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26
In the last Report reference was made to a. survey following
complaints which had been received of excessive grit deposition alleged
to be emanating from the Power Station. Due to the variable factors
relating to plant operation and weather conditions, such surveys are
often protracted and the results inconclusive. The snowfall on the
31st Decemberj, 196l, however. presented an opportunity to carry out a
widespread survey of the Borough over a period of 43 hours between the
end of the snowfall and the Collection of the samples. Specimens were
taken by skimming a layer of snow from an area of a quarter of a square
metre at seven different points in the Borough, The material collected
was submitted to the Public Analyst, and the results were collated with
the hourly wind readings during the period. The results of this survey
can best be summarised in the concluding paragraphs of the Public
Analyst' s report:-
"In my opinion the collection of these deposits from
the surface of the snow under the conditions obtaining
at the time is of great importance as it eliminate
pollution due to wind-borne dust from roads ground
surfaces and roofs of houses. This is confirmed by
the virtual absence of ordinary siliceous particles.
The conclusion to be drawn from the magnitude of the
deposit at Canbury Car Park as compared with the other
sites chosen is inescapable. There can be little doubt
also, that the pollution over the Kingston area derived
from the power station is heaty and that particles of
substantial size are carried for a considerable
distance,"
These conclusions were reported to H,M,District Inspector of
Alkali etc. Works and upon his approach to the authorities at the
Power Station a full investigation was carried out which was followed
by the adoption of improved methods both of operation and maintenance
of the grit collecting equipment. It is reasonable to assume that the
action taken at the Station is reflected in the improved figures
reported from the deposit gauges and the absence of complaints by
residents. As weather conditions also affect the results from deposit
gauges„ it may be some years before the full effects ©an be ascertained.
Recording of Atmospheric Pollution. Instruments are maintained on
the Guildhall roof and at Tiffin Girls' School for the recording of
smoke and sulphur dioxide by the volumetric method. The advantage of
this method over the deposit gauge is that it is possible to obtain
daily readings of pollution and to observe more closely the effects of
weather conditions on the state of the atmosphere. The following tables
and graphs indicate the results obtained, Steoke and sulphur dioxide are
expressed in microgrammes per cubic metre.