Collection System

Collection System:

HISTORY OF THE COLLECTION SYSTEM

Chattanooga's sewer "collection system" refers to the network of pipes, manholes, and pump stations that are required to transport wastewater from homes, businesses, and industries to the Moccasin Bend Wastewater Treatment Plant.

The first sewer pipes in Chattanooga were built in about 1890.  At that time, large pipes made of brick were constructed, which carried both storm water and sanitary sewage from the buildings in the downtown area.  Since there was no treatment provided for this sewage in 1890, these pipes carried the sewage directly to the river.  Many of these pipes were constructed in the shape of an egg, allowing the small end to carry lower flows when there was no rain.

As the boundaries of Chattanooga grew, more sewers were constructed.  Outside of the downtown area, however, the sewers were built to carry only sewage, and not storm water.  Separate lines were built for the storm water.  The sewage pipes were often constructed of vitrified clay, and later of concrete.In the 1950's sewage pipes that would divert the dry weather sewage away from flowing directly into the river were constructed.  These pipes carried the sewage to the property at Moccasin Bend, which later became the wastewater treatment plant site.  This property first contained a pumping station that pumped the sewage to the river.

During rainstorms, however, because of the large volume of "combined" sewage and storm water, the sewers in downtown Chattanooga would overflow a small "dam" constructed in the pipe, and continue to flow to the river as it originally did in 1890.

After 1961 and 1970, when the wastewater treatment plant was constructed and improved, expansions to the sewer collection system took place.  Large pipes were generally constructed of concrete, and small pipes were now made of plastic.  Manholes were being built of concrete, also, instead of the original brick structures.  More pump stations had to be constructed to pump the flow over hills or whenever sewage pipes would be too deep.

After many outlying areas were annexed in the 1980's Chattanooga began another major sewer expansion program.

In early 1990, new federal regulations for cities like Chattanooga having "combined" sewers required that the "combined" flow originally designed to flow to the river must be dealt with in several approved ways.  Between 1990 and 2000, Chattanooga constructed Combined Sewer Overflow (CSO) Facilities, which capture this combined flow and provide holding area and primary treatment.  There are eight of these CSO facilities in operation.