PRESENT AGING STATE OF SEWER SYSTEM – CONDUIT

Sewer 1/8

While sewer system spread for its total conduit length to reach 440,000 kilometers, severe progressive aging
appeared. Further accelerative increase is anticipated at ones of 50-year age or above.

Conduit Aging Examples

Built-length by Fiscal Year (As of FY2002 )Approx.
440,000 km

20

Built-length by Fiscal Year(x 1,000km)

Cumulative
累計整備延長15Rapidincrease inAge > 50 yrs

500

400
Cumulative Built-length(x 1,000km)

布設年度別整備延長
By Fiscal Year

300

10200

5100

0

Concrete Corrosion/Aggregate Exposure

Concrete Corrosion/Rebar Exposure

Collapsed Conduit

Underground Water Leak-in

0S29以前
1954

S37
1962

S45
1970

S531978

S611986

H61994

H142002

H22201050 yrs

As of FY2002

10 yrs later

Length & % of Age > 50 yrs
Approx. 10,000 km(2%)

20 yrs later
Approx. 100,000 km(23%)

Approx. 30,000 km(7%)

Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

CONDUIT AGING PROBLEMS

Sewer 2/8Conduit aging causes 4,000 to 5,000 road cave-ins annually.
Number of Nationwide Road Cave-ins1981

Depth of Road Cave-ins
6%1%

1986

1991

1996

2001

Mostly in small-scale, more than 90% of cave-ins
are less than 50 cm in depth.

2006

Car Accident induced by Road Cave-in
Nagoya City in 2009

0～50cm93%

50～100cm
100cm～FY2010 Occurrence

Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

2011

Chiba City in 2009

PRESENT AGING STATE OF SEWER SYSTEM – TREATMENT PLANT Sewer 3/8
About a half of mechanical/electrical equipment at nationwide treatment plants already went beyond theirservice lives. The number of treatment plants implementing renewal will continue to increase.

Treatment Plants in Service by Fiscal Year (As of FY2002 )Equipment Aging Examples

By Fiscal Year
Cumulative

1930

1940

1950

1960

Ingress Gate difficult toopen/close

Approx. 2,200
existing plants
Cumulative Commenced Service

Number of Commenced Service by Fiscal Year

Damaged Bearings at
Heavy-duty Pump

1970

1980

1990

2000

自動除塵機(ｶﾞｲﾄﾞﾛｰﾗ)の偏摩耗

Fire induced by Electric Leak at Aged Transformer

2010

15 yrsApprox. 1,100 plants haveserviced longer than 15 yrs
and commenced or arescheduled to commence
equipment renewal.
Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

A meter transformer waslocated.

PRESENT AGING STATE OF SEWER SYSTEM – TREATMENT PLANT Sewer 4/8
 Local government offices with set-out programs of survey and inspection for conduits account for only
20% of all.
 About 40% of sewer data books have not been yet computerized.

Local Government’s Programs set out for
Survey and Inspection on Conduits

Maintenance of Sewer Data Book

Unanswered: 1%

With program: 20%
Not yet:41%
Computerized:
59%

Without program: 79%

1,504 sewer operators were surveyed at
the end of FY2010.

Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

1,496 sewer operators were surveyed at
the end of FY2011.

COPE WITH AGING SERWER SYSTEM –(1) PROMOTE ASSET MANAGEMENT PRINCIPLE

Sewer 5/8

Implement asset management based preventive maintenance to seek for reducing;1) Risks of accidents and breakdowns from increasing aged system
2) Future retrofitting costs through system’s lifetime improvement

Maintenance methods for sewer conduits

Leveling retrofitting works by lifetime improvement

Inspection

Cleaning

Retrofitting Length (km)Whole retrofitting at 50 year lifetime
20018016014012010080604020

Inside Visual
Inspection

9590858075

7065

6055

5045

403530252015

51000200
180

Occasional
retrofitting through lifetime
140
improvement
and soundness evaluation
120
160

10080
60
40

2095

9085

80

75

70

65

6055

50

45

40

3530

25201510500Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

Remote-operated
camera survey

COPE WITH AGING SERWER SYSTEM –(2) IMPLEMENT ECONOMICAL RETROFITTING

Sewer 6/8

Execute retrofitting without open-cut to minimize cost and adverse effect to traffic. Many specialist
contractors have 20 to 30 methods and are actively developing more technology.
Examples of conduit retrofitting【EX 1: Inflatable Inner Tube】
STEPS
FlushGuideInflateFix【EX 2: Spiral Inner Tube】

Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

UPGRADING AT PLANT RENEWAL

Sewer 7/8

Promote upgrading of treatment plants at renewal besides lifetime improvement.

Electric Power Saving

Energy Recycle from Sewer Waste

Install energy saving equipment

Aeration BlowerTreatment Plant

1) Better and lessCoal-fired PowerStationSludge
Cake
Carbonized FuelPlant

Upgrade toefficient system

Aeration Tank

BeforeFuel

2) Aeration refinement

After

20% Reduction at Power Consumption

Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .

Recycle Sludge

New Energy Alternative
Greenhouse Gas ReductionVERIFY CONDUIT MAINTENANCE TECHNOLOGY

Sewer 8/8

 Required preventive maintenance for sustainable sewer system needs effective inspection and surveytechnology.
 The Government takes initiative in verifying more effective screening technology than ever for promoting
local governments’ implementation.
 Public invitation is called to select three research groups.

Verification project for effective conduit maintenanceby advanced optic recognition technology

Multiple-lenses Camera

Attachments

Conduit Portal Camera

Inner-conduit Profiling Camera

Wide-Angle Camera

Impact Elastic Wave Method

Verification project for effective conduit maintenanceby profiling technology

Verification project for effective conduit maintenanceby wide-angle camera and impact elastic wave method

Copy right (c) 2013 Ministry of Land, Infrastructure, Transport and Tourism, Japan, All rights reserved .