Received an order for large pumps for FY2025 Shonai Sewage Treatment Plant System 2 Rainwater Pump Facility Renewal Project from Toyonaka City Waterworks Bureau [Orders Received in May 2025]

The Shonai Sewage Treatment Plant is located on the right bank of Kanzaki River at the southern tip of Toyonaka City, Osaka Prefecture. Following the modernization of Amagasaki Port after the Meiji era, factories were successively built along the rivers in Toyonaka City, forming a heavy chemical industrial zone by the early Showa era. During the period of high economic growth, pollution from household and industrial wastewater severely degraded the Kanzaki River, to the point it was called the River of Death. Groundwater extraction for industrial water use also
caused land subsidence, leading to recurring flood damage during high tides and heavy rains. This prompted strong demands from local residents for the construction of a sewage treatment plant.

Responding to these demands, the first phase of the plant’s construction began in 1970, with operations commencing in 1973. The second phase was completed in 1980, finalizing the majority of the overall plan. The water quality of the Kanzaki River improved significantly, recovering to a state where diverse organisms could thrive. Flood damage in the area was also reduced, allowing residents to live with peace of mind.

In recent years, frequent torrential downpours caused by sudden heavy rains and stationary linear rainbands have led to concerns about flooding damage. To counter these natural disasters, Toyonaka City is implementing a Spare Pump Conversion Initiative to enhance the reliability of its facilities. This involves increasing the drainage capacity of each individual rainwater pump while maintaining the total number of pumps. This ensures that even if one pump fails, the pump station as a whole can still maintain its drainage capacity.

For example, in a station with five pumps each capable of discharging 1 m³/s (total discharge capacity of 5 m³/s), increasing each pump’s capacity to 1.25 m³/s means four pumps can maintain the total discharge capacity of 5 m³/s.

This project is also part of the Spare Pump Conversion Initiative. Since 2018, four of the five rainwater pumps have been progressively overhauled and modified, with this being the final phase of work.

Currently, plans for the pump design, manufacturing, and construction are progressing, aiming for completion in May 2027. The renovation and renewal of the pump facilities are expected to further enhance the overall reliability and functionality of the facility, contributing to the creation of a safe and secure environment for people living in the watershed.