Schedule 6 - Porirua City Council Trade Waste Bylaw 1990 Schedules I-III

Section contents

Schedule I Description of simple trade wastes
Schedule II Description of controlled trade wastes
Schedule III Measurement and sampling of the characteristics of a trade waste discharge

Schedule I - description of simple trade wastes

  1. Any trade waste discharge, is a simple trade waste if it has no trade waste characteristics which exceed the limits or maximum values specified in clause 2 and Table 1.1 of this Schedule.
  2. For the purposes of clause 1 of this schedule simple trade wastes are those discharges which: -
    1. do not contain any: -
      1. chlorinated bi-phenols, or
      2. halogenated hydrocarbons, or
      3. organo-tin compounds, or
      4. pesticides, herbicides, insecticides, fungicides or material of a similar nature, or
      5. cooling water, condensing water, or surface water, or,
      6. any garbage that contains any particle that will not pass freely through a twelve millimetre mesh, or
      7. any solid liquid or gaseous matter or any combination of such matters, which in relation to the sewerage system may be prejudicial to the safety of any person, or
      8. any solid liquid or gaseous matter or any combination of such matters, which in relation to the receiving waters, may be toxic to fish or animals or affect the growth of plant life or vegetation, or
      9. any solid, liquid or gaseous matters or any combination or mixture of such matters which by themselves or in combination with any other matters may immediately or in the course of time interfere with the free flow of the contents of the sewer or injure any part of the sewerage system, or in any way directly or indirectly cause the quality of effluent from any treatment plant in the catchment of the discharge to no longer comply with the conditions of a water right, or permit, or
      10. any liquid, solid or gas which could be flammable or explosive in the wastes,
      11. any petroleum, benzene, naptha, fuel or oil, or
      12. any significant quantity of soap or detergent or other surfactant, that is in excess of that in an equivalent volume of domestic sewage, or
      13. any noxious or malodorous gas or substance which is of a quantity or nature to be more offensive to the public than the same quantity of domestic sewage, or
      14. any colour or colouring substance that causes the discharge to the sewerage system to be excessively coloured,
    2. do not have -
      1. a pH greater than 10, or less than 6, or
      2. a temperature greater than 50°C, or
      3. any characteristic determined by analysis of a four hour average sample or of a twenty four hour flow proportionate sample as the case may be, which exceeds the values in Table 1.1, or
      4. any characteristic determined by analysis of an instantaneous sample which exceeds two times any of the values in Table 1.1, or
      5. any characteristic determined by analysis of two instantaneous samples taken at different times within a twenty four hour period which both exceed the values in Table 1.1, or
      6. a twenty four hour flow volume, or an instantaneous flow rate as the case may be, which exceeds the values in Table 1.1.

Table 1.1: Maximum values for specific characteristics of simple trade wastes

Characteristic Maximum value   Units
Twenty four hour flow volume 2,000   1
Instantaneous flow rate 0.5   1 / s
Biochemical oxygen demand 2,000   g / m3
Suspended solids content 1,000   g / m3
Settleable solids content 50   ml / l
Animal oil fat and grease content 200   g / m3
Mineral oil and grease content 20   g / m3
Sulphates, and sulphites expressed as SO4 50   g / m3
Sulphide content, that may be released as H2S on acidification, expressed as H2S 1.0   g / m3
Hydrocyanic acid or any compounds producing hydrocyanic acid on acidification, expressed as CN 0.5   g / m3
Phenols (hydroxy derivatives of benzene), expressed as phenol 1.0   g / m3
Dissolved solids fraction either as a compound, element, salt or ion:
As 0.2   g / m3
Cd 0.05   g / m3
Cr (total) 1.0   g / m3
Cu 1.0   g / m3
Hg 0.05   g / m3
Ni 1.0   g / m3
Pb 1.0   g / m3
Sn 1.0   g / m3
Zn 1.0   g / m3

