In this section, the general requirements, methodology, equipment, and mitigation measures for the monitoring and audit of noise impacts associated with the construction and prior to commissioning of the Designated and Potentially Designated Projects are described below. The specific noise EM&A requirements for each of the Designated and Potentially Designated elements are defined in Annexes A and B of this EM&A Manual.
6.2.1 Methodology and Criteria
Noise level measurements shall be carried out using the methodology set out in Sub-section 3 of the Annex - General Calibration and Measurement Procedures, as stated in the Technical Memorandum on Noise from Construction Work other than Percussive Piling (GW-TM).
The appropriate parameter for measuring construction noise impacts shall be the A-weighted equivalent continuous sound pressure level (LAeq) measured in decibels (dB). The two statistical sound levels L10 and L90 ; the levels exceeded for 10 and 90 percent of the time respectively, shall also be recorded during the monitoring for reference. A sample data record sheet is shown in Annex D (Report Sheet 1.2) for reference.
Noise impact arising from general construction works during normal working hours (i.e. 0700 to 1900 hours on any day not being on a Sunday or public holiday) at the operable windows of noise sensitive uses, is guided by the EIAO-TM. The recommended standards are presented in Table 6.2a.
Table 6.2a EIAOTM Standard - General Construction Works
|
Uses |
Noise Standard |
|
Domestic Premises |
75 |
|
Educational Institutions
(normal periods) |
70 |
|
Educational Institutions
(during examination periods) |
65 |
With reference to the EIAO-TM, there is no recommended construction noise standard currently provided for places of public worship. Therefore, a comparable type of land use criterion, those specified for educational institutions (non-exam period), has been applied as an indication of potential noise impacts. In this Study, the Leq, 30min 70 dB(A) daytime construction noise criterion will be adopted for places of public worship.
The NCO provides statutory controls on general construction works during the restricted hours (i.e. 1900 to 0700 hours Monday to Saturday and at any time on Sundays and public holidays). The use of powered mechanical equipment (PME) for the carrying out of construction works during the restricted hours will require a CNP. The EPD is guided by the GW-TM when vetting such an application.
The NCO provides statutory controls on general construction works during restricted hours (i.e. 1900-0700 hours Monday to Saturday and at any time on Sundays and public holidays). The Acceptable Noise Levels (ANLs) for evenings (1900-2300) and holidays and for night-time (2300-0700) are dependent on the Area Sensitivity Rating (ASR) at the NSR. The relevant ANLs are provided in Table 6.2b.
Table 6.2b Acceptable Noise Levels (ANLs)
|
Time
Period |
Area Sensitivity Rating |
||
|
|
A |
B |
C |
|
All days during the evening
(1900-2300 hours) and general holidays (including Sundays) during the day and
evening (0700-2300 hours) |
60 |
65 |
70 |
|
All days during the
night-time (2300-0700) |
45 |
50 |
55 |
6.2.2 Monitoring Equipment
The ET Leader shall be responsible for providing and maintaining a sufficient number of sound level meters to conduct the necessary baseline monitoring, regular impact monitoring and ad hoc monitoring at the agreed monitoring locations.
Sound level meters and calibrators shall comply with the International Electrotechnical Commission (IEC) Publication 651 : 1979 (Type 1) and 804 : 1985 (Type 1) specification as referred to in the GW-TM. The sound level meters shall be supplied and used with the manufacturers recommended wind shield and with a tripod.
The calibration of the sound level meters shall be carried out in accordance with the manufacturer's requirements. The sound level meters, including the calibrators, shall be verified by the manufacturers once every two years to ensure that they perform to the same level of accuracy as stated in the manufacturers specifications. Calibrated hand-held anemometers capable of measuring the wind speed in ms-1 shall also be supplied for the measurement of wind speeds during noise monitoring periods. The anemometers shall be used and calibrated in accordance with the manufactures recommendations.
