Unexpected noise complaints at unfavourable conditions Henk Wolferta European Policy Advisor DCMR EPA P.O. Box 843 3100 AV SCHIEDAM The Netherlands

ABSTRACT During the nineties many complaints were registered by the Central Monitoring Room of the DCMR EPA. Those complaints were sent in by some citizens of Oostvoorne, a little community opposite the industrial area of Rotterdam. Since that time many surveys were carried out in Oostvoorne and near and on the industries settled on the nearest part of the industrial area in the Greater Rotterdam Area. In 2003 a survey was conducted by the Noise Section of DCMR to find the origin of these complaints. Besides erecting a noise monitoring network, complaints were thoroughly analyzed and when complaints occurred experts have listened in Oostvoorne and near the industries that where suspected to induce the complaints. The complainers reported a droning noise similar to noise from yet engines. Remarkably, the noise, heard by the Noise Experts too, appeared stronger on a great distance from the industry than nearby. It was thought that meteorological conditions, like an inverse temperature profile, could be the cause of the nuisance because no abnormalities of the industrial operations could be found. Odd enough most of the complaints and the highest noise levels were found during a sea breeze perpendicular on the line Oostvoorne - suspected enterprises. .

a E-mail: henk.wolfert@dcmr.nl

1. INTRODUCTION In the village of Oostvoorne many people are annoyed by noise originated by industrial sites which are nearby at just a few kilometers (1.5-3 km). Oostvoorne is a small village situated near the North Sea and is known as a seaside resort. The number of inhabitants amounts approximately 7.000 but during the summer this number is more than tripled because of tourists visiting this spa. The hinterland of Oostvoorne can be defined as quite rural with natural and agricultural areas. The village borders on a huge nature reserve which includes a quiet area. In the North West Oostvoorne borders on the Lake of Oostvoorne (Oostvoornse Meer) which

separates the village from the Maasvlakte I, a large industrial area that belongs to the Rotterdam port area.

Figure 1: Maasvlakte 1

This industrial area was built in the sixties of last century and comprises large container terminals, a power plant and two large mass good storages of minerals, oil and coal. Currently this area is completed and in 2008 Rotterdam started with the construction of the second Maasvlakte, an area that will have a size of 2000 hectares, see figure 2. The Rotterdam harbour is one of the largest harbours in the world and the largest in Europe. In the past (as from 1975) measurements were carried out frequently in Oostvoorne by the Noise Section of DCMR EPA. During these measurements rather low noise levels were found ( LAeq’s between 38 and 43 dB(A). Those measurements ended in the nineties because determination of noise levels in the Greater Rotterdam Area was often done by calculations in that period. During the acoustical zoning of the Rotterdam port area, in 1990, the Province of South Holland decided, by decree, that the maximum noise levels in Oostvoorne in future shall not exceed 50 dB(A) LAeq, 24 hrs. This meant that a very limited grow of the noise levels was allowed from that time (1-2 dB). Regarding to the Environmental Impact Assessment that has been carried out in the last years it seems that the construction of the second Maasvlakte hardly doesn’t affect the noise levels in Oostvoorne. The contribution of industrial noise from the second Maasvlakte will be marginal and will raise the noise levels with just a few tenths of decibels. Noise caused by inbound and outbound transport of the second Maasvlakte could have a more significant effect because a considerable increase in the number of Heavy Good Vehicles and train movements are expected. To mitigate the environmental effects of transportation the Rotterdam Port Authorities decided to install an Environmental Zone for the Maasvlakte which means that

Heavy Good Vehicles that can not comply with the so called EURO V limits for NOX, Hydro-Carbons, Particulate Matter and CO, are banned from those industrial areas from 2013. It is not known if cleaner HGV are quieter therefore we cannot conclude that this measure will affect the noise levels as well.

