Composite sample means a combination of individual samples of wastewater taken at 1 hour intervals, for eight (8) hours (or for the duration of discharge, whichever is less), to minimize the effect of variability of the individual samples. Individual samples must be of equal volume. (Example: one (1) liter per hour.)
Retail Price Index means the general index of retail prices published by the Office for National Statistics each month in respect of all items or:
Composite means a combination of individual samples collected at periodic intervals of the entire discharge day. The composite must be flow proportional; either the time interval between each individual sample or the volume of each individual sample must be directly proportional to either the wastestream flow at the time of the sampling or the total wastestream flow since the collection of the previous sample. Samples may be collected manually or automatically.