2023 Workshop for the elderly of the 2023 Wa Neighborhood Association was held! Visit to Kita Sorachi Wide-area Water Purification Plant" to express our gratitude for safe, secure and delicious water.

Friday, October 27, 2023

On Monday, October 23, 2023, a training session and an exchange meeting of the 2023 Wa Neighborhood Association Senior Citizens Club (President: Nobuyuki Kanayama) was held. Twenty-two participants were very energetic! They spent a pleasant and congenial time together for two days and one night.

The tour was followed by a lecture by Noboru Terauchi (portal operator of Hokuryu Town) titled "Wonderful Hokuryu Town" at the multi-purpose hall (2F) of Sunflower Park Hokuryu Onsen as a workshop. The social gathering was held in the banquet hall (1st floor).

From 1:00 p.m., a courtesy bus from Sunflower Park made the rounds of each participant's home before heading to the Kita Sorachi Regional Water Filtration Plant in Numata Town.

In the shuttle bus

Inspection tour of Kita Sorachi Wide-area Water Purification Plant Water Purification Plant (Kita Sorachi Wide-area Water Supply Company)

North Sorachi Wide-area Waterworks Guide Map

View Introduction Video

First, at the office on the second floor of the facility, the participants listened to an explanation by Mr. Takeshi Tsuji, the head of the water purification section of the secretariat, and watched a video introducing the water purification plant and the dam.

事務局・辻健史 浄水係長のご説明
Explanation by Mr. Takeshi Tsuji, Water Purification Section Manager, Secretariat
Everyone listening attentively

Jointly established and operated by one city and four towns (Fukagawa City, Numata Town, Chichibubetsu Town, Hokuryu Town, and Imosegyu Town)

  • The North Sorachi Wide-Area Water Supply Company is jointly established and operated by one city and four towns in North Sorachi (Fukagawa City, Numata Town, Chichibubetsu Town, Hokuryu Town, and Imosegyu Town).
  • In 1985, the water purification plant was completed and began supplying water to one city and four towns.
  • Construction of the Numata Dam began around 1973 as an agricultural dam using the Horoshintachibetsu River, a tributary of the Uryu River, as its water source.
  • Lake Horopiri is an artificial lake created by the Numata Dam.
  • The dam supplies up to 22,000 m3 per day. Drinking water is supplied to 54,580 people in 1 city and 4 towns.
Supplying drinking water to 1 city and 4 towns

water purification facility

The water purification plant "Kita Sorachi Wide-area Water Purification Plant" is co-located with the administrative office. To ensure the safe delivery of tap water, employees are stationed 24 hours a day in the central control room to consolidate, monitor, and control information.

Inside the water purification plant

At the facility, raw water (taken from Lake Holopiri) is cleaned, disinfected, and purified at a water purification plant to make it suitable for drinking tap water.

  1. Landing ponds:Capturing raw water from Lake Holopili
  2. Mixed ponds:Add chemicals that are less likely to cloud or sink.
  3. Flock forming ponds:Agitate the water to form flocs (clumps of turbidity)
  4. Sedimentation ponds:Allow the flock to sink for approximately 5 hours.
  5. Filtration ponds:Small turbidity is removed through a layer of sand (there are six ponds, with a layer of sand and pebbles about 80 cm thick lining the bottom of the ponds, allowing water to percolate from the top down).
  6. Add disinfectant and purified water (tap water) is ready
  7. Send water to the town's water distribution ponds.

Numata Dam

A "rock-fill" dam constructed by piling up rocks, using the Horoshin-tachibetsu River, a tributary of the Uryu River in the Ishikari River system, as its source of water. It stores water for tap water and agriculture.

Numata Dam
  • The size of the lake: 2.77 km2 (equivalent to 190 Sapporo Dome grounds)
  • Total water storage capacity : 34.8 million m3 (3.4 million m for water supply)

In summer, rainwater flows from the forests into the river, and in winter, melt water (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," absorbing and storing rainwater in the soil and slowly delivering clean water to the river over time. It is precisely because of these forests that the river does not endure water.

In recent years, the amount of water used has decreased due to population decline, and only about half the amount of water has been used to date.
Plans are underway to reduce the size of the facility to 60% of its original size (13,200 m3).

Three key words

  1. Safety:Creating safe, reliable, and delicious water
  2. Toughness:Earthquake and disaster resistant facilities
  3. Sustained:Sound and stable business

With these three keywords, Kita Sorachi Wide-area Waterworks Company will continue to deliver safe, reliable, and delicious tap water. The video ends with these words.

Youtube video "Water of Kita Sorachi" Kita Sorachi Wide-area Water Supply Company

Facility Inspection

Tour of the facility

settling basin

settling basin

Listening to the explanation....

Listening to the explanation....

Yamame fish tank to ensure safety

In one corner of the control room is a water tank in which water from the dam is injected and landlocked salmon are kept. In the unlikely event that the dam's water quality deteriorates, the landlocked salmon are the first to react and warn of danger.

A tank for landlocked salmon injected with water from the dam
Mr. Tsuji, Water Purification Section Chief, explains in response to a question and answer session.

All the way to Sunflower Park Hokuryu Onsen

After the tour, we boarded the bus and headed for Sunflower Park Hokuryu Onsen.

Autumn-colored scenery from the window of the water treatment plant facility
Mysterious rays of sunlight seen from the car window
Continue to the article on the workshop and social event at Sunflower Park Hokuryu Onsen.
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Youtube Video

More Photos

Click here for 133 photos of Wa Neighborhood Association Senior Citizens Club Workshop and Social Event 2023 >>

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◇ Reporting and writing by Ikuko Terauchi (Photography and editorial assistance by Noboru Terauchi)