Figure 2: Enlargement Maasvlakte

Many inhabitants of Oostvoorne fear an increase of environmental effects like air pollution and noise caused by this enlargement. Last years the Central Monitoring Room (CMR) of DCMR EPA saw an increase of noise complaints. Compared to other villages in the Greater Rotterdam Area, see next chapter, the number of complaints was doubled or more . The Noise Section of DCMR contacted the Rotterdam Port Authorities and persuaded them to start an investigation to find the origins of the annoyance. The Rotterdam Port Authorities agreed very quickly and financed the project. The project included an analysis of historical noise complaints, long term noise measurements, temporary listening posts and a survey among the inhabitants of Oostvoorne on noise perception. The last part was conducted by the Rotterdam Health Service (RHS). The project was led by DCMR EPA and started in 2003.

2. HISTORY AND ANALYSIS OF THE NOISE COMPLAINTS As mentioned afore the CMR reported an increase of noise complaints sent in by the inhabitants of Oostvoorne. The CMR, founded in 1972, registers all environmental complaints that are sent in by inhabitants of the Greater Rotterdam Area. Therefore it was rather easy to compare the complaints of Oostvoorne with other dwelling places and to determine if there had been an increase in the past years. DCMR EPA took the complaints that were registered in the past eleven years (1993-2003). The observations done by the CMR could be confirmed, see figure 3.

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Figure 3: Complaints about industrial noise

The graph in figure 3 shows that there is a decrease in the years 1993-1996 and an increase of complaints from 1996 with some years (’99 and ’02) with less complaints. The reasons for the lower number of complaints in those years are manifold. Climatologically conditions, communications from the governments and enterprises and last but not least the process of zoning and sanitizing the existing industries on the Maasvlakte that could have raised false expectations among the citizens of Oostvoorne. When comparing the number of complaints per thousand inhabitants it was noticed that the village of Oostvoorne could be defined as an outlier, see figure 4.

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Figure 4: Complaints per 1000 inhabitants

Other findings that were found during the analysis showed that most of the complaints were sent in during the evening and night period. It became also clear that in the first three months of the year (January, February and March) most of the complaints had been sent in which was remarkable because one should expect that most of the complaints would be registered during the summer period because people live outside and if inside windows are often open. One of the reasons raised during the analysis suggested that due to the great number of tourist during summer the noise from cars, mopeds, recreations could mask the noise from the industry. The complainers often pointed to the industry located on the Maasvlakte and especially to one specific company. The complainers described the noise as a droning, blustering noise. A last finding that was found was that most of the complaints appeared during wind that was more or less perpendicular on the line Maasvlakte-Oostvoorne (195-2550).

In 2007 a new survey started. This survey was based on the recommendations done in the report of the investigation reported here. A more detailed analysis (only over the first three months in the years 2000-2006) showed that during wind at 225-2850

most of the complaints appeared. The percentage of complaints was sorted out per wind sector of 150. By using a weighting that estimated the chances on complaints per wind sector it was found that this chance amounts 66%! Knowing that downwind is between 255-3450 we may again conclude that complaints appeared under unfavourable meteorological conditions. In this more detailed study (2007) a study was done to the correlation between wind direction, wind velocity, a combination of both, profiles of temperature and wind, sunset and sunrise and relative humidity. The main conclusions of this report is given elsewhere in this paper.

3. MEASUREMENTS IN AND NEAR OOSTVOORNE Another part of the project has been the noise measurements. By use of two mobile noise monitoring units (NMU), mounted on a trailer,see figure 5 a lot of measurement were done on several spots (3) in and near Oostvoorne. A small noise measuring unit (a suitcase with noise level meter) was located at the dwellings of the complainers. We ask them to activate the system

