Using ModelBuilder to Evaluate Risk and Prioritize Sewer Upgrades

Transcription

1 ESRI User Conference 2015 Using ModelBuilder to Evaluate Risk and Prioritize Sewer Upgrades July 2015 Presenters: Erin Smith (City of Alameda) Andy Baldwin (RMC Water and Environment)

2 ESRI User Conference 2015 Using ModelBuilder to Evaluate Risk Agenda 1. Background and Goals 2. Risk Analysis 1. Likelihood / Consequence of Failure 2. Risk Model Approach 3. Risk Analysis using ArcGIS ModelBuilder 1. Model Design and Development 2. ModelBuilder: Tricks and Tips 4. Risk Analysis Results and CIP Planning 2

3 Sewer Master Plan - Background Project Background Flow monitoring and hydraulic modeling used to identify infiltration/inflow and capacity issues Evaluate Structural condition assessment through CCTV Sewer master plan defines 20+ year CIP Background and Goals Risk Analysis Goals Evaluate likelihood and consequence of failure of sewer infrastructure Assign total risk scores to all pipes Use risk scores to identify and prioritize CIP projects Update risk scores as collection system changes 3

4 Using ModelBuilder to Update Risk Risk Management General: Implement standard procedures for updating the risk model to support the City s on-going CIP program Key requirements: Re-evaluate risk using GIS Use ModelBuilder to automate process Update risk when GIS is updated Use risk scores to prioritize CIP projects 4

5 Risk Analysis - Approach Risk Analysis Likelihood of Failure: Structural Hydraulic Operational I/I Consequence of Failure: Triple Bottom Line Evaluation in GIS 5

6 Why Evaluate Risk? CIP Prioritization Risk Model General: Use risk factors (total score) to identify and prioritize CIP projects Replace or rehab pipe prior to failure Minimize expensive emergency repairs Meet regulatory requirements CIP Projects (Example)

7 Likelihood of Failure - Factors LOF Factors Likelihood Category Indicator Weight (%) Likelihood Score 1 (Low) (High) Condition 1 Highest structural grade (from CCTV) Pipe Age < 20 years 20 to < 40 years 40 to < 60 years 60 to < 80 years >= 80 years Operations O&M Score (from CCTV) 20 <= > 9 Capacity Predicted Surcharge 10 No surcharge or not in model Model predicts surcharge resulting from backwater conditions N/A Model predicts surcharge resulting from throttle conditions Model shows surcharging due to throttle pipe resulting in spills Inflow / Infiltration Inflow Grade 20 Low N/A Medium N/A High 7

8 Risk Model - Condition Scoring Approach Risk Model 10 Grade 4/5 Grade 2/3 Score Score Ratio (R) Grade Defect Count (C) Number of Grade 4/5 defects that would trigger a pipe replacement. This value is defined by the user based on pipe replacement policies Score = Score Ratio (R) x Defect Count (C) Total Score = (R 4/5 x C 4/5 ) + (R 2/3 x C 2/3 ) + (R 1 x C 1 )

9 Hydraulic: Surcharging Indicates Capacity and Overflow Risks LOF Factors 9

10 LOF Factors Inflow / Infiltration: Consent Decree Targets to reduce Wet Weather Flows to Bay 10

11 Triple Bottom Line Consequence of Failure (COF) Evaluation Economic Environmental Social Economic Direct cost to repair Social Impacts to society and customers Environmental Violations and degradation to the natural environment

12 Consequence of Failure - Summary COF Factors Consequence Category Indicator Weight (%) Consequence Score 1 (Low) (High) Economic Diameter (Flow Volume) 30 <= 8 10 to to to 27 > 27 Road Type Local NA Collector Arterial CALTRAN Community (Social) 30 Land Use Other N/A Commercial District School Hospital, Fire Station Easements N/A N/A Yes N/A N/A Environmental Distance to Surface Waters 40 N/A N/A N/A 50 to < 250 ft. < 50 ft. Distance to Storm Inlet N/A N/A N/A 50 to < 250 ft. < 50 ft. 12

13 Environmental: Water Bodies and Storm Inlets COF Factors Water Bodies Bay Inland waterways Storm Water Storm Inlets 13

14 Risk Model Approach Total Score Risk Model LOF Scores COF Scores 14

15 Risk Model - COF Weighted Scoring Example Risk Model Pipes Pipe 1 Pipe 2 Pipe 3 Economic (30%) Pipe Size Social (30%) Highest Score Used Roads Land Use Easements inch Arterial Comm. Public None inch Local Comm. Private None inch Local Comm. Public None Env (40%) Highest Water Score / Storm Weighted Average Score Weighted Average Score = 3.9 = 5 x 30% + 8 x 30% + 0 x 40% Non-Weighted Average Score = 4.3 = ( ) / 3 (= 5 x 33.3% + 8 x 33.3% + 0 x 33.3%)

16 GIS Tools Risk Analysis using ArcGIS ModelBuilder Use ArcGIS ModelBuilder to build and document risk model Tools designed for City to update risk model Utilize out-of-the-box GIS processes (no custom software) 16

17 ModelBuilder Risk Tools ModelBuilder Design and Development Risk tools bundled into an ArcGIS Toolset Tools grouped into Pre-Processing, Risk Analysis and Mapping Core processes utilize sub-models similar to software library routines (eg; Risk Core Engine) 17

18 ModelBuilder Risk Tools ModelBuilder: Pre-Processing Example 18

19 ModelBuilder: Risk Engine Module ModelBuilder Risk Tools Risk Scoring Engine calculates the risk score for each sewer pipe. Risk criteria entered Core processes utilize submodels similar to software library routines (eg; Risk Core Engine) Utilizes the Iterator Row Selection 19

20 Using ModelBuilder ModelBuilder: Tips and Tricks Spatial Join tool works intermittently Test tools before adding to model layout Use model variable to define absolute project path name Linking tables from MS Access is painful! 20

21 Risk Analysis Results LOF Scores Risk Analysis Results 21

22 Risk Analysis Results COF Scores Risk Analysis Results 22

23 Risk Analysis Results Total Scores Risk Analysis Results 23

24 Using the Risk Model CIP Prioritization Risk Model General: Use risk factors (total score) to identify and prioritize CIP projects Other factors that impact CIP projects: Pavement program schedule Regulatory / internal rehab targets (miles per year) Project grouping practical benefits CIP budget CIP Projects (Example)

25 Summary: Using ModelBuilder to Evaluate Risk Summary Risk model provides a rational basis for prioritizing projects for CIP Use of GIS tools and ModelBuilder provide an efficient and repeatable process Agency staff can update the risk analysis and CIP as data and conditions change 25

26 THANK YOU! ESRI User Conference 2015 Using Model Builder to Evaluate Risk and Prioritize Sewer Upgrades Presenters: Erin Smith (City of Alameda) Andy Baldwin (RMC Water and Environment)