risk assessment toolbox - esriproceedings.esri.com/library/userconf/water16/papers/water_18.pdf•...
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Risk Assessment ToolboxA Custom ArcGIS 10.2 Toolbox for Wastewater Asset Management
Case Study: The City of Mesquite, TX
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Presenters: Christina Hickey, PE, CFM; Umer Khan, EIT; Matt Stahl, EITProject Managers: Tim James, PE; John D’Antoni, PhD, PE; Preston Dillard, PE
City of Mesquite and Alan Plummer Associates, Inc.February 9, 2016
Agenda
• Project Description• Problems Solved• Technical and Python Highlights• Project Results• What’s New & Lessons Learned
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Project Description
• Scope: Perform a business risk assessment of the City of Mesquite, TX wastewater collection system. – 476 miles of gravity mains
• 8,512 pipeline segments • 3 to 72 inches in diameter• First pipe installed in 1922 • Mostly PVC (57%) & Clay (32%)
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Project Description
City of Mesquite, Texas4
• Mesquite Situation – Aging Infrastructure
Project Description
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• Mesquite GIS - Current: – Utility Data stored in Geodatabase– Relationships to other data (work order system, PAVER)– Web Service to allow editing of items in the field
• Future: Relating more of the assessment data
• Why GIS Centered?– Neighborhood Planning and Prioritization– Project coordination– Data already in GIS– Spatial factors used in the risk analysis
Project Description
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Project Description
• 9 Steps to a Business Risk Assessment
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Project Description
Risk of Failure = (Likelihood of Failure x Consequence of Failure)
How Severe Are the Consequences of Pipe Failure?
How Likely is It For the Pipe to Fail?
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Project Description
• Scoring: Custom risk assessment criteria and scoring were developed for the assets in the system.– Likelihood of Failure (LOF)– Consequence of Failure (COF)– Risk of Asset Failure (ROF)
• Prioritization: ROF scores prioritized individual assets for rehabilitation in Mesquite’s 5 year and 10 year capital improvement plan (CIP) and to manage future asset renewal priorities.
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Topics
• Project Description• Problems Solved• Technical and Python Highlights• Project Results• What’s New & Lessons Learned
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Problems Solved
• Risk Assessment Challenges– Geoprocessing (location-aware analyses) – Efficient and accurate asset scoring, from preliminary
through final iterations– Summary results and reporting by asset and asset
group
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Problems Solved
• Error Reduction With Database (vs Spreadsheet)
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Problems Solved
• Generic Risk MatricesSTRUCTURAL 100 100
YES NO Pipe Properties Wt. YES NO Health and Safety (injury, illness) Wt.
x 1 Condition (rating via direct inspection) x 1 Public health and safety 15
x x 2 Staff opinion of condition 25 x 2 Utility employees health and safety 10
x 3 Repair history (# / 1,000 ft / yr)
x 4 Time since second most recent repair (yr) Financialx 5 Age (yr) 25 x 3 Customers - Loss of revenue 10
x 6 Material 25 x 4 Utility - Loss of revenue
x 7 Joint Type x 5 Utility - Repair cost 5
x 8 No of connections (# taps/mile) x 6 Utility - Liability
x 9 Installation Contractor x 7 Utility - Inhouse Repair Capability
External Corrosion Public Conficencex 10 Soil resistivity (ohm-cm) x 8 Number of customers affected (interruption of service)
x 11 Soil chemistry - sulfates in soils (%) x 9 Loss of service to critical facilities (incl. lift stations) 15
x 12 Soil Moisture x 10 Public perception - service calls
x 13 Stray current
x 14 External corrosion protection Infrastructurex 11 Proximity to main roads or railroads 10
Internal Corrosion x 12 Aerial Crossing 10
x 15 Internal sewer corrosion levels
x 16 Sulfates in wastewater (mg/L) Regulatoryx 17 Internal corrosion protection x 13 Discharge to Sensitive Environments 10
x 14 SSO’s (# / 1,000 ft / yr) 10
External Stresses x 15 100-yr Floodplain 5
x 18 Burial depth (ft) 15
x 19 Embedment zone backfill (quality of pipe bedding)
x 20 Traffic Load
x 21 Canopy
HYDRAULICx 22 Flow Profile (% full)
x 23 Blockage history (# / 1,000 ft / yr)
x 24 Surcharge conditions
QUALITYx 25 Odor complaints 10
LIKELIHOOD OF FAILURE COMPONENTS CONSEQUENCE OF FAILURE COMPONENTS
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Problems Solved
• Custom Risk Matrices
LOF ParameterWeight
(%)Staff Opinion 25Age 25Material 25Burial Depth 15Odor Complaint 10
TOTAL 100
COF ParameterWeight
