Beginning this month, the city of Wixom will be conducting its annual sanitary sewer system study to identify and isolate excess wet weather inflow and infiltration within the system.
To improve the city’s sanitary sewer system and save money, the city hired Hubbell, Roth & Clark (HRC) to facilitate the work that will attempt to identify new sources that are contributing to increased water flow in the system. The work includes smoke testing, which involves charging the sanitary sewers with odorless and non-toxic smoke and then identifying locations where the smoke escapes.
“By using the smoke process we can identify problems connecting to the sanitary sewers or problems such as leakage or cracks in the manholes that can cause infiltration,” said Department of Public Works Director Mike Howell. “You don’t want storm water going into the sanitary system.”
“The study helps identify potential areas of infiltration and is the first step in an investigative process,” he said.
Excess flow could be stormwater (rain), snow melt or groundwater that enters the sanitary sewers through cracks in sewer pipes or manhole structures or through sanitary or storm sewer cross connections. This storm water is then unnecessarily sent through the sanitary sewers to the Wixom Wastewater Treatment Plant where it is treated as if it were sanitary flow. This unnecessary treatment is costly and results in higher user fees and creates a situation where the capacity of the wastewater plant could be exceeded, resulting in the discharge of untreated sewage into the Norton Creek.
The city budgeted $45,000 for the project.
“It costs money if it goes into the sanitary system and becomes an environmental issue,” Howell said. “By implementing this process it keeps costs down at the plant and benefits the creek and environment because excess water could result in the system to overload and we don’t want that.”
During smoke testing, residents should be aware that some smoke may enter their home or building if the vent stack is blocked or a sewer trap is dry.
The smoke emitted is harmless and will dissipate after several minutes. Howell suggests ventilating a room should smoke occur.
If a situation arises that seems unusual, dial 911 and notify the Fire Department. As a precaution, residents should check their basement sewer trap to make sure it is filled with water. This is always a good check to prevent sewer odors and gases from entering your home.
Road lane closures may be necessary during smoke testing if field engineers must access manholes.
Prior to smoke testing, notices will be posted on doors and at each subdivision entrance.