Mamaroneck Valley District Portion
Sanitary Sewer Smoke Testing
Scarsdale, NY
H2M conducted a smoke test program on the Mamaroneck Valley District portion of the sewer system in the Village of Scarsdale to identify sources of infiltration and inflow (I/I).
All sewer flows in the Village of Scarsdale are tributary to trunk sewer mains and sanitary sewer treatment plants owned and operated by Westchester County Environmental Facilities (WCDEF). The WCDEF Sewer Act defines excessive infiltration and inflow (I/I) as the following: “Excessive Infiltration and Inflow means the quantity of flow entering the County sewer system which is greater than 150 gallons per capita per day”. To determine if the Village Sewers are contributing excessive I/I, the Village has been conducting a muti-year program to evaluate the sewer that are tributary to three WCDEF sewer districts.
In 2017, the Village initiated a Sanitary Sewer Evaluation Study (SSES) of the Mamaroneck Valley District. The recommendations in the Study included a multi-year program to conduct additional smoke testing. During the summer of 2021, the Village retained H2M to conduct smoke testing on more than 98,000 feet of sewers in the Mamaroneck Valley Sewer District that were not smoke tested during the SSES.
Notifications to property owners were hand delivered prior to the smoke testing. H2M coordinated with the Scarsdale Police Department for the one-day testing conducted in high traffic areas. During smoke testing, direct and indirect connections on public and private property were observed at 14 catch basins, four driveway area drains, four roof drain leaders, and several other pathways that are a source of inflow. Dye testing of suspect municipal fixtures a potential field service in the project scope, however no dye testing was determined to be necessary.
The results of this investigation were detailed in a report that included an estimate of the flow during rainfall events from direct connections and a cost opinion to repair the direct connections.
Repairing the sewer system infrastructure will reduce the cost of conveying and treating extraneous flows in the sewer system. In addition, reducing extraneous flow will also reduce impacts currently caused by high flow during storm events at the publicly owned treatment plant.
