. Method of data collection
The study was done with noise level data
obtained from the environmental monitoring unit of
WRPC for four plants which were: Carbon Black
Plant, Power Plant & Utilities, Waste Water
treatment Plant and Fuels Plant. Data obtained was
for a period April to November 2012 with the
exception of the month of July 2012 when there was
general shutdown for maintenance purpose.
The environmental monitoring unit used an
integrated Average Sound Level Meter , model
NO. CR812B that was developed by the Cirrus
research PLC, in UK for capturing their data.The
instrument was placed on the broad band mode and
measurement duration was 15 minutes at each
location for each plant studied.The calibration of the
instrument was checked before and after each set of
measuremnts as recommended by ISO [18]. The
reading was taking on daily basis but reports and
presentations were done on monthly basis, thereby
making the data used for the study to be