Feasibility and design of seabed gallery intake systems along the red sea coast of Saudi Arabia with discussion of design criteria and methods

Geological characteristics of the Red Sea coastline of Saudi Arabia were evaluated to assess the technical feasibility of designing and constructing seabed gallery intake systems to provide feed water for seawater reverse osmosis (SWRO) desalination plants. Five sites were investigated in detail at King Abdullah Economic City, Om Al Misk Island, Jeddah, Shoaiba, and Shuqaiq. It was found that a large part of the Red Sea nearshore area contains a low-sloping inner reef area from the beach seaward to the reef tract. Water depth ranges from 0 to 2 m in this shelf area and there is minimal coral growth and a small percentage of seagrass cover. There is a carbonate or siliciclastic sand cover over a moderately hard to soft limestone. It was found that seabed gallery systems could be designed and constructed at each of the sites investigated. The site-specific conditions varied which necessitated different designs of the filter with the upper, reactive layer varying with regard to the mean grain diameter of the media to match the site conditions and the layer thickness to provide adequate water treatment. Preliminary design infiltration rates varied between 5 and 10 m/d with hydraulic retention times ranging from 3.4 to 7 h. Each gallery intake design was divided into a number of cells, each to be equipped with a pump to achieve overall high system reliability. The Saudi Arabia nearshore area of the Red Sea appears to be an ideal location for the development of seabed gallery intake systems based on the shallow water and relative ease of construction.