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Next Generation Sewer

Inspection Techniques:

The TISCA research program:

Technology Innovation for

Sewer Condition Assessment

Jeroen Langeveld, TU Delft/Partners4UrbanWater

Francois Clemens, TU Delft/Deltares

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Sewers and pressure mains in NL

97.300 km gravity sewer, diameter range

200 – 2.500 mm, mainly concrete and PVC

13.000 km pressure main, diameter range

150-1.500 mm, AC, concrete, steel, DI,

PVC

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Gravity sewers: main properties • Hydraulic performance

• Structural performance

• No leakage

• => CCTV dominant inspection technique

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Gravity sewers

• Hydraulic performance

• Structural performance

• No leakage

• => CCTV dominant inspection technique

for decades

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CCTV inspection: clean sewer first

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Insert camera and assess footage

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BAA Deformation

BAB Fissure

BAC Break/Collapse

BAD Defective brickwork or masonry

BAE Missing mortar

BAF Surface damage

BAG Intruding connection

BAH Defective connection

BAI Intruding sealing material

BAJ Displaced joint

BAK Lining defect

BAL Defective repair

BAM Weld failure

BAN Porous pipe

BBA Roots

BBB Attached deposits

BBC Settled deposits

BBD Ingress of soil

BBE Other obstacles

BBF Infiltration

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From inspection to decision making

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Humans are weakest link in visual

inspection

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+ some more inherent limitations….

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Pressure mains

• Limited number failures/operator/year

• Average 1 failure/100 km/year (6 for

drinking water mains)

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Current status?

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Consequences of failure

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Inspection of pressure mains?

• No ‘one size fits all’ inspection technology

available (same for gravity sewers)

• Pressure mains not designed for O&M:

– No redundancy

– No access for inspection equipment, smart

pigs

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Inspection of gravity sewers and

pressure mains

Both require inspection data on:

I. Hydraulic performance

II. Structural stability

III. Leakage: infiltration or exfiltration

=> As one-size fits-all doesn’t work, we

need to move towards the next generation

sewer inspection techniques

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TISCA Program

• 5 projects:

– FEM failure model for deteriorated concrete

pipes including soil

– Automatic pattern recognition of CCTV

footage

– In sewer drone/multi-sensor platform

– Flying drone with IR camera, ground

penetrating radar

– Geo-electric leak detection

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Automatic pattern recognition

Or: how to get rid of the human factor

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Laser profiler

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Sonar

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Infrared camera

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UV camera

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Water quality sensors

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ground penetrating radar (GPR)

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Electro scanning

From within the pipe

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Geo-electrical methods

I. Electrical Resistivity Tomography (ERT)

II. Self Potential measurements (SP).

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TISCA Challenges

• Combining data from several types of

sensors in assessment

• Valuing information quality: inspection

has been too cheap in last decade

• Operators/municipalities need to specify

what they are afraid of….