Traffic and noise

What is known

At a 48,500 t/yr food-waste plant in Bridgend (Wales), the council report speaks of an average of 60 heavy-vehicle movements a day; the traffic study gives 33 a day on average in the busy season and 102 at the peak[1]. The same plant was approved to run 24 hours a day, 7 days a week[1]. In Torres Novas the project would move about 300 t of feedstock a day[3]. In Ireland a 90,000 t/yr plant was refused, among other reasons, because the local road was too small[4].

We found no noise studies specific to biogas plants. The noise sources are trucks, pumps, compressors, upgrading units and flares. In France, where ambient noise is above 45 dB(A), a classified installation may add no more than 5 dB(A) by day and 3 dB(A) at night; with ambient noise between 35 and 45 dB(A), the limits are +6 and +4 dB(A)[5]. These rules measure noise above the background: where the background is low, as in a quiet village, even a small increase is noticeable.

In Guarda

The capacity, tonnage and number of trucks have not been disclosed[2]. We make no estimates of our own: the real number has to come from the project's traffic study.

What to ask the promoter

• How many trucks a day, on normal days and in spreading seasons?
• On which roads, and through which villages?
• At what times do trucks arrive and leave? Does the plant run at night?