Author(s): Patrizia Piro; Marco Carbone; Giuseppina Garofalo; John Sansalone
Linked Author(s):
Keywords: CSO; Detention tank; BMPs; Continuous simulation model; SWMM; TSS
Abstract: One common water quality objective of combined sewer flow management is the reduction of the pollution load discharges to receiving waters during wet weather for particulate matter (typically measured as total suspended solids, TSS), oxygen demanding matter, nutrients, toxics and pathogens. (Field et al., 2004). Over the last several decades, various treatment technologies and strategies have evolved for reducing the pollutant impact of urban runoff on receiving waters. An frequently used solution for combined sewer overflow (CSO) mitigation is a class of structural devices known as best management practices (BMPs), such as volumetric storage basins. Such systems represent one typology of a structural BMP designed for control and management of pollutant loads. The objective of this research consists of determining the effectiveness of detention tanks with different spatial characteristics, and without treatment capabilities other than the clarification provided through detention storage. Results are evaluated with a continuous simulation model of the urbanizing catchment in Cosenza, Italy. One of the most complete and widely used continuous simulation models, the Storm Water Management Model (SWMM), has been utilized to simulate the pollutant reduction provided by two alternative scenarios. The SWMM model for this catchment has been calibrated using catchment data. Two alternative scenarios were examined in this study. The first scenario involved concentrating volume in a single detention tank at the downstream end of the catchment. The second scenario involves a distributed arrangement of detention tanks in the combined sewer system catchment in Cosenza, Italy. Specifically, in this study, the efficiency, in TSS separation, of a concentrated tank placed downstream the same catchments have been compared with that of the distribution of three tanks located throughout the combined sewer system. Results obtained by the model simulations have demonstrated the differences between the performance of concentrating a single detention tank and locating distributed tanks, especially in terms of the pollutant mass discharged into the receiving water. The modelling approach, allows stakeholders to evaluate intercepted pollutant mass removal for a wide range of alternative scenarios. Results suggest that planning and design scenario can be optimized for a given set of catchment constraints and loadings.
Year: 2007