The characteristics of dry weather infiltration/inflow (I/I) and its effects on
combined sewer overflows (CSOs) in a dense urban area were evaluated. If I/I were
reduced within allowance range after sewer rehabilitation, the occurrence frequency
and pollution load of CSOs would be reduced to a certain level. The simulation using
stormwater management model (SWMM) showed that the removal of I/I below 5percentage of
the average dry weather flow resulted in reducing the number of 5 occurrences and
simultaneously intercepting 13.1percentage of the total yearly CSOs discharge volume.
Furthermore, it was simulated that COD and SS load could be reduced by 14.9percentage
and 20.4percentage, respectively, as the capacity of intercepting sewer were
increased.Keywords : infiltration/inflow(I/I), combined sewer overflows(CSOs),
stormwater management mode (SWMM)
