Noise reduction - Vroom Foundation Technology
Img 07

Noise reduction

Vroom Funderingstechnieken (Vroom Foundation Technology) was one of the pioneers in developments to limit noise pollution. Where necessary, noise-reduction measures such as noise-reducing jackets are used to significantly reduce noise pollution. An alternative solution is to opt for a different, low-noise pile system.

The branch organisation for the foundations industry in the Netherlands, the NVAF, wants to reduce the average noise level by a full 5 dB(A), and has thus entered into a covenant with the Dutch Ministry of Social Affairs and Employment (SZW).

The Convenant Geluid & Begaanbaarheid (Noise & Accessibility Covenant) created by the foundations industry highlights the following noise-reduction measures:

  • reduction of noise at source 
  • noise-screening 
  • use of personal protective equipment

The first two of these objectives relate to what is reasonably possible. In the context of the third objective, Vroom Funderingstechnieken has provided all workers with ear defenders and gives them the opportunity to be measured for personal otoplasty by an audiological specialist.


What does the Dutch Health and Safety at Work Decree (Arbobesluit) say about this?

According to the Dutch Health and Safety at Work Decree, machines in the workplace may not operate at an average noise level above 85 dB(A), except where that cannot reasonably be expected. Where the level exceeds 80 dB(A) businesses must make ear defenders available and provide information on the dangers of such noise levels as a matter of course. If the noise level exceeds 85 dB(A), additional measures are required and a the hazard zone must be indicated as such. Furthermore, use of ear defenders must be mandatory.


What noise levels are generated in foundation work?

Building and construction work lasting less than 1 month is subject to a government-imposed environmental threshold value of a daily equivalent of 65 dB(A). In the vicinity of sensitive buildings and structures (such as hospitals), this may be 60 dB(A). A 'daily equivalent’ is the average noise level measured over a period of 12 hours. Whether the environmental threshold value is actually exceeded or not depends on the actual amount of time that pile driving work continues, the noise emitted and the distance to the place which is affected. And, of course, the time of day at which the work is carried out: during the day, in the evening, at night or at the weekend.

Environmental threshold value 

The question to be asked is: 'How far away is the noise level still at an acceptable level?’ The higher the noise level, the further away the environmental threshold value in relation to the source of noise. Where this threshold value lies may be determined on the basis of measuring the noise level 15 metres from the source, at a height of 5 metres. With this data it is possible to calculate the distance from the noise source to the point at which the environmental threshold value is no longer exceeded. Generally, the noise level drops by 6 dB(A) each time the distance doubles. Sound waves bouncing off buildings or other surfaces could have the effect of absorbing noise or, indeed, amplifying it, depending on the surface.


Health and safety at work

In terms of health and safety at work, noise levels in the immediate vicinity of the workforce are of greatest importance. The table shows the average noise levels to which the pile-driving foreman and machine operator have to deal with on a daily basis. These are the average levels for an entire working day, i.e. Including the quiet periods when there is little ambient noise.


Type of foundation work


Noise level dB(A), during pile-driving work (not to be confused with the daily equivalent)

Distance at which the standard is reached (m)

Foreman

Operator

At 15 m

Without soundproofing

Hydraulic

102-107
90-100
95-100
300-500


Ram

90-100
85-95
85-95
100-300

With soundproofing

Hydraulic ram – soundproofed (+ vibro casing and bellows)
88-93
80-90
78-95
30-100

Diesel ram with 'Rotterdam jacket', i.e. sound-proof doors
90-98
150-400

Low-noise foundation work


80-90
80-90
65-85
30-100

Screw piles, drilling, hydraulic pressing (plant and equipment not sound-proofed)
less than or equal to 80
less than or equal to 80
less than or equal to 80
less than or equal to 30

Screw piles, drilling, hydraulic pressing (sound-proofed plant and equipment)


Source: NVAF 'Geluidsniveaus bij funderingstechnieken'.