PRINCIPAL POLICIES OF THE TOKYO METROPOLITAN GOVERNMENT

PUBLIC ENTERPRISE BUREAUS

Bureau of Sewerage

Overview

The Bureau of Sewerage supports the cycle of water in Tokyo as well as healthy and cultural life for Tokyoites and smooth urban activities. Total coverage of sewerage services in the ward area was achieved at the end of fiscal 1994 and 97% of the Tama area at the end of fiscal 2006.
In line with the Sewerage Operation Plan 2007 (formulated Feb. 2007), environmentally-oriented projects are currently underway to restore Tokyo's beauty as a city of water and greenery, have Tokyo become the city with the lowest environmental load in the world, and strengthen Tokyo's disaster preparedness. Among these, reconstruction projects, flood control measures, and improving combined sewage systems are implemented as priority projects.
In addition, in line with the Earth Plan 2004―a plan to mitigate global warming effects in sewerage projects formulated in fiscal 2004―and the Ten-Year Project for a Carbon-Minus Tokyo―a project aiming to lower carbon dioxide and other greenhouse gas emissions―initiatives are taken to preserve the global environment by promoting measures to reduce greenhouse gas emissions. These include conversion to energy-saving systems in all sewerage facilities and conversion of incinerators to carbonization or gasification incinerators.

Sumidagawa River water quality and sewerage service rate

Note1: Sewerage service rate for Itabashi, Kita and Nerima wards of the Sumidagawa River basin Note2: Water quality is annual BOD at the Odaibashi survey point (75% water quality) (graph formed by the Bureau of Sewerage based on data from the Bureau of the Environment)

Sewerage in the Ward Area

Wastewater Sludge Carbonization Plant (Tobu Plant)

*Facility carbonizing wastewater sludge. This is supplied to power suppliers as an alternative to fossil fuel

Reconstruction of Aging Facilities

Over 80% of sewer pipes in the city center have exceeded the legal service life of 50 years. The bureau is promoting the reconstruction of key facilities in sewerage works such as the sewer mains that comprise the backbone of support for the removal of wastewater.

Flood control measures

Because a large proportion of storm water from the increasingly frequent occurrences of torrential rainfall runs into the sewer lines in a short period of time, sewer lines have an extremely important role in the removal of rainwater. To this end, priority status is given to areas at high risk of flooding with work underway to bolster the performance of sewage lines and rainwater removal facilities and to upgrade facilities controlling the overflow of storm water. The rainfall information system, Tokyo Amesh, will be renewed in an effort to strengthen response capabilities.

Wadayayoi Sewer Main (storm water storage pipe)

Upgrading Combined Sewage Systems

82% of the ward area is served by combined sewage systems in which wastewater and storm water are channeled through the same sewer line. This results in problems arising during times of heavy rainfall, with some of the wastewater diluted by storm water flowing out to the rivers and sea.
The bureau is undertaking ways to cope with this issue by installing wider sewer lines to channel the especially polluted storm water in the initial period of rainfall to the water reclamation center, as well as by constructing storm water reservoir tanks. Efforts are also taken to raise public awareness on the harm of pouring oil down the drains.

Tokyo Amesh		Recipes for low-fat cooking
Real-time rainfall information that can be accessed through the Internet		Preventing Tokyo residents from washing oil down the drains, by offering recipes for low-fat cooking, prepared by the bureau; contributes to the health of the people as well as the sewerage system.