Bathymetric, seismic, geotechnical, oceanographic, numeric model studies made for design of sea outfall line for treated water discharge. Dia. 400mm HDPE pipe is 1775 meter long under sea water. Diffuser at -27.m depth. Maximum discharge 220 lt/sec. General Method for Sea Outfall Projects Bathymetric Studies; A number of GPS equipment and an echo-sounder type depth meter have been used to record position versus water depth. Then the data obtained have been used to plot the bathymetric map showing depth versus local coordinates by using special mapping software. 3-D Mathematical Model Studies; In order to determine the distribution of the pollutants resulting from the wastewater discharge into sea, three-dimension hydrodynamic models were prepared by using software Telemac3D Version 2.2, developed by Electricitéde France, Département Laboratoire National D'Hydraulique (EDF-LNH), and Plume-RW (3D), developed by HR Wallingford. Seismic Studies; In order to determine the geological and lithological structure below 5 to 10 meters of the sea bottom, the seismic work over three different lines was performed. One of those lines was just over the proposed discharge line and the other two lines were 100 m. away to the left and right of the proposed discharge line. Seabed/Oretech 3010. Sub-bottom Profiler System was used in this work . Geotechnical studies; In order to identify the stratigraphy, morphology and soil properties of the sea bottom, a series of boreholes have been drilled along the proposed discharge line . The samples of sediments extracted by means of Van Veen Grap type sampler. The following laboratory tests have been conducted over those samples; •Grain Size (Sieve and Hydrometer) Analysis •Determination of Atterberg's Limits •Shear tests for the cohesive samples.(Pocket Vane Tester, Pocket Penetrometer) Oceanographic Studies; In order to determine the properties of seawater at the outlet of the discharge line and its surrounding environment, oceanographic studies were carried out. Salinity, Temperature, Density, BOD (Biological Oxygen Demand), DO (Dissolved Oxygen) and Conductivity of the seawater were measured at each station located at the depths of 10 m., 20 m., etc., along the discharge line. ValePort Model 302 type instrument was used to measure the current velocity and direction in project region around proposed location of the diffuser and at various depths. Combining all these information application drawings for pipe profile, trenching, diffuser, fixing blocks, buoys and pumps details have been prepared.