• The key resource consent requirements for LFG are:

  • The collection of LFG must be maximised. [RM975261-F(3)]

  • LFG must be treated or removed from the site to minimise adverse effects on the environment. [RM975261-F(3)]

• The LFG collection and flaring system must be constructed and operated in accordance with the “Landfill Gas Management Plan for York Valley Landfill, Nelson” by SCS-Wetherill Environmental, Revision 1.0, 27 July 1999. [LMP 3.4, 4.6]

• The LFG control system includes the following major components: [LMP 3.4]

  • Approximately fifty vertical extraction wells.

  • 90 mm and 150 mm LFG collection pipes.

  • 250 mm ring main header pipe.

  • Condensate knock out facilities.

  • Landfill gas flare.

  • Hospital pump compressor station and hospital pipeline.

• The LFG collection system is shown on a suite of drawings in the Landfill Management Plan Appendix B (LFG System Expansion Works) that show both the existing system and future proposed expansion works. [LMP 3.4]

• The LFG collection and flaring system is the responsibility of the NTRLBU nominated subcontractor who must employ suitably qualified personnel to operate, monitor and maintain the system. [LMP 4.6.]

• The compressor station, plant and pipeline to the NMDHB hospital boiler is the responsibility of the NTRLBU that now owns the gas installation. [LMP 4.6]

• Vertical and horizontal gas extraction wells and leachate drainage wells are used to extract the LFG from within the landfill.

• As the landfill expands new wells must be installed to ensure LFG extraction.

• LFG is collected at four manholes off site of the landfill face and connected to the LFG extraction system by means of a 430m (approx.) long header pipeline.

• Any new wells must be connected to this extraction system.

  [MS - We will need to check this against the new leachate pipe system on the new lower buttress.]

• LFG is drawn out of the landfill gas extraction system and leachate collection system under vacuum.

• Any condensate accompanying the LFG is removed to the leachate collection system.

• The LFG is conveyed to the flare station, where it is pumped through to the drying plant which remove any water (including water vapour) from the gas.

• The dry LFG is pumped to compressor station adjacent to the flare station where it is compressed.

• The compressor speed and pressure are displayed via a SCADA system which can be viewed on the mobile app and on the NTRLBU office TV (note the Floc Shed SCADA des not display gas).

• The resource consent conditions require the extracted LFG is monitored for:

  • gas flow rate.

  • methane (percentage).

  • carbon dioxide (percentage).

  • oxygen (percentage).

  • nitrogen (percentage) calculated as balance gas.

  • carbon monoxide (parts per million).

  • hydrogen sulphide (parts per million).

• In-situ measurement of the above parameters is measured by in real time by sensors and displayed via a SCADA system which can be viewed via the mobile app or on the digital readout on the NTRLBU office TV (note the Floc Shed SCADA des not display gas).

• The flare station has been programmed to run as a dual operation, either to pump the LFG to the NMDHB hospital or burn the LFG through the on-site flare.

• The LFG will, in the first instance, be pumped to the NMDHB hospital for use. However, this is only possible when the hospital has capacity to use the LFG.

• The compressed LFG is pumped to the NMDHB LFG Boiler at Nelson Hospital.

• The following parameters for the NMDHB LFG Boiler are measured by sensors and displayed via a SCADA system:

  • Inlet Pressure (kPa)

  • Firing Rate (%)

  • Backend Pressure (°C)

  • Steam Output (ton/hr)

• When the LFG cannot be delivered to the NMDHB LFG Boiler it will be diverted and burnt through the on-site flare.

• The LFG flare must be designed, operated and monitored in accordance with the requirements of the US EPA Code of Federal Regulations 40 CFR Part 60, Subpart A General Provisions, Section 60.18 (1997).

• The resource consent conditions require the LFG flow rate and chemical composition to be measured every 6 months and reported to NCC within 1 month of measurement. [RM975261-F(5)]

• However, the use of in-situ sensors means the LFG flow rate and chemical composition can be measured and reported in real-time.

• A summary of the operation of the LFG System (including flow rate and chemical composition data) is included in the Landfill Annual Report. [RM975261 Sch 1(18)]

F(3)     The Consent Holder shall maximise the quantity of landfill gas collected, and all landfill gas so collected shall be flared, in accordance with the requirements of condition 4 of this consent, or otherwise treated or removed from the site to minimise adverse effects on the environment.

F(4)     Landfill gas flares shall be designed, operated and monitored in accordance with the requirements of the US EPA Code of Federal Regulations 40 CFR Part 60, Subpart A General Provisions, Section 60.18 (1997).

F(5)     Compliance with Condition 4 of this consent shall be demonstrated by monitoring of all landfill gas flares that are being used to flare gas, at six monthly intervals while flaring is taking place for the following parameters:

• gas flow rate

• methane (percentage)

• carbon dioxide (percentage)

• oxygen (percentage)

• nitrogen (percentage) calculated as balance gas

• carbon monoxide (parts per million)

• hydrogen sulphide (parts per million)

• gas pressure

• barometric pressure

 The results of such monitoring shall be reported to the Nelson City Council within one month of sampling.

DN1.6.viii       As a safeguard against possible accumulation of gases within the landfill, suitable gravel filters will be brought up through the landfill to enable the free escape of any such gases.

Chapters 3.4 & 4.6.

Landfill Gas Management Plan for York Valley Landfill by SCS-Wetherill Environmental, Revision 1.0, 27 July 1999.

The LGMP is included as Appendix D of the LMP 2023.