The Macdonaldtown Gasworks Remediation site was contaminated from its former use as a gasworks. From 1892 until 1958, coal and shale were processed under heat and pressure to create gas for the lighting of railway carriages and the Eveleigh Railway Workshops. Following an Environmental Assessment, RailCorp received approval in January 2013 from the Department of Planning & Environment to remediate the site. The Environmental Assessment was instrumental in planning the remediation project, which involved the excavation and removal of the gasworks wastes.
Contaminants of concern
The main contaminants of concern in both soil and groundwater at the site were polycyclic aromatic hydrocarbons (PAHs, including benzo(a)pyrene and naphthalene), total petroleum hydrocarbons (TPH), benzene, toluene, ethylbenzene and xylenes (BTEX), and non-friable, bonded asbestos. Elevated concentrations of heavy metals had also been identified in groundwater.
Environmental controls are measures put in place to mitigate environmental impacts. The primary environmental controls for the project included an Environmental Control Enclosure (ECE), which covered the middle section of the site where tar-impacted soil and other contaminated materials were excavated, and an Emission Control System (ECS), which filtered air extracted from the enclosure. A Water Treatment Plant (WTP) was used to remove contaminants from water collected onsite.
Environmental monitoring was conducted when the ECE and ECS were operational to confirm their effectiveness as environmental controls. After the completion of remediation excavations, environmental monitoring continued until all project finalisation works were complete to ensure the health of workers, the community and the surrounding environment was maintained.
The environmental monitoring program included the measurement of dust, odour, volatile organic compounds, noise and vibration levels. Monitoring occurred onsite, at the project site boundaries and at locations in the community. For some contaminants, such as volatile organic compounds, measurements were collected continuously and reported in real time; for others, samples were collected periodically and taken for analysis to laboratories accredited by the National Association of Testing Authorities (NATA).
Environmental monitoring results were published two to three weeks after the end of each month on this website (see below).
What was monitored?
Environmental monitoring was performed for the following contaminants and impacts:
- Volatile organic compounds (VOCs) including benzene and volatile total petroleum hydrocarbons (TPHs);
- Polycyclic aromatic hydrocarbons (PAHs) including benzo(a)pyrene;
- Deposited dust;
- Total suspended particulate (TSP);
- Particulate 10 microns in diameter or less (PM10);
- Heavy metals;
- Noise; and
Where and how often was monitoring conducted?
The following equipment was set up on the western boundary of the site, adjacent to the nearest residences, to monitor environmental conditions:
- Noise and vibration monitoring stations that each logged continuously;
- A dust deposition gauge that collected dust continuously for later measurement;
- A ‘DustTrak’ that measured PM10 continuously; and
- A direct reading instrument (AreaRAE) that monitored for volatile organic compounds (VOCs) continuously.
In addition to the equipment listed above, the following portable equipment was used for environmental monitoring on and around the site:
- A photo-ionisation detector (PID) for the daily measurement of total VOCs at various locations during remediation works;
- A sound level meter for measuring noise at various locations once per fortnight;
- A high volume air sampler (HVAS) for measuring PM10 near the western boundary over a 24-hour period once per fortnight;
- A sampling pump for measuring polycyclic aromatic hydrocarbons (PAHs) once per month during remediation works; and
- Asbestos-in-air pumps for when soil containing non-friable, bonded asbestos was being removed.
What criteria were monitoring results compared to?
A number of project goals and limits for contaminants, known as Response Levels (RLs), were established at or below the maximum allowable limits for the contaminants. Environmental measurements collected on and around the site were compared to these RLs. If an RL was reached, procedural actions were followed which usually included a review of work practices or the implementation of additional environmental controls. The responsible Environmental Engineer was notified immediately through an e-mail message to his mobile phone if an RL was reached at one of the monitors that continuously measured noise, PM10 or VOC levels.
How were the Response Levels developed?
A number of national and state regulations, standards and measures were used to develop the project criteria RLs. The applicable documents were:
- NSW Department of Planning & Environment Project Approval (2013);
- National Environment Protection (Ambient Air Quality) Measure (1998);
- National Environmental Protection (Air Toxics) Measure (2011, amended);
- Technical Framework: Assessment and management of odour from stationary sources (NSW EPA, 2006);
- NSW DEC Approved Methods for the Modelling and Assessment of Air Pollutants in New South Wales.
ENVIRONMENTAL MONITORING RESULTS
Monthly summaries of the environmental monitoring results obtained during the project are provided under the Monitoring Results section. See here