The intent of this presentation is to explain the existing function of combined sewer systems and their impact on human health and public safety. This handbook highlights the usage of sustainable measures such as green infrastructure techniques to manage stormwater.
Older cities have combined stormwater and sanitary sewer systems. As cities grew and development increased, so did the amount of impervious surfaces and has caused these combined systems to overflow. Stormwater has played a major role in the overflow events. The combined sewer systems are adequately sized to handle the sanitary components of the system when storm events occur, rain water flows into the combined system at a rapid rate and overwhelms the existing infrastructure. When this occurs, raw sewage and untreated water are emptied into local waterways to relieve the local water treatment plants and prevent basement backups. The untreated spillage causes harmful pollutants to overflow into locations where people fish, swim and play in the local waterways.