An investigation of leaky sewers as a source of fecal contamination in the stormwater drainage system in Singapore

Abstract

A preliminary investigation was conducted into possible pathways for fecal contamination to enter stormwater drains from leaky underground sewer lines in Singapore. The island's drainage channels flow into catchment reservoirs that are used to store water for future supply needs. Singapore's Public Utilities Board wishes to open up the reservoirs for recreational purposes and requires the water quality in the reservoirs to meet certain standards. Findings were assembled from the literature on sewer-groundwater interaction and Singapore's geology, the history and current state of Singapore's sewer infrastructure, the results of a groundwater model, field observations, and GIS data on the sewer and drainage network layout. It was found that sewer pipe connections between buildings and the sewer network are particularly susceptible to damage, and that high-flow-rate pathways are likely to exist between a sewer leak near a building and the small drains typically laid along the building periphery. These drains flow into a network of larger drains that eventually flow into a reservoir. Hence, sewer leaks near building connections may be a significant source of fecal contamination in the stormwater system and are worth investigating further.