History of Imatra Water

Establishment

The beginning stages

Imatra, which started its independent existence as a town on January 1.1.1948, XNUMX, was one of the largest towns in our country. The water supply in the area of ​​Nuore Imatra township was almost completely unorganized. Almost as its first decision, the town council decided on the design of the water supply system.

In May 1948, the municipal council of Imatra decided to commission a plan for a water supply system that would cover the entire area of ​​the municipal district of Imatra. It was decided to order the plan from the General Engineering Office in Helsinki.

Yleinen Insinööritoimisto presented to the municipality the clarification of water and drainage issues in stages. According to the program, in the first phase, the water quality of alternative water intake locations will be investigated using water analysis. The quality and quantity of water was submitted for examination at the following locations:

•  Lake Immalanjärvi
•  Pyhälampi
•  Saimaa
•  The source of Korvenkanna

In the opinion of the Engineering Office, Vuoksi's water was considered dirty and unusable for large-scale industry.

According to the General Engineering Office, cleaning Vuoksi's water might not be possible even with chemical methods. In addition, it was thought that the hypothermia of Vuoksi's water would make it difficult to take water.

In the second phase of the program, the water sufficiency of different water intake options was investigated.

In the third phase of the program, based on the results of the previous phases, the water intake locations of the Imatra municipality were defined and a general water supply plan was drawn up. The preparation of the general plan was considered to require the completion of the general plan. Likewise, it was considered possible to give the final plan for the water supply system only after the master plan has been completed.

The program of the General Engineering Office satisfied the City Council and the program was approved. In August 1949, the General Engineering Office submitted the master plan of the Imatra water supply system to the municipality. This plan included two options and their approximate cost estimates. In November of the same year, the Engineering Office supplemented the master plan with a third option.

General plan of the water supply system of Imatra township

Assumptions used in the plan

In the water supply plant's plans, the area's water demand was first assessed. It again depended on the population of the area and its growth. In Imatra's master plan, the number was used as the basis for estimating the number of inhabitants, which was obtained based on the population forecasts of the master plan drawn up by Alvar Aalto and the General Engineering Office's own estimates. Alvar Aalto estimates that 114 residents will come to Imatra. The estimate of the General Engineering Office was 200 people, which number had to be reached by 60. The engineering office's forecast was obtained by comparing the population growth of Kuopio, Oulu, Vaasa, Tampere, Turku and Vyborg. Alvar Aalto's calculated population numbers of the sub-regions were changed to correspond to the population forecast of the General Engineering Office.

In the general plans of the water supply facilities, the sizing of the facilities was usually done for twice the population compared to the time of planning. Imatra's plan was drawn up for 2.24 times the number of residents.

In the options A and B of the plan, water procurement was assumed to take place from the sources of Korvenkanna (Naatus) and Mellonmäki, as well as Lake Immalanjärvi. However, a reservation was presented in the plan for the use of the water of Lake Immalan; it was considered that if usable groundwater were found somewhere, the use of the water from Lake Immalanjärvi would be abandoned.

Option C used the same population and water consumption projections as the previous options. The basis of the alternative was the effort to make Imatra's future water supply plant as clear and easy to maintain as possible. In option C, water intake was concentrated from Lake Immalanjärvi. The centralization was justified by the following points:

•  centralized water intake minimizes treatment costs
•  Imatra had relatively little groundwater (only 30% of the assumed need)
•  part of the groundwater would also have to be treated
•  The Immalanjärvi water treatment plant would have to be built in any case, and expanding it to cover the entire water intake does not require very large additional costs and
•  water taken from one place simplifies the use of the plant

Establishment of the water supply system of Imatra township

On 24.11.1949 November 24, the town council of Immala had gathered for the meeting of the town council. Since the municipality of Imatra was young, there were enough far-reaching issues to be decided at every council meeting. Still, item No. 22 on the agenda of the November XNUMX meeting, titled the construction of a water supply facility, was in a class of its own in terms of importance and cost.

At the meeting held on November 9.11.1949, XNUMX, the Construction Committee had discussed the alternatives presented by the General Engineering Office regarding the construction of the water plant. The building committee unanimously considered option C of the plan to be the best. The board considered the positive aspects of option C to be its clarity and the certainty of water supply. Option C was also easily expandable as the need grew.

