_______ condition exists when the sewer is laid at a depth between 9m to 12m.
(a) Trench ditch
(b) Trench
(c) Tunnel
(d) Embankment
The question was asked in an international level competition.
Question is taken from Forces and Loads on Sewer topic in portion Construction of Sewers, Sewer Appurtenances and Sewage Pumping of Environmental Engineering