The facilities which EYATH S.A. owns or manages pursuant to the contract of 27.7.2001 with the Greek State include: a) water abstraction works, b) external aqueducts, boreholes and pipelines, c) pumping stations and tanks and d) the distribution network comprised of pipelines and water meters.
EYATH S.A. uses the Karst system of aquifers in the Paiko Mountain, specifically its point of discharge at the Aravissos springs, to supply water to Thessaloniki. Water is abstracted from the Aravissos springs from two natural supply shafts, a spring fitted with a pump and 11 water boreholes which pump water via connecting pipes to the Aravissos aqueduct. The quantity of water obtained from the Aravissos springs ranges from 65,000 to 130,000 m3 a day, depending to a large degree on snowfall and rainfall recorded every year.
Water is abstracted from the Aliakmonas River in the area known as Varvares around 40 km from the river delta. Water is diverted via a 50 km long free-flowing channel to the Axios River where it reaches the water treatment plant (known as the refinery).
Clean drinking water is then directed to 75,000 m3 storage tanks and distributed via a network of pipes 36 km long to existing water supply tanks at Diavata, Evosmos, Polichni, Neapoli, Vlatades, Toumba and Kalamaria as well as the Industrial Area.
Boreholes down to the Kalochori aquifer are no longer used because of concerns over adequate water quantities. Two have been handed over to the Municipality of Echedoros. The quantity of water which can be abstracted from the aquifer in the Sindos area (via 26 boreholes) is around 30,000 m3 a day. In the wider Axios River area (Gefyra, Nea Halkidona, Eleousa, and Agios Athanasios) there are a total of 46 boreholes in use producing around 70,000 m3 of water a day.
In the Narres area water is abstracted from the bed of the Gallikos River via 3 water collection shafts. The quantity that can be collected at Narres varies from 5,000 m3 to 25,000 m3 a day depending on rainfall and snowfall recorded each year. The Narres aqueduct is currently out of use and is on stand-by.
The Agia Paraskevi springs at Hortiatis are used to provide additional water to the Hortiatis Municipal District and as a back up to supply water to the G. Papanikolaou Hospital.
In the plains to the east of Thessaloniki (in the areas of Mikra and Neo Rysio) there are 6 boreholes producing 4,500 m3 a day overall. This quantity is used to top up the Kalamaria tank. These boreholes are currently not in use and are on stand-by.
The Thessaloniki Water Treatment Facility (the Refinery) lies 2km north of the Sindos Industrial Area close to the Thessaloniki – Edessa National Road.
The refinery became operational in August 2003. EYATH S.A. owns the facilities and has outsourced running to a third party. It does, however, oversee how the facilities are run by sending expert staff from the relevant company division.
At present the facilities can treat 150,000 m3 a day. A study is currently being carried out to expand production by an additional 150,000 m3 a day. When fully deployed the refinery will be able to treat 600,000 m3 a day.
Water is transported from the Aliakmonas Dam (at Agia Varvara near Veria) to the treatment facilities via an open channel, twin siphon pipes and sealed pipes.
In short, water treatment entails the following stages:
The refinery houses chemical storage, preparation and dosage facilities (sulphuric acid, polyelectrolytes, aluminium sulphate, chlorine and lime), a treatment line for sludge generated by the flocculation and sedimentation tanks, a washing water treatment line including special units for removing solids, rainwater / water supply / waste and fire-fighting networks, as well as other ancillary facilities.
The installed capacity is around 1,400 KW and power comes from the PPC network and two independent lines. A 450 KW backup generator has also been installed.
To a large extent the production process is automated and includes a large number of on-line instruments which continuously record operating parameters and water characteristics in the various treatment stages (flow meters, pH meters, conductivity meters, turbidimeters, chlorine residue counters, etc.). The signals from those instruments are sent to the control centre at the Facility where an operations mimic diagram has been installed. The control centre also has a SCADA (Supervisory Control and Data Acquisition) system for the Sindos pumping station.
Lab tests on the water which is produced and on all interim processing stages are carried out by the lab on-site at the Facility and at the EYATH Drinking Water Quality Control Lab which examines a large number of samples every day in line with the relevant legislation on the quality of water for human consumption (Joint Ministerial Decision No. Y2/2600/2001).
The Greater Thessaloniki Area is today supplied with water from the Aravissos – Axios aqueducts and the Refinery and the Narres, Sindos and Kalochori aqueducts are on stand-by for use if needed.
The Aravissos aqueduct is around 56 km long and uses gravity to transport water from the Paiko Aquifer to Thessaloniki. Construction work was completed in 1978 and since then it has been supplying water to Thessaloniki and the Thessaloniki Industrial Area.
The Axios aqueduct commenced operations in 1976 and is connected to the Aravissos aqueduct via a series of valves. The aqueduct pipe collects water pumped from the Axios, Eleousa, Gefyra and Agios Athanasios boreholes near Thessaloniki.
The external Narres aqueduct became operational in 1968 and its water abstraction facilities have been built in the bed of the Gallikos River. The aqueduct operates using gravity and supplies water to the Diavata tank which used to supply water to a section of Western Thessaloniki and the EKO facilities. Today it is no longer used but is held on stand-by.
The Sindos aqueduct collects water from boreholes in the Sindos aquifer and operates under gravity. It is on stand-by today and is used in cases of drought.
The Kalochori aqueduct collects water from boreholes in the Kalochori aquifer and is today a covered pipe some 1,000 m long. The water is directed to the Kalochori pumping station where it can either be forwarded to the Diavata tank or the Dendropotamos pumping station. Today its boreholes are not in use.
Water from the Dendropotamos pumping station is supplied to the centre of Thessaloniki via a high pressure steel pipe. Using the Evangelistria pumping station, water is sent to the Agios Pavlos Tank to supply water to the city centre and the Saranda Ekklisies tank to supply water to the Saranda Ekklisies and Triandria areas.
The Dendropotamos pumping station also supplies water to all of Eastern Thessaloniki and part of the western suburbs via a low pressure steel pipe. Water is pumped via a low pressure pipe to the Kassandrou pumping station where it is then sent on to the Toumba tank. From there a pumping station and pressure pipe direct the water to the Pylea tank from whence it supplies water directly to the upper Kalamaria area, and water is also pumped on to the wider area.
In June 2007 the new Kallirachi pumping station – tank became operational. The pumping station was built to improve water supply in the Hortiatis and Exochi municipal districts. The new pumping station – tank which can store up to 80 m3 and provide around 750 m3 of water daily is part of phase I of the project, and plans exist to increase the daily flow to 1,000 m3. The project budget is € 25,000.