(%)Public Health 15Utility Repair Safety 10Customer Loss 10Utility Repair 5Critical Service 15Proximity To Road 10Aerial Crossing 10Discharge To Sensitive Environment 10Sanitary Sewer Overflow 10100-yr Floodplain 5
TOTAL 100
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Problems Solved
• Multiple iterations performed quickly
Risk Results
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Topics
• Project Description• Problems Solved• Technical and Python Highlights• Project Results• What’s New & Lessons Learned
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Technical and Python Highlights
• Custom toolbox developed from geoprocessing tools
• Toolbox Layout– LOF– COF– Score and Plot
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Technical and Python Highlights
• Field Mapping to Import Data to Geodatabase
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Technical and Python Highlights
• Arcpy.da Cursors – Ex 1: Data Processing (Pipe Age)
Cursor scores data per matrix
Pipe Age tool
Variables
AgeYrs AgeYrsScore
> 0 – 10 1> 10 – 20 3> 20 – 30 5> 30 - 50 7> 50 10
<null> 5
Dictionary input
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Technical and Python Highlights
• Arcpy.da Cursors – Ex 2: Geoprocessing (Road Prox)
Pipe Proximity to Roads tool
(Spatial selection by roads)
Cursor scores data per matrix
Lookups
DiamInch RoadClass ProxRoadsScore DiamInch RoadClass ProxRoadsScore0 to 8 5 0 to 8 88 to 24 7 8 to 24 824 to 30 9 24 to 30 10> 30 10 > 30 100 to 8 3 0 to 8 2
8 to 24 4 8 to 24 3
24 to 30 5 24 to 30 4
> 30 6 > 30 5
0 to 8 28 to 24 324 to 30 4> 30 5
FREEWAY; FRONTAGE;
ACCESSRAILWAY
UNKNOWNMAJOR
LOCALDictionary input
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Technical and Python Highlights
• Arcpy Cursors – Ex 3: Calculations (Hydr Capacity)
Calcs
Hydraulic Capacity tool
Cursor assigns values per matrix
Variables
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Technical and Python Highlights
• Risk Calculation
LOFtool
COFtool
Risk Score and Ranktool 22
Topics
• Project Description• Problems Solved• Technical and Python Highlights• Project Results• What’s New & Lessons Learned
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Project Results
• Risk Analysis Workflow– Import asset data and custom scoring matrices– Geoprocessing (point, polyline features)– Database processing and matrix scoring– Results and reports (draft through final)
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Project Results
• Prioritize to Evaluate– Rank and prioritize every pipe– Triage physical evaluation
(CCTV, inspection)– Evaluation guides decisions:
• Rehabilitation• Replacement• Monitor
• Risk matrix refinement
High Moderate Low
High ImmediateRehab/Replace
ProgrammedRehab/Replace
Repair/Replaceon failure
Moderate ImmediateRehab/Replace
Proactive Assessment
Monitor and Forecast
Low Proactive Assessment
Opportunistic Assessment/forecasting
Monitor and ForecastLi
kelih
ood
of F
ailu
re
Consequence of Failure
Risk based Framework for Prioritization
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• Map reports (Data Driven Pages) - link
Project Results
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Project Results
• Summary reports (Data Driven Pages)
Summary Statistics (ArcGIS table)
Individual Values (ArcGIS table)
Locator Map (ArcGIS DDP)
Summary Plots (Matplotlib jpegs via
Raster Catalog)
Report/Plot Tools
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Topics
• Project Description• Problems Solved• Technical and Python Highlights• Project Results• What’s New & Lessons Learned
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What’s New & Lessons Learned
• What’s New– Arcpy.da cursors
– Python dictionaries
– Data Driven summaries
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What’s New & Lessons Learned
• Dictionary lookup - Personal geodatabase via Excel named range
– Excel table (name range) is source and editable – Personal geodatabase (linked to Excel) is dynamic*– Arcpy reads dictionary from .mdb
*Avoids schema locks; instantaneous updates from source30
What’s New & Lessons Learned
• Map summaries with charts/tables (Data driven)
Data Driven Pages
Image path - index layer field
Bar & scatter charts (stand-alone script)
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What’s New & Lessons Learned
• Future Work– Regular Risk
Assessment updates– Custom tool validation,
default values, etc– Layer selection tools– Toolbox as client
deliverableFuture
Client Meeting
Risk Matrices
Toolbox Dictionary
Results
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Questions?
• Useful References– ESRI.com– Python.org– Matplotlib.org– Stackoverflow.com
• Contact Information– Christina Hickey - chickey@cityofmesquite.com– Umer Khan - mkhan@apaienv.com– Matt Stahl - mstahl@apaienv.com
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