This document may not be reproduced in full or in part without the written consent of Marshall Day Acoustics Limited Rp 001 R0 20210601 SJP (Waihi North Noise Assessment) ISSUE 49 of 79 11.0 GENERAL NOISE MITIGATION AND MANAGEMENT MEASURES The specific mitigation recommendations that may be implemented for each component of WNP is discussed in detail in Sections 6 to 9, and to some extent in Appendix C. This section discusses in general terms mitigation and management best practice, which is focussed on construction activity, but is also generally applicable to management of general longer-term operations as well. 11.1 Noise Barriers Noise barriers are required in some locations to ensure noise levels meet the performance criteria. In general terms, noise barriers are required to be constructed with no gaps and have a minimum surface density of 10 kg/m2. The required heights will vary depending on the source and receiver locations (and the intervening ground), but around 3 metres is a common starting point for analysis. Earth bunds or a combination of bunds and screening walls or fences are also acceptable provided they are constructed to the same specified height. We note that the extent of required noise barriers is highly dependent on the noise sources in each scenario and where they are located. Because of this, noise barriers are not necessary in all scenarios. The ones that we have specified are not needed for the duration of the project and can be removed when not required. Mechanisms to ensure noise barriers are performing as expected should be put in place through the use of an Operational Noise Management Plan. 11.2 Receiver Building Mitigation Building mitigation for receivers aims to achieve appropriate internal noise levels if external levels cannot be practicably mitigated at (or near) the source. We consider an appropriate internal daytime noise criterion to be 40 dB LAeq. At high external noise levels (for example 65 dB and above), this criterion generally requires upgrades to the building envelope, such as improved glazing, joinery or internal wall and ceiling linings. New houses often do not need additional upgrades as standard building code compliant designs are often good enough. In all cases, these upgrades only work if windows and doors remain closed. This therefore also triggers a requirement to provide alternative forms of ventilation and comfort cooling (through mechanical systems). At moderately high external noise levels (for example 55 – 65 dB), existing buildings perform adequately (can achieve 40 dB LAeq) with windows closed. Therefore, the only additional requirement would be a mechanical ventilation system for all habitable rooms. At moderate external noise levels (for example 50 – 55 dB), existing buildings normally perform adequately with windows open. A typical New Zealand weatherboard house will achieve a noise reduction (from outside to inside) of approximately 15dB with the windows slightly open. However, if a dwelling has seriously degraded joinery or other construction defects, or unusually large areas of glazing the noise reduction performance may be lower. In the case of Gladstone (Section 6.3.1), noise levels are only just above the criteria so many houses would not require any specific building treatment. If they did, by simply ensuring windows and doors can remain closed is going to be sufficient from a noise reduction perspective. Therefore, the only additional requirement would be a mechanical ventilation system for all habitable rooms. Because there are no significant night-time noise emissions of concern for the affected dwellings there would be no additional night-time requirements for bedrooms (however they are still considered as a habitable room). The provision of a suitable ventilation system could take the form of a heat pump (with a fresh air supplement) or ducted ceiling fan system. These systems are not cost prohibitive, nor generally invasive in terms of installation. The provision of such a systemmay also enable written approval to be sought. 11.3 Management of Plant and Equipment When selecting construction equipment: • Use quieter construction methodologies where practicable; • Use electric motors rather than diesel engines where practicable; • Use rubber tracked equipment rather than steel tracked equipment where practicable; • Use equipment that is suitably sized for the task; • Maintain equipment well to minimise rattles, squeaks etc.; • Fit engines with exhaust silencers and engine covers where practicable; • Avoid tonal reversing or warning alarms (beepers). Alternatives include broadband alarms (squawkers/quackers), flashing lights, proximity sensors, reversing cameras and spotters; • Apply appropriate setback distances for certain high noise equipment; • Limiting high noise equipment to a particular year/height of excavation. 11.4 Helicopter Noise All helicopter operations should be flown to avoid residential areas of Waihi township and where possible, rural dwellings as far as is practicable. Wherever practicable, we recommend that the helicopter operates in a manner in accordance with the “Fly Neighbourly” guide published by Helicopter Association International and recommend by the New Zealand Helicopter Association. 11.5 Noise Management 11.5.1 Community liaison Consideration of written communication (e.g. newsletter) provided to nearby building occupants prior to starting construction operations. This could include: • Details of the overall works, its timing and duration; • Contact details and names of personnel whose job is to receive complaints and enquiries ; • Acknowledge that some activities could potentially generate elevated noise levels and may result in small disturbance for short periods. 11.5.2 Complaint handling Complaints should be acknowledged immediately where practicable and responded to within a short timeframe. If a more detailed response is needed, it should be provided within a set timeframe. All construction noise complaints should be recorded in a complaints file that could be made available to the Council on request.
RkJQdWJsaXNoZXIy MjE2NDg3