33%)

Scenario No. 1 Inundation Area ComparisonExisting Conditions

10-yr Inundation Area (acres)

Scenario No. 1 10-yr Inundation

Area (acres)

Scenario No. 1 10-yr Reduction

Area (acres)

Scenario No. 1 10-yr Increase Area (acres)

Scenario No. 110-yr Total ReductionArea Reduction (acres)

6,390 6,366 220 197 24

Scenario No. 2

15/XX

Definition:Channel Cleaning, Widening of the Pharr Canal, and Removing Existing Spoil Banks Along Tete Bayou

16/XX-10

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atio

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Main Channel Distance (ft)

Existing - Scenario 2 Comparison

10-yr Existing WSE

10-yr Scenario 2 WSE

Ground

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet Rd

Scenario No. 2 – Water Surface Elevation Comparison

0.6’ Reduction inWater Surface Elevation

Scenario No.2 – Inundation Comparison

17/XX

Scenario No. 2 – Results

Scenario No. 2 Flood Duration Comparison

BridgeWater Surface Elevation > 7’ NAVD 88

Existing Scenario No. 2

Emile Verret Rd 24 hrs 14 hrs (42%)Belle Place Olivier Rd 18 hrs 12 hrs (33%)

Scenario No. 2 Inundation Area ComparisonExisting Conditions

10-yr Inundation Area (acres)

Scenario No. 2 10-yr Inundation

Area (acres)

Scenario No. 2 10-yr Reduction

Area (acres)

Scenario No. 2 10-yr Increase Area (acres)

Scenario No. 210-yr Total ReductionArea Reduction (acres)

6,390 6,209 289 108 181

Scenario No. 3

19/XX

Definition:Channel Cleaning, Widening of the Pharr Canal, Removing Spoil Banks, and Diverting Flow From Tete Bayou to Bayou Teche Through a Sub-surface Box Culvert System

20/XX-10

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Elev

atio

n (f

t)

Main Channel Distance (ft)

Existing - Scenario 3 Comparison

10-yr Existing WSE

10-yr Scenario 3 WSE

Ground

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet Rd

Diversion

Scenario No. 3 – Water Surface Elevation Comparison

1.7’ Reduction inWater Surface Elevation

Scenario No. 3 – Inundation Comparison

21/XX

Scenario No. 3 – Results

Scenario No. 3 Flood Duration Comparison

BridgeWater Surface Elevation > 7’ NAVD 88

Existing Scenario No. 3

Emile Verret Rd 24 hrs 5 hrs (79%)Belle Place Olivier Rd 18 hrs 10 hrs (44%)

Scenario No. 3 Inundation Area ComparisonExisting Conditions

10-yr Inundation Area (acres)

Scenario No. 3 10-yr Inundation

Area (acres)

Scenario No. 3 10-yr Reduction

Area (acres)

Scenario No. 3 10-yr Increase Area (acres)

Scenario No. 310-yr Total ReductionArea Reduction (acres)

6,390 5,835 619 64 555

Scenario No. 4

23/XX

Definition:Channel Cleaning and Pharr Canal Diversion

24/XX-10

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Main Channel Distance (ft)

Existing - Scenario 4 Comparison

10-yr Existing WSE

10-yr Scenario 4 WSE

Ground

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet Rd

Diversion

Scenario No. 4 – Water Surface Elevation Comparison

1.5’ Reduction inWater Surface Elevation

Scenario No. 4 – Inundation Comparison

25/XX

Scenario No. 4 – Results

Scenario No. 4 Flood Duration Comparison

BridgeWater Surface Elevation > 7’ NAVD 88

Existing Scenario No. 4

Emile Verret Rd 24 hrs 9 hrs (62%)Belle Place Olivier Rd 18 hrs 10 hrs (44%)

Scenario No. 4 Inundation Area ComparisonExisting Conditions

10-yr Inundation Area (acres)

Scenario No. 4 10-yr Inundation

Area (acres)

Scenario No. 4 10-yr Reduction

Area (acres)

Scenario No. 4 10-yr Increase Area (acres)

Scenario No. 410-yr Total ReductionArea Reduction (acres)

6,390 5,977 463 50 414

Scenario Comparisons and Costs

Scenario

Flood Duration Reduction at Emile Verret

Flood Duration Reduction at

Belle Place Olivier

Inundation Reduction

Area

Inundation Increase

Area

Total Planning

Cost*(hrs) (hrs) (acres) (acres)No. 1 9 6 220 197 $1,177,000No. 2 10 6 289 108 $1,964,000No. 3 19 8 619 64 $6,416,000No. 4 15 8 463 50 $2,641,000* It should be noted that these figures represent approximated cost only to be used for planning purposes.

Additional Analysis – Dredge Tete Bayou Mouth

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Main Channel Distance (ft)

Dredging Tete Bayou

10-yr Existing WSE

Existing Ground

Dredged 10-yr WSE

Dredged Ground

Emile V

erret Rd

Mullins Rd

Belle Place Olivier Rd

Crochet Rd

Definition:Dredging of Tete Bayou into Lake Fausse Pointe

Negligible Water Surface Elevation Change

Experience · Innovation · Results

Drainage Assessment of Tete Bayou

Engineers ∙ Surveyors · Environmental Consultants

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