Case

Murano Water Treatment Plant (tiered water treatment plant)

Water utility

Osaka Water Supply Authority

General information of the utility (as of 2021)
Operation

Public (wholesale watertypesupply)

Population
servedService area (km2)

1,678.42―

Distribution (m3/d)

1,482,993―

Pipe length (km)604.770.61

Number of staff

353

Servicecoverage(%)
NRW (%)
Number ofwater

Surface water (1), Groundwater (0), Others (0)sources
Water rates(JPY)(unit price of drinking water to retail72/m3municipalities)

As of 2021, the Osaka Water Supply Authority supplies approximately
75% of the total water used by 42 cities, towns, and villages in theOsaka Prefecture.
Although water demand in Osaka Prefecture is currently on thedecline, during the period of high economic growth from the 1960s tothe 1980s, its demand increased rapidly, and there was a constantrequest for purchasing water from the Authority from municipalities in
the prefecture. Therefore, the planned maximum daily water supply for
approximately 20 years from 1960s to 1980s increased by 2,300,000
m3/day in total.

SummaryTable 1 Changes in Water Demand of the Authority
Approved date

Project Name

Planned maximum watersupply volume (m3/d)

11/25/1948

1st construction

3/25/1960

4th expansion

375,000

10/13/1962

4th expansion (modified)

533,000

10/14/1964

5th

11/25/1970

5th expansion (modified)

1,450,000

3/31/1972

6th expansion

2,000,000

3/31/1980

7th expansion

2,650,000

35,000・・・

expansion

1,150,000

To secure water treatment facilities that could meet such water
demand in the rapidly urbanizing Osaka Prefecture, the decision wasmade to construct a layered water treatment plant (two buildings of
300,000 m3/day each) that would house water treatment facilities in athree-dimensional structure within a single building, based on acomprehensive evaluation of the required land area, acquisition
method, layout plan, project cost, treatment efficiency, and rationalityof operation, maintenance, and management. Construction of Building
No. 1 began in October 1974 and was completed in November 1977,and construction of Building No. 2 began in October of the same year
and was completed in November 1980. Since then, the plant has been
supplying water to Osaka Prefecture up to the present, while addingadvanced water treatment processes in 1994 to cope with thedeteriorating water quality of the Yodogawa River.

Figure １ Murano Water Treatment Plant
1 Development of Facilities to Meet Rapidly Growing Water Demand
During the period of rapid economic growth from the 1960s to the1980s, water demand in Osaka Prefecture increased rapidly, with anannual increase in demand of more than 100,000 m3/day. Therefore, it
was necessary to plan and develop a distribution capacity ofapproximately 600,000 m3/day over 10 years.
Current
Status &2 Limited Water Sources and Project SiteChallenges

The Yodogawa River is the only water source that can meet the water
demand in Osaka Prefecture, and the existing water intake facilities at
the Murano Water Treatment Plant and the Isoshima Water Intake
Plant had to be utilized if facilities from intake to distribution were to be
expanded within the required time frame.
Therefore, it was necessary to secure a project site in the vicinity of
the Murano Water Treatment Plant, but the surrounding area was
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rapidly urbanizing, making it difficult to secure a large site as in thecase of conventional water treatment plant development.
3 Response to Deterioration in Raw Water Quality
As the area around Lake Biwa, which is upstream from the Yodo
River, the main source of drinking water, had been developed, thedeterioration of raw water quality, as typified by odor, had become aproblem since the 1970s. Therefore, the new water treatment facilities
were required to be designed to allow additional deodorization
treatment even after the facilities got into operation.
1 Determination of the type of water treatment plant
In summary, the requirements for the new water treatment facility
were: "to secure a large treatment capacity in a short period of time,""on a site that can be secured even in an urbanized area," and "withthe expectation of adding deodorization treatment in the future.”
In the first place, it was generally difficult to secure a large site in ashort period of time, and in addition, the site area required for
additional deodorization treatment was uncertain, and the cost of land
was rising due to urbanization. Therefore, it was determined that atiered system was more suitable than a flat system, taking into accountthe construction cost and required construction technology.
2 Determination of Unit Configuration for Tiered Water Treatment
Plant
Measures &Based on the policy of constructing a two-tiered water treatment

Solutionsplant, the next step was to determine the number of buildings, andafter organizing and evaluating the various performance requirements,etc., it was decided that two buildings (300,000 m3/day x 2) would beused. This was because the project cost was relatively inexpensive,and because two buildings of the same design could be symmetricallyplaced and constructed consecutively, which was advantageous in thatit would produce early and gradual effectiveness in response to everincreasing water demand.

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Table 2 Evaluation to determine the number of buildings
Conditions A(performance)

Conditions B(number of buildings)

Water demand

6 buildings (100,000 m3/d/building)Site layout plan

4 buildings (150,000 m3/d/building)Site area

Maintainability

3 buildings (200,000m3/d/building)

Structure

2 buildings (300,000 m3/d/building)Construction cost

1 building (600,000m3/d/building)Investment effectivenessWith the number ofbuildings determined to be

Rapid filtration basin

two, the next step was todetermine how each
Granularactivatedcarbonadsorption
basin

treatment facility would becontained within thebuilding. After comparing
the proposals of arranging
each treatment facility

Ozon
contactbasin

vertically within thebuilding, arranging eachtreatment facility on a flat
surface on each floor, andOzone
Generator

dividing the treatment

In-building
clean water
storagestages across buildings, theproposal of "arranging eachtreatment facility verticallySedimentation
pond(inclined type)within the building" wasadopted because of itsadvantage in terms ofWater
intake well

Pump

required area and facility
Figure 2 Adopted facility layout

maintenance andmanageability. As a result, thescale of each building was decided tobe 2 stories below ground and 3 stories
above ground (height: 31 m), with astandard plane of 72.3 m x 88.8 m,
and a unit configuration of 66 watertanks inside.

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3 Structural Planning and Design
At the time of the aforementioned consideration in the 1960s, there
were no examples of a layered water treatment plant of this scale in
the world. In designing its structure, stress analysis was conducted inaccordance with the various standards set by the Architectural Instituteof Japan, while also taking into account related three-dimensional
effects. In addition, with the cooperation of the Faculty of Engineering
at Kyoto University, vibration tests were conducted using a 1/50-scale
plastic model, and the results were reflected in the structural design.
As of 2021, approximately 45 years have passed since the completionof this facility, and it has been operating stably and is expected tobecome indispensable as the overall treatment capacity has been
declining due to renewal of other water treatment plants of the Osaka
Water Supply Authority.
On the other hand, while the "Future Vision of Osaka Water SupplyFuture Plans

Authority" currently being formulated calls for the renewal of the west
system of the Murano Water Treatment Plant and the Mishima Water
Treatment Plant during the planning period (~2052), water demand in
the prefecture is on a downward trend.
Therefore, in the next plan, which will be approximately 80 years
after the No. 1 Building began operation, it is necessary to examine thedesirable form of the relevant facilities from multiple perspectives,
including more efficient operation and emergency response capabilities.
○ Osaka Water Supply Authority, Various Management Plans

References

https://www.wsa-osaka.jp/joho/plan.html○ Osaka Water Supply Authority, Pamphlets
https://www.wsa-osaka.jp/koho_hodo/pamphlet.html

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