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

0

0.5

1

1.5

2

2.5

Date

Flo

w m

gd

10/92 4/93

10/93 4/94

10/94 4/95

10/95 4/96

10/96 4/97

10/97

f low _ma

flow _dx

design

Avg Trend

DayMax Trnd

What do you see?

• Influent Color– Muddy– Clear

• Influent Debris– 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– 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.– 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?

– 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

– 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?