DGMR. Meer dan een oplossing

© DGMR, ir. J. (Rob) Witte

dgmr Consulting Engineers bv.
PO box 82223
2508 EE The Hague
The Netherlands

1. INTRODUCTION
The interest in noise immission control is increasing all over the world. It is especially of concern in the Netherlands, because of the population and industrialization density. Furthermore the industry is growing into a 24 hours economy, which gives an even higher noise rating on the residential areas. This paper will show that within certain limits it is possible to combine these need for space for both industry and residential areas.  To clarify the possibilities a simplified version of an acoustic study of a harbor area in Rotterdam is used.

2. DUTCH REGULATIONS REGARDING INDUSTRIAL NOISE
The noise levels are evaluated as A-weighted equivalent sound pressure levels (LAeq) during three periods of the day[1]. These three periods are combined into one 24-hour value using the following relation:
L24-hour = maximum{LAeq, day , LAeq, evening + 5 dB, LAeq, night + 10 dB}

To build new houses near an industrial area, a noise survey must be made to make sure that the 24-hour level is lower then or equal to 60 dB(A). Inside the houses the maximum 24-hour level is 35 dB(A).
The maximum 24-hour level for existing houses is 65 dB(A). The preferred level is lower than 50 dB(A). In both cases the level inside the houses remains the same as above.

3. the rotterdam HARBOR area: WAAL / EEm HARBOR
Many of the older parts of the Rotterdam harbor area are surrounded by residential areas. To accommodate new industry (110.000 m2) and new housing areas a plan was made up. New industry and industry from a neighbouring harbor, mainly in the container sector, would be concentrated in the Waal / Eem harbor. The decreasing activities in this neighboring harbor makes way for new residential areas. On the northern side of the Waal / Eem  harbor, building activities of residential areas should not be jeopardized by noise. On the other hand the terminals in general should be open for 24 hours.

This plan was made up with all parties concerned: the Rotterdam harbor authorities, as owners of the land for industrial activities, as well as the developers of the residential areas. The industrial area Waal / Eem harbor is surrounded with residential areas, see figure 1. The question for the acoustical engineers therefor was:

“Can this growth of industrial activities in the Waal / Eem harbor be accommodated within the limits of the Dutch Regulations?”

4. ACOUSTIC STUDY
First a study was conducted into the noise emission of the different types of existing industry. Because of the legislation procedures, a lot of acoustical data from different companies is available. Comparing these reports, it showed that the noise emission for new container terminals were in good agreement, the standard deviation was within 1 dB. These comparisons were made on the basis of sound power per square meter (SPM) for the companies who installed their equipment based on “best practical means”. The differences in predictions of the noise immission with the actual acoustical model (with screening and reflections on the companies terrain) and a model based on its SPM was, for the container terminals, averaged over all directions within 1 dB.

Other types of industry showed larger standard deviations, but are still very useful. The depots for empty containers showed large systematically difference of 5 dB between actual modeling and a model based on SPM.

The figures for the SPM for several types of industry are given in table 1, together with the areas, standard deviation and number of plants/ terminals/ companies under research [2].

Table 1: SPM for different types of industry

These SPM’s for different types of industry were the basis of an acoustic optimization model for the Waal / Eem harbor. In this case no internal screening effects were subtracted from the SPM’s and the averaged SPM’s were used.

On the basis of this model it showed that it is possible to accommodate this type of industry. A total 24-hours economy was not always realized: different areas had to be restricted in their activities during the night and even some during the evening period. This restriction is realized by working less hours or using less equipment during this period. It is also possible that the installed installations have a lower noise emission than expected on the basis of  best practical means or the internal screening is higher than normal. The restrictions can therefor be less severe. The activity level is given as a percentage, as is shown in figure 1. In this figure the 60 dB(A) 24-hours noise contour is also presented. It shows that this is within the limits on the northern side.

5. PRACTICE OF CONTROLLING THE NOISE IMMISSION
The noise immission for planning purposes have been predicted with these SPM studies for over five years now. The predictions have been made with the influences of all parties concerned and for the total harbor of Rotterdam. So now the acoustical limits of the harbor and the residential areas are known.

But the use of this model goes on. It serves also as a guideline to accommodate individual new companies. The noise immission of the SPM model for a certain location is the limit for the noise immission of an actual company who wants to hire this location. In an acoustical report the new company has to show that his noise immission does not exceed this limit.

In order to keep track of the SPM-models, the actual models, the legislation of the companies and the actual noise immission, specialized software is needed.

6. CONCLUSIONS
In order to control the noise from large industrial areas, commitment is needed from all parties involved. Only then it is possible, with knowledge of the noise emission per type of industry, to make a SPM-model for the total area that may serve as a boundary between residential areas and industry. The SPM-model can also serve as a noise limit for each individual company in this area.

7. REFERENCES
[1]  “Reken- en Meetvoorschrift Industrielawaai.”, De minister van Volksgezondheid en Milieuhygiëne, H.E.A. Brakkenhof e.a, 1981 (in Dutch).
[2]  Witte, J.; Haverman, R.A.: “Onderzoek kentallen geluidemissie in de Rijnmond”. dgmr  report W.95.0708.A, The Hague, 1996 (in Dutch)