Sanitary and storm pipes start to deteriorate as soon as they're put in place. The cost of rehabilitation often falls on the homeowner's shoulders. Photo: C&K Industrial Services

Cities are faced with excessive flows in aging separate sewer systems that originate from infiltration of groundwater and inflow of stormwater. Even newer housing developments can have problems with water in basements. Private property infiltration and inflow (I/I) problems have increased and will continue to increase until municipalities develop structured programs that identify the problem, define the needed rehabilitation, and oversee the repair.

During the 1980s, funding from the construction grants program was offered to municipalities to evaluate their sewer systems and rehabilitate any deficiencies. Engineers and outside contractors performed I/I studies on the mainline sewer system, which is considered public property, and most of the deficiencies found were repaired.

Sometimes problems found on private property also were repaired, but most were left to deteriorate further. Political pressures caused private property rehabilitation to be tabled with the hopes that rehabilitation of public sector or mainline sewers would solve the problem of flooded homes.

In many cases that hope has proven false. Reducing I/I to the municipal sewer system from private property requires a common-sense approach to developing and implementing a program, whether administered in-house or performed by outside consultants.

Private Property

The piping network of the residential or private property sewer system is made up of small pipes, generally 4 to 6 inches in diameter. These pipes receive little preventive maintenance and, as a result, begin to deteriorate as soon as they're installed. The foundation drainage pipes and the sanitary and stormwater laterals are the main components of the private property piping network.

Foundation or footer drain: Intended to drain groundwater that accumulates near the walls of the concrete footer, the foundation drain is installed at the base of the foundation wall and generally surrounds the house or building as a perforated pipe. In some older homes this drain is connected to the sanitary lateral. When public storm sewers are installed below the basement elevation, though, the foundation drain can be connected to the storm sewer system. Newer homes have a sump pit connected to the foundation drains. A sump pump is installed and the discharge line is connected to the stormwater lateral so that groundwater can be pumped to the storm sewer system.