Liquefaction analysis was not carried out due to the fact that the basement floor is composed of Blocky Silty Sandy Pebbles with very little Clayey sand and / or rock type materials, the groundwater level is about 4.00 meters and the working area is the 4th Degree earthquake region, it was assessed that the floor was not available for liquefaction. 

The settlement values for Giresun Wastewater Treatment Plant units are within the permissible limits and no problem is expected regarding the settlement. Since the ground was composed of various sizes of gravel-block material, it is thought that these bases can give different settlements characteristics. In order to prevent, the raft foundation type is proposed to be chosen for all building. 

In order to investigate the stability of the foundation and slope, the natural topographic sections of the site for each unit were prepared in accordance with the depth of the basement and the maximum excavations were assessed in the geological and geotechnical survey. 

There is very high topographic slope at the south-west part of the plant area. As a result of the stability analysis for this part, it is thought that the sloping and crawler (e.g. one horizontal/ four vertical) excavation will be safer. Since the excavation height is too high and the plant boundary is insufficient, it is very difficult to apply such excavations. In order to increase stability and work-labor safety in this area; the geotechnical precautions such as floor nails, steel mesh, retaining walls, shotcrete etc. are recommended. As a result of the study; for Giresun WWTP construction, the methodology of excavation shall be prepared and the plant units excavation application projects-geotechnical projects and preparation of required excavation shall be prepared as stated in the methodology of excavation. These projects are subject to the Engineer’s approval. 

The geotechnical evaluations are subject to change according to the plant structures and layout in the actual plant design. The survey is given only for information purpose. The Contractor shall conduct new soil investigations according to the locations, dimensions, foundation depths and weights of the structures in his detailed design. The Contractor surveys should meet the below requirement; 

 At least one borehole for each main process units, 

 In new survey, the depth of borehole shall be at least 15 m if it shall not meet with the main rock. In cases where the number of SPT pulses "N> = 30" on cohesive soils, and the number of SPT pulses "N> = 50" on cohesionless soils, the drilling shall be end in 3m. If it shall meet with the main rock, it will proceed in 3 m. If the main rock shows a cracked feature, it will proceed in 5 m. 

 For samples and experiments should be performed according to Ilbank Specification. 

The methodology of excavation and the geotechnical precautions are subject to the Engineer’s approval. The Contractor shall prepare the plant units excavation application projects-geotechnical projects stated the methodology on how to make unit excavations and preparation of required excavation. These projects are subject to the Engineer’s approval. 

