After 21 long years the Rockfield Overflow Basin (Trops-Plein Rockfield) is set to come on line. The overflow basin is located in Ville St-Pierre and will capture excess sewage water in the case of heavy rainfalls. In the past an overflow would cause an automatic 72-hour shut-down of the Lachine canal.  The new basin will reduce the frequency of overflows from 4-8 times a year to once every 5 years.