Civil and Architectural Engineering
Civil and Architectural Engineering Department-College of Engineering-Sultan Qaboos University
Effects of Leakage from Septic Tanks on Groundwater Quality in South East
of AL-Seeb
Tariq Yasser AL-Belushi
Abstract
Groundwater is one of the most valuable resources in Oman. AL-Seeb city is one of the most
cities storing groundwater. The rapid residential activities took place during the last 15 to 20
years, especially in the South East of AL-Seeb until it became one of the most congested cities
across the country. The buildings have been designed and built with septic tanks as a basic
sewage system. Many of these septic tanks are very old and outdated. Furthermore, many of
them have not been built according to the required specification, which resulted in the leakage if
wastewater through the soil to the groundwater.
This research study aims at studying the effects of septic tanks leakage on groundwater quality
in south east of AL-Seeb area. Seven different drinking water wells have been selected to
evaluate the quality of the groundwater. The result were compared with the drinking water
standards. Five visits were conducted to each well between February and October 2013.
Samples were collected and analysed for different water quality to evaluate the risk on
environment and public health due the wastewater leakages from the septic tanks. Tests
included microbiological test, biochemical oxygen demand ( BOD), pH, electrical conductivity
(EC) turbidity, alkalinity, hardness, total organic carbon ( TOC ), anions ( Fluoride, Chloride,
Bromide, Sulphate), and cations ( Sodium, Potassium).
The obtained results showed evaluated values of specific tests such microbial test ( coilform
bacteria reached 200 MPN per 100 ml in some cases), BOD ( reached 10 mg/l in some cases,
TOK ( reached 100mg/l in some cases) and nitrate ( exceeded 100 gm/l in some cases) indicated
possible contamination due the wastewater.
However, this problem needs more detailed studies to collected sufficient data to reach solid
conclusions. Consequently, appropriate recommendations and action plans can be taken to
prevent and alleviate this long term problem.