Скачать или смотреть How to: Understanding the Science of Sanitary Sewer Drop Manholes - Priority Infrastructure

As you can see this rare double drop manhole plus one direct small 6 inch lateral connection in the middle. This large Sewer Collectors are older 1972 Vintage PVC Pipe before SDR-35 Standard Evolution. The 6 inch pipe is first generation PVC therefore the first to color the pipe greenish blue....
These drops can easily clog, hydrogen sulfide gas issues is the main issue melting away the concrete and rebar of infrastructure over time. Ideally vents should also be designed for these high priority sewer manholes to prevent catastrophic failure. Depth of drops should never exceed three or four feet due to factor of hydrogen sulfide forming from the cascading water fall like effect.
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This is priority infrastructure that requires annual of semi annual inspection to ensure the complex piping configuration has not clogged or the H2S Gas has not destroyed the fragile concrete structure.
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