Urban Groundwater Rise Control: Case Study

Seepage of wastewater from cesspools, and of leachate from green areas and parks, results in an annual groundwater rise of 0.5 m in Jeddah, Saudi Arabia. The rise causes several environmental and structural problems. A network of 110 observation wells is built to collect information regarding groundwater conditions, and to estimate soil settlement rates under different groundwater lowering conditions, and soil drainage rates. The hydraulic conductivity values range from 0.3 to 0.4 m/day. The groundwater recharge is mainly from cesspools and irrigated areas and its rate ranges from 0.6 to 1.2 mm/day. Three alternates, namely sanitary sewer, vertical drainage, and horizontal drains are evaluated. The horizontal drainage system is selected and a procedure is presented for its design in urban areas. Computer programs are developed for the analysis of steady and nonsteady flows into drains. Vitrified clay pipe material is selected because of its local availability and resistance to corrosion. The drained water is not suitable for irrigation because of its high salinity and sodium hazard. However, the quality of the drained water meets the local sea‐discharge standards, and is therefore discharged into the Red Sea.