Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...

The water and sewer utilities are managed on a municipality basis, i.e., the local town or city government
takes responsibility for the sewers and water mains. It has recourse to the prefecture and to the central
government to obtain funds to supplement locally raised revenue for capital expenditure, but it funds
maintenance work from its own budgets. With the economy at a low ebb, tax revenues which fund this
expenditure are stressed, and this is in part responsible for the downturn in pipeline construction and
maintenance.
The development of a piped sewer system in Japan commenced in the latter half of the 19 th century –
prompted by major cholera outbreaks in Nagasaki and Yokohama in 1877. Piped sewers were
constructed in the foreigners’ settlements in Yokohama and Kobe. Tokyo Metropolitan Government
began public sewer construction in 1884. Thereafter, other major cities began sewer construction, but the
pace of development lagged somewhat behind Europe and the United States. Sewerage was generally
managed with an efficient system of collection and transportation of night soil for disposal as agricultural
fertilizer. The system collapsed during World War II due to fuel shortages caused by the Allied blockade
of shipping. The development of a modern sewerage system was a priority in post-war recovery and
sewer construction became an important source of employment for unskilled labor.
However, network growth was slow and sewerage services were only available to 7% of the population in
1963, until it was accelerated by a series of Five Year Plans for Sewerage Construction. Thereafter, a
network of public sewers was rapidly developed to collect and deliver sewage to treatment facilities.
Sewer pipe construction peaked at 68,000 km per annum in 1986. As of 2007, 72% of the population had
connected to the public sewer system and construction continues at about 10,000 km per annum. The
traditional night soil collection system was progressively abandoned, but is still practiced for about 25
million people living in small towns and in country districts. In those communities with fewer than
50,000 population, the connection rate to a public sewer is still only about 29%. Over time, the night soil
collectors have evolved into small local sewer construction and maintenance contractors and some have
entered the growing rehabilitation business to exploit their important connections with local government.
The Japanese sewer network currently comprises about 380,000 km of pipeline. It is funded by a
combination of local and central government support in equal measure at a cost of about ¥ 2,392 billion
(U.S. $29.17 billion) per annum. The Tokyo Metropolitan budget is ¥ 120 billion (U.S. $1.46 billion) to
provide for repair, rehabilitation, and new construction of its 15,000 km network and treatment facilities.
At the present time, this work involves rehabilitation of about 80 km of sewer per annum.
In common with many countries, the life of a sewer pipe in Japan is designated as 50 years. However, in
contrast to other countries where the actual life is often substantially longer, the life cycle of pipes
installed in Japan is often compromised by a combination of aggressive corrosion and frequent
earthquakes. Whilst European and U.S. cities benefit from a legacy of soundly built 19 th century
underground infrastructure, much of Japan’s sewer network was built in a post-war boom by day labor
using basic pipe products. Much of the network is reinforced concrete pipeline constructed until the mid
1980s from plain ended (Type A) centrifugally spun concrete pipe with cement mortar joints.
According to the Japan Sewerage Works Agency (JSWA), sewer pipe reconstruction commenced around
1946 and continued through the 1970s by open cut methods at a rate of 15 to 40 km per annum. From
about 1975, the rate of replacement increased steadily from 40 to 90 km per annum. The Agency has
analyzed the age of pipe at reconstruction finding two peaks of activity, 10 to 20 and 50 to 60 years after
installation. The Agency has concluded that the first major peak (at 10 to 20 years) is associated with
construction faults and that the latter peak is associated with aging of the fabric of the pipe. JSWA
estimates that 6,000 km of the network is more than 50 years old and 50,000 km is over 30 years old. For
these reasons, Japan experiences an unusually high and increasing level of sewer collapse. In 2005, there
were 6,600 collapses (see Figure 8-1). Thirty-year-old pipes are exhibiting about 40 collapses per 1,000
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