Licence conditions for pollution studies and reduction program


  

Licence conditions for pollution studies and reduction programs

Summary
 
Licence number: 4627
Title: Hazardous Ground Gases Risk Assessment (HGGRA) Implementation Program
Start date: 13 Jun 2022
 
Licence Condition
Objectives The licensee is required to implement the additional works, controls and mitigation measures identified in sections 10 and 11 of the “M8 St Peters Interchange Hazardous Ground Gases Risk Assessment” (HGGRA), dated 10 March 2022, prepared by Golder Associates Pty Ltd (EPA DOC22/239737), as detailed in U2.1 to U2.9.  The objective of this Pollution Reduction Program is to ensure that the risk mitigation measures identified in the HGGRA are implemented in a timely and effective manner.
Passive Gas Collection System (PGCS) a)  The licensee must install all components of the PGCS, as shown in the design specifications, by 30 June 2023 (design specifications M5N-GOL-DWG-900-116-EV-0022, dated 3 July 2020, Golder) or an alternate design solution approved by the EPA Accredited Site Auditor and the EPA. b)  The licensee must engage an independent certifier or equivalently qualified professional to conduct inspections of the relevant components of the PGCS, as detailed in section 10.2 of the HGGRA, to ensure the PGCS is installed in accordance with the design specifications or the alternate design solution approved by the EPA Accredited Site Auditor and the EPA. c)  The licensee must install any additional necessary components as identified in U2.2a) and U2.2b) and as identified by an independent certifier or equivalently qualified professional, as per U2.2b), and by the EPA Accredited Site Auditor, to ensure that the PGCS meets the relevant design specifications. A program of the installation works, approved by the Site Auditor, must be provided to the EPA by 31 May 2024. This program will include the required steps and milestone dates for the installation of all additional necessary components to ensure that the PGCS meets the relevant design specifications. The final installation of these components must be completed by 30 September 2024. d)  The licensee must conduct monitoring on at least a quarterly basis at both the existing and newly installed components of the PCGS to verify that the PGCS is working and establish whether the completion of the system has altered the distribution of gas observed in the vents. e)  The licensee must prepare a report documenting the outcomes of the investigations and works under conditions U2.2a), U2.2b) and U2.2c). This report must be reviewed by the EPA Accredited Site Auditor who must provide interim site auditor advice to verify works have been completed and verify that the PGCS is suitable to manage risks identified in the HGGRA by 31 December 2024.
Additional M8 Sub-surface Gas Wells a)  The licensee must install five additional sub-surface gas wells to complement the perimeter gas network, in accordance with section 10.3.1 of the HGGRA, by 14 October 2022. b)  The licensee must monitor the wells installed in accordance with condition U2.3a) on a fortnightly basis for a minimum of six rounds. This monitoring must be conducted in accordance with the NSW EPA Assessment and Management of Hazardous Ground Gases (2020). c)  Following the completion of the monitoring in accordance with condition U2.3b), the licensee must continue undertaking monitoring of the five additional wells on a quarterly basis. 
Additional Stage 3A Sub-surface Gas Wells a)  The licensee must install at least two additional sub-surface gas wells in the ‘Stage 3A’ area. The locations of these wells must be approved by the EPA Accredited Site Auditor, in accordance with section 10.6 of the HGGRA, by 31 December 2022. b)  The licensee must monitor the wells installed in accordance with condition U2.4a) on a fortnightly basis for a minimum of 6 rounds. This monitoring must be conducted in accordance with the NSW EPA Assessment and Management of Hazardous Ground Gases (2020). Note: The ‘Stage 3A’ area refers to the C10 site identified in the EPL 21149 premises maps (WestConnex M4-M5 Link Tunnels Premise Boundary Maps version 13, approved on 26 March 2020 (EPA DOC20/260826)).
Basal Passive Gas Collection System (BPGCS) a)  The licensee must design and install a passive gas pipe connection from LDS-GM-028 to the T2 BPGCS. A design for this connection and a schedule for the works, both approved by the Site Auditor, must be provided to the EPA by 30 April 2024 and installation of this connection must be completed by 30 October 2024. b)  The licensee must undertake quarterly validation monitoring at all T2 BPGCS vents, in addition to the requirements outlined in condition M2.2, to verify any changes in concentrations and flows that may indicate effectiveness of the works undertaken in accordance with condition U2.5a). c)  The licensee must submit a report to the EPA by 30 October 2025, commenting on the effectiveness of the works undertaken in U2.5a) by assessing the results of the quarterly monitoring undertaken at LDS-GM-028, LDS-GM-029, and the T2 BPGCS.
Utilities Investigation and Sealing a)  The licensee must undertake investigations in accordance with section 10.4 of the HGGRA to identify utilities within future or current public access areas (including the Northern Share Path and MOC 4 surrounds) that may be acting as preferential pathways for gas migration. b)  The licensee must complete works to seal any areas identified under condition U2.6a) within two months of becoming aware of the preferential pathways.
MOC4 Alarm Installation a)  The licensee must install gas detection alarms and at least one remote sampling port to allow for monitoring of the air quality in the MOC 4 basement level, in accordance with section 10.4 of the HGGRA, by 14 October 2022.
RW101A rectification works a)  The licensee must rectify the landfill capping for the RW101A area in accordance with section 10.3.2 of the HGGRA, the NSW EPA Environmental Guidelines: Solid Waste Landfills (second edition, 2016), and the design specifications outlined in “Technical Report: St Peters Interchange – Landfill Closure Management Plan LCMP” prepared by Golders Associates, dated 4 August 2017, ref: EPA DOC20/476070-3. A design for these rectification works and a schedule for the works, both approved by the Site Auditor, must be provided to the EPA by 30 April 2024. The rectification works referred to in this condition must be completed by 30 October 2024.
Vertical Barrier Wall Performance Wells a)  The licensee must conduct an investigation to confirm the status of all Vertical Barrier Wall paired wells identified in section 10.3.4 of the HGGRA and confirm that each well is accessible and in good condition by 31 December 2022. b)  The licensee must repair or replace any damaged wells identified under condition U2.9a) within two months or as soon as practicable upon becoming aware of their status. c)  The licensee must conduct quarterly monitoring of water levels at the Vertical Barrier Wall paired wells. This monitoring must commence by 30 May 2022. d)  The licensee must provide a submit a report to the EPA that has been reviewed by the EPA Accredited Site Auditor, who must provide interim site auditor advice referring to data collected in accordance with condition U2.9c) and which verifies that the Vertical Barrier Wall is functioning by 31 December 2023.