Sound level meters shall be calibrated using a portable calibrator before and after each measurement. The calibration levels shall be noted with the measurement results and where the difference between the calibration levels is greater than 1 dB(A) the measurement shall be repeated.
The ET Leader shall ensure the equipment shall be kept in a good state of repair in accordance with the manufacturer's recommendations and maintained in proper working order with sufficient spare equipment available in the event of breakdown to maintain the planned monitoring programme.
Noise measurements should not be made in the presence of fog, rain, wind with a steady speed exceeding 5 ms-1 or wind with gusts exceeding 10 ms-1. The wind speed shall be checked with the hand-held anemometers. The equipment requirements for each of the Designated and Potentially Designated Projects is outlined in Annexe’s A and B.
6.2.3 Monitoring Locations
The noise monitoring locations for each of the Designated Projects are outlined in Annexe’s A and B, and the figures showing the location of the environmental sensitive receivers are included in Annex C.
6.2.4 Baseline Monitoring
The ET Leader shall carry out the baseline noise monitoring prior to the commencement of the construction works. To obtain fully satisfactory baseline results, a waterproof sound level meter and noise logger shall be used. Baseline noise levels shall be measured over one consecutive 7-day calendar week at a minimum logging interval of 15 minutes. The LAeq, L10 and L90 shall be recorded at the specified interval. The survey period shall be selected prior to the commencement of construction activities and so as to avoid other atypical noise sources. The proper functioning of the logger shall be ensured during this period and shall be visited for a period of not less than one hour every two days to ensure its continued operation and to detail specifics of audible noise sources at the monitoring locations. The calibration of the logger kit shall be as recommended by the manufacturer. Measurements shall be recorded to the nearest 0.1 dB.
Checking for changes in the baseline noise levels throughout the construction phase shall be carried out by taking "sample" noise measurements every six months, when no noisy construction activities are in progress. If significant changes that can be validated are observed to have arisen, the baseline may be adjusted accordingly after consultation and agreement with the Engineer, IEC and EPD.
6.2.5 Impact Monitoring
During normal construction working hours (0700-1900 Monday to Saturday), monitoring of LAeq, 30min noise levels (as six consecutive LAeq, 5 min readings) shall be carried out at the agreed monitoring locations once every six days in accordance with the methodology in the GW-TM. The six consecutive LAeq, 5 min readings shall be used to calculate the LAeq, 30 min noise level and this shall be compared to the LAeq, 30 min noise criteria and reported against.
If restricted hours works are undertaken, monitoring of LAeq, 5min noise levels shall be carried out at the agreed monitoring stations at the same frequency as specified for normal working hours. Three consecutive LAeq, 5 min readings shall be taken to ensure the validity of the results. Each of the LAeq, 5min noise readings shall be compared to the LAeq, 5min noise criteria and reported against.
In relation to the monitored noise levels, other noise sources such as road traffic may make a significant contribution to the overall noise environment. Therefore, the results of the noise monitoring activities will take into account any such influencing factors which were not present during the baseline monitoring period. All measurements shall be recorded to the nearest 0.1 dB.
6.2.6 Compliance Assessment
Action and Limit (A/L) Levels provide an appropriate framework for the interpretation of monitoring results. The noise impact monitoring data shall be checked against the agreed A/L Levels as listed in Table 6.2c.
