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  Council » Policies and Plans » Rules and regulation » Waikato Regional Plan » Waikato Regional Plan (online version) » 3.5 Discharges* » 3.5.6 Implementation Methods - Discharge of Biosolids* and Sludges or Liquids from Activated Sludge Treatment Processes to Land

3.5.6 Implementation Methods - Discharge of Biosolids* and Sludges or Liquids from Activated Sludge Treatment Processes to Land

3.5.6.1 Good Practice

Waikato Regional Council will, in conjunction with organisations, industry groups and individuals, provide guidance on good practice techniques for the reuse of biosolids and nonhazardous byproducts from industrial and trade premises as soil conditioners or fertiliser substitutes.

3.5.6.2 Permitted Activity Rule – Discharge of Sludges and Liquids from Activated Sludge Treatment Processes to Land

The discharge of sludges and liquids from activated sludge treatment processes onto or into land outside the Lake Taupo Catchment and any consequent discharge of contaminants to air is a permitted activity subject to the following conditions:

  1. There shall be no direct discharge to water.
  2. The material shall not enter surface water by overland flow.
  3. The material shall not contain any human/animal pathogens or hazardous substances.
  4. The total nitrogen loading onto grazed pasture shall not exceed the limits as specified in Table 3-7, including any loading made under Rules 3.5.5.1, 3.5.5.2, 3.5.5.3 and 3.5.6.3.
  5. The discharger shall maintain daily records of the volume discharged to each paddock or relevant area and the concentration of nitrogen in the discharge in, as a minimum, monthly samples.
  6. The records required under condition e) shall be made available to the Waikato Regional Council upon request.
  7. The maximum loading rate of effluent onto any part of the irrigated land shall not exceed 25 millimetres depth per application.
  8. The material shall either
    1. not be stored for longer than eight hours prior to application, or
    2. have been stabilised by storage and dewatering for a period of at least 6 months.
  9. The discharge location should provide for the following buffer zones between the discharge area and neighbouring land uses or sensitive environments:
    1. 300 metres from any school, residential zone or rural residential zone as identified by the relevant district plan
    2. 150 metres from any residence or building of regular occupation such as community halls, marae and public or community facilities
    3. 50 metres from any property boundary
    4. 10 metres from any surface water body
    5. 20 metres from a Significant Geothermal Feature*.
  10. Any discharge to air arising from this activity shall comply with the permitted activity conditions in Section 6.1.8 of this Plan.
  11. Where fertiliser is applied onto the same land on which activated biosolids have been disposed of in the preceding 12 months, the application must be in accordance with Rule 3.9.4.11.
  12. The soil pH where the biosolids are discharged is not less than pH 5.5.

Advisory Notes:

  • Discharges of contaminants into or onto land within 20 metres of a Significant Geothermal Feature are addressed by Rules 7.6.6.1 to 7.6.6.3 of this Plan. Significant Geothermal Features are defined in the Glossary, and in Development and Limited Development Geothermal Systems, identified on maps in Section 7.10 of this Plan.

3.5.6.3 Controlled Activity Rule – Discharge of Biosolids and Sludges and Liquids from Activated Sludge Treatment Processes

The discharge of biosolids or sludges and liquids from activated sludge treatment processes onto or into land outside the Lake Taupo Catchment, and any subsequent discharge to air, that is not permitted by Rule 3.5.6.2 is a controlled activity (requiring resource consent) subject to the following standards and terms:

  1. Concentrations of pathogens or hazardous substances in the material shall not exceed the values given in Table 3-9.
  2. The discharge shall not:
    1. result in ponding where the contaminant remains on an area of more than 10 square metres 24 hours after being irrigated.
    2. cause a direct discharge to surface water or ground water.
  3. The discharge shall not occur within 20 metres of a Significant Geothermal Feature*.
  4. Any discharge to air arising from this activity shall comply with the permitted activity conditions in Section 6.1.8 of this Plan.
  5. The soil pH where the biosolids are discharged is not less than pH5.5.

Waikato Regional Council reserves control over the following matters:

  1. The season during which the discharge can occur.
  2. The frequency at which the discharge can occur at the same location.
  3. The maximum annual nitrogen loading rate for the discharge site given the proposed land use.
  4. Measures to manage the effects of contaminants such as heavy metals, mineral salts or hazardous substances on the long-term health of the soil resource and on the existing and range of foreseeable uses of the soil resource.
  5. The means of controlling objectionable odour.
  6. Measures to avoid significant adverse effects of the activity on tangata whenua values of the site.
  7. Measures for managing effects of the discharge upon the soil’s hydraulic loading capacity and compaction.
  8. Measures to ensure that adverse effects on nearby land uses, water bodies or areas of significant indigenous vegetation, significant habitats of indigenous fauna and significant natural features such as cave and karst systems are avoided, remedied or mitigated.
  9. The maximum level of soil contamination that is acceptable at the application site.
  10. The method of application.
  11. Separation distances from sensitive areas.
  12. Record keeping and nutrient budgeting.

