TEHRAN -- Sepanir is one of the main affiliated establishments of Khatam Ol-Anbeya Construction Headquarters. Sepanir has been established in 1999 to deal with oil & gas industrial projects in Persian Gulf and Caspian Sea regions. The company commenced business with almost 300 personnel as well as 15 Ph.D graduated specialized engineers, 20 M.Sc and 40 B.Sc engineers. They implemented important seawater intake for the South Pars Oil & Gas Development. This project has been constructed in high quality, and certified according to NIOC standards within an adopted time schedule. The cost has been minimized for both Rial national currency and foreign currency. The engineering procurement and construction activities of this project were successfully achieved on concurrent direction. Mainly local resources were well engaged in this project resulting in a noticeable economy. Otherwise if constructed by foreign contractors the cost would be doubled. The engineering activities for his project included performing all required studies as well as geotechnical, soil investigation, topography, hydrography, preparing the basic design package, preparing the detailed design documents, performing the engineering services needed for procuring the project items, supervising construction of the project, providing as built drawings for the implemented items, programming the project activities and adopting project control system, and engaging a quality control system. The procurement activities included preparing data sheets and material requisitions for different items and submitting to suppliers, pre-qualification of manufacturers and adopting the acceptable, procuring material for civil works including steel and metal elements e.g. steel beams, reinforcement, etc., and procuring other construction materials, offshore pipelines items including providing 56'' dia. pipes with flanges fittings, expansion joints, steel manholes, testing facilities, etc, providing the electrical and control system items, procuring mechanical equipment, procuring all onshore piping system, instrumentation items including flowmeters, pressure meters, pressure transmitter and thermometers, corrosion protection system items including sacrificial anodes, etc. The offshore activities included dredging works for four pipelines using marine dredging facilities. Explosives had been used for hard layers of seabed. Four 56'' offshore steel pipelines were implemented to supply seawater from a recommended location inside the sea. The length of each pipeline is about 750 meters and the total length is about 3000 meters. The pipelines were protected internally by cement lining using cement mortar by special equipment. Externally a polyurethane coating was applied saving money and foreign currency, which would be needed for the alternative epoxy coatings. For establishing the pipeline system, 12 meters pipes were used to fabricate 36-meter spools. Those spools were rolled from onshore site down to seashores then floated and pulled to position by tugboats. Also barges with 120 tons cranes were used for laying the spools at location. To carry out the construction of the main basin Sepanir had to excavate up to a depth of 8 meters below the underground water table. The location of the basin is very close to the seashores (about 50 meters). Moreover, the texture and soil characteristic is very bad for its high permeability and also the quick action of the thick silt layers, therefore high flow inside the excavation was very serious problem. Dewatering was needed to avoid the accumulated seepage water and establish the construction works under relatively dry conditions. Unavoidably Sepanir had to adopt one of the following alternatives: Performing a curtain wall around the basin construction to prevent the flow into the excavation; Inserting sheet piles for the excavation and providing continuous pumping out of the accumulated water into excavation; Arranging for a well point dewatering by digging deep pumping wells. Finally pumping wells method was adopted and performed. The concrete seawater intake basin is the main project structure, which needed precise technology and capability. There were serious problems faced the design and the construction of the basin. A significant uplift pressure governed many design data, the mass concrete structure and the necessary consideration for the heat of hydration, which may exceed the allowable limits causing many problems, the existence of seawater in vicinity to the structure and effect of corrosion of the concrete and reinforcement, the low water cement ratio, which was needed for producing high strength concrete, causing a minimum workability for the concrete, the optimum staging of the concrete works and scheduling stage by stage (four stages) to fulfill an optimum construction operations. The main basin equipment, which had been manufactured and installed were stop logs, bar screens, traveling band screen, and gantry cranes. Other main facilities which must be mentioned as upstream piping network, including three pipelines 2 x 24'' & 32'' diameter for supplying seawater for South Pars Gas Plant. This system includes surge tanks using confined air for water hammer action, air compressors for providing air, sophisticated valves & fittings, instrumentation for flow, pressure temperature, etc., Electrical substation building was performed including all electrical equipment: e.g. transformers, switch gears, switch boards, panels, cables. Also a control building was built including a complete control system with a sophisticated equipment covering all control processes for e.g. motor operated valves, pumps and other equipment, according to the collected data. The chlorinating plant for producing hypochlorite and injection in seawater before discharging for the plants, return seawater system, flood diversion system for the whole project site and other required facilities were constructed as well.