Hydraulic Transient Analysis of Tarp Phase II System

The O'Hare System of the Tunnel and Reservoir Plan (TARP), which services 11.2 square miles of combined sewers, as shown in Fig. 1, is the smallest of the four systems comprising the 352-square mile combined sewer service area operated by the Metropolitan Sanitary District of Greater Chicago (MSDGC). After completion of this system in 1980, the O'Hare System area has still experienced problems, including basement flooding from sewer back-up and foundation seepage, overbank flooding, transportation delays caused by flooded streets, water quality degradation of area watercourses from combined sewer overflow, and public health hazards resulting from sewer back-ups. The average annual damage due to flooding in the O'Hare System are estimated to be in excess of $2.5 million