Table 6.2c Action and Limit Levels for Construction Noise
|
Time
Period |
Action
|
Limit |
|
|
|
0700-1900 on any day not
being a Sunday or public holiday. |
When one or more documented
complaints are received |
75 dB(A)(1) |
|
|
|
1900-2300 on all days and
0700-2300 on general holidays (including Sundays). |
When one or more
documented complaints are received |
60/65/70 dB(A)(2) |
|
|
|
2300-0700 on all days |
When one or more documented
complaints are received |
45/50/55 dB(A)
(2) |
|
|
|
1)
For educational establishments the limit level shall be 70 dB(A),
reduced to 65 dB(A) during examination periods. 2)
Acceptable Noise Levels for Area Sensitivity Rating A/B/C. |
|
|
||
To account for cases where ambient noise levels, as identified by baseline monitoring, approach or exceed the stipulated Limit Level prior to commencement of construction, a Maximum Acceptable Impact Level, which incorporates the baseline noise level and the identified construction noise Limit Level, may be defined upon agreement with the EPD. This amended level will, therefore, be greater than 75 dB(A) and will represent the maximum acceptable noise level at a specific monitoring station. Correction factors for the effects of acoustic screening and / or architectural features of NSRs may also be applied for, from the EPD, as specified in the GW-TM.
For the purposes of compliance checking, after taking into account any adjustments agreed with EPD, comparison with either the Limit or the Maximum Acceptable Impact Level shall represent the governing criteria for noise impact assessment during the Project EM&A.
6.2.7 Event and Action Plan
The principle on which the EAP is based is the prescription of
procedures and actions associated with the measurement of defined levels of
noise impact recorded by the environmental monitoring process and defined in
the table above. In cases where
exceedance of these criteria occurs, the ET Leader, IEC, the Engineer and the
Contractor shall strictly observe the relevant actions of the EAP shown in Table 6.2d.
Table 6.2e 6.2d Event and Action Plan for Construction Noise
|
EVENT
|
|
ACTION |
|
|
|
|
ET Leader |
IEC |
Engineer |
Contractor |
|
Action Level |
|
|
|
|
|
Exceedance for
one sample |
1. Identify source
(s) of exceedance and inform IEC, Contractor and Engineer 2. Repeat dust
measurements to confirm findings 3. If repeat measurements
confirm exceedance ,increase monitoring frequency to daily 4. Assess efficacy
of remedial measures and keep the Contractor, IEC, and Engineer informed 5. If exceedance
stops, inform Contractor and cease additional noise monitoring. |
1. Check monitoring
data submitted by ET 2. Check monitoring
data trends and Contractors working methods 3. Check and
confirm Contractors proposed remedial actions and working methods are
appropriate |
1. Confirm receipt
of notification of exceedance in writing 2. Remind the Contractor
of his contractual obligations and review the Contractor’s working methods 3. Discuss remedial
actions with the Contractor and IEC 4. Inform
complainant of actions taken, if necessary |
1. Rectify any
unacceptable practice 2. Liaise with
Engineer and IEC to develop appropriate remedial measures to reduce noise
impact 3. Amend working
methods and remedial proposals if required by the Engineer or IEC 4. Implement the
agreed remedial actions upon instruction from the Engineer and IEC |
|
|
|
|
|
|
|
Limit Level |
|
|
|
|
|
Exceedance for
two or more consecutive samples |
1. Identify source
(s) of exceedance and inform IEC, Contractor and Engineer 2. Repeat
measurements to confirm findings 3. Increase the
monitoring frequency to daily 4. Discuss remedial
actions with IEC, Engineer and the EPD 5. Assess the
efficacy of remedial measures and keep the Contractor informed 6. If exceedance
continues, arrange meeting with Engineer, IEC and Contractor to review
working practices and identify further remedial actions 7. If exceedance
stops, inform the Contractor and cease additional monitoring. |
1. Check monitoring
data submitted by ET 2. Check monitoring
data trends and Contractors working methods 3. Discuss with
Contractor and Engineer on possible remedial measures 4. Check and confirm
Contractors proposed remedial measures are appropriate 5. Determine the
efficacy of remedial actions and keep the Engineer informed |
1. Confirm receipt
of notification of exceedance in writing 2. Remind the Contractor
of his contractual obligations and review the Contractor’s working methods 3. Discuss remedial
actions with the Contractor and IEC 4. Ensure remedial
measures are properly implemented 5. If exceedance
