sentences:  The practices are expected to reduce stress on traditional water drainage infrastructure--storm sewers and combined sewers—which are typically extensive networks of underground pipes and/or surface water channels in U.S. cities, towns and suburban areas.Improved stormwater management is expected to reduce the frequency of combined sewer overflows and sanitary sewer overflows, reduce the impacts of urban flooding, and provide other environmental benefits.Though green infrastructure is yet to become a mainstream practice, many US cities have initiated its implementation to comply with their MS4 permit requirements.