Two terms referred to throughout this Report,> Infiltration and Inflow and I/I, are interchangeable. They refer to entire sanitary sewer systems, such as City of Springfield, Missouri operates. Both the Northwest Waste Water Treatment Plant and the Southwest Waste Water Treatment Plant eventually receive the sewage from our SASS Neighborhood; there, it is separated into solids and liquids and undergoes a complex process of recycling so that safe drinking water is provided to you and me.
WHEREAS, the city is concerned with the broadest city wide spectrum, you and I are concerned with how the city's I/I problems affect us--our families, our homes, our finances and even our pets--from the smaller, individual viewpoint. It is from that personal perspective that I have approached the problems we mutually share. These definitions will help you understand what the city is dealing with--and we receive as a liquid-based legacy.
SOURCE: FINAL REPORT FOR SANITARY SEWER EVALUATION SURVEY, CITY OF SPRINGFIELD, MISSOURI, Prepared by Wade & Associates, Inc., Lawrence, Kansas--Mark G. Wade, P. E.
BACKUP: Wastewater that enters into basements and other low-lying areas during intense rainfall periods. Normally a result of excessive storm water and ground water entering into the sanitary sewer system or blockage in the public or private sewer lines. (COMMENT: See Overflow.)
BASIN: An area defined by the network of interconnected sewer line systems that are tributary to and terminate at a designated control point. (COMMENT: In the SASS-area context, a low area where water from higher elevations collects as, for example, the South Avenue-Washita Street juncture or the South Jefferson Avenue-Cherokee Street intersection before stormwater improvements and new pavement were installed in 2005. )
I/I: Acronym meaning "Infiltration and Inflow"
INFILTRATION: Ground water that enters into the sanitary sewer through defects in pipes and manholes such as cracks, separated joints, deteriorated manhole components, building foundation drains, and defective service laterals. (COMMENT: If your basement, crawl space or yard is saturated by blackwater sewage from the ground, this is private-sector inftltration.)
INFLOW: Surface storm water that enters into the sanitary sewer through direct sources such as vented manhole lids, downspouts, area drains, indirect storm water connections, storm sewer cross-connections, and uncapped cleanouts below grade. (COMMENT:When your property is inundated by a stormwater flood or blackwater sewage spill at street level, which then encroaches on your driveway or yard from surface level. that's a form of private-sector inflow.)
OVERFLOW: A condition in which the waste water flow rate in a sewer system exceeds the capacity of the sewer to the extent that raw wastewater is discharged directly to a receiving storm sewer or drain. (COMMENT: When wastewater and solid sewage matter, which are drained or flushed through the private-sector lateral pipe connecting your residence to the public-sector sanitary sewer pipeline, reverses direction of flow, it is "backup" if it remains confined to your pipes and/or toilet, but becomes "overflow" if it spills or backs up in such a manner that you must clean it up, as, for instance, when sludge enters your tub through the drain grate, or spills over from a pipe, wash basin or sink.)
STORM EVENTS: Rainfalls of various intensities. For instance: I-Year Storm Event--A single rainfall event which statistically occurs one time each year; 5-Year Storm Event--A single rainfall event which has 20% statistical probability of occurring during any given 12-month period.