Sewer Inflow & Infiltration Removal Program

Infiltration & Inflow

The Town of Tewksbury is regulated by the Massachusetts Department of Environmental Protection and must abide by the Guidelines for Performing Infiltration/Inflow (I/I) Analyses and Sewer System Evaluation or face substantial fines. The regulations have stringent guidelines that all towns and sewer authorities must identify and remove I/I entering their sewer system. To meet these requirements The town has formulated and implemented an I/I identification and reduction plan to investigate the source of these extraneous flows. View the Massachusetts Department of Environmental Protection Regulations (PDF).

Infiltration and Inflows (I / I) are defined as extraneous flows that cause many sewers overflow, backups, direct connections of sump pumps and surface drains, and/or increase operating costs in the conveyance and treatment portions of the sanitary sewer system. Infiltration and Inflow are defined as follows:

• Infiltration is surface or groundwater which enters the collection system through defective pipes, joints, connections, and manhole walls.
• Inflow is the quantity of water discharged into the system from holes in manhole covers, roof drains, foundations or surface drains, basement sump pumps, prohibited connections or overflow from streams.

The Town of Tewksbury Department of Public Works Engineering Division along with its engineer consultants assessed the condition of the entire sewer system and identified priority areas to concentrate resources to reduce I / I. To date, 27,000 linear feet of sewer pipe have been inspected by smoke testing, video pipe inspections, flow metering, and / or sump pump tie-in investigation. Currently, the Town continues to inspect, monitor, and repair sewer pipes and manholes in these priority areas.

A significant source of inflow has also been attributed to homes and businesses with sump pumps and/or foundation drains directly tied into the sewer lines. These connections are prohibited under the town's By-law and burden the town with increased treatment costs and furthermore contribute to the sewer lines overflows (SSOs) due to the increased volume of water.

The goal of the I/I Removal Program is to reduce the financial constraint that these unmetered flows place on the Town's budget and be able to invest these cost savings into other areas of the Town's sewer infrastructure.