Friday, October 27, 2023
On Monday, October 23rd, the 2023 Wa Neighborhood Association Senior Citizens Club (Chairman Nobuyuki Kanayama) held its training and social gathering. 22 very energetic people participated! They all enjoyed a harmonious and fun two-day, one-night stay.
The group visited the Kita Sorachi Regional Water Purification Plant (Kita Sorachi Regional Waterworks Corporation) in Numata Town, followed by a training session in the multipurpose hall (2nd floor) of Sunflower Park Hokuryu Onsen, where a lecture titled "Wonderful Hokuryu Town" was given by Noboru Terauchi (operator of the Hokuryu Town Portal), and then moved to the banquet hall (1st floor) for a networking event.
Starting at 1:00 p.m., a Sunflower Park shuttle bus made the rounds between each participant's home and headed to the Kita Sorachi Regional Water Purification Plant in Numata Town.
Visit to the Kita Sorachi Regional Water Purification Plant (Kita Sorachi Regional Waterworks Corporation)
Watch the introductory video
First, we went to the office on the second floor of the facility where we received an explanation from the secretariat, Tsuji Takeshi, head of the water purification section, and then watched a video introducing the water purification plant and dam.
It is jointly established and operated by one city and four towns (Fukagawa City, Numata Town, Chishibetsu Town, Hokuryu Town, and Imosei Town).
- The Kita Sorachi Regional Waterworks Corporation is jointly established and operated by one city and four towns in Kita Sorachi (Fukagawa City, Numata Town, Chishibetsu Town, Hokuryu Town, and Imobeushi Town).
- The water purification plant was completed in 1985 (Showa 60), and water supply to one city and four towns began.
- Construction of Numata Dam began in 1973 as an agricultural dam using the Horoshin-Tachibetsu River, a tributary of the Uryu River, as its water source, and was completed in 1992 as a multipurpose dam that also supplies tap water.
- Lake Holopiri is an artificial lake created by the Numata Dam blocking the river.
- The dam's maximum water supply volume is 22,000 m3 per day. Drinking water is supplied to one city and four towns with a population of 54,580.
Water purification facilities
The Kita Sorachi Regional Water Purification Plant is located alongside the secretariat. To ensure the safe delivery of tap water, staff are stationed in the central control room 24 hours a day to collect, monitor, and control information.
Within the facility, raw water (water taken from Lake Holopiri) is purified, disinfected, and purified at a water purification plant to produce water suitable for drinking.
- Landing pond:Taking in raw water from Lake Holopiri
- Mixing pond:Add chemicals that are prone to turbidity or sinking
- Flocculation pond:Stirring the water to create flocs (cloudy masses)
- Sedimentation tank:Allow the flocs to settle for about 5 hours.
- Filtration pond:Small turbidities are removed through a layer of sand (there are six ponds, and the bottom of each pond is covered with a layer of sand and pebbles about 80 cm thick, allowing the water to permeate from top to bottom).
- Add disinfectant and the purified water (tap water) is ready.
- Sending water to the town's water reservoir
Numata Dam
This rockfill dam, built by piling up rocks, uses the Horoshin-Tachibetsu River, a tributary of the Uryu River in the Ishikari River system, as its water source. It stores water for both tap water and agricultural use.
- Lake surface area: 2.77 km2 (190 Sapporo Dome fields)
- Total water storage capacity: 34.8 million m3 (3.4 million m3 for water supply)
In the summer, rainwater flows from the forest into the river, and in the winter, meltwater from snow (in areas where snow accumulates more than 2 meters) flows into the river.
Most of the forests around Lake Holopiri are designated as "water source conservation forests," and they absorb and store rainwater in the soil, slowly releasing clean water into the river. It is thanks to the forests that the river is able to withstand the water.
In recent years, the amount of water used has decreased due to a declining population, and only about half of the amount used previously is being used.
Plans are underway to reduce the size of the facility to about 60% of its size (13,200 m3).
Three keywords
- safety:Producing safe, secure and delicious water
- Tough:Earthquake and disaster-resistant facilities
- Duration:A healthy and stable business
With these three keywords, the Kita Sorachi Regional Waterworks Corporation will continue to provide safe, reliable and delicious tap water," the video concludes.
YouTube video "Water of Kita Sorachi" by Kita Sorachi Regional Waterworks Corporation
Facility tour
Sedimentation pond
While listening to the explanation...
Checking the safety of the yamame trout tank
In one corner of the control room, there is a tank filled with water from the dam, and yamame trout are kept in it. In the unlikely event that the water quality of the dam deteriorates, the yamame trout will react quickly and alert the fishermen to the danger.
Head straight to Sunflower Park Hokuryu Onsen
After receiving a thorough explanation from the secretariat staff, we finished the tour and boarded a bus, heading straight for Sunflower Park Hokuryu Onsen.
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◇ Interview and text: Ikuko Terauchi (Photography and editing assistance: Noboru Terauchi)
