Mitigating Noise AND Computer Modelling
The 1998 Noise Study (performed by SS Wilson) for the Tyandaga Westhaven Drive Subdivision approval was based on a Theoretical Computer Modelling approach.
Simply put, Computer Models produce results that investigators HOPE captures the TRUE situation, however, this has NOT always been the case. Like other predictive modelling approaches the software used by SS Wilson, was also susceptible to the “garbage in, garbage out (GIGO)” phenomenon, a phrase that originated in the computer science and information technology fields to CAUTION the reader that the quality of the output received from a ‘predictive’ modelling program not only depends on the quality of the algorithms but also depends on the quality, quantity, relevance, and integrity of the information that was input.
Input to this model were a number of important parameters, for example, the location of the all the sources of noise (bulldozers, front-end loaders, trucks, etc.), the magnitude of the noise from these sources, and how long this noise would last and occur within a given time period (1 hour).
As stated in their study – page 15, Section 4 – some of these noise ‘events’ included:
” … The ripping and excavation of the shale material, the transporting of the shale internally within the site from the pit face or active face to the storage stock pile, or loading areas, and the haulage truck movements within the site which include movements and idling … “
To exemplify the potential vulnerability of Noise Modelling and how the parameters can be changed to create very different results we present two examples below. We point out that although the model used in these examples is minimal in functionality it does use as input what seems to be the main noise contributing components in the SS Wilson Noise Study – the equipment used, the noise expectancy (loudness) of this equipment, and their time and occurrence of operation over a specified time period (1 hour).
In the first example we assume that a bulldozer performs 15 ‘heavy duty’ events per hour (e.g. deep digging and moving ore to the stockpile) and each event has a maximum noise level of 90 dB with an event duration of 180 seconds (3 minutes). Using a handy-dandy calculator we get a noise value (Leq) of ~77db
We now assume that the same bulldozer performs 10 ‘light duty’ events per hour (e.g. redistributing the stockpile, idling, moving between locations, etc.) with a maximum noise level of 60 dB and an event duration of 30 seconds then the noise value (Leq) would be ~40dB
(Note: the values (77dB and 40dB) could be considered as being the ‘average‘ noise value taken over a 1 hour time-period. This value can, however, be somewhat misleading in practice since it does not necessarily represent what may be considered a nuisance value. For example 4 very loud noises every 15 minutes lasting only a few seconds could result in an acceptable ‘average’ value (within the MOECC guidelines) YET such operating conditions could be intolerable to the average person’s ear, nerves, health, and well-being!)
In these examples, the VERY different results obtained (77dB compared to 40dB) clearly shows a strong dependence on the values assigned to the input parameters which, in turn, shows a strong dependence on the actual Operational Plan – what equipment is used (noise level), what work the equipment is doing, and for how long. In fact, this Operational Plan dependence on the noise level is also confirmed by SS Wilson in their Study (page 15, Section 4):
“… this operation (the quarry) is somewhat complex in nature and modelling of the noise events include a thorough knowledge of the operations and the ability to model these noise events at various locations and phases of the site operation process”.
Now remember, the original Quarry Operational Plan (see pages 14, 25 – 30) has undergone MAJOR changes since the one presented and used in the SS Wilson 1998 Study yet according to SS Wilson, the Operational Plan is a MAJOR component that MUST be thoroughly known if we are to have REALISTIC noise predictions!
We therefore conclude that the SS Wilson Noise Study is outdated and hence irrelevant and that there needs to be an INDEPENDENT Noise Study conducted by an INDEPENDENT consultant – one that is not associated with the aggregates!.
Another interesting aspect of the SS Wilson Noise Study is presented in the diagram below and has been used in the countless Hanson / Forterra / Meridian communications and presentations
It essentially shows a miniature bulldozer, front-end loader, and truck over-shadowed by an enormous working quarrying area that is MANY meters below the existing quarry plateau. In the study,SS Wilson state that this ‘deep dig’ operational ‘approach’ is essential if they are to attain their committed noise level.
Unfortunately, we suspect that the time required to reach the level of depth that is necessary for this recommended approach to significantly affect the noise of the operation (AND, of course, assuming that the Operational Plan does not change) will take far longer than most people would have either the patience or years to survive and we may have to live with sound levels that could “exceed the applicable criteria by significant margins“!
Finally, to have Meridian choose SS Wilson to be the adjudicator for the Noise Level policing is quite remarkable and shows their apparent lack of transparency – remember the SS Wilson statement (page 3, Section 1.1) in the Noise Study:
“It is also the objective of this report to support an application for Final Approval and Registration of the proposed development”
Only now we possibly need to take out “support an application for Final Approval and Registration of the proposed development” and replace it with “support Meridian in their east cell noise evaluation”