3 NOISE

3.1.1 The EIA Report points out that there is a need for both construction and operational phase EM&A. The general EM&A is described in subsequent sections while the specific operational phase EM&A is given in Section 3.6.

3.2 Construction Noise Monitoring

Noise Parameters

3.2.1 Monitoring and audit of noise levels should be carried out by the ET to ensure that any unacceptable noise impacts could be readily detected and timely and appropriate action be undertaken to rectify the situation.

3.2.2 The construction noise level shall be measured in terms of the A-weighted equivalent continuous sound pressure level (Leq). Leq(30 min) shall be used as the monitoring parameter for the time period between 0700-1900 hours on normal weekdays. For all other time periods, Leq(5 min) shall be employed for comparison with the NCO criteria.

3.2.3 As supplementary information for data auditing, statistical results such as L10 and L90 shall also be obtained for reference. A sample data record sheet is shown in Appendix B for reference.

Monitoring Equipment

3.2.4 As referred to in the Technical Memorandum (TM) issued under the Noise Control Ordinance (NCO), sound level meters in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications shall be used for carrying out the noise monitoring. Immediately prior to and following each noise measurement the accuracy of the sound level meter shall be checked using an acoustic calibrator generating a known sound pressure level at a known frequency. Measurements may be accepted as valid only if the calibration level from before and after the noise measurement agree to within 1.0 dB.

3.2.5 Noise measurements should be made in accordance with standard acoustical principles and practices in relation to weather conditions.

3.2.6 The ET Leader is responsible for the availability of the monitoring equipment. He/she should ensure that sufficient noise measuring equipment and associated instrumentation are available for carrying out the baseline monitoring, regular impact monitoring and ad hoc monitoring. All the equipment and associated instrumentation should be clearly labelled.

Monitoring Locations

3.2.7 Seven construction noise monitoring stations are proposed at the following sensitive receivers in Table 3.1:

Table 3.1 Proposed Noise Monitoring Stations for Construction Phase EM&A

Work Section	Noise Sensitive Receiver	Monitoring Station	Description
Ngau Hom Shek	E24	AN1(AP8010)	Village house at Ngau Hom Shek
Ngau Hom Shek	E24	N2(AP8025)	Village house at Ngau Hom Shek
Between HSK Exit and Lam Tei Interchange	E14	AN3(AP8329)	Tsing Chuen Wai
	E13	N4(AP8601)	Tsoi Yuen Tsuen
	E8	N5(AP8414)	Fuk Hang Tsuen village
Lam Tei Interchange	E13	AN6(AP8605)	Tsoi Yuen Tsuen
Lam Tei Interchange	E4	AN7(AP8801)	Lam Tei Gospel School

Note:

For locations of NSR, please refer to Figure 2.1

Exact monitoring point for sensitive receivers shall be selected as close as practical to the construction work boundary.

3.2.8 The locations of the proposed construction noise monitoring are shown in Figure 2.1. The status and locations of noise sensitive receivers (NSRs) may change after issuing this Manual. If such cases exist, the ET Leader should propose updated monitoring locations and seek approval from ER and agreement from the IEC and EPD of the proposal.

3.2.9 When alternative noise monitoring locations are proposed, the monitoring locations should be chosen based on the following criteria:

(a) at locations close to the major site activities which are likely to have noise impacts, with proper position/siting and orientation of the monitoring equipment ensured;

(b) close to the noise sensitive receivers (any domestic premises, hotel, hostel, temporary housing accommodation, hospital, medical clinic, educational institution, place of public worship, library, court of law, performing art centre should be considered as noise sensitive receiver); and

(c) for monitoring locations located in the vicinity of the sensitive receivers, care should be taken to cause minimal disturbance to the occupants during monitoring.

3.2.10 The monitoring station should normally be at a point 1m from the exterior of the sensitive receivers building facade and be at a position 1.2m above the ground. If there is problem with access to the normal monitoring position, an alternative position may be chosen, and a correction to the measurements should be made. For reference, a correction of +3dB(A) should be made to the free field measurements. The ET Leader should agree with the IEC on the monitoring position and the corrections adopted. Once the positions for the monitoring stations are chosen, the baseline monitoring and the impact monitoring should be carried out at the same positions.

Baseline Monitoring

3.2.11 The ET Leader should carry out baseline noise monitoring prior to the commencement of the construction works. The baseline monitoring should be carried out daily for a period of at least two weeks. A schedule on the baseline monitoring should be submitted to the ER for approval before the monitoring starts.

3.2.12 During the baseline monitoring, there should not be any construction activities in the vicinity of the monitoring stations.

