Sewer System Infiltration and Inflow Program: Sanitary Sewer System Smoke Testing Phase 1 completed- Fall 2019 Phase II will begin in Fall of 2020

Town Contact

Valerie Doerrer, Public Works Engineer - Water Systems

Concord Public Works - Water & Sewer Division: 978-318-3250 or


Flow Assessment Services, LLC of Auburn, NH

FAS logo

Smoke Testing

Program Background

The goal of the inflow and infiltration (I/I) program is to identify and reduce sources of I/I in the sanitary sewer system.   I/I is clear stormwater and groundwater that enter the sewer system that should otherwise be collected by a system that allows for the water to infiltrate back into the ground locally.  I/I must be removed at the source, before it enters the sewer system, otherwise the clear stormwater and groundwater is conveyed to the Wastewater Treatment Facility (WWTF) where it is processed and treated as wastewater resulting in an overall reduction in sewer system capacity and increased operating costs for treatment.

The Town uses multiple inspection methods to identify I/I in the sewer system, and sources of I/I that are found during these inspections are prioritized for repair.  Repairs to reduce I/I include sealing leaking pipe joints, lining pipes with cracks or holes, and lining leaking manholes with cement to stop the infiltration of groundwater.  Whenever feasible, the Town attempts to fix I/I sources using trenchless methods, meaning excavation is not required to perform the repairs.  When these methods are not feasible, excavation of the ground is required so the pipes can be replaced.

Project Overview

Smoke testing is an inspection method used to locate sources of I/I to the sanitary sewer system.  During this smoke testing, harmless white smoke is introduced into portions of the sanitary sewer system via a smoke-generating machine. While the test is being conducted white smoke will be visible venting from holes in manhole covers located on the street, and from plumbing vent pipes located on or near a building’s roof surface in the test area.

Smoke testing is scheduled to begin on November 12, 2019 

If your home or business is located in the vicinity of an upcoming smoke testing area, your will receive a notice, which crews will deliver by going  door to door approximately 24 to 48 hours in advance of the testing. Police, Fire and the Public Works Division will also be notified daily of work area.  

Testing will occur along all or portions of the following streets and adjoining streets:

Subarea 1

Subarea 4

Subarea 10

Comm Ave (from Laws Brook Rd to Rail Trail)

Florio Dr

Bedford Ct & Davis Ct

Conant St

Lowell Rd

Bow St & Lang St

Laws Brook Road

Main St (from Wood St Macarthur Rd)

Court Ln

Main St (from Comm Ave to Elm St)

Wood St

Lexington Rd (from the Square to Ridge Rd)

Maple St

Martin Rd

Warner Rd

Monument St (from the Square to Ripley Hill Rd)