The Board of Trade dealt with the construction of the water supply system on 14.11.1949 November XNUMX. The Board of Trade had asked an impartial expert for an opinion on the plan of the General Engineering Office. The statement was requested from Helsinki city engineer Akseli Linnavuori, who was considered to represent a sufficiently high level of expertise. City engineer Linnavuori reviewed all three options given by the General Engineer's Office in his statement. In favor of options A and B, Linnavuori calculated their operational reliability, because if one plant were to have a malfunction, the others could take care of the water distribution. However, in Linnavuori's opinion, the importance of this fact was reduced by the small share of groundwater in the total water supply.

On the other hand, Linnavuori found several positive aspects of option C. He considered it important that the water of Lake Immalan didn't need to be cleaned chemically and that the water of Lake Immalan was otherwise very usable for the needs of the industrially powerful Imatra. City engineer Linnavuori considered the only downside of option C to be the large costs at the beginning, which would, of course, level off over time. According to engineer Linnavuori, option C presented by the General Engineering Office was the most suitable for Imatra's water supply plant. The Board of Trade unanimously decided that the water supply system of the Imatra municipality will be built in accordance with option C presented by the General Engineering Office.

Water intakes

Immalanjärvi water intake

 
Photo: Imatra water intake construction site in 1950.

It was decided to build the water intake for the Imatra township on the water of Lake Immalanjärvi. The purity of the lake's water has long been known to the locals. Laboratory studies on the water quality of Lake Immalan were also carried out in the late 1940s. In all studies, the water has been found to be of high quality.

The factor hindering the use of drinking water in Lake Immalan has been the temporary clouding of the water. Efforts have been made to reduce the problem by extending the intake of raw water as far from the shore as possible. Temporary taste disturbances caused by algae have sometimes occurred in Lake Immalanjärvi.

The location of Immala's water intake has been influenced by many factors. The water intake was located in the most advantageous place in relation to the planned water tanks, so the length of the supply line was minimized.

The General Engineering Office started the construction work of the water intake on March 29.3.1950, XNUMX. According to an article in Ylä-Vuoksa in May, there was a trench on the shore of the Vuoksenniska school at that time for water intake. Paavo Aromaa was the construction foreman responsible for the water intake site, and Keijo Suomi was the supervisor for the town.

Imatra municipality's water supply plant started water distribution on January 1.1.1952, 350. The Immalanjärvi water intake was managed by Immala electricity. In the beginning, the daily usage time of the water intake was quite short. Only approx. 3 mXNUMX/day of water was pumped.

After the shop started taking care of the water intake, it was commissioned as a side job. With the constant increase in water consumption, the position of machine operator of the water supply plant was established in October 1952. Taisto Matilainen, who handled the recruitment side-by-side, was elected to the position. He and his family moved to an apartment in the water intake building.
 
Photo: Vedenottamo's first pumps installed in 1950. In the photo, water intake operator Taisto Matilainen.

Extensions before the 1970s

After the completion of the water supply plant, intensive construction of the distribution network began. A new line was built and new consumers joined the network. At the end of 1956, the daily pumping time of the water intake was 10-12 hours. It was decided to increase the capacity of the water intake. Based on the plan drawn up by the General Engineering Office, new raw water and clean water pumps and new meters were installed at the water intake. The work was commissioned by the General Engineering Office at the end of 1957 and the beginning of 1958. At the same time, the municipality built two new filter basins on its own. These extensions were practically the commissioning of the water intake facilities completed in 1952.

During 1965, the design of the additional building for the water intake was also started, which was done by Vesi Hydro Oy. The machine installation work according to the plan was commissioned by Vesikemia Oy, which submitted the cheapest offer in the tender. The other construction works were done by the municipality's construction department. The acceptance inspection of the annex to Vedenottamo was held in December 1966. The volume of the annex was 570 m3. This water intake expansion, like all other water intake renovations, was characterized by the fact that the work had to be done without interrupting the normal water intake.

Extensions after 1970

In 1971, the city commissioned Vesi-Hydro Oy to design the plans for renewing the wooden suction pipe of the water intake. In October of the same year, it was decided to award the renewal work to Oy Vesto, which submitted the lowest bid in the contract competition. The intake inspection was held on May 17.5.1972, XNUMX.
 
Photo: Vedenottamo's new 800 mm suction pipe is built on the ice of Lake Immalan in 1972.

