Investigating the effect of improper design of septic tanks on construction costs

Abstract

There has been an increased use of on-site sanitation technologies globally and more so in developing countries with the use of septic tank systems for wastewater treatment in dwellings without access to main drainage. This is because of the low levels of technology and financial power required to construct and operate them coupled with their simplistic design and limited maintenance requirements. However, the researcher found no studies showing how the design of the septic tanks affects construction costs. This study focuses on the effect of improper design of septic tanks on construction costs. It involved collecting preliminary data associated with 19 households in the form of surveys, observations of septic tank features and physical measurements of existing tanks. The preliminary data collected was then used to come up with 3 different designs of septic tanks for each household basing on the predominant sizing methods found. The as built and designed tanks were then costed basing on the current market rates to determine the cost of construction if the tanks were constructed today. In order to find out the significance between the physical measurements and the costs of the existing and designed tanks, ANOVA tests were carried out. The study shows that there is a significant difference between the existing and designed tanks and that the physical measurements of the existing tanks were much greater than those of the designed tanks. The study also showed that there is a significant difference between the costs of the existing and designed tanks.