4/19/2012
Ivan Howitt
John Fishburne

What is the Problem?

Acoustic Inspection
InfoSense, Inc
CMU
◦ What is it? / How does it work?
◦ CMU/InfoSense Field Trial Brief Summary

Condition Based Maintenance (CBM) for
Collection System Cleaning
◦ Concept / Trade-Offs
◦ Scenarios
2012 NC AWWA-WEA Spring Conference
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4/19/2012

Overflows are a Symptom – Not the Problem
2012 NC AWWA-WEA Spring Conference
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Charlotte
Mecklenburg
County, NC
~4
miles




Five Year Overflow Record –
Different Color / Year
Overflow locations
– “Random”
Historical GIS –
Helpful – But
Insufficient
Where & When to
Deploy Cleaning
Resources
Cost Effective &
Timely Condition
Information
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4/19/2012
25
Sixteen Municipalities’
Overflows/100mi vs.
% System Cleaned Annually
Overflows / 100mi
20
15
Linear Regression –
Standard Deviation: 2.5
10
Charlotte
76%
5
2
0
10
20
30
40
50
60
70
% System Cleaned Annually
80
One Sigma Below
Mean 45%
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
Requirements
◦ Determine Where & When to Deploy Cleaning
Resources
◦ Cost Effective – Inspection Cost << Cleaning Cost

Benefit
◦ Reduce Wasted Cleaning Effort
◦ Improved Performance
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How It Got Started –
UNCC & CMU “Brainstorming” Session
Sewer Lines – Natural Acoustic Wave Guides
Obstructions – Acoustic Signals Absorb & Reflect
Diagnostic Tool – Evaluates Aggregate Blockage
Transmitter
“Yells”
Receiver
“Listens”
2012 NC AWWA-WEA Spring Conference
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




No Flow Contact / No
Confined Space Entry
Low Cost–Pennies/foot
Rapid Onsite Results –
Under 3 min./segment
Portable < 30 lbs
GIS Integration – GPS
Enabled
Archive Pipe Segment
Blockage Assessment
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
Two Central Questions Performance &
Operational Cost
◦ Evaluated During 2010 CMU / InfoSense SL-RAT
Field Trial
◦ NC-AWWA 2010 Spring Fling & Annual Meeting

Blockage Assessment Performance Evaluation
Based on Comparison with CCTV
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No Obstructions
10
Root Fibers Limited Growth
Grease Limited Build Up
8
Root Fibers and/or Grease
Robot Can Pass Through
5
Root Fibers and/or Grease
Robot Cannot Pass Through
2
Obstructed
0
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5
CCTV Blockage
Assessment 10
CCTV Blockage
Assessment 7
CCTV Blockage
Assessment 5
CCTV Robot was Able to
Pass Through Root Fibers
4/19/2012
CCTV Blockage
Assessment 2
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SL-RAT Blockage Assessment
10
SL-RAT Standard Threshold
• 61% Reduction in Cleaning
• All Pipes Requiring Cleaning
are Cleaned
8
6
SL-RAT Critical Threshold
• 85% Reduction in Cleaning
• Identify Pipes in Critical Need
of Further Action
4
2
0
0
2
4
6
8
CCTV Based Blockage Assessment
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
10
CCTV & SL-RAT Acoustic Inspect
>50% Pipe Segments Did Not Require Cleaning
SL-RAT Assessment Correlated with CCTV
SL-RAT Provides Conservative Assessment
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
Typical Industry Values : Cleaning Crew $1.00/foot

Estimated SL-RAT Inspection Crew
Number of Crew Members
Annual Fully Loaded Salary Per Crew Member
Annual Equipment Costs (Including Truck & SL-RAT)
Work Days Per Year
Onsite Work Hours Per Day
SL- RAT Average Number of
Segments Inspected Per Hour
Average Sewer Line Segment Length in feet
Cost Per Foot
2
$68,000
$24,000
251
5.5
6
220
$0.09/ft
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SL-Segment Condition
P, Potential
Failure
D, Detect
Potential
Failure
ΔTD
F-D
CBM
Inspections
ΔT
F-P
F,
Functional
Failure
Operation Time


Resource Efficiency Utilization Through
Condition Assessment
Trade-Off - Inspection vs. Cleaning
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Cleaning Cost / 100 mi Pipe (Millions $)
4/19/2012

0.4
0.35
0.3
Baseline Cleaning
Program

◦ Cleaning Cost / Foot $1
0.25
% Collect System for
2 Overflows/100mile
Based on One Sigma
Lower Bound
0.2
0.15


0.05
30
40
50
60
70
Total Pipe Segments in Cleaning Operation (%)
Performance Model
◦ Linear Regression for 16
Municipalities Overflows
vs %System Cleaned
0.1
20
Cleaning Program Current Practice
Cost Model
Benchmark
◦ 2 Overflows/100mi
◦ 45% System Cleaned –
Low Confidence
◦ 75% System Cleaned –
Modest Confidence
2012 NC AWWA-WEA Spring Conference
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

1000ft
SL-RAT
Assessment
Blocked (0)
Poor
(1– 6)
Clean (6 – 10)
SL-RAT Inspection
Prior to Cleaning
Only Clean Segments
Below Standard
Threshold
Illustrative Case
◦ 52,000 ft Basin
◦ 30,000 ft Assessed by
SL-RAT as “Clean”
◦ 22,000 ft Below
Threshold & Cleaned
◦ 58% Reduction in
Cleaning
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4/19/2012

Cleaning Cost / 100 mi Pipe (Millions $)
% Collect System for 2 Overflows/100mi
Based on One Sigma Lower Bound
◦ Use CMU/InfoSense
Field Study Results
◦ SL-RAT Cost/Ft $0.09
0.3
Baseline Cleaning
Program
0.25
CBM
Cleaning
Program I
0.2

1
20
Point “1”
◦ 20% SL-RAT Acoustic
Inspection
◦ ~7.8% Cleaned
2
0.1
0.05

x 2.1
0.15
Evaluate CBM
Cost/Performance
Point “2”
◦ 42% SL-RAT Acoustic
Inspection
◦ ~16.6% Cleaned
30
40
50
60
70
80
Total Pipe Segments in Cleaning Operation (%)
2012 NC AWWA-WEA Spring Conference
Cleaning Cost / 100 mi Pipe (Millions $)
% Collect System for 2 Overflows/100mi
Based on One Sigma Lower Bound

0.3
0.25
Baseline Cleaning
Program
0.2
0.1
20
◦ Same CBM Program I
◦ 20% Acoustic Inspection
◦ ~7.8% Cleaned
x 2.1
0.15
0.05

CBM
Cleaning
Program I
2
1
Prioritize - Target
High Risk Segments
Point “1”
CBM
Cleaning
Program II
30
40
50
60
70
80
Total Pipe Segments in Cleaning Operation (%)

Point “2”
◦ 63% Acoustic Inspection
◦ ~14.1% Cleaned
◦ ~9.5% Evaluated as
Critical
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4/19/2012

Collection System Cleaning Operations
Condition Based Management (CBM) Benefits
◦ Cleaning Resources Efficiently Deployed
◦ Reduces Non-Productive Cleaning Effort
◦ Prioritizes Cleaning & Provides Flexibility in
Balancing Risk with Cost

Acoustic Inspection Enabler for CBM Cleaning
Program
◦ Inspection Cost << Cleaning Cost
◦ Assessment Correlated with Cleaning Requirements
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