Drainage Services Department

Guidelines on Application for Reassessment of COD

Hide
Back
  1. Who Can apply
  2. How to apply
  3. Procedure
  4. Points requiring special attention
  5. Sampling frequency, effective date and validity
  6. Procedural flowchart
  7. Maintenance of wastewater treatment, operation practices and measures, and record keeping during validity period
  8. Notes
  9. Appendices
  10. General Forms
  11. Enquiries

 

Who Can apply

1. A consumer liable to pay trade effluent surcharge (TES) but produces trade effluent of Chemical Oxygen Demand (COD) values lower than the generic values as stipulated in the Sewage Services (TES) Regulation can apply for a variation of the TES rate.
 

How to apply

2. This can be done by having the COD values of the trade effluent, thus the TES rate, reassessed at the consumer's expense by a laboratory accredited under the Hong Kong Laboratory Accreditation Scheme (HOKLAS laboratory)1 in accordance with the "Technical Memorandum on procedures and methods for sampling and analysis of trade effluents" ("TM")2, issued pursuant to section 13 of the Sewage Services Ordinance.

Procedure

3. This guideline explains the general procedures and requirements for the application for reassessment of COD values in the trade effluent. For detailed procedure of the reassessment, sampling, and testing, please refer to the TM.

3.1 The applicant should appoint a HOKLAS laboratory (see Appendix I) to submit the application and sampling proposal3.

3.2 In general, the application should include all information listed in Appendix II. A typical example of an application with sampling proposal, relevant information and forms to be submitted is given in Appendix III for reference.

3.3 Upon receipt of the application and sampling proposal, Drainage Services Department (DSD) will review and check the completeness of information submitted. If necessary, DSD will request the applicant to submit any missing information, further information, or clarification.

3.4 When all the required information is received, DSD will inspect, if necessary, the site of the concerned premises normally within ten working days 4 to confirm the sampling arrangement (working days are defined as Monday to Friday except public holidays).

3.5 After the above inspection (if applicable) and the receipt of all the required information, a sampling schedule, taking into account the criteria set out in Appendix IV, will be mutually agreed between DSD and the HOKLAS laboratory/the applicant. DSD will then issue a notification of the confirmed sampling arrangement to the HOKLAS laboratory and the applicant.

3.6 The HOKLAS laboratory should arrange the sampling to be conducted by competent samplers (see Appendix V), and testing for the trade effluent discharged from the premises concerned in accordance with the agreed sampling arrangement. The HOKLAS laboratory is required to split the sample collected, and submit one of the split samples to DSD for checking.

3.7 When testing is completed, the HOKLAS laboratory shall submit a formal test report to DSD.

3.8 If DSD considers that the COD reassessment results are adequately representative, the COD values will be approved and used to determine the new TES rate accordingly.

 

Points requiring special attention

4. When submitting an application, the applicants should pay attention, but not limited, to the following:-

4.1 All water meter(s) must be functional (no sampling should take place unless dysfunctional meter is properly repaired by the Water Supplies Department or a licensed plumber).

4.2 All drainage outlets are free from blockage and functioning properly.

4.3 Sampling tools are appropriate and in good condition.

4.4 All water pipes (including the fire hose), water tanks (both fresh water and saline water), cooling tower(s) of air conditioning system etc. should be leakage free.

4.5 All hydro-vents, if installed, must be operating normally and well maintained.

4.6 All wastewater treatment facilities, including central grease trap (CGT), if installed, are operating normally and free from overflow and blockage.

4.7 The date and frequency of cleaning for the CGT(s) as well as all pollution control measures such as the use of solid traps (strainers/spongy filters etc.) must be explicitly declared before commencing of the sampling and should be strictly adhered to at all times.

4.8 Documentary evidence for use of chemical and/or biological treatment of the wastewater, if applicable, should be available upon request by DSD.

4.9 All equipment and machinery in the premises that may affect the quality of the effluent must be operating normally. A suggested list of items to be checked for normal operation is given in Appendix VI for reference.

4.10 DSD may inspect the site at any time during or after the sampling. The site inspection is to confirm that the agreed sampling methodology has been adopted during sampling, and that the trade activities and practices including all pollution control measures (such as dates and frequency of cleaning of CGT(s)) affecting the effluent quality are normal and strictly adhered to at all times.

4.11 DSD may also collect sample(s) of trade effluent(s) discharged from the premises of the applicant concerned to verify the representativeness of the COD results submitted by the applicant.

4.12 Resisting and delaying DSD's staff in carrying out inspection and sampling without reason is deemed as acts of deception, and the COD reassessment application will be suspended by DSD.

4.13 Any non-compliance will be deemed unacceptable. Once revealed, the sampling work of the day will be cancelled and test results of any sample collected will become void. DSD may terminate the processing of an application if the non-compliance is serious. Practices that are considered as serious non-compliances include but not limited to the following:

  1. Abnormal storage of wastewater;
  2. Disposal and discharge of wastewater at point(s) other than that declared;
  3. Disturbance of central grease trap(s) (scheduled periodic cleaning must not coincide with sampling day);
  4. Water supply from sources (e.g. fire hose, water meter for toilet-flushing) other than the designated water meter(s);
  5. Kitchen activities that do not match the signed "Declaration of kitchen practice for restaurant and food factory (Form DSD/TES 3(e))";
  6. Some specific examples in which the applications are not accepted are given in Appendix VII.

