5 Sampling, Testing & Monitoring

Section contents

5.1 Introduction
5.2 Sampling and measurement
5.3 Monitoring of consents
5.4 Independent analysis
5.5 Sampling and testing
5.6 Flow metering
5.7 Estimating discharge
5.8 Interpretation of test results and flow measurements

5.1 Introduction

Sampling, testing and monitoring shall be undertaken to determine whether:

  1. or not a discharge is in breach of the provisions of this Bylaw
  2. a discharge is to be classified as a controlled, conditional, or prohibited trade waste, refer 3.1
  3. or not a discharge is in breach of the provisions of any consent to discharge
  4. any trade waste charges are applicable to that discharge.

5.2 Sampling and measurement

5.2.1 When taking samples, measurements or readings, then any form of sampling or measurement that is described in 5.5 or 5.6 of this Bylaw shall be used unless other methods are described in the consent to discharge, when these methods shall be used.

5.2.2 When an authorised officer or authorised agent has need to investigate a characteristic of a discharge not covered by a consent then any form of sampling or measurement that is described in 5.5 or 5.6 of this Bylaw may be used as specified by the authorised officer.

5.3 Monitoring of consents

5.3.1 The Council may require the consent holder to monitor the discharge of the trade waste under the terms of their consent. The details of the monitoring to be done by the consent holder shall be at the discretion of the Council.

5.3.2 The Council may independently monitor the compliance of any consent holder in discharging trade wastes.

5.4 Independent analysis

5.4.1 An independent analyst may be either appointed by the Council or be chosen by the consent holder to the approval of the Council.

5.4.2 An independent analyst shall operate within the requirements of the Bylaw and shall:

  1. take samples and make measurements at times and in the manner specified by the Council
  2. distribute samples in accordance with 5.5.7
  3. analyse samples and report results in accordance with 5.5.10 and 5.5.1
  4. deliver the results of any such analysis in accordance with 5.4.6.

5.4.3 Prior to any scheduled inspection period, the Council shall give not less than five working days notice to an independent analyst of the commencement date of the inspection period.

5.4.4 When an independent analyst chosen by the consent holder fails, for whatever reason, to carry out their function at the consent holder's premises, then an independent analyst chosen by the Council may be appointed to carry out the function.

5.4.5 During any inspection period, the independent analyst shall take such samples, recordings and measurements at such time as may be directed by an authorised officer prior to the commencement of the inspection period.

5.4.6 Every independent analyst shall provide to the Council a certificate signed by the analyst at the time when any sample or finding is delivered to the Council. The certificate shall:

  1. describe the source of any sample, the time and date it was taken and the method used to take it
  2. certify that the sample has been taken in accordance with the requirements of this Bylaw
  3. describe the findings of any analysis, their source and the methods used to determine them
  4. certify that the analysis has been made in accordance with the requirements of this Bylaw.

5.5 Sampling and testing

5.5.1 Samples shall be taken in accordance with a programme approved by the Council.

5.5.2 Sampling shall be undertaken by an authorised officer, authorised agent or independent analyst.

5.5.3 All authorised officers, or authorised agents of the Council, or any independent analyst may enter any premises believed to be discharging trade waste at any time in order to determine any characteristics of any discharge by taking:

  1. readings and measurements and/or
  2. samples for testing

of any solid, liquid, or gaseous material or any combination or mixture of such materials being discharged.

5.5.4 The sample location shall be as defined in the consent or an alternative location advised or approved by the authorised officer.

5.5.5 Sampling shall be in accordance with the procedure contained in Schedule 4 and ISO 5667: Parts 2, 3 and 10 or some other procedure designed in accordance with ISO 5667: Part 1, with the consent of the Council.

5.5.6 An authorised officer may require that samples taken under this Bylaw are retained as separate samples, or that they are mixed to form a composite sample or samples.

