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the main sewers which have manholes for cleaning purposes, traps being formed in connection with the manholes. These sewers are intended to carry off the house drainage and in part the rainwater. When practicable the rain flood water is carried off through open nullahs. The main sewer is provided with overflow connection with nullahs as a provision for floods. The main sewer finally runs out into the sea and discharges in the harbour. There is only one ventilating shaft in connection with the whole system. The system is defective in the following respects. That, owing to the want of ventilation the various traps must during heavy rains become unsealed by syphon action and sewer gases consequently escape freely into the streets through the manholes and gullies. And, that as the main sewer opens directly into the sea, there must result during the time of high tide, what amounts practically to a cessation of the working of the whole drainage system as owing to the low level of the site of the village the head or pressure from behind can effect but little in the discharge of the sewer. During this time there must be an accumulation of drainage water, as a considerable portion of the main sewer is then filled by the tide
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491
3
the main sewers which have wanholes for cleaning purposes,
traps being formed in connection with the manholes.
These sewers are intended to carry off the house drain-
age and in part the rainwater. When practicable the
rain flood water is carried off through open nullahs.
The main Bewer is provided with overflow connection with
nullahs as a provision for floods. The main sewer
finally runs out into the sea and discharges in the
harbour. There is only one ventilating shaft in con-
nection with the whole aystem. The system is defective
in the following respects. That lat., owing to the want
of ventilation the various traps must during heavy rains
become unsealed by syphon action and sewer gasses con-
sequently escape freely into the streets through the
manholes and gullies., End., that as the main server
opens directly into the sea, there must result during
the time of high tide, what amounts practically to a
cessation of the working of the whole drainage system
as owing to the low level of the site of the village
the head or pressure from behind can effect but little
in the discharge of the sewer. During this time there
must be an accumulation of drainage water, as a conaider-
able portion of the main sewer is then filled by the
tide
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