Noise Pollution .1 Noise Source

During the construction phase, the bulk of the noise is expected from construction activities involving piling and drilling machinery, excavators, dump trucks, backhoes and compactors. These will produce noise during their operations. Their noise levels will be predicted to assess their disturbance onto the sensitive receptors.

6.3.5.2 Methodology

In the assessment of noise, a common statistical descriptor is LAeq. LAeq is the constant, average noise level, which over a period of time, contains the same amount of energy as the varying levels of the background or traffic noise. The total equivalent sound level for a typical workday during a particular construction phase can be computed as follows:

LAeq = 10 x log10 ∑[ 10(LAeq i / 10)] (dB) Where,

LAeq, total = the total equivalent noise level for a typical workday during a given period;

k = the number of different types of equipment; and LAeq, i = the equivalent noise level for equipment type, i.

Giving the total equivalent sound level from a construction site or point source, noise at specific distances from a point source is calculated using the formula for distance attenuation:

L = L0 - 20 Log D Where,

L = noise level at D meters away from the source;

L0= noise level measured at 1 m from the source; and D = distance from the point source in m.

6.3.5.3 Assessment Results

Table 6.5 presents typical noise levels from equipment and machinery likely to be used at the construction site. The estimated highest noise levels are expected during cut and fill activities at the TUDM area, where noise sources include trucks, dozers, backhoes, tractors and generators. The combined noise level from these sources is estimated at 88.4 dBA.

Table 6.5: Typical Noise Level from Construction Equipment

No. Equipment Typical Noise Level, LAeq, at 15 m

in dB(A)

1 Truck 88

2 Portable air compressors 81

3 Concrete mixer (truck) 85

LAeq, total Estimated on-site noise level 88.4

Source: May, D.N., 1978; Noise and Vibration, 2006.

Note: The noise levels presented are without noise reduction mechanisms.

During the construction phase, the actual noise level is expected to be much lower than the predicted level as not all equipment will be used simultaneously. The equipment will not remain stationary and will likely be scattered over the site. Hence, the impact is expected to be localized and temporal.

Nevertheless, mitigating measures are proposed during the construction phase. In addition, the noise level during the construction phase will be closely monitored.

Sensitive receptors along the Project‟s alignment have been identified and baseline noise monitoring at the sensitive receptors was conducted in conjunction with the EIA study. During the daytime, the highest background noise was recorded at 69.0 dBA. With the baseline results as background noise, the cumulative noise level due to the construction noise and background noise is estimated at 88.45 dBA. Noise level guideline limits for construction activities are referred to Schedule 6 of the Planning Guidelines for Environmental Noise Limits and Control, DOE 2007. The estimated cumulative noise levels at sensitive receptors are indeed below the Lmax – 90 dBA. Compliance to L90 and L10 during the construction phase could be achieved via mitigating measures and noise control management as highlighted in Chapter 7. Close monitoring should be implemented in this regard.

6.3.6 Vibration

The potential for vibration impact at the adjacent sensitive locations along the alignment during the construction phase is mainly from piling operations and vehicular movements. The more significant of these is the vibration impact from piling operations.

Vibration standards are categorised under two levels: those dealing with human comfort and those dealing with cosmetic or structural damage to buildings. In both instances, it is appropriate to consider the magnitude of vibration in terms of Peak Particle Velocity (PPV).

The Planning Guidelines for Vibration Limits and Control by the Department of Environment provides guidelines to protect against both adverse human response and structural damage to buildings during the construction phase. The vibration limits are shown in Table 6.6 and Table 6.7 below:

Table 6.6: Recommended Limits for Human Response and Annoyance from Short Term Vibrations (refer Figure 6.3)

Receiving Land Use Category Daytime

7.00 am - 10.00 pm

Source: Schedule 6 (Planning Guideline for Vibration Limits and Control in the Environment, 2004) Table 6.7: Recommended Limits for Damage Risk in Buildings from Short Term Vibration

Type of Structure Vibration Velocity vi [mm/s]

Industrial buildings and buildings of similar design Curve C 40

Commercial building, dwelling and buildings of similar design and/or use

Curve B 15

Structures that, because of their particular sensitivity to vibration, do not correspond to those listed above, or of great intrinsic value (e.g.

residential houses, or buildings that are under preservation order)

Curve A 8

Source: Schedule 2 (Planning Guideline for Vibration Limits and Control in the Environment, 2004)

Figure 6.3: Building vibration z-axis curves for peak velocity

Figure 6.4: Foundation Vibration Velocity Limiting Values for Vectorial Sum of

Additional applicable guidelines were also extracted from the following:

 BS 6472: 1992 – Guide to Evaluation of human exposure to vibration in buildings (1 Hz to 80 Hz).

 BS 5228: 1992 – Noise control on construction and open sites – Part 4: Code of practice for noise and vibration control applicable to piling operations.

 DIN 4150 – Part 3: Structural vibration in buildings.

Based on the above DOE Guildelines, the acceptable criteria for short term vibration such as piling operations are Curve 8 to Curve 16 for daytime and Curve 4 for night time for residential landuse. As bored piling will be used, no significant vibration impact is anticipated during the construction phase.

6.3.7 Ecology