3.—(1) A local authority which before 11th July 2018 has—
(a)reduced the frequency of sampling for a parameter under paragraph 2(2) of Schedule 2 to the 2016 Regulations; or
(b)excluded a parameter from audit monitoring under paragraph 3(3) of Schedule 2 to the 2016 Regulations,
must on and after that date instead monitor in accordance with the provision made in Schedule 2 to the 2016 Regulations as amended by regulation 2(10) of these Regulations.
(2) But a local authority may rely upon any data collected before 11th July 2018 for the purposes of justifying any variation in monitoring under Part 2A of Schedule 2 to the 2016 Regulations as amended by regulation 2(10)(a) of these Regulations.
(3) Despite regulation 2(11)(b) and (d)(ii), paragraph 2(3), (4) and (6) of paragraph 2 of, and Table 2 in, Schedule 3 to the 2016 Regulations as in force immediately before 11th July 2018 remain in force in the transitional period with the modification in paragraph (4) and for the purposes set out in paragraph (5).
(4) The modification is that paragraph 2(6) of Schedule 3 is to be read as if for ““limit of detection”” to the end there were substituted—
““limit of detection” is to be calculated as—
three times the standard deviation within a batch of a natural sample containing a low concentration of the parameter; or
five times the standard deviation of a blank sample (within a batch);
“precision” is to be calculated as a measure of random error and may be expressed as the standard deviation (within and between batches) of the spread of results from the mean. A precision measurement of twice the relative standard deviation is acceptable. The term “precision” is further specified in ISO 5725 entitled partly “Accuracy (trueness and precision) of measurement methods and results”(1), as amended by the technical corrigendum entitled “Accuracy (trueness and precision) of measurement methods and results - Part 1: General Principles and Definitions TECHNICAL CORRIGENDUM 1”(2);
“trueness” is to be calculated as a measure of systematic error which is the difference between the mean value of the large number of repeated measurements and the true value. The term “trueness” is further specified in ISO 5725 entitled partly “Accuracy (trueness and precision) of measurement methods and results”, as amended by the technical corrigendum entitled “Accuracy (trueness and precision) of measurement methods and results - Part 1: General Principles and Definitions TECHNICAL CORRIGENDUM 1”.”.
(5) For the whole of the transitional period or any part of it beginning with 11th July 2018, a local authority may, in respect of any parameter specified in the first column of Table 2 in Schedule 3 to the 2016 Regulations, elect to be subject to the saved provisions instead of paragraph 2 of, and Table 3 in, Schedule 3 to those Regulations as amended by regulation 2(11)(b) and (e) of these Regulations.
(6) In this regulation—
“saved provisions” means the provisions saved by paragraph (4) as modified by paragraph (5);
“transitional period” means the period beginning with 11th July 2018 and ending with 31st December 2019.
This standard was published by the International Organization for Standardization (ISO) on 22nd December 1994. Under reference BS ISO 5725-1:1994 to BS ISO 5725-6:1994, it is published as UK standards by the British Standards Institution (ISBN 0 580 24034 7, 0 580 24033 9, 0 580 24029 0, 0 580 24028 2, 978 0 580 63299 0 and 0 580 24024 X).
ISO 5725-1:1994/Cor 1:1998 published on 2nd May 1998.