Sandro Artina

Short communication: Simulation of a storm sewer network in industrial area: Comparison between models calibrated through experimental data

The purpose of this article is to test the performance of two commercial models for the simulation of sewer systems (InfoWorks, developed by Wallingford Ltd and Mouse, developed by DHI), basing on the experimental data sampled in a 1.15ha watershed located near Bologna, Italy. The experimental catchment is part of a truck transit and parking area, completely asphalt paved and drained into a first flush tank. Hydrologic and water quality data collected for almost 8 months inside the tank have been used to calibrate the models through a trial and error procedure for both quantity and quality aspects. A sensitivity analysis for the most relevant quality-quantity parameters has also been performed, testing therefore the behaviour of these models in a small impervious watershed and their reliability as a support tool in the design phase.

Toxicity and pollutant impact analysis in an urban river due to combined sewer overflows loads

The Navile Channel (Bologna, Italy) is an ancient artificial water course derived from the Reno river. It is the main receiving water body for the urban catchment of Bologna sewer systems and also for the Waste Water Treatment Plant (WWTP) main outlet. The aim of this work is to evaluate the Combined Sewer Overflows (CSOs) impact on Navile Channels water quality. In order to collect Navile flow and water quality data in both dry and wet weather conditions, two measuring and sampling stations were installed, right upstream and downstream the WWTP outflow. The study shows that even in case of low intensity rain events, CSOs have a significant effect on both water quantity and quality, spilling a considerable amount of pollutants into the Navile Channel and presenting also acute toxicity effects. The collected data shown a good correlations between the concentrations of TSS and of chemical compounds analyzed, suggesting that the most part of such substances is attached to suspended solids. Resulting toxicity values are fairly high in both measuring points and seem to confirm synergistic interactions between heavy metals.

Multiobjective Design of Water Distribution Networks through the Generation of Pseudofronts in the Hydraulically Feasible Region

AbstractThe design of a water distribution network (WDN) is conceptually a multiobjective problem characterized by stringent constraints. Even in its most simple formulation, which requires only the maintenance of minimum pressures, it is difficult to solve, and the simplifications introduced often impair the practicality of the solutions. The paper aims at integrating an engineering approach to the optimization problem by generating pseudofronts in the hydraulically feasible region of the search space. The optimization algorithms provide an entirely feasible trade-off between cost and considered constraints, which may be directly used by a hypothetical decision maker. This engineering approach requires a fast tool to search for feasible solutions: the recently developed genetic heritage by stochastic evolution transmission (GHEST) algorithm, used herein, has proved to be effective and efficient in solving the optimal design problem of WDNs. Tests are carried out on two large-size water distribution netwo...

The role of settling velocity formulation in the determination of gully pot trapping efficiency: comparison between analytical and experimental data

Roadside gully pots are the connecting points between surface runoff and the underground drainage network; therefore they can be considered as the most superficial component of urban drainage systems. Gully pots are supposed to trap particulate matter washed off the catchment surface, but also to collect and convey stormwater into the network. The continuous accumulation of particulate matter results in a progressive loss of the gully pot hydraulic conveyance, thereby increasing the probability of urban flooding during rainstorm events. This study has therefore the objective to determine which variables influence the gully pot capability of retaining solids (efficiency), both experimentally and analytically. Several laboratory tests have been performed on a simple plastic gully pot, with different inflow rates and using both mono and hetero-disperse particle samples. Particular attention has been given to the influence exerted by the way particle settling velocity is expressed: efficiency has been analytically determined by means of multiple settling velocity formulas proposed by various authors and eventually compared to experimental data. Results deriving from the adoption of each single settling velocity formula have been extensively analysed, showing fairly different outcomes.

Can Surface Overflow Rate Predict Particulate Matter Load Capture for Common Urban Drainage Appurtenances

AbstractUrban drainage appurtenances separate particulate matter (PM) and detritus unintentionally and by design. Such PM separation impacts conveyance, treatment, and maintenance practices. This study examines two common appurtenances: Gully pots (or catch basins) and screened hydrodynamic separators (HS). Under steady and controlled physical model testing, PM separation was measured for influent granulometry [particle size distributions (PSDs), PM specific gravity]. Catch basin separation ranged from 40 to 99% for a monodisperse (well-graded sand, SW) PSD and 60 to 83% for a hetero-disperse PSD. With similar testing, a clean HS (to avoid scour dominating PM separation), the HS was also loaded with a heterodisperse sandy silt (ML) and tested as a function of flow, with separation of 40 to 65%, as compared to 70 to 99% for the SW, similar to the catch basin. Physical model results were compared to the surface overflow rate (SOR) model, illustrating that the SOR overestimated PM separation by 3–13%. The SO...