Smoke tests will be done on sanitary sewers in the central-east area of Joplin in upcoming weeks as part of the city's effort to identify where repairs are needed to reduce the infiltration and inflow of stormwater.

The testing area will be from Fourth to Ninth streets from High to Ozark avenues. A map showing the area is available on the city's website at www.joplinmo.org/smokemap.

Smoke testing is done by forcing a nontoxic, odorless smoke into sewer lines. The smoke leaks out of cracks and openings in the sewer lines and is visible on the ground, enabling workers to mark locations where the smoke escapes.

The smoke also will follow lateral lines and escape through roof vents of houses. City officials said that sometimes the smoke will enter a house or building through floor drains or the plumbing system. If that happens, a resident should be able to get rid of the smoke by opening some windows.

The work is being done by the engineering firm Trekk Design Group.

Residents will be notified about where they are working by placing door hangers on houses. Those hangers will include instructions on filling floor drains and p-traps with water to prevent smoke seepage if they wish.

Portable signs also will be posted in the areas where the work is being done.

Trekk personnel also will provide assistance and answer questions of residents. They will be wearing identification and their vehicles will be marked so they are identifiable.

The city has been working to fix the problems with rainwater inundating the sanitary sewer system and treatment plants since 2008. The overflows can contaminate the streams into which the plants discharge.

The system is being operated under an abatement order with the Missouri Department of Natural Resources with a schedule to make repairs to reduce overflow issues from excess stormwater infiltration.

Before the new agreement was approved in May, the city had been operating the sewer system under a voluntary compliance agreement that had been in place since December 2011 while a plan was developed to address peak flow discharges at the treatment plants. Joplin Public Works Director David Hertzberg said the abatement order replaces that agreement.

It establishes a schedule for work to be completed and sets out fines if the schedule is not met.

Also, the city has undertaken a number of repair projects that have included inspecting and filling holes or cracks in the sewer line system and upgrading lift systems. The city prepared a hydraulic model that allows evaluation of the system's efficiency such as identifying bottlenecks so fixes can be tailored to the problems illustrated by the model rather than guessing what repairs should be made.

Collector system

The city has 400 miles of sanitary sewer lines in its collector system.