continues, instruct the Contractor to stop the relevant portion of work until
the exceedance is abated 6. Inform
complainant of actions taken, if necessary. |
1. Rectify any
unacceptable practice, if possible 2. Submit proposals
for remedial actions to Engineer and IEC within three working days of
notification 3. Discuss and
amend remedial actions, if required, by the Engineer and IEC 4. Implement the
remedial action (s) immediately upon instruction from the Engineer 5. Discuss with
Engineer and IEC, to optimise the effectiveness of the agreed remedial
actions 6. Stop the relevant
portion of work as determined by the Engineer until the exceedance is abated |
The EIA (DE) has recommended noise control and mitigation measures during the construction phases of the Project. In the event of exceedances or complaints, the Contractor shall be responsible for reviewing the effectiveness of the following measures and for proposing, designing and implementing alternative measures as appropriate (a full list of measures is outlined in the Implementation Schedule detailed in Annex E:
· Using quieter powered mechanical equipment (PME);
· Only well-maintained plant shall be operated on-site and plant shall be serviced regularly during the construction programme;
· Machines and plant (such as trucks and cranes) that may be in intermittent use shall be shut down between work periods or should be throttled down to a minimum;
· Silencers or mufflers on construction equipment shall be utilised and be properly maintained during the construction works;
· Mobile plant shall be sited as far away from NSRs as possible;
· Material stockpiles and other structures shall be effectively utilised, where practicable, to screen noise from on-site construction activities;
· Restrictions on the types of PME used concurrently.
A summary of the recommended mitigation measures for each of the construction activities is presented in Table 6.2e.
Table 6.2e Summary of Proposed Mitigation Measures for Construction Noise Assessment
|
Activity ID |
Description |
Mitigation Measures |
||
|
101 |
General Site
Clearance - /Demolition
Works |
· Use of quiet PME · Site hoarding along site boundary of the pumping station sites |
||
|
102-P1 102-P2 102-P3 102-P4 102-P5 102-P6 102-P7 |
Construction of Sewage Pumping Stations P1, P2, P3, P4, P5, P6 & P7 |
· Use of quiet PME · Site hoarding
along site boundary of the pumping station sites |
||
|
103 |
Sewers and
Rising Mains using Open Trench Method |
· Use of quiet PME · Replacing excavator mounted breakers with handheld breakers during the initial road opening activities · Use of movable noise barrier or enclosures during the initial road opening activities where there are NSRs located within 50m of the works area |
||
|
104 |
Sewers
and Rising Mains using Pipe Jacking Method |
· Use of quiet PME |
||
|
105 |
Road Pavement and Finishes |
· Use of quiet PME |
||
If
the above measures are not sufficient, upon the advice of the ET Leader, the
Contractor shall liaise with the ET Leader to agree further mitigation
measures, propose the recommended measures to the Engineer for approval, and
then implement the mitigation measures.
Operational noise monitoring shall be carried out during the commissioning stage of the ventilation buildings. The purpose of this monitoring is to ensure that compliance with the noise limits specified in this EIA report has been achieved.
It is recommended that noise monitoring should be carried out for the ventilation buildings on two occasions; day one of commissioning and day 60 of operation.
Noise measurements shall be made in accordance with the procedures outlined in the “Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places and Construction Sites” (IND-TM) and shall be conducted at a time when the SPS are operating at its maximum capacity.
The monitoring location shall be at a distance of 1m from the center of SPS openings, such as louvres. Two types of measurement shall be carried out:
(a) Broadband measurement of LAeq(t). Note that the measurement period (t) shall normally be 30 minutes. However, if it can be demonstrated that the noise level is constant, then a shorter measurement period (no less than 5 minutes) may be used.
(b) Frequency analysis between 31.5 and 16 kHz measured at 1/3 octave intervals. If the noise emanating from the louvre is found to be tonal (as defined in IND-TM) then an appropriate tonal correction should be applied to the measured noise level (MNL) to achieve the corrected noise level (CNL). This CNL shall be compared with the noise specifications.