Advisory Notes:

  • Discharges of contaminants into or onto land within 20 metres of a Significant Geothermal Feature are addressed by Rules 7.6.6.1 to 7.6.6.3 of this Plan. Significant Geothermal Features are defined in the Glossary, and in Development and Limited Development Geothermal Systems, identified on maps in Section 7.10 of this Plan.
  • Biosolids that carry the registered Biosolids Quality Mark (BQM) accreditation are likely to comply with this Rule.

3.5.6.4 Discretionary Activity Rule – Other Discharges of Biosolids and Sludges and Liquids from Activated Sludge Treatment Processes

The discharge of biosolids into water or onto or into land that does not comply with Rules 3.5.6.2 and 3.5.6.3 is a discretionary activity (requiring resource consent).

Exclusion to Rule 3.5.6.4:
Discharges of contaminants (not including stormwater or contaminants associated with the take and use of geothermal water), into Natural State Water Bodies, natural wetlands (that are habitat for indigenous vegetation or fauna communities), cave entrances or lakes (excluding artificial lakes and Lake Rotoaira) are excluded from this rule. The effects of these activities are managed by Rule 3.5.4.6 of this Plan.

Exclusion to Rule 3.5.6.4:
Discharges of contaminants within 20 metres of Significant Geothermal Features are excluded from this Rule. The effects of these activities are managed by Rule 7.6.6.1 to 7.6.6.3 of this Plan.

Advisory Note:

  • Information requirements to enable the assessment of any application under this Rule are set out in Section 8.1.2.2 of this Plan. In addition, assessment shall also take into account the matters identified in the policies of Section 3.5.3 of this Plan.
  • Significant Geothermal Features are defined in the Glossary, and in Development and Limited Development Geothermal Systems, identified on maps in Section 7.10 of this Plan.

Table 39 Pathogen and Contaminant levels

E.coli <100 MPN/g
Campylobacter <1/25g
Salmonella <1/25g
Enteric Viruses <1 PFU/4g
Helminth ova <1/4g
Arsenic 20 mg/kg dry weight
Cadmium 1 mg/kg dry weight
Chromium 600 mg/kg dry weight
Copper 100 mg/kg dry weight
Lead 300 mg/kg dry weight
Mercury 1 mg/kg dry weight
Nickel 60 mg/kg dry weight
Zinc 300 mg/kg dry weight
DDT/DDD/DDE 0.5 mg/kg dry weight
Aldrin 0.02 mg/kg dry weight
Dieldrin 0.02 mg/kg dry weight
Chlordane 0.02 mg/kg dry weight
Heptachlor and Heptachlor epoxide 0.02 mg/kg dry weight
Hexachlorobenzene (HCB) 0.02 mg/kg dry weight
Hexachlorocyclohexane (Lindane) 0.02 mg/kg dry weight
Benzene Hexachloride (BHC) 0.02 mg/kg dry weight
Total polychlorinated biphenyls 0.02 mg/kg dry weight
Total dioxin TEQ 0.00003 mg/kg dry weight

 

Explanation and Principal Reasons for Adopting Methods 3.5.6.1 to 3.5.6.4
Method 3.5.6.1 identifies that guidelines defining good practice techniques are a valuable tool in managing the effects of these discharges. Waikato Regional Council will provide guidance on the development of these guidelines. In particular, good practice guides need to focus on means of applying these wastes to land so that neither soils nor ground water are contaminated as a consequence of over-application or application during the wrong season.

The rule framework in Rules 3.5.6.2 to 3.5.6.4 recognises that biosolids and other nonhazardous byproducts from industrial or trade premises can be suitable for use as soil conditioners and fertiliser substitutes in accordance with Policies 1, 2 and 4. However, because of their source, these substances may contain hazardous contaminants to levels that will contaminate soil or water. Due to their source and typical composition, these substances may also generate objectionable levels of odour. Because of these risks, some control must be exercised to ensure that the substance will not contaminate soils, generate odours or result in contamination of surface and ground water.

Only discharges of biosolids, sludges and liquids from activated sludge treatment processes are permitted by these Rules. The treatment process that they have been subject to means that the objectionable odours associated with anaerobic processes are largely removed. For example, material can be processed through a clarifier and aerated, resulting in an activated sludge. Provided they are applied in the same way as other fertilisers such as farm animal effluent, the risk of adverse effects is minimal.

Rule 3.5.6.4 provides for the beneficial reuse of biosolids sourced from municipal wastewater treatment plants and industrial sources provided that contaminants within the biosolid are sufficiently low that there is little risk of creating a new contaminated site through continual application of the material. The contaminant levels in Table 3-8 are derived from the Guidelines for the Safe Application of Biosolids in New Zealand (NZWWA, 2003). To ensure that the objectives and policies in Chapter 5.2 of the Plan are achieved, the levels are set at the contaminant levels deemed by that guideline to be acceptable from 2012 rather than the less conservative values recommended from 2003 - 2012. With this exception, biosolids or other effluents that have obtained registered Biosolids Quality Mark accreditation or equivalent are enabled by this Rule.

As biosolids can be high in nutrients, it is not appropriate to allow their discharge within the Taupo catchment as a Permitted or Controlled Activity. For this reason, the discharge of biosolids to land in the Taupo catchment is a Discretionary Activity under rule 3.5.6.4. Such discharges may also be assessed in accordance with the Taupo land use rules 3.10.5.1 to 3.10.5.12 if they result from farming activities.

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