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<br />Figure 6. Overhead Sewer <br /> <br />J <br /> <br />e <br /> <br />I <br /> <br />I <br /> <br /> <br />~. 0 <br /> <br />'-- J'r <br /> <br />\.':> <br /> <br />'. . . ~. . . ". ' ,'.~. . . ". ' .' <br />'-. '-"'-' .'" ....',.-.-<.-.. <br />. "., .:-. ...., .:., ...., <br />,.' '-' ,.' '.' ,".- '-. <br />. ,'.~. ' ,..', . . ", ' ,'.~. . . ", . " <br /> <br />Backed up sewage kept in pipe <br /> <br />KNO~_3i'o>!4.N"F_" ,~~"~''-'''r~-=;-3' m:; <br /> <br />"" ^'''}~''o <br /> <br />Sump intercepts basement sewage ./ <br /> <br />Ejector pump discharges sewage ebove flood level <br /> <br />Backup Valve: A backup valve stops the water inside the sewer pipes. Older versions of <br />this approach were located in the basement and relied on gravity to close the valve. If debris <br />caught in the flapper, the valve did not close securely. Because of their unreliability, use of <br />valves was discouraged and even prohibited in some communities. <br /> <br />The "balanced valve" has corrected these design shortcomings. A system of counterweights <br />keeps it open all the time so debris won't catch and clog it. When the sewer backs up, <br />instead of relying on gravity, floats force the valve closed. A balanced valve is usually <br />installed in a manhole in the yard so there is less disruption during construction. This is also <br />preferred for older buildings which may not have cast iron sewer pipes under the basement. <br />An outside location prevents water pressure from breaking the pipes under the basement floor. <br /> <br />As with overhead sewers, a valve is fully automatic. It can even work when there is surface <br />flooding. The installation is outdoors, so there is minimal disruption in the basement during <br />construction. The owner still can use the sanitary sewers during flooding, as long as there is <br />power to run the ejector pump which ejects wastewater when the valve is closed. <br /> <br />Cost: $3,000 to $4,500 for an automatic backup valve located outside the building. <br /> <br />Basement Flooding: Basement flooding caused by saturated ground can be corrected by <br />installing drain tile around the foundation. The tile drains into a sump and water is pumped <br />out, usually onto the ground away from the building. Depending on local conditions, the pipe <br />and pumping system may have to handle large volumes of water. In some parts of the <br />country, all new houses with basements are built with drain tile and sump pumps. <br /> <br />-8- <br />