Meaning of unit symbols used in Schedule I

Unit symbol Meaning of unit symbols
1 litres
ml millilitres
g gram
m3 cubic metre
s second

Schedule II - Description of controlled trade wastes

1. Controlled trade wastes are those discharges which:-

  1. do not contain any:-
    1. chlorinated bi-phenols, or
    2. halogenated hydrocarbons, or
    3. organo-tin compounds, or
    4. pesticides, herbicides, insecticides, fungicides or material of asimilar nature, or
    5. cooling water, condensing water, or surface water, or
    6. any garbage that contains any particle that will not pass freely through a twelve millimetre mesh, or
    7. solid liquid or gaseous matter or any combination of such matters, which in relation to the sewerage system may be prejudicial to the safety of any person, or
    8. any solid liquid or gaseous matter or any combination of such matters, which in relation to the receiving waters, may be toxic to fish or animals or affect the growth of plant life or vegetation, or
    9. any solid, liquid or gaseous matters or any combination or mixture of such matters which by themselves or in combination with any other matters may immediately or in the course of time interfere with the free flow of the contents of the sewer or injure any part of the sewerage system, or in any way directly or indirectly cause the quality of effluent from any treatment plant in the catchment of the discharge to no longer comply with the conditions of a water right, or permit, or
    10. petroleum, benzene, naptha, fuel or oil or other liquid, solid or gas which could be flammable or explosive in the wastes, or
    11. synthetic detergents, soaps or other surfactants in sufficient quantity to interfere with the operation of the sewerage system, or adversely affect the quality of the receiving waters, or
    12. any noxious or malodorous gas or substance which is of a nature or sufficient quantity to create a public nuisance, or
    13. any colour or colouring substance that is capable of causing the discharge of any sewerage treatment plant or to receiving waters to be coloured, and
  2. do not have:-
    1. a temperature greater than 50°C, or
    2. a pH greater than 10, or less than 6, or
    3. any characteristic determined by analysis of a four hour average sample or of a twenty four hour flow proportionate sample as the case may be, which exceeds the values in clauses 2 or 3 or Table 2.1 of this Schedule for that characteristic, or
    4. any characteristic determined by analysis of an instantaneous sample which exceeds two times the value in clauses 2, or 3 or Table 2.1 of this Schedule for that characteristic, or
    5. any characteristic determined by analysis of two instantaneous samples taken at different times within a twenty four hour period which both exceed the value in clauses 2, or 3 or Table 2.1 of this Schedule for that characteristic.

2. Maximum permitted five day bio-chemical oxygen demand in g / m3

The maximum concentration of BOD for average four hour flow rates less than or equal to 5 1 / s is 2000g / m3.

The maximum concentration of BOD for average four hour flow rates between 5 1/s and 25 1 / s is 2000g / m3 for average four hour flow rates equal to 5 1 / s, reducing at a uniform rate of 87.5 g / m3 for every 1 1 / s increase in the flow rate up to 25 1 / s.

The maximum concentration of BOD for average four hour flow rates greater than or equal to 25 1 / s is 250g /m3.

3. Maximum Permitted Concentration of Suspended Solids in g / m3

The maximum concentration of suspended solids for average four hour flow rates less than or equal to 5 1/s is l000g / m3.

The maximum concentration of suspended solids for average four hour flow rates between 5 1/s and 25 1/s is l000g / m3 for average four hour flow rates equal to 5 1 / s, reducing at a uniform rate of 37.5g /m3 for every 1 l / s increase in the flow rate up to 25 l / s. The maximum concentration of suspended solids for average four hour flow rates greater than or equal to 25 1 / s is 250g / m3.