Figure 5: NMU on a trailer

when the “noise” was recognizable and to take notes about the length, the quality of the noise et cetera. This suitcase was placed at 9 locations during the project. By combining the results of the triggered measures with the long term noise measurement done with the noise monitoring units on the trailers we expected to get more insight in patterns, properties and circumstances during the moments of complaining. Process conditions of the enterprises have been checked as well during the project. It was found that there were no correlations between complaints and the process conditions of the industries. No abnormalities were found at the industries, they were working under normal conditions. Another thing that was found in the project was that the noise on a greater distance from the industry was a few decibels higher than at a short distance. Additional calculations were made by use of the I2 (say I square) system, the system for zone

control in the Greater Rotterdam Area. It was found that the noise levels that were measured hardly differed from those that were calculated (1-2 dB). The measured noise levels (L95) amounted 33-43 dB(A) during the day, 33-40 dB(A) during the night and 27-37 dB(A) during the night near the dwellings in Oostvoorne (the 9 spots).

Figure 56: spectrums

Based on the noise levels we can say that the levels found indicated that Oostvoorne from a acoustically perspective could be defined as a rural area and a quiet area in a dwelling place. Nothing to be anxiously about and certainly no noise levels which can be expected to arouse complaints. In some cases the noise levels registered with the suitcase during the complaints were lower than the noise levels that were normally found at that spot. The measured spectrums of the noise, see figure 6 are showing a “normal” spectrum for industrial noise at a certain distance. The spectrum, as usually at greater distances comprises a lot of noise at low frequencies. Most of the energy is present between 160 Hz and 500 Hz. An odd phenomenon was found on 63 Hz. No explanation was found other than that the adjacent 50Hz could be a peak originated by het net frequency (50Hz) of the electric power. Combining the time of the complaints with the measured noise levels of the suitcase and the NMU’s on the trailers no correlation could be found; noise complaints were sent in with high noise levels and with low noise levels, see figure 7. Combining the complaints with the measured L95 levels show that the background levels and the complaints do correlate. The complaints appeared during having a high background level. No correlation was found between the triggered measurement outcomes and the noise measured with the NMU’s. At the time of this survey remarkable changes of the noise level or spectrums were noticed. An increase of the lower frequencies 125-250 Hz was noticed.

Figure7: L95 levels and complaints

During the project DCMR EPA frequently visited Oostvoorne and have listened on several places. This was done at times that complaints appeared and on other moments as well. The observers noticed a few times the noise that was defined as a droning and blustering noise like military tanks or airplanes with jet propulsion. It was noticed as well that at a greater distance the noise sounds louder and more droning than at a short distance. Checking the process conditions at the same time no abnormalities were found, the enterprises were working under normal conditions at the times that the complaints appeared. During the measurements and by means of calculations the contribution of the separate enterprises has been checked at the control point mentioned in the environmental permit. None of the enterprises exceeded the noise limits of the environmental permits.

4. NOISE PERCEPTION IN OOSTVOORNE To complete the project a survey was done by the Rotterdam Health Service (RHS) to the perception of noise in Oostvoorne. A small questionnaire was sent out among the citizens of Oostvoorne. The survey found that the number of annoyed and highly annoyed people was rather high compared with other dwelling places and that the noise levels, compared with other dwelling places are rather low. The percentages are given in table 1 below and are compared with the city of Rotterdam and with the whole Greater Rotterdam Area (GRA) including Oostvoorne. Perceived Annoyance

Oostvoorne Rotterdam GRA

Sometimes Presence 14 7 7 Often + sometimes Frequently 7 2 2 Very Annoying Highly Annoyed 7 3 3

Table 1:Annoyance Oostvoorne

The citizens of Oostvoorne have been asked to give a qualification on a number of subjects. In table 2 the scores are presented.

Oostvoorne Rotterdam GRA Air Quality 6.9 6.7 6.9 Safety (industrial) 6.7 7.0 7.1 Stench 7.2 7.3 7.5 Industrial Noise 7.1 7.5 7.7 Traffic Noise 7.0 6.5 6.7 Aviation Noise 7.0 7.2 7.4 PM from industry 6.9 7.3 7.5Total Environmental quality 7.1 7.1 7.2

Table 2: Justment of environmental factors

From the tables can be concluded that the citizens of Oostvoorne are rather confident (table 2) but in table 1 one can see that people in Oostvoorne are more often annoyed than in Rotterdam or in the Greater Rotterdam Area. This is comparable with the complaints that appear more in Oostvoorne than elsewhere.

