5. POTENTIAL IMPACTS
5.3 Onshore construction
5.3.3 Airborne noise
The construction activities will generate airborne noise of varying frequencies and intensities from the work site. Furthermore, there will be noise from the construction related traffic to and from the work site (see further description in Section 5.3.2). The noise may impact the closest
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surroundings, including neighbours and the users of nearby recreational areas and activities. The following description is related to noise from the work site.
Noise sources
The noise from machines and activities at the landfall is calculated based on the noise source power (sound power, LWA in dB(A)). Source power is an expression of how much noise energy the source of noise emits to the environment and is not indicative of the noise level measured at the noise source. The noise calculations use the source power to calculate the noise level in the surroundings. The noise level around a noise source will always have significantly lower values than the source strength, and it will be lower with increased distance.
The source powers for the noisy machines applied in the study of noise from construction work are shown in Table 5-16. The noisy machinery may be subject to change during the construction phase if the contractors decide on alternative equipment, but the identified noisy machines are assessed as representative for assessing noise from the onshore construction activities.
Table 5-16 Overview of the noisy machinery expected to be used during construction at the landfall. The construction work is divided into five main construction phases. Several types of machinery will be used, but the types listed are the noisiest and will be decisive for the noise caused by construction activities.
The source strengths do not include any additions for clearly audible impulses.
Construction phase Type of machinery Energy [kW]
Sheet piling 250 125 (Vejdirektoratet, 2016)
Dredger 385 108 (Defra, 2006)
Dredger 29 97 (Defra, 2006)
Phase 3 Tunneling
Generator for machines
used during tunneling 1519 106 (Defra, 2006)
Crane for lifting tunnel
elements 254 101 (Jacobsen & Kragh, 1986) Phase 4
Pre-commissioning Flooding pumps 522 110 (Defra, 2006)
Phase 5
Restoration of launch shaft and work site
Dredger 385 108 (Defra, 2006)
Compression 11 103 (Vejdirektoratet, 2016)
The individual machinery will be used alone or in combination with other equipment for carrying out the construction activities that are part of the overall construction project. There may be other activities, but these selected activities are considered the noisiest. The individual activities can also be performed differently, which may result in a different number of machinery (e.g. the number of trucks involved in soil works) or different machinery not being in operation all the time.
The individual machine will not normally be in constant operation without interruptions. During the night period, the noise is assessed for the ½ hour in which the most noise occurs. Therefore, if night work occurs, it is not unrealistic that each machine is in continuous operation for the worst ½ hour. It is therefore assumed as a worst-case consideration that most machines are in constant operation.
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When sheets are to be brought into the soil, it is assumed that it will be done by piling, which is the noisiest method, and this will be used as a conservative premise for noise calculations. It is possible to vibrate the sheets into the soil, and this method is less noisy than regular sheet piling; however, use of this method will depend on the local soil conditions.
It should be noted that this noise study of the construction work involves several activities that may cause noise above the applied guiding limit values at dwellings (see the following paragraph and Section 9.9). There will be other noisy construction activities that will be part of the overall noise picture, but this noise will be less important and subordinate to the construction activities studied.
Calculation of noise from construction works
Noise that will occur in the future cannot be measured but must be calculated. The basis for calculating noise from the construction activities at the landfall is the information about the type of machinery expected to be used, the noise that the machinery is expected to cause and extensive experience from other major construction projects. For certain noise sources, typical standard data are applied (e.g. for trucks). In addition, a worst-case consideration has been applied in selecting noise data. The basis for noise calculations also includes the preliminary plans for construction work, as they are known at present. It should be noted that the subsequent detailed planning of the construction activities may lead to changes in the assumptions that have been applied. For example, the contractor may choose to use other types of equipment and methods than currently anticipated.
The calculations in this EIA study will, however, be a guide to the noise impact of construction work. In addition, the contractor must report noisy construction work to Faxe Municipality prior to initiation with information on how it will be carried out and information about the impact on dwellings from noise and vibration.
The noise sources will be used to calculate the noise from the work site. The noise will be
calculated in a grid net and illustrated as a noise map displaying which surrounding areas can be exposed to noise above the following two noise levels:
• 70 dB(A): The guiding limit value used for construction works within regular working hours;
and
• 40 dB(A): The guiding limit value used for construction works outside regular working hours if construction work exceptionally is to be carried out outside normal working hours.
Details regarding the guiding limit values applied for the assessments of this project are elaborated in Section 9.9.
The information on the noise emissions of the various sources (their sound power levels, operating times and the noise frequency composition) has been used to calculate how far away the noise will fall to the two guiding limit values for noise from construction work (70 dB(A) during regular working hours and 40 dB(A) during other periods). These calculations were performed in accordance with the Danish Environmental Protection Agency's guidance on the calculation of noise from companies (Miljøstyrelsen, 1993). However, a few simplifications and assumptions have been applied to the calculations:
• It is assumed that the terrain is acoustically soft everywhere;
• It is assumed that the noise sources are located 2 m above ground (apart from sheet piling, for which the noise source is located 6 m above ground) and the receiver is located 1.5 m above ground.
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As previously discussed, audible impulses are likely to occur in the noise from activities involving sheet piling if the distance to the piling work is less than a few hundred meters. At greater distances, the probability of audible impulses may be reduced because other noises can mask how clearly the impulses can be heard. The calculations of noise from sheet piling contain an underlying precautionary measure by including an additional 5 dB both when illustrating the 70 dB(A) and the 40 dB(A) curve.
