Delft Blue Farms, a veal farm located in the vicinity of Cambridge, Ontario is at the forefront of farm environmental innovation and sustainability. At the center of its environmental sustainability is a 499 kW biogas production facility, which converts the manure from the farm’s 3000 cows into methane gas via an anaerobic bio-digester. The gas is then refined into biofuel and used to drive large onsite power generators, which produce “green” electricity that is then sold into the Ontario power grid.
Predictive Acoustic Analysis of BioGas Production Facility
Prior to its development in 2010, HGC Engineering was contracted by PlanET to undertake a predictive acoustic analysis of the planned power generating operations and to investigate the need for noise control measures based on the guidelines of the MOE, including publication NPC-232, “Sound Level Limits for Stationary Sources in Class 3 Areas (Rural).”
Under MOE noise assessment guidelines, power generation equipment is classified as a stationary source of sound (as opposed to traffic noise sources, for instance). In essence, the sound from a stationary source is evaluated by comparing it to the existing background sound levels during a period of low background sound. Specifically, publication NPC-232 states that the sound level criterion for a stationary source that can operate during both daytime and night time hours in a rural environment is the greater of the minimum one-hour background sound level or the exclusionary minimum night time limit of 40 dBA at night, at any potentially impacted point of reception. A point of reception is defined to include any location on the premises of a person (e.g., a residence).
Power Generator Noise Control Measures
The site geometry and manufacturers’ sound level data were taken to develop an acoustical model of the site using Cadna/A software. Typical acoustical engineering calculations were also made to determine the proportion of sound inside the generator room that would exit through ventilation openings. The study revealed that the majority of sound would be emitted by engine exhaust stacks, but ventilation-air intakes would also be a contributing factor. The analysis indicated that with recommended noise control measures in place (ie. exhaust mufflers and acoustical louvres), sound levels would be within the applicable criteria.
Acoustical Engineering Services Delivered Include:
- Predictive Acoustic Analysis
- Acoustic Measurement
- Noise Assessment
- Detailed Noise Impact Studies
- Noise Control Investigations
- Recommendation of Noise Control Measures