Gravity Sewer Collection Design, Using GIS & SewerCAD

Abdul Wahid Amiri1, June-ichiro Giorgos Tsutsumi2, Ryo Nakamatsu2, and Mohammad Asaduzzman1

1. Graduated School of Engineering and Science, Univeristy of the Ryukyus, Okinawa, Japan

2. Department of Civil Engineeirng & Architecture, University of the Ryukyus, Okinawa, Japan

Abstract: The objective of sanitary gravity sewer collections is to provide a sewer system at the lowest annual cost compatible with its function while providing sufficient durability for design period. Despite, the plans and new development of Peruzi Residential Town shall be designed to accommodate gravity sewer collection. In this paper steady-state gravity flow developed in which designed and analyzed by SewerCAD software was considered. This program together with GIS is applied to analyze the area’s topography such as slope, surface features, and physical design calculation to delineate the sub-watersheds, to locate manholes, and determine the right path for the gravity main. In addition, sewer pipes havecontained solid particles which arenecessary to be transformed and needed to consider in design calculation according to minimum slope (Smin) and minimum velocity (Vmin) that should not be less than required standards. For the computation of uniform flow velocity and discharge in partially filled circular sewers, Manning’s equation is used. The objective of this paper is to provide gravity flow sewer collection by emphasizing thestudy of self-cleansing method. This approach results in a self-cleansing pipes slope value (Smin) for the design minimum flow rate (Qmin) in each sewer reach. Thereby gravity design approach integrated with software can result some technical benefits, for instance, showing the right path of gravity networks, setting up an exact location of manholes, location of the pump station, and drafting detailed sewer profiles. Consequently, this method facilitates sewer network design processing, easily and cost-effective maintenance services. Moreover, resulting an eco-system friendly environment in the region in term of wastewater collection and treatment, as well as conforming municipal codes and requirements.

Key words: gravity sewer network design, self-cleansing, and green environment