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RIVERS POLLUTION
Water from the surface water drainage system in the Borough finds
its way into the River Lea and the River Thames from which the
Metropolitan Water Board extracts its water supply. It follows that the
surface water drain must be kept free from pollution by sewerage.
A drainage inspection assistant in this Department carries out a
continuous inspection of house drains in the Borough. Defects are reported
to the district public health inspector who then takes the necessary
action for remedying the defects. The following figures give an indication
of the need for this regular inspection:
Premises inspected by drainage inspection assistant 3,263
Re-inspections 1,291
Premises inspected by district public health inspectors 521
Re-inspections 1,031
Number of premises in which defects were remedied after
service of written or verbal notices 394
Summary of defects found:
Interceptor obstructed 93
Interceptor cap missing or displaced 86
Surface water cap missing or displaced 105
Drain obstructed 33
Wrong connections (soil drain to surface drain) 85
Total No. of defects: 402
The "Moselle"
The area drained by the "Moselle" includes portions of Muswell Hill
Cranley Gardens, Highgate, Crouch End East, and Central Hornsey.
It is the drainage system for the surface water in the area which eventually
flows untreated into the River Lea. The properties in the catchment area,
however, have two systems of drainage, one for surface water and one
for foul water but as long as dual inspection chambers for the two
systems exist, so pollution is always likely to recur.
The main cause is obstructions in the traps of the intercepting manholes,
due in a large number of cases to displaced caps of the rodding
eyes of the surface or soil drains. As a result sewage either passes to the
surface drainage system, or percolates through defective joints. In
addition it may cause rat infestation of the premises. This may go on
unknown to those concerned until found by routine inspection, and
thus involves a lengthy and costly process. Better and quicker control
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