Since 1970 costal structures in the Port of Koper are designed as reinforced concrete slabs founded on vertical and inclined steel piles with a slope under the deck. This method of construction requires the excavation of large quantities of silt with bad characteristics, which is used mainly for acquiring new surfaces. The amount of pumped silt, derived from construction of new docks and deepening waterways, exceeds needs. Therefore it is necessary to take the extra silt elsewhere, which represents an increasing cost for the port. In the thesis is analyzed the possibility of using sheet pile wall on the particular case of the extension of dock number 11. The proposed coastal structure consists of concrete slab founded on steel tubular piles and steel sheet pile wall, which has a soil retaining and bearing function. This method of construction does not required addition excavations. Because of the complexity of the structure, individual elements and appropriate geometry models are acquired step by step. Initially the possibility of using a concrete slab on ground level founded on steel tubular piles and combined sheet pile wall that consist of different types of primary and secondary elements is analyzed. Because of the poor bearing capacity of the soil such type of structure is not an option. The following steps show the need of anchorage, inclination of piles and sheet wall and a relieving platform. Deep relieving platform 4 m below the ground anchored by Müller-Verfahren piles with inclined tubular piles at an gradient of 3:1 and sheet pile wall at a gradient of 5,5:1 is appropriate. Cross section and length of elements are set according to the required bearing capacity. The thesis also shows the positive effects of using deep mixing method and additional foundation of the storage area. At the end a list of further controls of cross sections and stability of steel elements is given.