SERVICE SUPPORT OF DEVELOPMENT ORGANIZATION OF CRETE (O.A.K. S.A.) FOR THE YEAR 2019 CONCERNING THE MAINTENANCE AND MONITORING OF THE NETWORKS AND OTHER ESTABLISHMENTS AND THE OPERATION OF THE QUALITY CONTROL LABORATORY OF APOSELEMIS WATER TREATMENT PLANT

CONSTRAT service includes the support of the Management Division of Transportation and Hydraulic Works

of O.A.K. S.A. for the operation and maintenance of the hydro-irrigation networks, the hydraulic equipment

of the pumping stations and the water treatment plants (Refineries – W.T.P.) of the water resources utilization projects,

managed by the Organization. The support of the O.A.K. S.A.  services for the operation and maintenance of irrigations

networks (pipelines, tanks, wells, operating and network protection systems, water supply sources, etc.) and the hydraulic

equipment of pumping stations, water treatment plants and other supporting projects (access roads, surrounding areas, etc.)

concerning the areas of Aposelemis works, for the water supply of the Municipalities of Heraklion, Hersonissos and

Agios Nikolaos. Constrat services, includes specific the operation and maintenance of Aposelemis Water Treatment Plant

(W.T.P.) in the context of management of the specific project. W.T.P.  Aposelemis is supplied with water from the Aposelemis

Water Barrier, which is the main infrastructure project for the water supply of the Municipalities of Heraklion, Hersonissos and Ag. Nicholas.

PART 1

SUPPORT OF OAK S.A. SERVICES FOR THE MAINTENANCE AND MONITORING OF THE NETWORKS AND OTHER HYDRAULIC INSTALLATIONS

PART 2

SUPPORT OF OAK S.A. SERVICES FOR COVERING OPERATION NEEDS

OF THE QUALITY CONTROL LABORATORY IN APOSELEMIS WATER TREATMENT PLANT

Specifically, it concerns the operation and maintenance of the hydraulic and electromechanical equipment of the main processes (ozonation, flocculation,

sedimentation, refining, chlorination, fattening and dehydration of sludge produced) taking part in the operation of Aposelemis W.T.P, as well as the chemical

building for the regulation of required doses of chemicals (flocculants, polyelectrolytes) added to the respective water treatment steps. The maintenance of

the hydraulic and electromechanical equipment of Apeselemis W.T.P. will take place in the context of preventing action / regular maintenance of the equipment,

as well as the repair of the faults. Furthermore, for the fulfillment of the purpose and the efficiency of the entire Aposelemis projects, to wit, for the regular

supply of the municipalities of Heraklion, Hersonissos and Ag. Nicholas, with the best quality drinking water from the water barrier, is the safety, good and

economical function of maintaining the hydraulic networks (central water pipelines from Aposelemi water barrier to W.T.P. and from W.T.P. to the

municipalities tanks) of the two (2) pumping stations (in the main waterworks of the Municipality of Agios Nikolaos) and of the (Shut-off and Checkout manholes)

of the central pipelines.

The operation – maintenance concerns the following parts of the project:

• From Aposelemis Water Barrier to Water Treatment Plants

This section includes the 7,5km long aqueduct for the transport of natural water from the Aposelemis reservoir to the Water Treatment Plant.

For its construction were used insulated steel pipes Ø1200 and Ø1100, for the passage of which two tunnels with a total

length of 3.7km were used.

• From Water Treatment Plants to Heraklion

This section of the aqueduct was constructed, for the transportation and distribution of drinking water,

from the clean water tanks of the W.T.P. to the city of Heraklion and the intermediate areas. The aqueduct consists of the

main waterworks of 26km total length and is made of insulated steel tubes of Ø900 to Ø1100, the transport lines to and

from both the Shut-off and Checkout manholes, with a total length of 1.3km and diameter Ø900, connecting pipes to

individual consumers and the ecological supply pipeline of the Aposelemis River.

The aqueduct operates naturally and supplies the areas of Agrians, Ascension, Gouves, Gournes, Karteros and

three main reservoirs of the city of Heraklion, with thepossibility of extending with another two, in the western part of the city.

• From Water Treatment Plants to Agios Nikolaos

The section towards Agios Nikolaos was constructed for the supply of drinking water in the city of Agios Nikolaos and certain intermediate areas, by the W.T.P.

The aqueduct comprises the main water supply pipeline, with a total length of 37 km, which is made of insulated steel pipes, cross section from Ø400 to

Ø900 and connecting pipes to the reservoirs of the water supply areas. It also includes the 5.200m3 Tunnel – Vrachasi reservoir, the D6 terminal of Agios

Nikolaos, with a capacity of 520m3 and two pumping stations, one inside the W.T.P. and one in the Sissi area.

In particular, the actions required to support the Development Organization of Crete S.A. services concern:

• Preventive maintenance of the main and auxiliary equipment of the networks, pumping stations, water supply

systems, wells, operating instruments (valves, piping, air extractors, etc.), as well as any spare equipment.

• Repair maintenance – restoration of any damages that will occur during the operation of the projects (networks,

pumping stations etc) through various interventions, reconstructions, repairs that will be carried out where necessary

in the area of ​​the Organization’s networks, with or without the collaboration of the engineering means Organization’s staff and only upon a mandate from the service

in which the contractor’s response time will be determined for their execution.

• Checking the hydraulic networks and tanks in order to verify their functionality, the measurement of pipeline supplies and pressures, the control of the proper

functioning of network instruments: air-jets, valves, anti-flood valves, float valves etc.

• Investigating the tightness of the tanks and performing repair work when a problem is found.
• Investigating functionality and cleaning of manholes.
• Constant leakage control and direct damage restoration action in pipelines, according to the Organization’s specifications and pipeline construction guidelines.
• The collaboration with the competent services of the Organization for the application of modern operating methods, such as automation and remote control of networks, tanks, pumping stations, etc. as well as with the Cathodic Protection Services.
• Continuous control of plumbing networks for the existence of operational irregularities by consumers or illegal connections and immediate restoration of the normal situation, as well as taking the necessary measures.
• Monitoring the good operation and recording of measurements of both central and consumer water meters.
• The increase of water connections in water supply and the connection of hydrometers to hydrostations.
• Co-operation with the Organization’s Hydraulic Works Coordinating Office and the Fault Center.
• Keeping a daily business log.