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Constructability Problems and Solutions in Ground Improvements: Grand Island Tank Case Study

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All accidentsare preventable

No repeatoccurrences

SafetyStandards

Job site Daily Task Analysis Meeting to review safety issues

related to the day’s tasks.

All Incidents investigated, corrective actions implemented

and shared in the Weekly Safety Update for awareness.

Safety Standards Document

Goal: Zero Injuries

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THINK SAFE WORK SAFE GO HOME SAFE

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Don’t be this guy!

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Grand Island, NE

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Grand Island Water Storage Tank• 2,000,000 Gal Storage• 6,000psf required

bearing capacity• 1” Total Allowable

Settlement

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SoilProfile

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Soil Profile

• 0’-5’ Surface CL Clay material

• 5’ – 15’ Poorly Graded Sand

• 15’ - 20’ Sandy Clay

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• Design Depth of 26ft FGS

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Design Layout

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Partial Pre-Drill – Vibro Pier

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Modulus Test

• Rounded Rock• 150% Design Load

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Problems Start

• Red – Less than 12’• Yellow – 14’-18’• Green – 19’ or Greater

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Problem: Clean Upper Sand Layer

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Solution

• Compaction Grouting• 9% Area Replacement

below the Stone Column supported area

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Process - Grout Mix

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• Aggregate (Soil)

− Sand

− Gravel

− Silt

• Portland Cement

• Water

• Additives and Admixtures (optional)

Typical LMG MaterialsPrimary ingredients include:

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Examples: Extracted Grout Column

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PAST PROJECT: Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Dakota Mill & Grain – Presho, SD

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Solution

• Compaction Grouting• 44 locations• + 2 Test Locations

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Grand Island: Compaction Grouting

• 8cf/ft• 28ft to 16ft FGS• Minimum 200psi CG

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Results

• Compaction Grout

• Secondary – Test Locations (Dotted Line)

Vibro Zone

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Lessons Learned• 30% Area

Replacement Ratio• Rounded Rock • Ground improvement

combinations - successful

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