3.2.13 In exceptional cases, when insufficient baseline monitoring data or questionable results are obtained, the ET Leader should liaise with EPD and in consultation with ER and the IEC to agree on an appropriate set of data to be used as a baseline reference.

Impact Monitoring

3.2.14 Construction noise monitoring shall be carried out at all the designated monitoring station. It was assumed in the EIA Report that no night-time work would be carried out under the proposed construction programme. However, the monitoring frequency shall depend on the scale of the construction and the actual timing of activities. The following is an initial guide on the regular monitoring frequency for each station on a per week basis when noise generating activities are underway:

(a) one set of measurements between 0700-1900 hours on normal weekdays;

(b) one set of measurements between 1900-2300 hours (if there is construction work);

(d) one set of measurements between 0700-1900 hours on holidays (if there is construction work).

3.2.15 For the measurements (b), (c) & (d) above, one set of measurements shall at least include three consecutive Leq(5 min) results and shall only be carried out when there are construction activities scheduled during those periods.

3.2.16 As a number of schools exist near the construction activity of DBL, noise monitoring shall be carried out at the monitoring stations for the schools during the school examination periods. The Contractor shall liaise with the school's personnel and the Examination Authority to ascertain the exact dates and times of all examination periods during the course of the contract.

3.2.17 In case of non-compliance with the construction noise criteria, more frequent monitoring as specified in the Action Plan as shown in Table 3.2 should be carried out. This additional noise monitoring should be continued until the recorded noise levels are rectified or provide to be irrelevant to the construction activities.

Event and Action Plan for Construction Noise

3.2.18 Since the monitoring would be carried out near site boundary, the ET should predict the
noise levels at the nearest NSRs using standard acoustic principles on the basis of the measured noise levels from monitoring. The predicted noise levels should then be compared with the action and limit levels in Table 3.2.

3.2.19 Attention is drawn to the fact that the above action and limit levels are applied to the cumulative noise levels i.e. all relevant activities within the site of DBL.

3.2.20 The Action and Limit levels for noise are defined in Table 3.2. Should non-compliance of the criteria occur, action in accordance with the Action Plan in Table 3.3 should be carried out.

Table 3.2 Action and Limit Levels for Construction Noise

Time Period	Action Level	Limit Level
0700-1900 hrs on normal weekdays	When one documented complaint is received	75* dB(A)
0700-2300 hrs on holidays; and 1900-2300 hrs on all other days		60/65/70** dB(A)
2300-0700 hrs of next day		45/50/55** dB(A)

* reduce to 70 dB(A) for schools and 65 dB(A) during school examination periods.

** to be selected based on Area Sensitivity Rating.

Table 3.3 Event/Action Plan for Construction Noise

EVENT	ACTION
EVENT	ET	IEC	ER	CONTRACTOR
Action level	Notify IEC and Contractor; Carry out investigation; Report the results of investigation to the IEC and Contractor; Discuss with the Contractor and formulate remedial measures; Increase monitoring frequency to check the effectiveness of mitigation measures.	Review the analysed results submitted by the ET; Review the proposed remedial measures by the Contractor and advise the ER accordingly; Supervise the implementation of remedial measures.	Confirm receipt of notification of failure in writing; Notify Contractor; Require Contractor to propose remedial measures for the analysed noise problem; Ensure remedial measures are properly implemented.	Submit noise mitigation proposals to IEC; Implement noise mitigation proposals.
Limit level	Notify IEC, ER, EPD & Contractor; Identify source; Repeat measurement to confirm findings; Increase monitoring frequency; Carry out analysis of Contractor’s working procedures to determine possible mitigation to be implemented; Inform IEC, ER and EPD the causes and actions taken for the exceedances; Assess the effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER informed of the results; If exceedance stops, cease additional monitoring.	Discuss amongst ER, ET, and Contractor on the potential remedial actions; Review Contractor’s remedial actions whenever necessary to assure their effectiveness and advise the ER accordingly; Supervise the implementation of remedial measures.	Confirm receipt of notification of failure in writing; Notify Contractor; Require Contractor to propose remedial measures for the analysed noise problem; Ensure remedial measures are properly implemented; If exceedances continues, consider what portion of the work is responsible and instruct the Contractor to stop that portion of work until the exceedance is abated.	Take immediate action to avoid further exceedance; Submit proposals for remedial actions to IEC within 3 working days of notification; Implement the agreed proposals; Resubmit proposals if problem still not under control; Stop the relevant portion of works as determined by ER, until the exceedance is abated.

3.3 Construction Noise Mitigation Measures

3.3.1 The EIA Report has recommended construction noise control and mitigation measures. The Contractor should be responsible for the design and implementation of these measures under the supervision of the Engineer and the Environmental Team.

