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Ivan Howitt InfoSense, Inc John Fishburne CMU
What is the Problem?
Acoustic Inspection
◦ 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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Overflows are a Symptom – Not the Problem
2012 NC AWWA-WEA Spring Conference 3
Overflow locations – “Random”
Historical GIS – Helpful – But Insufficient
Where & When to Deploy Cleaning Resources
Cost Effective & Timely Condition Information
2012 NC AWWA-WEA Spring Conference
Charlotte
Mecklenburg
County, NC
~4
miles
Five Year Overflow Record –
Different Color / Year
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2012 NC AWWA-WEA Spring Conference
10 20 30 40 50 60 70 800
5
10
15
20
25
% System Cleaned Annually
Ove
rflo
ws /
10
0m
i
76%
Charlotte
Sixteen Municipalities’
Overflows/100mi vs.
% System Cleaned Annually
2
Linear Regression –
Standard Deviation: 2.5
One Sigma Below
Mean 45%
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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2012 NC AWWA-WEA Spring Conference
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”
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
2012 NC AWWA-WEA Spring Conference
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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
2012 NC AWWA-WEA Spring Conference
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10
5
0
8
2
Obstructed
No Obstructions
Root Fibers Limited Growth
Grease Limited Build Up
Root Fibers and/or Grease
Robot Can Pass Through
Root Fibers and/or Grease
Robot Cannot Pass Through
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NC AWWA-WEA 90th Annual Conference
CCTV Blockage
Assessment 10
CCTV Blockage
Assessment 7
CCTV Blockage
Assessment 5
CC
TV
Ro
bo
t w
as A
ble
to
Pass T
hro
ug
h R
oo
t F
ibe
rs
CCTV Blockage
Assessment 2
11
0 2 4 6 8 100
2
4
6
8
10
CCTV Based Blockage Assessment
SL
-RA
T B
locka
ge
Asse
ssm
ent
12 2012 NC AWWA-WEA Spring Conference
SL-RAT Standard Threshold
• 61% Reduction in Cleaning
• All Pipes Requiring Cleaning
are Cleaned
CCTV & SL-RAT Acoustic Inspect >50% Pipe Segments Did Not Require Cleaning
SL-RAT Assessment Correlated with CCTV
SL-RAT Provides Conservative Assessment
SL-RAT Critical Threshold
• 85% Reduction in Cleaning
• Identify Pipes in Critical Need
of Further Action
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Typical Industry Values : Cleaning Crew $1.00/foot
Estimated SL-RAT Inspection Crew
Number of Crew Members 2
Annual Fully Loaded Salary Per Crew Member $68,000
Annual Equipment Costs (Including Truck & SL-RAT) $24,000
Work Days Per Year 251
Onsite Work Hours Per Day 5.5
SL- RAT Average Number of
Segments Inspected Per Hour
6
Average Sewer Line Segment Length in feet 220
Cost Per Foot $0.09/ft
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2012 NC AWWA-WEA Spring Conference
Resource Efficiency Utilization Through Condition Assessment
Trade-Off - Inspection vs. Cleaning
F, FunctionalFailure
P, PotentialFailure
D, Detect Potential Failure
SL
-Seg
men
t C
on
ditio
n
Operation Time
CBM
Inspections
ΔT
F-P
ΔTD
F-D
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Cleaning Program - Current Practice
Cost Model ◦ Cleaning Cost / Foot $1
Performance Model ◦ Linear Regression for 16
Municipalities Overflows vs %System Cleaned
Benchmark ◦ 2 Overflows/100mi
◦ 45% System Cleaned – Low Confidence
◦ 75% System Cleaned – Modest Confidence
2012 NC AWWA-WEA Spring Conference
20 30 40 50 60 70
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Total Pipe Segments in Cleaning Operation (%)
Cle
anin
g C
ost
/ 100 m
i P
ipe (
Mill
ions $
)
Baseline Cleaning
Program
% Collect System for
2 Overflows/100mile
Based on One Sigma
Lower Bound
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
2012 NC AWWA-WEA Spring Conference
1000ft
Poor (1– 6)
Clean (6 – 10)
Blocked (0) SL-RAT
Assessment
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2012 NC AWWA-WEA Spring Conference
% Collect System for 2 Overflows/100mi
Based on One Sigma Lower Bound
Baseline Cleaning
Program
CBM
Cleaning
Program I
x 2.1
1
2
20 30 40 50 60 70 80
0.05
0.1
0.15
0.2
0.25
0.3
Total Pipe Segments in Cleaning Operation (%)
Cle
anin
g C
ost
/ 100 m
i P
ipe (
Mill
ions $
)
Evaluate CBM Cost/Performance ◦ Use CMU/InfoSense
Field Study Results
◦ SL-RAT Cost/Ft $0.09
Point “1” ◦ 20% SL-RAT Acoustic
Inspection
◦ ~7.8% Cleaned
Point “2” ◦ 42% SL-RAT Acoustic
Inspection
◦ ~16.6% Cleaned
Cle
anin
g C
ost
/ 100 m
i P
ipe (
Mill
ions $
)
20 30 40 50 60 70 80
0.05
0.1
0.15
0.2
0.25
0.3
Total Pipe Segments in Cleaning Operation (%)
2012 NC AWWA-WEA Spring Conference
Prioritize - Target High Risk Segments
Point “1” ◦ Same CBM Program I
◦ 20% Acoustic Inspection
◦ ~7.8% Cleaned
Point “2” ◦ 63% Acoustic Inspection
◦ ~14.1% Cleaned
◦ ~9.5% Evaluated as Critical
Baseline Cleaning
Program
CBM
Cleaning
Program I
CBM
Cleaning
Program II
x 2.1
1
2
% Collect System for 2 Overflows/100mi
Based on One Sigma Lower Bound
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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
2012 NC AWWA-WEA Spring Conference 19
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