# Commission Implementing Decision (EU) 2017/2117 of 21 November 2017 establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for the production of large volume organic chemicals (notified under document C(2017) 7469) (Text with EEA relevance), Division: Averaging periods for emissions to water

Extent: E+W+S+N.I.

Unless stated otherwise, the averaging periods associated with the environmental performance levels associated with the best available techniques (BAT-AEPLs) for emissions to water expressed in concentrations are defined as follows.
Time-proportional composite samples can be used provided that sufficient flow stability can be demonstrated.
Averaging period
Definition
Average of values obtained during one month
Flow-weighted average value from 24-hour flow-proportional composite samples obtained during 1 month under normal operating conditions
Average of values obtained during one year
Flow-weighted average value from 24-hour flow-proportional composite samples obtained during 1 year under normal operating conditions
Flow-weighted average concentrations of the parameter (cw ) are calculated using Equation 3:
Equation 3:
c w = ∑ i = 1 n c i q i ∕ ∑ i = 1 n q i
where:
n number of measurement periods;
ci average concentration of the parameter during ith measurement period;
qi average flow rate during ith measurement period.
Where BAT-AEPLs refer to specific emission loads, expressed as load of emitted substance per unit of production output, the average specific emission loads are calculated using Equation 1.

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Source: https://www.legislation.gov.uk/eudn/2017/2117/annex/division/n2/division/5 (the official version)
Page: https://openlegislation.uk/eu-decision-2017-2117/annex/division-n2/division-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.