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Improving Aging InfrastructureCase Study of Barrigada Tanks

Barrigada Team Members

Owner

Construction Manager

Project Designer

General Contractor

Tank Builder

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Project Overview: June 2005 1.0MG steel tank fails due to

corrosion. Tank failure damages existing 2.0MG & 3.0MG

tanks. GWA takes action and performs

assessment of existing tanks. Guam’s unique environment is evaluated.

Highly Corrosive High Seismic High Wind

Replacement: 2.0MG AWWA D110 Type I Prestressed

Concrete Tanks are selected for construction due to their proven track record in all of the above conditions.

DN Tank’s first project in 1962

In Service for more than 50 years

Highly Corrosive Environment

High Seismic

DN Tanks has constructed over 600 tanks along Coastal Pacific Rim to date

Point Loma, CA – 8 x 4.0 MG

AWWA D110 Type I Prestressed Concrete Tank History

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AWWA D110 Type I Tank Overview

Operational Water Level200PSI

• Inner 10” concrete core

• Horizontal prestressingproviding compression: Efficient use of Materials

• Flexible floor‐wall connection

• Secondary Assurance of Water‐Tightness:Vertical post tensioning

Wall Footing

Seismic Cables

PVC Waterstop

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Completed Floor

PVC Waterstop

Bearing Pad

Seismic Cables

Improves Operational Performance

Enhances Ductility

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PVC Waterstop

Bearing Pad

Seismic Cables

Pour Window

Vertical Threadbars

Injection Tube

Wall Rebar & Vertical Threadbars

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Seismic Reliability

Los Angeles, CaliforniaJanuary 1994, Northridge 6.8M

Tested Proven

Pour Windows

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Column Construction

Cast-in-Place Flat Slab Roof

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Cast-in-Place Flat Roof

Construction Outline

Wall Footing and Floor

Cast-in-place Corewall Columns

Vertical Prestressing Roof Horizontal

Prestressing

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Wall-to-Roof Connection

Wall Can

Improves Operational Performance

Enhances Ductility

Resists Secondary Bending Due to Thermal Differential

Vertical Post-Tensioning

Electronic Recorder Hydraulic Ram

Continuous Electronic Monitoring137.3 Kips – 1 1/4’’ 173.9 Kips - 1 3/8’’

Biaxial Compression

Improves Ductility

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Electronic Recording

Epoxy grout following Post-Tensioning

Vertical Post-Tensioning: Epoxy Grout

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Specialty Prestressing Operations Overview

PrestressingSequence Sand Blasting

Circumferential prestressing

Automated Shotcrete

Cab

Tower

Base

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Sand Blast Removes oils and roughens

surface for shotcrete application

Circumferential Prestressing

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Quality Control - Calibration Equipment

7-wire galvanized strand

Wraps at 14,950 pounds Instantaneous Force

Application Correction ±1.5% tolerance

Differential gear gripping head

Circumferential Prestressing - Stressing Head

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Circumferential Prestressing - Stressing Head

7-wire galvanized strand

Wraps at 14,950 pounds Instantaneous Force

Application Correction ±1.5% tolerance

Differential gear gripping head

Circumferential Prestressing - Lockoffs

22,000 ft.

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Circumferential Prestressing - Continuous Electronic Recording

Automated Shotcreting

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Automated Shotcreting

No Structural Coatings Required!• Improved, lasting performance without

relying on the maintenance of a coating.

• Less maintenance required over the life of the tank.

Durability

Quality

Efficiency

Value

Flexibility

Aesthetics

Technical expertise

Investment in the Local

Economy

An AWWA D110 Type I Tank Means:

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