Quantification of sewer system infiltration using δ18O hydrograph separation

摘要

The infiltration of parasitical water into two sewer systems in Rome (Italy) was quantified during andry weather period. Infiltration was estimated using the hydrograph separation method with twonwater components and d 18O as a conservative tracer. The two water components werengroundwater, the possible source of parasitical water within the sewer, and drinking waterndischarged into the sewer system. This method was applied at an urban catchment scale in ordernto test the effective water-tightness of two different sewer networks. The sampling strategy wasnbased on an uncertainty analysis and the errors have been propagated using Monte Carlonrandom sampling. Our field applications showed that the method can be applied easily andnquickly, but the error in the estimated infiltration rate can be up to 20%. The estimated infiltrationninto the recent sewer in Torraccia is 14% and can be considered negligible given the precision ofnthe method, while the old sewer in Infernetto has an estimated infiltration of 50%.