4.14 If there is a reasonably doubt that the water usage or sewage discharge from the premises of the applicant may have contravened any Ordinances, DSD may refer it to other departments for their information without giving prior notice.
 

Sampling frequency, effective date and validity

5. According to the Technical Memorandum, the sampling frequency should be determined by using the current trade effluent surcharge estimate of COD load discharged (i.e. using water meter readings for the latest billing period; discharge factor, if any; and COD concentrations from generic characteristics).

5.1 Taking a restaurant case with latest daily water consumption of 70m3/day as an example, the range of discharged COD in kg/day shall fall into 51-100 kg/day (70m3/day x 0.8 discharge factor x 1630 g/m3 ÷ 1000 g/kg). As a result, the number of sampling days required for the case is three.

5.2 If the approved COD values are lower than the generic values as shown in Appendix VIII, a new TES rate will be determined according to the charging matrix shown in Appendix IX and will take effect for three years.

5.3 The effective date of the new TES rate is determined as follows:

i. For a new application, the effective date of the new TES rate shall be the first day of the billing period within which the first date of sample collection falls and the COD values of such samples are accepted by DSD and used to determine the new TES rate.

ii. For a re-application, if the first day of the billing period mentioned in paragraph 5.3i. falls immediately after or prior to the expiry of the last approved TES rate, the effective date of the new TES rate shall be the date immediately after the expiry of the last approved TES rate; otherwise, it shall be the first day of the billing period within which the first date of sample collection falls and the COD values of such samples are accepted by DSD and used to determine the new TES rate.

5.4 Several hypothetical examples of approved application are shown in Appendix X.
 

Procedural flowchart

Procedural flowchart

Maintenance of wastewater treatment, operation practices and measures, and record keeping during validity period

7. Throughout the validity period, the applicant shall maintain the wastewater treatment, operation practices and measures as declared, and observe any other applicable conditions. DSD may also collect grab samples of the effluent discharged from the premises for the purpose of verifying the effluent strength against the approved COD values.

7.1 All records showing that ongoing wastewater treatment, operation practices, and measures are in line with those last declared must also be kept by the applicant on site for inspection. These records pertain, but are not limited, to those declared by the applicant under General Forms DSD/TES 3(e), DSD/TES 4(e), DSD/TES 5(e) ,DSD/TES 6(e) and DSD/TES 9(e). DSD will also request submission of these records by the applicant from time to time. In considering a re-application, DSD may take into account any failure to maintain the declared wastewater treatment, operation practices and measures, or failure to submit such records upon request.

7.2 The applicant should inform DSD if, during the validity period, the business operation mode, manufacture, sewage treatment practices, etc. have been changed.  DSD will examine if the revised TES rate is still applicable.  The applicant should also appoint a HOKLAS laboratory to submit a COD reassessment application as soon as practicable.
 

Notes

1 A list of HOKLAS laboratories accredited with the test method in COD reassessment is attached in Appendix I for reference. For details, please refer to the Accredited Conformity Assessment Bodies at the Innovation and Technology Commission website: (https://www.itc.gov.hk/en/quality/hkas/)

2 The TM can be downloaded at the DSD website: (http://dsd.gov.hk/EN/Sewage_Services_Charging_Scheme/Reassessment_of_TES_rate/)

3 In order to allow sufficient time for processing of a re-application, the consumer is advised to submit application at least one month before the expiry of the last revised TES rate should the applicant wish to have the new TES rate, if it is lower than the generic TES rate of the trade concerned, to be effective right after the expiry of the last revised TES rate.

4 The time quoted may vary depending on the prevailing number of applications received by DSD.

 

Appendices

Appendix I List of HOKLAS Laboratories accredited with the test method in COD Reassessment
Appendix II Relevant information to be submitted with the application of variation of Trade Effluent Surcharges (TES) rate
Appendix III Typical example of sampling proposal and related information to be submitted with the application for COD reassessment
Appendix IV Guidance notes on arrangement of sampling
Appendix V Criteria for competent sampler
Appendix VI Suggested list of items to be checked for normal operation
Appendix VII Some examples in which the application for COD reassessment will not be accepted
Appendix VIII TES chargeable trade, business or manufacture, their TES rates and generic COD values
Appendix IX TES rate matrices
Appendix X Hypothetical examples of approved applications

 

General Forms

Form No. Form Title Means of Submission
DSD/DF_COD Application form for revision on discharge factor/COD values By email, post, fax or in person
DSD/TES 1(e) Application form for reassessment of Chemical Oxygen Demand (COD) values in trade effluent By email, post, fax or in person
DSD/TES 2(e) Letter of undertaking By email, post, fax or in person
DSD/TES 3(e) Declaration of kitchen practice for restaurant and food factory By email, post, fax or in person
DSD/TES 4(e) Declaration of proposed cleaning frequency and date(s) for central grease trap(s) (CGT) By email, post, fax or in person
DSD/TES 5(e) Declaration of use of strainers at drainage outlets and surface channels By email, post, fax or in person
DSD/TES 6(e) Declaration of use of sponges at drainage outlets and surface channels By email, post, fax or in person
DSD/TES 7(e) Declaration of giving up effective period of previously revised TES rate By email, post, fax or in person
DSD/TES 9(e) Grease trap waste disposal record By email, post, fax or in person

 

Enquiries

Enquiries may be made to the Drainage Services Department at:-

G/F Western Magistracy,
2A Pok Fu Lam Road,
Hong Kong
Tel.: 2834 9432
Fax : 3104 6433

Back to Top