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RIVER POLLUTION
On the 7th September, 1970, a complete survey was made of the River Colne, the survey
commenced in the North at the boundary of the Borough in the vicinity of Springwell Lane,
Harefield and terminated in the south at the Bath Road, Longford. A boat was used and samples
of river water were taken from thirty points along the course of the river. The samples were examined
in the departmental laboratory and the results were typical for water samples taken from a river
flowing through mixed agricultural and industrial development and receiving discharges from
surface water sewers serving industrial development. The samples did not indicate any excessive
pollution from any particular source.
During the survey oil was observed entering the river from surface water connections at
four points along the course of the river; these points were: (1) north of Maple Lodge sewage
works outfall; (2) the Uxbridge Industrial Estate; (3) adjacent to Accommodation Lane, Harmondsworth;
and (4) Moor Bridge, Bath Road, Longford. Rodent infestation was noted in the banks of
the river adjacent to industrial premises at Uxbridge and following the service of notices this
infestation was cleared by the Industrial company concerned. An accumulation of refuse on the
bank of the river opposite to Denham Studios was cleared by the owner of the land.
In addition to this special survey of the River Colne, 184 inspections and re-inspections
were made of rivers, ditches and water courses in the Borough and 14 specific sources of pollution
noted in the rivers were investigated and dealt with. It had been hoped that the publicity which
has been given to river pollution would produce a public response and that pollution would
diminish. Unfortunately, this has not occurred so far as the following four specific investigations
demonstrate:
Oil pollution of the River Colne was traced back to a road gulley on an Industrial Estate.
It was obvious that the oil had originated from the deliberate drainage of motor oil from a car
stationed over the gulley. It was necessary to remove the oil from the gulley by use of a gulley
exhauster, to prevent widespread and serious pollution to the river during the next heavy rainfall.
The Grand Union Canal was heavily contaminated with oil when a fuel oil storage tank at
an Industrial premises was over-filled during a night delivery to the company when none of the
company's administrative staff were present. There was no bund walling to the storage tank and
there is no legal authority whereby the Council can require the provision of such walling to an
existing storage tank. The company have agreed to restrict deliveries of fuel oil to such times as
a competent member of their staff is present.
Glass jars of chemicals were deliberately deposited into the canal feeder at Ruislip. Fortunately
they were recovered before causing any pollution. Serious dark discolouration was caused to the
canal following the breakdown of a private sewage pumping station situated on industrial premises
and soil water overflowed into the canal. The pumping station is automatic and situated at the
rear of the factory. A duplicate set of pumps would have prevented this accident but unless there
is frequent routine inspection of the pumps or, in the event of breakdown, the first pump is coupled
to an automatic alarm system, there is no guarantee that the first pump would be repaired before
the reserve set also broke down.
Owing to the shortage of inspectorial staff it has not been possible to carry out the investigation
of oil pollution arising from industrial estates in the Borough which it had been hoped to make
during European Conservation Year.
MAPLE CROSS SEWAGE DISPOSAL WORKS
Eight chemical samples were taken at the point where the effluent from the Maple Cross Sewage
Works discharges into the canal and then into the River Colne or from a point downstream of this
discharge channel. Results of the examination of these samples are set out on page 111.
Samples numbered 5 and 6 were taken at the time of an industrial dispute when the sewage
works were not fully staffed. Normally there is a brown discolouration at the point of the effluent
discharge across the width of the canal and downstream almost to the junction with the River
Colne. During the dispute this discolouration also spread upstream for approximately 50 yards.
Generally the samples indicate discharge of a satisfactory effluent.
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