RECONNAISSANCE INVESTIGATION OF POLLUTION FROM INADEQUATE SANITATION SYSTEM INTO SHALLOW QUATERNARY AQUIFER, ENGILA AREA: A CASE STUDY IN TRIPOLI-LIBYA

The pressure of growing population especially in the developing countries has resulted in more and more housing projects to be built in isolated areas. These new housing sites require sewage disposal systems. However, in many developing countries rural and suburban or even old developed towns, sewer less sanitation would appear to be only feasible and appropriate method of providing on-site sanitation. In Engila area, western suburb of Triopoli, a new government project to build 5000 housing units was constructed in the late eights. The swage system for disposal of domestic wastes was not completed and the treatment plant was not implemented. Therefore, the waste was disposed on the ground surface and accumulated in open surface sewer bond. The area of this artificial sewer bond is approximately 20,000 m² with 15 m depth. A reconnaissance field study was carried out just around the bond in June-July 2006. The conducted investigation containing electrical geophysical sounding and chemical analysis of ground water samples collected from some existed nearby water wells around the sewer bond. The objectives of this investigation are firstly how to obtain rapid indication by the electrical method as if no wells are existed and finally to assess the impact of the sewer bond on the shallow Quaternary ground water aquifer and soil environment around the bond site. The uppermost Quaternary aquifer in the study area is free aquifer (unconfined) its average water table depth in the study area is 45 m and its average saturated thickness range from 10 to 90 m. The transmissivity coefficient range from 2x10 to 1x10 m²/s, the storage coefficient range from 6x10 to 1x10 and discharge rate ranging from 20 to 80 m/h.