5.5.7 On completion of sampling, each of the samples or the composite sample, shall be divided into a minimum of three equal portions dependent on the testing requirements. If the consent holder:

  1. makes no requirement as in (b) below, the samples shall be delivered to the independent analyst nominated by the Council
  2. requires one portion of each sample, or composite sample, shall be delivered to the consent holder and at least two portions of each sample, or composite sample, shall be delivered to an authorised officer of the Council or to their appointed independent analyst
  3. has nominated their own independent analyst, the consent holder or their independent analyst shall receive two portions and Council may, on request, receive one portion of the sample or composite sample.

5.5.8 Where any portion of a sample or composite sample is to be delivered in accordance with this Bylaw, it shall be delivered within four hours of the sampling being completed.

5.5.9 Any portions retained for reference and any unused portions of each sample, or composite sample, shall be retained for a period of not less than 20 working days from the date of receipt. It shall be retained in a manner that preserves as far as is reasonably possible the characteristics of the sample.

5.5.10 The sample or composite sample shall be analysed to determine those characteristics specified by the Council in the consent to discharge trade waste or for some other range of characteristics approved by the Council.

5.5.11 Any testing shall use methods or procedures in accordance with, or validated against, the Standard Methods for the Examination of Water and Wastewater.

5.6 Flow metering

5.6.1 Flow metering may be required in the following situations where the Council:

  1. determines there is not a reasonable relationship between a metered water supply to the premises and the discharge of trade waste
  2. does not approve a method of wastewater flow estimation
  3. decides there is a need for the continuous reading of flow.

5.6.2 Meters provided by the consent holder for the measurement of the rate or quantity of discharge shall be subject to the approval of the Council, but shall remain the property of the consent holder.

5.6.3 Measurement of flow shall be carried out by the consent holder in accordance with ISO TR 9824: Part 1, ISO TR 9824: Part 2 and BS 5728:Part 3.

5.6.4 Records of flow and/or volume shall be available for viewing at any time by the Council and shall be submitted to the Council at prescribed intervals.

5.6.5 Meters shall be located in a position that is readily accessible for reading and maintenance.

5.6.6 The consent holder shall arrange for in-situ or external calibration of the flow metering equipment and instrumentation by a person and method (usually that given in NZS 10012:Part 1) approved by the Council. Calibration shall be done at the time of installation and at least once a year thereafter to ensure performance of the meter is within ±10% of its reading. In use, meter readings shall be within ±5% of the most recent calibration check. A copy of independent certification of each calibration result shall be submitted to the Council.

5.6.7 Should any meter, after being calibrated, be found to register a greater or lesser discharge than the quantity of wastewater actually passed, the Council may make an adjustment to flow readings in accordance with the results shown by such tests.

5.7 Estimating discharge

5.7.1 Where no meter or similar apparatus is warranted, the Council may require that a percentage of the water supplied to the premises, or other such basis as seems reasonable, be used for estimating the rate or quantity of flow.

5.7.2 Should any meter be out of repair, or cease to register, or be removed, the Council shall estimate the discharge for the period since the previous reading of such meter, based on:

  1. the average of the previous four measurement periods, or
  2. any other factors for the purpose of arriving at a reasonable estimate when there is reasonable evidence that the average of the previous four measurement periods would be an unreasonable estimate of the discharge.

5.7.3 Where, in the judgement of the Council, a meter has been tampered with, the Council (without prejudice to the other remedies available) may declare the reading void and estimate discharge as provided above.

5.8 Interpretation of test results and flow measurements

5.8.1 Any characteristic shall be considered in excess of a consent or Bylaw limit if the result was determined by analysis of:

  1. an instantaneous composite sample and the result exceeds two times the relevant value
  2. two instantaneous composite samples taken at different times within a twenty-four hour period which both exceed the relevant value
  3. a four hour average composite sample
  4. a twenty-four hour flow proportionate sample.

5.8.2 Any flow measurement shall be considered in excess of a consent or Bylaw limit if the result was determined by analysis of a twenty-four hour flow volume, or an instantaneous flow rate as the case may be, which exceeds the relevant values.