Sewer maintenance of foreign settlements

With the opening of Yokohama in 1859 (1859), the aspect of Yokohama, which was only a small fishing village, changed completely.

Starting with the construction of wharfs and the development of settlements, town development as an opening port has been started. Yokohama brought various technologies and artifacts that could be said to be the cutting edge of the time because of its character as a point of contact with foreign countries. Even today, those features can be seen in various parts of the city.

In addition to parks, newspapers, horse races, railways, telegraphs, water supply, gas, and other technologies that are used in Yokohama for the first time in Japan are often introduced. These technologies are the latest technologies of developed countries in Europe and the United States, which had been accomplishing the Industrial Revolution at the time, and this is why Yokohama is called the place of introduction of modern technology.

R.H. Blanton (collected by the Port Opening Museum)

Foreigners in the settlements were keenly aware of the situation in their own country, which had been polluted with the development of industry, and were keenly aware of the importance of urban infrastructure development. Also, at that time, cholera was prevalent both in foreign countries and in Japan, so the drainage of settlements and the improvement of sewerage were a longing for the residents. At that time, digging was laid on the main road in Yokohama and played a role as a sewer, but it was structurally inferior, that is, overflowing in various places, It was less than compared to Western sewers, which drained sewage into buried pipes.

After the Meiji New Government was born by the Meiji Restoration, it was British Blanton (Richard Henry Brunton), the first employed foreigner in the Meiji government, based on the "Yokohama Relocation Memorandum" exchanged between the consuls of each country and the Shogunate in November 1864.

The sewerage maintenance plan for the settlement was started in 1869 (1869) and completed in 1871 (1871). This sewer buried a sewer pipe with a tile pottery pipe.

The number of foreign residents living in Kannai foreign settlements was 1,071 in 1871 (1871), but in 1880 (1880), nearly four times more than 3,937, and the amount of wastewater exceeds the capacity of the sewer pipe, and the sewage pipe is often clogged due to sewage contamination caused by sewage clogging due to sewage from each house. In addition, from 1877 (1877) to 1879 (1879), cholera, which killed 110,000 people, became widespread nationwide, and sewerage renovation work was carried out.

Zentaro Mita

Kanagawa Prefecture began investigating and planning renovation work since 1880 (1880), and Zentaro Mita was the responsible person. Zentaro Mita was born in Shigeki Shimonokuni in 1855 (1855) and enrolled at Daigakuminami School (now the University of Tokyo) as a tribute to the Hitachi Yatabe Domain. Mita, a first-year student at the Department of Civil Engineering, Faculty of Science, The University of Tokyo, became a civil engineering worker in Kanagawa Prefecture in 1879, and has made significant achievements in urban development in Yokohama.

Mita's design was a 3-2 oval tube with a vertical and horizontal ratio of tubes, which is said to have been devised by the British John Philip in 1846. This was a gradient of 1/200 to ensure the flow velocity so as not to sink the waste into the sewer pipe, and the shape was oval-shaped so that the flow velocity did not fall even when there was little water flow.

The egg-shaped pipe is a brick pipe made of bricks and cement, and the three types of brick pipes with different diameters were constructed instead of large sewage, medium sewage, and small sewage in place of the main pipe.

The renovation work was carried out from 1881 (1881) to 1887 (1887), and about 4 km of brick egg-shaped pipes and 12.6 km of ceramic pipes were laid. This sewer is Japan's first modern sewer, and Zentaro Mita can be said to be the first Japanese person to design the modern sewer.

Large sewage

Middle sewage

Small sewage

The large sewage (brick egg-shaped pipe) discovered in Yokohama-zeikan-mae during the construction of the NTT Pipeline in May 1996 is part of the 4km brick egg-shaped pipe designed by Mita. The laying status of brick egg-shaped pipes is clear in the "Kannai Settlement Sewer Pipe Laying Map" created in 1899, but this is the first time a large sewage was discovered in that.

It is thought that many of the brick egg-shaped pipes have been modified with the development of the city, but there is a possibility that they will be discovered in the future. It is necessary to find a better way to preserve and utilize the shape pipe.

Reference Materials

"Yokohama Sewer History" Published: Yokohama City Sewerage Bureau

Published by "History of Sewer in Japan - Total Edition" Japan Sewerage Association