Using Your Own Resources,
or CSI
City Sewer Investigation
Crime / Inflow and Infiltration Scene
• Crime Scene
– Examine the evidence
to determine what
happened to the
victim.
– Process
•
•
•
•
•
Secure the scene
Search the scene
Collect evidence
Interview people
Follow the evidence
– Determine the Facts.
• I/I Scene
– Examine the evidence
to determine what is
happening
underground.
– Process
•
•
•
•
Interview operators
Collect data
Collect evidence
Follow the evidence
– Determine the Facts.
CSI, the Operators Way
• Use Investigative
Skills
– Locate the evidence
– Determine the
message in the
evidence
– Follow the evidence
• Common Sense
What do you already know?
•
•
•
•
•
•
Maps
Plant Flow Data
Pump Station Run Times
Overflow records
Violations, Backups
Employee Knowledge
• Where does the data lead
you?
• Where is the “Most likely
suspect?”
What’s the Fact
in the Figures
• Long columns of Data
can be misleading.
–
–
–
–
Summarize it
Graph it
Trend it
Analyze it
• Statistical Analysis
helps us find the
“facts in the figures.”
Date
Peak Flow
Avg Flow
1/00
1.5
0.725
2/00
1.7
1.02
3/00
2.22
0.89
4/00
3.1
1.12
5/00
1.4
0.503
6/00
1.7
0.396
7/00
1.11
0.346
8/00
1.13
0.387
9/00
1.17
0.36
10/00
1.2
0.341
11/00
1.2
0.478
12/00
1.5
0.554
1/01
2
0.767
2/01
3.1
1.29
3/01
1.5
0.829
4/01
1.5
0.676
5/01
1.2
0.429
6/01
1.2
0.322
7/01
2.9
0.448
8/01
1.14
0.586
9/01
0.98
0.343
10/01
1.12
0.346
11/01
0.9
0.336
12/01
2.7
0.897
Wow! Moment
2.5
f low _ma
Avg Trend
f low _dx
DayMax Trnd
design
Flow mgd
2
1.5
1
0.5
0
10/92
10/93
4/93
10/94
4/94
10/95
4/95
Date
10/96
4/96
10/97
4/97
What do you see?
• Influent Color
– Muddy
– Clear
• Influent Debris
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Fish, crawdads
Grass clippings
Leaves
Magnolia Pods
• What’s the Message?
What does the Evidence Say?
Follow the Evidence
• Use your maps
• Go look, Ground Inspection!
• Walk the lines, take your camera, notebook
– Dry Weather
•
•
•
•
Missing manhole lids
Manhole damage
Illegal dumping
Missing manholes
– Wet Weather
What does the Evidence Say?
What does the Evidence Say?
CSI in the Dark
• Night time flows,
~ 2:00 am
– Small systems should
have little flow
– Residential mains
should have little flow
– Test the flow:
•
•
•
•
ORP,TDS
Ammonia
TSS
BOD
Wet Weather
• Flooded or
overwashed
manholes
• Leaking manholes
• Check flow
– Visual
– Depth of flow
– Percentage of pipe
What does the Evidence Say?
Wet Weather
• Follow up checks after the rain
– As soon as it stops raining
– An hour or so later
– The next day
• What did the evidence tell you?
• What is the next step?
• Perhaps now you need a TV camera.
Extended Dry Weather
• Best time for smoke
testing.
• Find the big leaks
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Catch basins
Clean-outs
Gutters
Open taps
Dry traps
So what do you do?
Cold Weather
• Check suspect stream crossings in bitter
cold weather.
• Check the sewage temperature in above
and below manholes.
• If the temperature drops the cold stream
water is leaking in!
Cold Weather & Warm Sewage
• Warm catch basins
• Warm manholes
Assistance of Others
• Meter readers, public works & safety
workers, public.
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Missing cleanout plugs
Missing houses with open service laterals
Surface water drains
Gutter connections
Leak-Leak where is the Leak?
• Where did the
evidence “lead” you?
• Did you find it?
• Could you fix it?
• Do you need help?
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–
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Camera crew
Engineer
Contractor
Other
Using Your Own Resources
• Use your existing data.
• Use your operators knowledge.
• Conduct Ground Inspections
– All seasons present inspection opportunities.
• Find problems:
– Fix them (inflow) or
– Use the knowledge for a larger project.
Inflow and Infiltration
• Benefits of sewer line rehabilitation
– Less Risk:
– of regulatory action,
– of legal action,
– of spreading disease.
– Lower Costs:
– for pumping, treatment, disposal,
– from clean-up,
– from fines.
– Enhanced Reputation:
– proper operation and maintenance,
– professional management of the system
– quality customer service.
Module #4
• Plans for reducing I/I in your community.
– What can you do?
•
•
•
•
One Month
Three Months
Six Months
Twelve Months
Summary
• Objective One:
– Listed your work and
the work of others
Summary
• Objective Two:
– Identify what cities are currently doing in
reducing I/I
– Metro Nashville’s Program
– Small City Example
Summary
• Objective Three:
• Ten Points
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Identify Goals
Select Target Area
Quantify Problem
Locate Defects
Select Pipe Segments
Estimate Cost-Benefit
Design & Install
Verify Performance
Follow-up Flow Monitoring
Calculate O & M Savings
• Using your Resources.
– If Ed Norton can…
Summary
• Plans for reducing I/I
in your Community.
– Action Plan
• Short Term
• Long Term
Summary
• Closing thoughts or comments?
• Any I/I Epiphanies?
• Moments of realization?
• New insights?