City of Greencastle

Flood Protection Plan

Presented by,

United Geotech, LTD

Introduction

Team Overview Project Overview Design Requirements Project Approach Final Design Questions

Team Overview

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

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

Project Overview (cont.)

Well field

Big

Wal

nut C

reek

Filter Facility

Lagoon

US-231

Project Overview (cont.)

Taken September 16, 2003 Taken September 2, 2003

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

Project Approach

Site assessment Codes and regulations Research design options

Flood protection Security

Choose final design Complete final design

Site Assessment

Topographic map Finished floor elevation = 688.54 feet (MSL)

Filter Facility

Lagoon

Big

Wal

nut C

reek

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)

Site Assessment (cont.)

Site Assessment (cont.)

Low head dam

0 100 200 300 400 500 600665

670

675

680

685

690

695

Big Walnut Creek (inline struc ture) Plan: Plan 01 1/14/2004

Main Channel Distance (f t)

Ele

vatio

n (f

t)

Legend

EG PF 1

WS PF 1

Crit PF 1

Ground

Big Walnut Creek Water Plant

Finished floor elevation

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 1:2.5 No levee construction restrictions

Design Options

Flood control options

Levee under construction Floodwall under construction

Design Options (cont.)

Flood control options (cont.)

Elevated structure

Dry floodproofing

Design Options (cont.)

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

Relocation1 5 5 1 3.2

Decision based on four criteria Initial cost Lifespan Maintenance Constructability

Levee Design

Obtained soil borings & performed tests

Clay (CH), silt (MH), and sand (SW) present

Suitable for levee

B1

B2 B3

B4

B5

B6

Levee Design (cont.)

Lagoon Expansion

Filter Facility

Levee Design (cont.)

Levee cross sections

Seepage Analysis

Used SefDam to calculate seepage

Elev. 692’

13’

Elev. 690’

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

Slope Stability

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

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 LinkFence with

Barbed Wire1 4 5 5 3.8

ColorWeatherproof

Camera5 2 4 1 3.0

Infrared SensorLights

5 1 5 3 3.5

Security (cont.)

Filter Facility

Cost

R.S. Means Manual used to estimate costs Levee

$71,500 Security

$24,000 Total cost

$95,500

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

Questions???