3.3.2 Noise emissions from construction sites during construction phase could be minimised by adopting good site practice, selecting quiet plant, using quiet working methods and installing temporary barriers. If the noise mitigation measures detailed below are not sufficient to restore the construction noise quality to an acceptable level upon the advise of ET, the Contractor should liaise with ET on some other mitigation measures, propose to the ER for approval, and implement the mitigation measures.

3.3.3 Recommended noise mitigation measures are detailed below.

Use of Quiet Plant and Working Methods

3.3.4 The use of quiet plant was identified to be a feasible solution to tackle the adverse impacts associated with construction works. The Contractor should obtain particular models of plant that are quieter than standard types given in the GW-TM. The benefits achievable in this way would depend on the details of the Contractors' chosen methods of working, and it would be too restrictive to specify that a Contractor has to use specific items of plant for the construction operations. It is therefore both preferable and practical to specify an overall plant noise performance specification to apply to the total SWL of all plant on the site so that the Contractor is allowed some flexibility to select plant items to suit his needs. It should be noted that various types of silenced equipment could be found in Hong Kong. However, the Authority, when processing a CNP application, will apply the noise levels contained in the relevant statutory TMs unless the noise emission of a particular piece of equipment can be validated by a certificate or through a demonstration.

3.3.5 Quiet PME is defined as PME whose actual SWL is less than the value specified in the GW-TM for the same item of plant. Reference can be made to the British Standard BS5228: Part 1:1997 Control on Construction and Open Sites.

Using Temporary and Movable Noise Barriers

3.3.6 Movable barriers that can be located close to noisy plant can be very effective at screening NSRs from particular items of plant or noisy operations. Movable barriers of 3 to 5 m height with a small cantilevered upper portion and skid footing can be located within a few metres of stationary plant and within about 5 m or more of a mobile equipment such as an excavator and mobile crane etc., such that the line of slight to the NSR is blocked by the barriers. It would be possible for the Contractor to provide purpose-built noise barriers or screens constructed of appropriate material (minimum superficial density of 15 kg/m2) located close to operating PME, in order to reduce the noise impact to the surrounding sensitive uses.
Reducing the Numbers of Plants Operating in Critical Areas Close to NSRs

3.3.7 In general the number of plant should be left to the choice of the Contractor so that in combination with the selection of quiet plant, any further reduction in the total plant noise level, or the site specific maximum sound power levels, as described above, can be achieved. It would be appropriate to restrict the number of operating PME within certain parts of the site that are very close to the NSRs in order to reduce the level of noise impacts. This method could be more effective for activities associated with foundation work, pile construction and excavation activities in which a large number of PME are anticipated, but not all of them would be utilised at the same time.

Purpose-built Noise Barriers along the Site Boundary

3.3.8 Considering the low-lying nature of surrounding NSRs (typically village houses or temporary houses), it would be effective to have noise screening structures along the site boundary to protect NSRs close to the construction site boundary. The following measures could be applied to reduce the construction noise:

i) Site buildings such as office and stores could be grouped together to form a substantial barrier separating site operations and nearby noise sensitive premises. This may be applicable for sites such as Lam Tei Interchange and general road alignment.

ii) Stacks of certain materials such as bricks, aggregate, timber or top soil can be strategically placed to form a barrier. This may be applicable for construction of road alignment.

iii) Earth bunds can be built to provide screening for major earthmoving operations. This may be applicable for sites such as Lam Tei Interchange, BCA, VHAs, road alignment.

iv) For adverse cases, purpose-built noise barriers or screens could be placed along the site boundary. This may be applicable for road alignment sites.

Good Site Practice

3.3.9 The following good site practice should be adopted during the construction phase:

The contractor should site noisy equipment and activities as far from sensitive receivers as practical. Also, temporary site offices (and other similar structures) should be located, as far as is possible, such that sensitive receivers are screened by these structures from the line of sight of the construction areas.
Intermittent noisy activities should be scheduled to minimize exposure of nearby NSRs to high levels of construction noise. For example, noisy activities could be scheduled at times coinciding with periods when the schools are likely to be unoccupied. Prolonged operation of noisy equipment close to the schools should be avoided.
Idle equipment should be turned off or throttled down. Noisy equipment should be properly maintained and used no more often than is necessary.
Construction activities should be planned so that parallel operation of several sets of equipment close to a given receiver is avoided.
Where possible, the numbers of concurrently operating items of plant should be reduced through sensitive programming.
Construction plant should be properly maintained and operated. Construction equipment often has silencing measures built in or added on, e.g. compressor panels, and mufflers. Silencing measures should be properly maintained and utilized.