For the other construction activities, it is less likely that audible impulses or tones will occur within the noise, regardless of distance. Therefore, an additional 5 dB is not included in the calculation of the other construction activities.
Noise modelling results
In Section 9.9, five construction phases for the onshore construction activities have been identified as the noisiest phases. The construction noise from these five phases at the landfall area has been calculated and compared to the applied guiding limit values of 70 dB(A) and 40 dB(A). Table 5-17 provides an overview of the approximate distances from the acoustical centre of the construction work at the work site to the noise impact zones for 70 dB(A) and 40 dB(A), respectively.
Table 5-17 Distances calculated from the acoustical centre of the construction work within each of the five construction phases to the extent of the noise impact zones, respectively within and outside regular working hours.
Construction phase Noise impact zone Distances
Phase 1
Air emissions from onshore construction mainly relate to the tunnelling activities and trucks driving with equipment and soil to/from the landfall area. The various equipment used for tunnelling will be powered by electricity provided by a diesel-driven generator. Furthermore, emissions will arise from pre-commissioning, which involves pumps for flooding, cleaning, and gauging as well as compressors for dewatering and drying.
Delimitation of air emission calculations
Construction of the proposed pipeline at the Danish landfall, Faxe S, will also have an impact on climate and air quality. As was the case with the offshore part of the project, the air emissions assessed relate to the direct activities of construction and operation of the pipeline, which include:
• Contractor machinery preparing the work site;
• Contractor machinery preparing the launch shaft for tunnelling;
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• Transportation of equipment for tunnelling and soil to/from work site by truck (assumption:
50 km on average each way);
• Generators used for running the tunnelling equipment;
• Contractor machinery restoring the launch shaft and work site;
• Pumps and compressors used for pre-commissioning activities.
Emissions from the production of the tunnel elements used for tunnelling are not included, as these were already included in the calculation of emissions associated with offshore construction activities.
Basis for emission calculations
The emission calculations are approximate, based on a realistic, worst case approach.
Furthermore, an uncertainty factor of 1.2 have been added to the input for the estimates of power consumption during tunnelling, which is one of the main contributors to emissions for the onshore part of the project. Thus, the results are considered as conservative.
The calculations are based on the information about construction machinery presented in Section 3.4.3, including operation time of the individual type of equipment and the effect (in kW) of the equipment.
The emission factors from construction machinery are based on Euro standards. It is assumed that construction machinery will be able to comply with emission factors in Euro standard stage IIIA (which went into force in 2006-2008). The emission factors are taken from the
administrative order on limiting air pollution from mobile non-road machines7.
Emissions factors for pumps, generators and compressors are based on the national Danish emissions inventories, made by Aarhus University for stationary combustion (Aarhus University, 2018a).
Air emissions from onshore construction
In Table 5-18, the air emissions from onshore construction are shown.
Table 5-18 Air emissions from onshore construction, including pre-commissioning.
Air emissions [tonnes]
CO2 NOX SO2 PM (TSP) PM10 PM2.5
Onshore
construction 540 9 22* 0.1 0.6* 0.4*
* It has only been possible to estimate SO2, PM10 and PM2.5 emissions from the generator used for tunnelling and from trucks driving to and from the work site. Thus, emissions from other contractor machinery are not included for these polluting components.
Modelling of air quality
The impact on the surrounding air quality as a result of the onshore construction activities has been modelled using the OML model, version 6.2. The OML model is an atmospheric dispersion model developed and maintained by the Danish Centre for Environment and Energy (DCE), Aarhus University.
The onshore construction activities are divided in different phases, where the most energy-consuming phase is related to tunnelling. OML modelling has only been performed for this phase
7 Administrative order no. 1458 of 07/12/2015 on limiting air pollution from mobile non-road machines (bekendtgørelse om begrænsning af luftforurening fra mobile ikke-vejgående maskiner mv.).
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of the project as a representation of the time during construction with the greatest impact on air quality.
The tunnel boring machine and supplementary equipment require electricity from a diesel generator. As the basis for the modelling, a 1650 kVA diesel generator from Perkins has been used as a reference (Perkins, no date), and information from the datasheet about fuel
consumption and dimensions has been applied. It is assumed that the generator will be using 75% work load on average during the entire tunnelling process. It has not been possible to determine the temperature of the exhaust gas from the generator. Test modelling shows that 200 degrees is a conservative estimate, which has been applied. The generator is registered as a point source in the OML model. Furthermore, a crane for lifting the tunnel elements will be in use simultaneously with the generator. The crane is registered as an area source in the OML model, as it can be used at the entire work site.
The modelling results are showed in Table 5-19 for NO2, SO2, PM10 and PM2.5 for averaging periods related to the limit values according to the Air Quality Directive (see Section 9.4.1).
Table 5-19 OML modelling results of the impact on air quality in the surrounding area during tunnelling (the results do not include the background levels of the air quality).
Distance
* The 19th greatest average concentration in an hour.
** The 25th greatest average concentration in an hour.
*** The 4th greatest average concentration in 24 hours.
**** The 36th greatest average concentration in 24 hours.
5.3.5 Employment generation
The onshore construction activities, which are mainly related to tunnelling and
pre-commissioning, will generate work for a limited number of personnel during approximately 13 months in total. As the tunnelling work is very specialised, it is expected that a contractor
specialised in tunnelling will be engaged, likely from outside the local area. A local contractor may be engaged to prepare the work site and launch shaft and to restore these areas after
construction. These activities may result in minor increased employment and turnover in the local area in relation to accommodation, food, etc. It is expected that approximately 12 people will be working with the tunnelling activities.
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