Inflow and Infiltration Reduction Program

What is inflow and infiltration?

Inflow and Infiltration are terms used to describe the ways groundwater and stormwater (“clear water”) enter the sanitary sewer system.

Inflow: Inflow is stormwater that enters the sanitary sewer system directly through connections such as roof downspouts, driveway drains, sump pumps, and cross connections with storm drains. Peak inflow can occur during heavy storm events or snow melts causing sanitary sewer surcharges resulting in sanitary sewer overflows and basement backups.

Infiltration: Infiltration is groundwater or groundwater that is influenced by surface water that enters sanitary sewer pipes and manholes through holes, breaks, joint failures, connection failures and other openings. Infiltration quantities often exhibit seasonal variation in response to groundwater levels. Storm events can trigger a rise in groundwater levels and increase infiltration flows. The highest infiltration flows are observed following significant storm events or following prolonged periods of precipitation.

What is being done to find a solution?

The City is performing Sanitary Sewer Evaluation Study's in an effort to locate, identify, and correct improper connections and defects that cause Inflow and Infiltration so that the system capacity improves, and sanitary sewer overflow's and basement backups are eliminated.

TREKK Design Group, LLC is performing smoke test to detect sources of inflow and infiltration (I/I) into the sanitary sewer collection system in Columbia. The purpose of the tests is to locate defects in the sanitary sewer collection system. The “smoke” that will be used for this project is non-toxic, harmless, has no odor, and creates no fire hazard.  During the testing activities, TREKK personnel will be identifying defects that are revealed when smoke escapes through them. Locations for defects may include roof downspouts, uncapped cleanouts, driveway drains, stairwell drains, yard or area drains, window well drains, foundation-perimeter drains and defective service pipes.

Map of Study Area's:

Priority Area 1: November 2010

Priority Area's 2, 3 and 4- August- October 2011

What is the Inflow and Infiltration Reduction Program?

The Inflow and Infiltration Reduction Program was designed to help homeowners with costs to repair defects that are connected to the city’s sanitary sewer system. Removing these defects will decrease the water that is allowed to flow into the sewer system. It will ultimately reduce the sanitary sewer overflows and basement backups.

Who is eligible for reimbursement under the Inflow and Infiltration Program?

Anyone with property in the study area that is an owner-occupied residence having three (3) units or less, that was constructed before 1996, and has a private inflow and infiltration source listed in the table in section 22-217.3(b) of the City Ordinance.

For more information about the program, contact:

Public Works Environmental Services Division

Phone: 573-874-7250

Email: pubw@GoColumbiaMo.com

TREKK, Inc.

Phone: 573-445-4275

Shown above is a sanitary sewer overflow during a rain event.