Table 2.1: Maximum values for specific characteristics of controlled trade waste

Characteristic Limiting
value
  Units
Settleable solids content 150   ml / l
Animal oil fat and grease content 200   g / m3
Mineral oil and grease 50   g / m3
Sulphate and sulphite content expressed as SO4 500   g / m3
Sulphide content, that may be released as H2S on acidification, expressed as H2S, 2.0   g / m3
Hydrocyanic acid or any compounds producing hydrocyanic acid on acidification, expressed as CN 2.0   g / m3
Phenols (hydroxy derivatives of benzene), expressed as phenol, 20   g / m3
Dissolved solids fraction either as a compound, element, salt or ion:
Ag 2.5   g / m3
As 0.5   g / m3
Cd 0.1   g / m3
Cr (total) 5.0   g / m3
Cu 5.0   g / m3
Hg 0.1   g / m3
Ni 5.0   g / m3
Pb 5.0   g / m3
Sn 5.0   g / m3
Zn 8.0   g / m3

Schedule III - Measurement and sampling of the characteristics of a trade waste discharge

Part 1: Measurement of flow rate and volume

1. An instantaneous flow rate is determined using the following method:-Determinations of flow shall be made from 3 readings of flow rate taken at not less than 1 minute intervals nor more than 15 minute intervals. The instantaneous flow rate is the average of the readings.

2.

  1. A four hour flow volume is determined by either:
    1. reading a volumetric flow meter at the start and end of the four hour period and calculating the volume of flow as the difference between the readings, or
    2. by taking the mean of the flow rates determined using a twenty four hour flow measurement over the four hour period.
  2. The four hour flow period used in calculating a four hour flow volume shall be a continuous period of four hours during which the discharge is occurring and:
    1. where the method specified in paragraph (a)(i) of this clause is used, shall, as far as practical be representative of the discharge occurring during a typical working day, and shall exclude periods of decreased discharge prior to or after the day's operations and,
    2. where the method specified in paragraph (a)(ii) of this clause is used, shall include the four hour period having the highest total flow volume as shown by the twenty four hour measurement.

3. An Average four hour flow volume is determined by taking the mean of no less than five determinations of the four hour flow volume of a discharge made within a charge period in accordance with the methods specified in clause 2 of this schedule.

4. A twenty four hour flow measurement is made using the following method:- Recordings shall be made continuously or at intervals of not more than 15 minutes evenly spaced throughout the twenty four hour measurement period.

5. A twenty four hour flow volume is the mean of the records of flow rate made using a 24 hour flow measurement.

6. An average twenty four hour flow volume is determined by calculating the mean of no less than five determinations of the twenty four hour flow volume of a discharge made within the charge period in accordance with the methods specified in clause 4 and 5 of this schedule.

Part 2: Sampling of a trade waste

5. An instantaneous sample is a sample taken using the following methods :- Three grab samples of the discharge shall be taken at intervals of not less than 1 minute nor more than 5 minutes. The three grab samples must be combined using equal volumes of all three samples to obtain the instantaneous sample.

6. A four hour average sample is taken using the following method:

  1. No less than 12 grab samples shall be taken from the discharge over a continuous four hour period. The samples shall be taken at reasonably even intervals over the whole period. The intervals between the samples must not be less than 5 minutes nor more than 30 minutes. The samples shall be mixed using equal volumes of all samples to obtain the four hour average sample.
  2. The four hour flow period used when taking a four hour average sample shall be a continuous period of four hours during which the discharge is occurring and:
    1. shall as far as practical be representative of the discharge occurring on a typical working day; and
    2. shall exclude periods of decreased discharge prior to or after the days operations.

7. A twenty four hour flow proportionate sample is obtained using the following method:

  1. No less than 18 grab samples shall be taken from the discharge over a continuous twenty four hour period. The samples shall be taken at reasonably even intervals over the whole period. The intervals between the samples must not be less than 15 minutes nor more than 60 minutes. Whenever more than one sample is taken within a 60 minute period the samples must be of equal quantity and may be stored with other samples taken during that 60 minute period in a common container.
  2. The twenty four hour flow proportionate sample is then obtained by taking a part of the contents of each container and mixing all such samples together. The size of the part of each container sample that is used shall be in direct proportion to the volume of discharge that occurred from the time a sample was first placed in the particular container to the time a sample was first placed in the next container.