by Andrew Carballeira
Massachusetts, like many other U.S. states, is on the fast-track toward a legal framework for medicinal and recreational cannabis. With an annual sales forecast of about $1 billion in Massachusetts alone, commercial-scale production of cannabis presents numerous opportunities through the supply chain from the grower to the distributor. With these opportunities come challenges that need to be considered in the design of cultivation facilities. This article will discuss the potential for community noise impacts from such facilities.
Cultivation facilities require careful regulation of temperature and humidity to maintain a suitable environment for cannabis plants. Because of these requirements, one of the main sources of noise at an indoor cultivation facility is heating, ventilating, and air-conditioning (HVAC) equipment. In a typical commercial building, this equipment can be operated at reduced capacity during nighttime hours, which saves energy and reduces noise emissions. However, to provide appropriate conditions in cultivation facilities, HVAC equipment needs to be operating nearly continuously (24 hours per day).
Providing this intense power demand is complex and expensive, and such considerations can be a deal-breaker for a cultivation facility. Typical practice is to deliver the electricity at high voltage (230 to 500 kV) to a transformer substation on the site of the facility, where the power is “stepped-down” to a more readily-usable voltage (110 or 220 V). The step-down transformers can generate a significant amount of noise, as anyone who has ever walked by an electrical substation can attest.
The main issue with transformer noise is not necessarily the loudness, but rather the constant frequency hum. We use 60 Hz power in the U.S., which produces strong harmonic tones at 120 Hz, 240 Hz and 360 Hz. Tonal sounds tend to be more disturbing to people than sounds with many frequency components. If a hum (single tone) and a hiss (many frequencies) have exactly the same sound level, people will say the hum is louder and much more annoying.
In addition to HVAC and power equipment, a third source of community noise is associated with transport of materials to and from the facility. Large quantities of CO2 gas are often used to boost production yields, and this gas is often delivered by tanker truck. Due to high demand, these deliveries could happen during off-hours when people in the community are sleeping. Backup alarms and loud engines have the potential to disturb and annoy those living nearby.
So what is a grower to do about these potential noise impacts? The first thing that should be considered is location! Siting a cultivation facility near an abundant source of power (hopefully far from where people live) is the ideal place to start. Once a suitable site is selected, existing sound levels should be measured to establish a baseline. A review of noise regulations should also be completed to ensure the facility does not exceed limits enacted by cities, towns, and states. With baseline monitoring and code review complete, design goals for facility-generated sound at nearby sensitive receptors can be established.
With a thoughtful approach and effective noise control treatments, there is no reason why a cannabis cultivation facility can’t be as good a noise neighbor as any other industrial facility.
Andrew Carballeira
Andrew Carballeira, INCE Bd Cert., is a principal consultant in the Acoustics group at Acentech.
