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Fall Creek/White River Tunnel

Evaluation Study

CITY of INDIANAPOLIS DEPARTMENT of PUBLIC WORKSU.S. ARMY CORPS of ENGINEERS

G.E.C., Inc.Black & Veatch Corporation

Clean Stream Team Advisory Committee Meeting – May 18, 2005

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Presentation Overview

Project Team Members

Scope of Tunnel Evaluation Study

How a Deep Tunnel Works

Tunnel Project Screening Criteria

Geology and Hydrogeology

Tunnel Design Considerations

Next Steps & Committee Feedback

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Project Team Members

Department of Public Works – Engineering

Department of Public Works – Operations

Department of Public Works – Environmental Services

U.S. Army Corps of Engineers – Louisville District

Indianapolis Clean Stream Team (CST)

Department of Parks and Recreation – Greenways

Indianapolis DMD Planning Division

Veolia Water Indianapolis

Indianapolis Water

United Water

Black & Veatch and G.E.C., Inc.

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Current Phase: Preliminary Study

Initial Geotechnical Exploration Program

Facility Planning

Detailed Design

Bid Phase / Contract Award

Construction

(10-15 Year Overall Schedule)

Tunnel Project Phases

Pogues Run Tunnel Shaft Construction

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Scope of Preliminary Evaluation Study

Project Summary and Description

Construction and Project Considerations (size, length, alignment, staging areas, pumping stations)

Risk Management

Preliminary Geotechnical Reconnaissance

Preliminary Cost and Schedule

Decision Screening

Conclusions and Recommendations

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Combined Sewer System - How It Works

River

CSO OutfallRegulator

WetWeather

Combined SewerTo WWTP

WWTP

Combined Flow to WWTP

and Outfall

SOILS

BEDROCK

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Deep Tunnel System - How it Works

CSO to Tunnel

River

CSO Outfall

Storage Tunnel

Drop Shafts

Consolidation Sewer

Regulators

WetWeather

Deep Tunnel Pump Station to WWTP

Working Shaft

Combined SewerTo WWTP

WWTP

CSO to Tunnel

Combined Flow to

WWTP and Tunnel

BEDROCK

SHALE

SOILS

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Impacts to Water Supply

Geotechnical Risk

Underground Easement Acquisition

Population Impacts

Environmental Contamination

Tunnel/Sewer Flexibility

Operations & Maintenance

Others

Primary Decision-Making Criteria

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~260’below

groundsurface

Geology and Hydrogeology

Reviewed Available Literature on Regional Geology

7.5–10.5 miles

~210’below

groundsurface

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Groundwater Monitoring Plan

Goals of the Groundwater Monitoring Plan

Regional Cooperation to Monitor Groundwater Level and Quality before Construction

Develop Predictive Models as Tools

Develop Instrumentation and Control Specifications

Map Geology during Construction

Monitor the Drawdown and Recovery of Groundwater Level

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Protecting Groundwater and Water Supply

Structural Controls During Construction

Short-Term: Pre-excavation and Cut-off Grouting

Long-Term: Contact Grouting and Permanent Concrete Liner

Operational Controls After Construction

Controlling Exfiltration

Limit Tunnel Fill Level and Duration of Storage

Minimize or Prevent Surges, Backflows and Rapid Pressure Changes

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Tunnel Size, Length and Diameter Alignments to Capture CSOs from 43 Outfalls

27 along Fall Creek, 16 along White River Working and Retrieval Shafts Consolidation Sewers/Drop

Shafts

Overview of Tunnel Components

Tunnel Shaft Workers

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Tunnel Size, Length and Diameter

Preliminary Sized for 95% (189.5 MG) or 97% (310 MG) Capture of CSO

Three Alternatives Evaluated West, Central and East

Length from 7.5-10.5 miles Diameter Varies based on Length and

Capture % Finished Diameters Range from 26 - 35 feet

Expandable Design for 99% (504 MG) Capture Unprecedented Diameter for Alignments Evaluated (45 feet finished)

Design of “Extension” Shafts for Future Tunnel Expansion

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Tunnel Alignments Evaluated

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Sized for 99% CSO Capture Consolidation Sewers

Used to Group CSO Outfalls Direct Flows to Tunnel Drop

Shafts Cost Savings over Tunneling Open-Cut Sewer Construction

Drop Shafts (21 Total) Transfer CSO from

Consolidation Sewers into Tunnel

Consolidation Sewers and Drop Shafts

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~260’below

groundsurface

7.5–10.5 miles

~210’below

groundsurface

Working Shaft Alternatives

Reilly Site, Southern Avenue, and Bluff Road

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~260’below

groundsurface

Retrieval Shaft Alternatives

7.5–10.5 miles

~210’below

groundsurface

Keystone Dam and Sutherland Avenue Sites

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Impacts to Water Supply

Geotechnical Risk

Underground Easement Acquisition

Population Impacts

Environmental Contamination

Tunnel/Sewer Flexibility

Operations & Maintenance

Others

Recap:Primary Decision-Making Criteria

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Summary of Screening Factor

Results of the Decision Screening Process Tunnel Alignment Preferred Alternative

West Alignment

Working Shaft Site Bluff Road

Retrieval Shaft Site Sutherland Ave.

Decision Screening

Geotechnical Risk

Impacts to Water Supply

Underground Easement Acquisition

Population Impacts

Environmental Contamination Risk

Tunnel/Sewer Flexibility

Others

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.0

0.1

0.2

0.3

0.4

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0.8

East Alignment West Alignment Central Alignment

Considerations

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Public Meeting on Preliminary Study Geotechnical Exploration Program Land Acquisition Study Environmental Site Assessments Groundwater Monitoring Plan Continued Public Outreach and Stakeholder

Involvement

Recommended Next Steps

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Proposed Public Meeting Format

Room Layout

Presentation

Public Seating

Station #1: Why Build a Tunnel?

Station #2: Alt. Tunnel Routes

Station #4: Construction Q&A

Station #3: Wellfields Q&A

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Discussion / Q&A