What project activities produced elevated noise?
From a noise perspective, the Macdonaldtown Gasworks Remediation was largely similar to other construction and excavation projects, meaning that noise was created through the use of tools and machinery on the site. The highest noise levels were generated from project works such as the installation of bored piles to create the underground retaining walls and the demolition of concrete and other materials using excavators fitted with hydraulic hammers. The project team was committed to reviewing its work practices on an ongoing basis during the remediation to minimise the impact of noise on the community as much as possible.
Where and how often was noise monitoring conducted?
A noise monitor continuously measured noise levels at the western boundary of the project site. The data that was downloaded and analysed regularly from this monitor was used to assess trends and fluctuations in ambient daytime, evening and night time noise levels. The monitor measured noise from all local sources combined.
In addition to the continuous monitoring method, a hand-held sound level meter was used to measure noise at various locations on and around the site once a fortnight. The environmental engineer identified each noise from the project or community and used the sound level meter to measure its level. This method determined the contribution of the project to the level of local noise.
Noise was minimised during the project through the following means whenever feasible:
- Plant and equipment fitted with low-pitched reversing alarms was used whenever available;
- Static equipment was screened and located as far away as possible from residences; and
- Temporary infrastructure and other items for the project were prefabricated offsite whenever possible.
In addition, the ventilation system for the environmental control enclosure was fitted with a ‘silencer’ that minimised noise.
Noise Response Levels
A project goal for noise, known as a Response Level (RL), was established below the ‘highly noise affected level’ described in the Interim Construction Noise Guideline for NSW. The project limit for noise was set at this ‘highly noise affected level.’ Measurements of noise obtained along the site’s western boundary, the boundary that is adjacent to the nearest residences, and at other locations were compared to these RLs. The RLs were:
- LAeq(15min) 72 dB(A) as the project goal.
- LAeq(15min) 75 dB(A) as the project limit or maximum RL.
dB(A) is a unit used to measure ‘A-weighted’ sound pressure levels. A-weighting is an adjustment made to sound-level measurements to approximate the response to the human ear.
LAeq(15 min) means an equivalent continuous noise level over 15 minutes i.e. the level of noise equivalent to the energy-average of noise levels occurring over a 15 minute measurement period.
What happened if noise was elevated?
If the noise criteria goal were exceeded at the stationary monitor, the environmental engineer was notified immediately through an email alert message to his mobile phone. In response, the noise was reduced using mitigation measures to a level below the project goal if possible.
When an activity could not be undertaken without exceeding the project noise limit (as measured at the boundary with the nearest residence), the activity did not commence before 8:00am and it was not ongoing for more than three hours whilst above the limit. In addition, a minimum 60 minute break was provided between periods of elevated noise.
Noise monitoring results
Monthly summaries of the environmental monitoring results obtained during the project, including noise results, are provided under the Monitoring Results section. See here