### a. Initiatives towards the septic system overview in roughly 10 years

In regards to the maintenance of sewage treatment facilities, individual disposal by using septic tanks are economical in areas where households are widely distributed throughout a region, while the collective disposal with sewerage systems and drainage facilities for agricultural communities becomes more economical as the population density rises. For this reason, each prefecture has established a “Prefectural Plan”, a compiled maintenance plan over sewerage treatment which reflects considerations over regional characteristics such as the economic efficiency and importance of protecting water quality. Currently, in light of the population decline of recent years, MLIT is promoting an immediate re-examination of prefectural schemes and the creation of mid-term (action plan)/long-term equipping plans, in order to work towards a septic system overview in roughly 10 years. In addition, efficient means of maintenance are also being actively promoted through the implementation of cooperative schemes between other waste water treatment facilities such as cross-jurisdictional wastewater treatment.

### b. Sewage quick project

Taking into account the population decline and the difficult fiscal situation, this project seeks to widely introduce—with the cooperation of the district citizens and verification of the performance by a committee of experts—maintenance methods that are not stuck in technological standards of the past, that meets the current conditions of the district, and that are low-cost, while making early and flexible maintenance possible. By FY 2014, a social experiment was conducted in 14 municipalities, and 6 technologies—such as the “Small-Scale Waste-Water Treatment Facility (contact oxidation method)”—were determined to be effective, leading to a user’s guide being put together for the use of these technologies. The verification/evaluation of the other technologies is in progress to make nationwide usage possible.

Figure II-8-4-5

Example of Implementing the Sewerage Quick Project (Small-Scale Waste-Water Treatment Facility in Engaru Town, Hokkaido)

Source) MLIT

## (2) Attaining durability in sewerage projects

### a. Proper stock management

Sewage systems possess enormous amounts of stock consisting of approximately 460,000 kilometers of pipes and conduits and approximately 2,200 terminal treatment stations (as of the end of FY 2014).

As these systems were rapidly developed during and after the period of high economic growth, aging facilities are expected to rapidly increase in number in the future. Although in FY 2014, mainly small scale issues were arising, road collapses have occurred in 3,300 places due to corrosion caused by hydrogen sulfide and aging of the conduit facilities. Because the sewage system is an important social infrastructure which supports the safe and secure social and economic activities of urban living and provides a lifeline that is difficult to replace with alternative means, there is a necessity to sustain the required functions by conducting efficient, planned measures to deal with aging facilities through the introduction of stock management that practices preventative maintenance, while at the same time considering the