Septic Pipeline Prioritization A Prioritization Decision Model

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Septic Pipeline PrioritizationA Prioritization
Decision Model

• Michael Lackore
• Ibrahim F. Al-Qudah

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Introduction

• Whats the Problem?
• Sewage Pipeline Design Basics
• Why is it Important?
• The Decision Model
• Variables
• Outputs
• Mathematical Design
• Does it Work?

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The Problem

• Goals
• Maintain Sewer Service to Citizens
• Minimize Risk of Sewer Failures
• Environmental EPA Regulations
• Monetary Punishment, Compensation, Repair
• The Problem Septic Lines Fail for a Wide Variety
  of Unpredictable Reasons

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The Problem
NODE
MAIN Flow Indicated
LINE Flow Indicated
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Why is it Important
A Failure Here, Affects 95 Homes! 95 X 3000.00
285,000.00
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Decision Model

• Application Variables
• of Houses Affected
• Probability of Failure
• Geology
• Pipe Parameters
• Age
• Diameter
• Length
• Material
• Depth

• Outputs
• Criticality
• Risk
• Cost

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Decision Model
Payoffs Vary By Location
Probability of Failure Varies By Location
Probability of Sewage Backup Varies By Location
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Model Design

• We used Weibull Formula to determine probability

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• x The year of life of the pipe
• Alpha Expected total life of the pipe
• Beta Skew of the graph
• Gamma First Fail of the pipe, the amount of
  time before a failure can mathematically occur

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Probabilities Types

• Theoretical
• Actual

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Inspection ResultsNASSCO Coding

• Defect 5 ? 5 years deduction
• Defect 4 ? 10 years deduction
• Defect 3 ? 20 years deduction
• Defect 2 ? 40 years deduction
• Defect 1 ? 80 years deduction

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New X Values

• Defect 5 ? X (X-20-5)
• Defect 4 ? X (X-20-10)
• Defect 3 ? X (X-20-20)
• Defect 2 ? X (X-20-40)
• Defect 1 ? X (X-20-80)

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Cost Types

• Severity cost
• Total Compensation
• Risk cost
• Total cost if pipe actually fails
• Cost to own
• Total cost of any potential event

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Cost Types - Continued

• Cost to own
• - No Sewer Backup emergency
• - No Sewer Backup No Emergency
• - Sewer Backup emergency
• - Sewer Backup No Emergency

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Factors Affecting Cost

• Emergency Double normal cost
• Backup 3000/each house
• Pavement is gtgtgt more expensive (Gravel)

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Cost Continued

• To make it easier, Cost was calculated on an
  annual basis
• The Different types of Cost would generate from
  No. Years Probability
• Create a comparative graph

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Comparative Graph
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Application Process

• Combination of software (GIS Access Excel)
• Multi Step Iteration

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