City of Greencastle Flood Protection Plan

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City of GreencastleFlood Protection Plan
Presented by, United Geotech, LTD
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Introduction

• Team Overview
• Project Overview
• Design Requirements
• Project Approach
• Final Design
• Questions

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Team Overview

• Sarah Bireley Project Manager
• Amee Wicks Project Engineer
• Brad Pickering Project Engineer
• Troy Cunat Project Engineer

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Project Overview

• Greencastle Water Treatment Plant
• Located in Greencastle, Indiana south of Big
  Walnut Creek
• Six wells provide 4,000 gpm peak
• Serves population of 10,000
• Site subject to flooding
• Located in the flood plain
• Rains on Labor Day flooded site

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Project Overview (cont.)
Big Walnut Creek
Well field
Lagoon
Filter Facility
US-231
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Project Overview (cont.)
Taken September 16, 2003
Taken September 2, 2003
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Design Requirements

• Confirm finished floor elevation of filter
  facility
• Confirm base flood elevation
• Investigate flood protection options
• Investigate security options
• Deliverables
• Proposal
• Progress report
• Final report

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Project Approach

• Site assessment
• Codes and regulations
• Research design options
• Flood protection
• Security
• Choose final design
• Complete final design

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Site Assessment

• Topographic map
• Finished floor elevation 688.54 feet (MSL)

Big Walnut Creek
Lagoon
Filter Facility
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Site Assessment (cont.)

• Watershed area obtained
• 216 mi2
• Determined base flood elevation
• Obtained Big Walnut Creek topographic map
• 100-year flow determined
• Q 21,400 cfs
• Maximum flows used in HEC-RAS to determine base
  flood elevation
• 690.0 feet (MSL)

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Site Assessment (cont.)
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Site Assessment (cont.)
Finished floor elevation
Low head dam
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Codes and Regulations

• Cannot raise base flood elevation more than 0.15
  feet
• Water tower must be enclosed in fence
• Maximum levee side slope of 12.5
• No levee construction restrictions

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Design Options

• Flood control options

Levee under construction
Floodwall under construction
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Design Options (cont.)

• Flood control options (cont.)

Dry floodproofing
Elevated structure
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Design Options (cont.)

• Decision based on four criteria
• Initial cost
• Lifespan
• Maintenance
• Constructability

Initial Cost (35) Lifespan (35) Maintenance (20) Constructability (20) Overall
Levee 4 4 3 2 3.6
Floodproofing 5 1 5 4 3.5
Floodwall 2 4 3 4 3.1
Building Relocation 1 5 5 1 3.2
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Levee Design

• Obtained soil borings performed tests

B6
B5
B3
B2
B4
B1

• Clay (CH), silt (MH), and sand (SW) present
• Suitable for levee

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Levee Design (cont.)
Lagoon Expansion
Filter Facility
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Levee Design (cont.)

• Levee cross sections

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Seepage Analysis

• Used SefDam to calculate seepage

Elev. 692
Elev. 690
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Section Permeability (ft/s) Height (ft) Width (ft) Seepage (ft3/s/ft)
A-A 3 x 10-10 5 28 6.494 x 10-11
B-B 3 x 10-10 6.5 35.5 1.238 x 10-10
C-C 3 x 10-10 13 68 4.578 x 10-10
D-D 3 x 10-10 12 63 4.005 x 10-10
E-E 3 x 10-10 11.25 59.5 3.639 x 10-10

• Total seepage is 0.0244 ft3/day

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Slope Stability
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Slope Stability (cont.)

• XSTABL utilized to analyze slope stability
• Eroding slope improved by Greencastle
• Additional load from levee analyzed
• Additional load does not cause failure

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Security

• Fencing, lighting, and cameras investigated
• Lighting and cameras may be added in future

Initial Cost (30) Lifespan (30) Maintenance (20) Protection (20) Overall
Chain Link Fence with Barbed Wire 1 4 5 5 3.8
Color Weatherproof Camera 5 2 4 1 3.0
Infrared Sensor Lights 5 1 5 3 3.5
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Security (cont.)
Filter Facility
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Cost

• R.S. Means Manual used to estimate costs
• Levee
• 71,500
• Security
• 24,000
• Total cost
• 95,500

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Conclusion

• Flood levels warrant need for flood protection
• Levee chosen as protection option
• Seepage and slope stability not a problem
• Fencing with barbed wire chosen for security
• Cameras and lighting may be added
• Total cost of 95,500
• Levee - 71,500
• Security - 24,000

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• Questions???