Inflow is ground or storm water discharged by connection to the sanitary sewer through basement sump pumps, floor drains, roof leaders, foundation and yard drains, catch basins and condensate lines, etc. These types of connections to the sanitary sewer are illegal as dictated by the Town Sewer Code. Inflow sources contribute to high flows in the system, resulting in sanitary sewer overflows. Such overflows can have a detrimental effect on the ecology of the Long Island Sound, reduce water quality for recreation, and create unhealthy environmental conditions for Town residents.
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This program is ongoing, with the remainder of Greenwich under investigation in our second investigation phase. The letters going out to residents include those for:
Learn more on the How to Comply page.
To help identify inflow sources, the Town of Greenwich embarked on a major investigation of its collection system. In the first phase, flow monitoring was conducted in several neighborhoods including Belle Haven, Byram, Old Greenwich, and Riverside. As a result of this monitoring, particular areas were targeted for more specific investigation in the form of smoke testing and building inspections. Additional inspections have identified other areas and the town is starting a second phase of flow monitoring to help identify sources.
From these inflow investigations, we found a total of 181 sump pumps and 30 drains directly connected to the sewer. Sump pumps have the potential to be connected to the sewer because of an unknown discharge location or flexible discharge pipe. The confirmed illegal connections have the potential to discharge 1.55 million gallons of inflow during a storm, approximately 15% of the Grass Island Wastewater Treatment Plant's average daily flow. This is clearly a significant issue for our collection system and treatment plant facilities.