1 March 1997
manholes were built of brick masonry, and are now frequently the source of significant volumes
of groundwater infiltration. More recently in attempts to alleviate this problem, precast concrete,
plastic, and fiberglass manholes have been utilized. In certain situations precast units will not be
suitable, and cast-in-place reinforced concrete will be required. Cast-in-place construction
permits greater flexibility in the configuration of elements, and by varying reinforcing the strength
of similar sized structures can be adjusted to meet requirements. In general, materials used
should be compatible with local construction resources, labor experience, and should be cost
4-2. BUILDING CONNECTIONS. Building connections will be planned to eliminate as many
bends as practical and provide convenience in rodding. Bends greater than 45 degrees made
with one fitting should be avoided; combinations of elbows such as 45-45 or 30-60 degrees
should be used with a cleanout provided. Generally, connections to other sewers will be made
directly to the pipe with standard fittings rather than through manholes. However, a manhole
must be used if the connection is more than 30 meters (100 feet) from the building cleanout.
Normally, the cleanout inside the building will not be adequate for complete rodding, thus outside
cleanouts will be provided. Installation of a two-way cleanout at the building connection (1.5
meters (5 feet) from the footing) is recommended. Manholes will be installed where cleanouts
are not feasible.
4-3. CLEANOUTS. Cleanouts must be installed on all sewer building connections to provide a
means for inserting cleaning rods into the underground pipe. An acceptable cleanout will consist
of an upturned pipe terminating at, or slightly above, final grade with a plug or cap. Preferably
the cleanout pipe will be of the same diameter as the building sewer, and never smaller than 150
mm (6 inches).