5. CONCLUSIONS AND RECOMMENDATIONS It can be concluded that a lot of the noise complaints occur at unfavourable meteorological conditions in Oostvoorne. Notwithstanding the fact that enterprises do comply with the limits of their granted environmental permits and do not have abnormal process conditions, complaints appear frequently in Oostvoorne. Most of the complaints appear in the first quarter of the year and during the evening and night period. The number of complaints is growing last year’s unfortunately. Observers heard the noise that according to the complainers is droning and blustering too on several places in Oostvoorne. The measurements that were carried out did not result in the expected yield. Expected was to determine and define the cause of the complaints. Therefore more investigation is needed by digging deeper (data mining) in the measured data and combining those data with more variables. It is expected that meteorological conditions play an important role in the noise propagation. The most important recommendations from the project are: • Additional investigation in meteorological effect • Introduction of an acoustical “ whether forecast” that warns people that noise can increase • Installing a permanent noise monitoring unit to inform the public

In 2007 an additional investigation as mentioned above has started. This additional investigation was completed in 2008 and will be reported in 2009. The investigation is carried out by a consortium existing from DCMR EPA, the Rotterdam Port Authorities and EMO and ECT, two enterprises which are situated on the Maasvlakte. Three consultants were hired by the consortium namely DGMR and DHV who did the acoustic surveys, a more detailed analysis of the complaints and TNO who made the acoustical-meteorological model and coordination of the substitute measurements to validate the acoustical-meteorological model. TNO will present a separate paper during the upcoming INTERNOISE 2009 congress. The first step in this additional investigation was to determine the noise complaints more detailed than already was done. By selecting a narrow time window and looking for correlations between complaints and wind direction, wind velocity, or a combination of both with complaints, temperature profile,

degree of clouds and the hours of sunshine. The findings of the first stage showed that the temperature profile, the wind direction and the combination of wind direction and wind velocity do have a correlation. The combination of these items are creating favourable conditions in the first quarter of the year and some hours after sunset. This at wind velocities of 8-10 m/s at 10m above the ground. Then wind is the most important factor. Temperature is the most important factor at lower wind speeds after a relatively sunny day. The coincidence of these factors result in more complaints in Oostvoorne. How to explain and to forecast was the second stage in the additional project. This will be presented by Mr. Frank van den Berg from TNO Delft, Netherlands in de following paper.

ACKNOWLEDGMENTS We gratefully acknowledge Mr. J.P. van Nieuwenhuizen for all his advice in order to complete this paper.

REFERENCES (TBFI)

1.Semi-permanente geluidsmetingen Oostvoorne, March 200 by H.Wolfert DCMR EPA 2.Annex with report Semi-permanente geluidsmetingen, March 2004 by H.Wolfert DCMR EPA 3.Maps with report Semi-permanente geluidsmetingen, March 2004 by H.Wolfert DCMR EPA 4.Relatie tussen geluidsklachten en weersinvloeden te westelijk Voorne, juli 2007 by Mark Trooster, DGMR 5.Zone control in the Greater Rotterdam Area, EURONOISE 2005 Tampere by H.Wolfert 6.Invloed Tweede Maasvlakte op geluidsoverdracht, 22 februari 2009 by P.A.Sloven, DCMR EPA 7.Geluidsvoortplanting over grote afstanden in de buitenlucht, 26 mei 2000 by R.Wigbels, DGMR 8. Sound propagation in areas with complex meteorology: a meteorological-acoustical model by

Frits van Eerden and Frank van den Berg (TNO-Netherlands),