USEPA RESEARCH ON INFILTRATION⊘INFLOW CONTROL

From the mid-1960s through the mid-1980s, the U.S. Environmental Protection Agency (EPA) conducted a series of research, development, and demonstration projects on the characterization, cause and consequence, and control of infiltration⊘inflow (I⊘I) in both sanitary and combined sewers under the Storm and Combined Sewer Pollution Control Research Program (now called the Wet-Weather Flow Research Program). The research effort was driven by the need to support the construction grants program which included the abatement of stormwater I⊘I that resulted in excessive flows to the municipal treatment plant and caused polluted overflows. Research projects focused on I⊘I detection methodology and instrumentation, preventive installation, structural materials, and construction and corrective techniques.This paper presents the results of past EPA I⊘I research efforts, many of which significantly advanced the state-of-the-art and assisted the practicing engineering community in sewer system evaluation and rehabilitation, both reactively and proactively. It addresses: (1) state-of-the-art problem assessment; (2) pressure sewer systems; (3) polymers to increase sewer carrying capacity; (4) sealing methods and materials for sewer rehabilitation; (5) demonstration and evaluation of Insituform; (6) trenchless sewer installation by “plowing in;” (7) house lateral rehabilitation; and (8) impregnated concrete pipe to increase corrosion resistance and strength.This paper also briefly presents the ongoing and planned sewer system research on operation and maintenance, design, and construction. An urban infrastructure initiative to promote the use of innovative and cost-saving technologies may be considered in conjunction with efforts to address the huge infrastructure funding gaps faced by local governments across the nation.For about two decades, from the 1970s to the 1980s, the impetus of sewer infrastructure work in a municipality was driven by federal requirements to eliminate “excessive I⊘I” and transport and treat “non-excessive I⊘I.” However, after a decade, the effectiveness of I⊘I reduction did not materialize as expected. In the early 1990s, as much of the nation's collection system infrastructure continued to age and deteriorate, there was a growing concern of the health and environmental risks of sanitary-sewer overflow (SSO) which is estimated to occur 40,000 times a year nationwide. The soon-to-be-issued SSO Rule will become the impetus for preventing SSO from contaminating our nation's beaches and receiving waters.