Sustainable stormwater management system: a conceptual design model for SLIIT, malabe campus, Sri Lanka

Abstract

In recent years, significant attention has been given to the utilization of water and its components. Management of the wastewater including run-off to maintain a balanced eco-system has been an irony issue mostly in urban areas. Conventional water management systems such as reducing peak flow rate, sewer systems, end of pipe mitigation measures do not tend to fulfill the tortuous developmental plan of growing cities. It is therefore, necessary to use the principle management concepts such as best management practices (BMPs), low impact developments (LIDs) focusing on micro-management design concepts to intensify the existing hydrological cycle. Structural practices such as perforated infiltration trench along with bio-retention pond is thought to control the storm water at Sri Lanka Institute of Information Technology (SLIIT) premises based on the biophysical, hydrological and ecological ascribes of the landscape. This was identified as a critical issue to the well-being of the students during the rainy periods. Impervious layers introduced in aesthetic purposes have reduced the infiltration and then, increase the temporary flooding / pooling of these impervious surfaces. Post-development water management requires multi-disciplinary understanding of watershed along with identification of predevelopment functions and their constraints. Therefore, parameters of soil properties like permeability, grain size, and other parameters like soil profile analysis, water quality analysis, water table depth, soil moisture condition and trench geometry based on terrain at two different sites were analyzed. Field tests were performed to find infiltration rates to compute the performance of the trench and to determine the storage volume based on rainfall events. Thus, this paper imparts colors upon an affordable, pragmatic and long-term solution to meet the need of modern water management at SLIIT. An infiltration trench network is being proposed to overcome the flooding / pooling problems in SLIIT premises and the proposal is being presented to the management of the institution.