Proposed Specific Construction Noise Mitigation Measures

3.3.10 To minimize the potential of adverse impact, the following measures are specifically recommended to be adopted for DBL:

i) a construction site boundary wall or hoarding is constructed in such a way to act as an acoustic screen/noise barrier for active carriageway construction work proximity to NSRs in locations shown in Figure 3.20 of the EIA Report. The boundary wall or hoarding should:

have a mass per unit of surface area in excess of 7 kg/m2 to prevent sound transmitted through the screen;
have no gaps or openings at joints in the screen material; and
have a vertical height of 3m.

The exact location of purpose-built construction site hoarding would be subject to local site conditions. Temporary noise barriers should be placed close to the noisy mechanical equipment in case the purpose-built site hoarding could not effectively screen the NSRs.

ii) Quiet plant/power mechanical equipment of sound power level lowered than those listed in Table 3 of the GW-TM shall be used for all construction sites.

3.3.11 To ensure implementation of construction phase mitigation measures with consideration of practicability in local levels, the exact location of the purpose-built construction site hoardings and other noise mitigation measures shall be reviewed during the construction phase. The changes or alternative proposals shall be reviewed by Environmental Team and the Independent Environmental Checker.

3.3.12 Table 3.4 summarizes the specific mitigation measures proposed for construction activities.

Table 3.4 Proposed Specific Construction Noise Mitigation Measures

Construction Sites	Proposed Mitigation Measures
All sites	Use of quiet equipment/plant
Locations indicated in Figure 3.20 of EIA report	Purpose-built boundary wall/site hoarding

Special Measures

3.3.13 In dealing with the construction noise at the four critical NSRs (E8, E13, E4 and E12) as identified in the EIA report, the special measures proposed require the reduction of the number of concurrent bridge pier constructions. The applicability of special measures shall be reviewed during the construction phase by the Contractor as a part of the EM&A process. The contractor is required to submit a construction noise mitigation proposal in consultant with the ET for IEC and EPD's approval. The construction noise mitigation proposal shall list out the powered mechanical equipment used, the predicted construction noise levels at NSRs and the proposed mitigation measures.

3.3.14 The Contractor shall also liaise with the NSR E4 Lam Tei Gospel School for proper arrangement of construction work during examination periods and non-school dates.

3.3.15 A detailed review of the construction noise assessment is recommended prior to the construction work commencement during the construction stage to re-conform the requirements for construction noise mitigation. The review should be carried out by the Construction Contractor and the Environmental Team using contemporary information regarding construction equipment and construction programme.

3.4 Operation Noise Monitoring

3.4.1 As the noise sensitive receivers close to the proposed road will be exposed to traffic noise during the operational phase, a noise monitoring programme shall be developed to include noise measurements at noise sensitive receivers during the peak traffic hour. The programme shall be carried out by the Environmental Team (ET) to ensure that the traffic noise levels are comparable to those predicted in the EIA under the full provision of the mitigation measures recommended.

3.4.2 This operation noise monitoring shall be reviewed during the detail design stage and submit to EPD for approval before the monitoring starts. The monitoring details such as methodologies, location and number of monitoring stations shall be agreed with EPD.

Noise parameters

3.4.3 The traffic noise level should be measured twice within the first year of the road opening. Measurements should be made in terms of the A-weighted L10 over 3 half hour periods during the peak traffic hour, other metrics like Leq may be added as seen fit. A sample data record sheet is shown in Appendix B for reference.

Monitoring Equipment

3.4.4 Sound level meters to be used shall be in compliance with the International Electrotechnical Commission Publications 651: 1979 (Type 1) and 804: 1985 (Type 1) specifications for carrying out the noise monitoring. Immediately prior to and following each noise measurement the accuracy of the sound level meter shall be checked using an acoustic calibrator generating a known sound pressure level at a known frequency. Measurements may be accepted as valid only if the calibration level from before and after the noise measurement agree to within 1.0 dB(A).

3.4.5 Noise measurements should be made in accordance with standard acoustical principles and practices in relation to weather conditions.

3.4.6 The ET Leader is responsible for the provision and maintenance of the monitoring equipment. He/she shall ensure that sufficient noise measuring equipment and associated instrumentation are available for carrying out the baseline monitoring, regular impact monitoring and ad hoc monitoring. All the equipment and associated instrumentation should be clearly labelled. The equipment installation location should be proposed by the ET Leader and agreed with the ER and EPD in consultation with the IEC.