In January 1973, the city again ordered plans for further expansion of the water intake. The plans were ordered from Vesi-Hydro Oy. This time the expansion included a new 1000 m3 clean water tank and the actual expansion of the treatment plant part. In the planned new part of approximately 85 m2 and volume of 700 m3, there was room for two new multi-layer filters. The city's construction department did the construction work under the leadership of construction master Villanen, the plumbing work was done by the water company itself, and the electrical work was given to Immala Sähkö as a contractor. The instrument work for the new equipment remained the responsibility of the suppliers of the equipment. The expansion work started in November 1973, it was in the ridge raising phase in March 1974, and the expansion was completed in September 1974. After the expansions of 1973-1974, the water intake capacity of the water intake rose from the previous 12.000 l/min to 18.000 l/min.

At the beginning of 1976, the city's technical board ordered a plan from Vesi-Hydro Oy to reorganize the operation of the water intake. All in all, they wanted to renew the water intake in such a way that it would be possible to use it in one shift. However, the implementation was postponed.

At the end of 1977, new magnetic water flow meters were installed at the water intake to replace the old, inaccurate meters.

In February 1979, the technical board listed the works of the water intake reorganization plan:

•  renewing the chemical system
•  plant automation
•  improving air conditioning and lighting
•  arranging electric heating
•  room arrangements

The trial operation of the completely renovated water intake was started at the beginning of October 1979. The final inspection of the water intake was held on October 26.10.1979, XNUMX, after which the water intake could be used in one shift.

Renovation in the 1980s

Information from the brochure on the renovation of the Immala water plant.

Immala water plant - partial transition to groundwater use

Overview

Throughout the city's history, water production has been based on the surface water of Lake Immalan, located in the western part of the city. The lake's raw water is of good quality. This is due to the fact that a significant part of the lake's water balance seeps as groundwater from the Salpauselkä ridge. However, environmental factors have increased the lake's nutrient load and caused eutrophication typical of a clear-water lake in the summer, and e.g. presence of algae. In the water supplied by the water utility, this has caused intermittent odor and taste problems in the summer, which has been increased by the rise in surface water temperature. It has not been possible to eliminate the problems that have arisen with the sand filtration/disinfection process alone.

Renovation of the waterworks

The goal of the renovation of the water plant of the city of Imatra was to secure the supply of good quality raw water and to eliminate the unpleasant odor and taste of the water that had been bothering consumers.

In order to realize these goals, a solution was chosen in which surface water treatment is enhanced and groundwater is also used. The enhanced treatment of surface water is rated for 13 m000/d, and the permit condition for groundwater abstraction is 3 m5/d. Hiekkoinlahti's groundwater intake is approx. 000 km from the water supply line from the water plant, where all water is treated and pumped into the network. By choosing the mixing ratio of surface water and groundwater, you can avoid e.g. difficulties caused by the warm period.

The renovation of the water plant included the expansion of the plant, structural renovation, renewal of the production process, groundwater extraction and transfer water pipeline. The total costs of the project were approximately FIM 14,3 million. The project implementation period was 1992-1993.

After the renovation, the operation of the plant has become smoother, the pressure shocks of the water supply network have also disappeared, while the pumping pressure has decreased by approx. 15%. therefore, the strain on the water supply network has decreased in this respect, which is reflected in a significant decrease in water supply failures.

Raw water intake

Both groundwater from Hiekkoinlahti and good quality surface water from Lake Immala can be taken to the Immala water plant.

There are five groundwater wells in Hiekkoinlahti, from which 350 m3/h of water can be taken at a time. The water is of good quality and does not require any treatment other than adjusting the pH value to reduce network corrosion.

Currently (year 2003), approx. 65% of the water is taken from Hiekkoilahti's groundwater and the remaining approx. 35% is taken from Immalanjärvi as surface water. Ozonation, precipitation with a filter and post-chemical treatment have been selected for surface water treatment.

The water treatment process can be found in its entirety on the water station's website.

Warehousing and distribution

The treated water can be partially stored in the facility's clean water tank, which has a volume of 1 m200. Water from the pool is pumped into two separate distribution circuits; Tuulikallio water tower area and Kurkvuori water tower area. The volumes of the water towers are 3 m5 and 200 m3. With the available storage volume, e.g. water consumption fluctuations so that the treatment capacity does not need to be changed very often.
 
Photo: Tuulikallio's first water tower completed. The new water tower is built around the first one.

Automation

The process is automated so that one person can run it via computer and monitor. During the night, the plant can also be left to operate fully automatically. During possible disturbances, the computer automatically calls the emergency operator's alarm device.

Pumping control is handled by a calculation program that also takes into account the estimated future consumption and the filling level of the water towers and the storage pool.