Whenever there is a human settlement, wastewater becomes an inevitable byproduct. The quality and quantity of the wastewater produced in a community depends on the population and the daily activities of the community. These activities are dynamic and greatly influenced by the lifestyles and technologies available to residents of a community. Wastewater is a heterogeneous mixture of water and various types of waste from residential areas, commercial and industrial facilities, and institutions. Communities all over the United States have established networks of sanitary sewer collection systems to transport wastewater to treatment facilities.
Treated wastewater is discharged into surface water systems such as lakes, rivers and oceans.
Although evidence of sanitary sewers has been uncovered in the ruins of ancient cities, the establishment of engineered sanitary sewer collection systems has been accomplished only during the 19th and 20th centuries. Sanitary sewer collection systems consist of sewer pipes and appurtenances such as manholes, inlet and outlet structures, and pumping stations. Most manholes are predominantly made of clay bricks or reinforced concrete. The sanitary sewer collection systems of major cities in the U.S. were constructed during the 1800s and early 1900s. As a result of physical, chemical, and biological phenomena, some of the components have incurred defects such as cracked and collapsed pipes, offset joints, and cracked manholes.