Monitoring Locations

3.4.7 Seven operational noise monitoring stations are proposed at the following sensitive receivers in Table 3.5:

Table 3.5 Proposed Noise Monitoring Locations for Operational Phase EM&A

Road Section	NSR	Monitoring Station	Description and Monitoring Facade Selection	Monitoring Objectives
Ngau Hom Shek	E24	OP4 (AP8018)	Village house Facade with angle of view dominant by DBL	To monitor the screening by DBL elevated structure and low noise surfacing
Near San San Tsuen	E22	OP5 (AP8201)	Village house Facade facing DBL	To monitor the cantilever barriers on central divider and bridge edge
Near HSKNDA	F5	OP6 (AP9006)	School Facade with angle of view facing the semi-enclosure	To monitor the semi-enclosure (the status of this station shall be checked to see if it is available within 1 year of operation)
Near HSKNDA	F3	OP7 (AP9315)	High-rise residential Facade facing DBL	To monitor the cantilever barriers and vertical barrier on DBL (the status of this station shall be checked to see if it is available within 1 year of operation)
Near Tsing Chuen Wai	E15	OP2 AP(8302)	Village house Facade facing DBL	To monitor barrier combination of 3m vertical barrier on bridge edge, 5m vertical barrier on central divider and cantilever barrier on the opposite side.
Lam Tei Interchange	E15	OP1 (AP8617	Village house north to Tsing Chuen Wai	To monitor barriers on several ramps
Lam Tei Interchange	E7	OP3 (AP8425)	Botania Villa Facade with angle of view mainly dominated by DBL	To monitor the medium-rise NSRs and the barrier combinations with cantilever barriers on bridge edge and on central divider together with 3m barrier on the opposite side.

Note:

For locations of NSR and monitoring station, please refer to Figure 2.1

(AP8018) - corresponding assessment point in the EIA report

3.4.8 The locations of the proposed operational noise monitoring stations can be found in Figure 2.1. The status and locations of noise sensitive receivers may change after issuing the EM&A Manual. In such cases, the ET Leader shall propose updated monitoring locations and seek approval from the ER, and agreement from the IEC and EPD of the proposal.

3.4.9 The monitoring locations shall be selected according to the following criteria:

(a) they should be at NSRs in the vicinity of recommended direct technical remedies; preferably, there should be one representative monitoring locations near each types of noise screening element (i.e. vertical barrier, cantilever barrier and enclosure);

(b) one high floor and one medium floor monitoring points should be chosen at each locations as far as possible; and

(c) selected monitoring locations should enable monitoring to be done twice within one year after implementation of the mitigation measures during operation of the proposed road.

3.4.10 When alternative monitoring locations are proposed, the monitoring locations shall be chosen based on the following criteria:

(a) alternative location shall be similarly exposed to potential noise impacts;

(b) it shall be close to the noise sensitive receivers; and

3.4.11 The operational noise monitoring shall be carried out at a distance of 1m from the openable window and 1.2m above the floor level of the noise sensitive receivers identified. The ET Leader shall agree with the IEC on any necessary corrections adopted.

Baseline Monitoring

3.4.12 No baseline operational noise monitoring is generally required.

Impact Monitoring

3.4.13 Noise monitoring shall be carried out at all the designated traffic noise monitoring stations. The following is an initial guide on the traffic noise monitoring requirements during the operational phase:

(a) one set of measurements at the morning traffic peak hour on normal weekdays;

(b) one set of measurements at the evening traffic peak hour on normal weekdays;

(c) a concurrent census of traffic flow and percentage heavy vehicle shall be obtained for far-side and near-side of the road and the existing road network in the vicinity of each measuring point.;

(d) average vehicle speed estimated for far-side and near-side of the road and the existing road network in the vicinity of each measuring point; and

(e) the two sets of monitoring data should be obtained within the first year of operation.

(f) Measured noise levels should be compared with predicted noise levels by applying appropriate conversion corrections to allow for the traffic conditions at the time of measurement.

3.4.14 A sample data record sheet for operational noise monitoring is shown in Appendix B for reference.

3.5 Operational Noise Mitigation Measures

3.5.1 In the EIA Report, a series of mitigation measures have been considered for the proposed road to reduce the noise impacts at the NSRs. The best practicable mitigation package is recommended, comprising a combination of measures such as roadside noise barriers, and semi-enclosures to protect NSRs. Details could be found in the Implementation Schedule and the EIA Report.

Event and Action Plan for Operational Noise

3.5.2 The measured/monitor noise levels should be compared with predicted results and the predicted traffic flow conditions (calculated noise levels based on concurrent traffic census obtained). In case discrepancies are observed, explanation should be given to justify the discrepancies.