INFOMASTER SEWERRISK ASSESSMENT CALIBRATIONInfoMaster User Group Meeting | December 9, 2016

LANI GOOD, PE COURTNEY HALL, PE

Presentation Outline

Introduction Initial Risk Model Setup Risk Calibration Results Validation

Introduction

USD Study

USD system: 787 miles of gravity sewer, 6 pump stations, and 25 miles of force mains

Project Goal: Use a business risk assessment to guide modifications to the CS preventative maintenance program

Initial Risk Model Setup

Risk Assessment Methods

Bi-directional Distribution Custom 3x3 or 5x5

LOFxCOF Matrix Linear Normalization

Classification For a monetary

assessment

Linear Normalization Classification Method

Risk Assessment Methods

Bi-directional Distribution Custom 3x3 or 5x5

LOFxCOF Matrix Calibrated by Value or %

Linear Normalization Classification For a monetary

assessment Multi-Criterion Classification

Optimistic risk vs. pessimistic risk

Asset Grading Classification

Developing Risk Factors/Criteria

Limit the number of criteria used Considerations for valid criteria: Evaluation information must be readily available

Example: Manhole proximity to storm drain outfall to creek

The same evaluation information should not be used for more than one criterion Example: Street classification as a factor for Emergency

Access and for Public Traffic Impacts

Evaluation information must be available for a majority of assets Example: Sewer Likelihood of Structural Failure partial CCTV

data vs. pipe age data used to evaluate

Filling Data Gaps Using Proxy Data

Typical Sewer Failure Modes

Structural Failure Maintenance Failure Hydraulic Capacity Failure

Likelihood of Failure Rating Factors

Structural Defect Score

Pipe Installation Year (Proxy for Structural Defects)

Likelihood of Failure Rating Factors

Typical Maintenance Failure Factors

CCTV Maintenance Defects Strong indicator if Positive Weak indicator if Negative

Pre-CCTV cleaning and root cutting Low-frequency CCTV inspection vs. maintenance defect

reoccurrence

High Frequency Maintenance Schedule Couldn’t use for USD because if high PM frequency = high

risk, then study couldn’t evaluate reducing the PM frequency

Number of Non-routine Work Order Hours Number of Total Work Orders

Maintenance Defect Score

Non-Routine Labor Hours

Rating Scale, Logic, Weighting

Rating Scale 1-10 scale vs. 1-5 scale

1-10: how do you define a difference between a 6 and a 7?

When to use 0 vs. 1

Rating Scale, Logic, Weighting

Rating Logic Weighting Internal weighting in 0-5 scale

Weighting factors

InfoMaster DemoRating Scale, Rating Logic, and Weighting

Typical Sewer Consequences of Failure Regulatory Compliance Impacts Impacts to Environmentally Sensitive Areas Public Health Impacts Emergency Response Cost

Consequence of Failure Rating Factors

Public Exposure

Risk Calibration

Calibration

Risk Assessment Goals Phasing – somewhat equal risk categories by %

Max/Min Scaling – pipes scored in both upper and lower risk areas

Monetary evaluation

Initial Results – Factor by Factor Looking for differentiation between scores – using

GIS figures

Adjust ranges of values in each rating category

Risk Calibration

Setting 5x5 or 3x3 risk matrix score boundaries By % of pipes (quantity or length) in each risk level

By value - using engineering judgement

InfoMaster DemoRisk Calibration

Demo – Risk Calibration

Final Risk Results

Results Validation

USD Map – Figure 20 Results

Risk Assessment Results

Results Validation

Results Validation

USD Map – Figure 20 Results

Risk Assessment Results

Results Validation

Results Validation

LANI GOOD, PE(925) 949-5822

lgood@westyost.com

Questions?COURTNEY HALL, PE

(530) 761-0233chall@westyost.com