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TAP <br />The point where a service line connects to the MAINLINE. This is a frequent location <br />for a DEFECT. Cracks and breaks at this connection often result in LEAKS. At times <br />service lines protrude into the MAINLINE resulting in inefficient hydraulics. Service <br />taps are sometimes referred to as hammer taps when not properly connected or factory <br />taps when properly connected. <br />TROUGH/CHANNEL/INVERT <br />That portion of a manhole in which sewage flows. The depth of a manhole is measured <br />from the top of the CASTING to the bottom of the invert. <br />TRUNK LINE <br />That portion of the sanitary system that collects flow from smaller pipe, sometimes called <br />lateral line. This normally larger diameter pipe carries the flow to a treatment plant or <br />major pump station. <br />TV INSPECTION <br />The process by which a collection line is viewed with a closed circuit television camera <br />while pipe conditions are simultaneously observed on a TV monitor. Documentation is <br />made by video tapes or with photographs from the monitor. TV inspection normally <br />follows LINE CLEANING. <br />WET WEATHER INSPECTION <br />The process by which a sanitary collection system is observed during a storm event. <br />Manholes are opened to check the effects of inflow, areas are observed to confirm <br />ponding and inundation, and DYE TESTS are conducted. <br />ADS Environmental Services, Inc. <br />VI-8 <br />