Proposed Changes to Ontario Noise Guidelines: NPC-300

Update: On October 21, 2013 the Ontario Ministry of the Environment released NPC-300.  A more current and up-to-date review by HGC Engineering of the final guidelines can be found by clicking here.

On November 16, 2010, the Ministry of Environment (“MOE”) posted a draft of its updated noise criteria guideline, Publication NPC-300. Once approved, NPC-300 will replace the three current guidelines: NPC-205, NPC-232, and LU-131 and will form the basis for assessing noise from all traffic and stationary sources in Ontario.

The creation of NPC-300 was motivated by the specific purpose of eliminating conflicts between LU-131 and NPC-205/232. LU-131 contains the noise criteria that municipalities in Ontario use in deciding whether to approve land use proposals that would allow a noise sensitive development in proximity to a noise producing facility, or vice versa. NPC-205 and NPC-232 contain the criteria that the MOE uses when assessing noise from “stationary” sources such as industries and commercial establishments, in the context of granting environmental Certificates of Approval.

The issue with the current guidelines is that some of the sound level limits in LU-131 are less stringent than those in NPC-205/232, allowing municipalities to approve sound-sensitive land uses, such as residential developments, in a location that could force an existing stationary source out of compliance with its Certificate of Approval.

The issue with the current guidelines is that some of the sound level limits in LU-131 are less stringent than those in NPC-205/232, allowing municipalities to approve sound-sensitive land uses, such as residential developments, in a location that could force an existing stationary source out of compliance with its Certificate of Approval.

In general, the approach proposed in NPC-300 to resolving the conflicts in criteria among the various existing guidelines, is to relax the more stringent criterion in cases where the existing criteria are at odds. The three main areas of conflict among the existing documents, and the proposed solutions are summarized below.

Perhaps the most problematic discrepancy among the existing guidelines is that LU-131 allows “latitude” for municipalities to approve sound sensitive developments such as residences, in areas where the sound levels from an existing stationary source, such as an industry, exceed the applicable limits by up to 5 dBA. The purpose of this latitude is purportedly to accommodate urban intensification, particularly in in-fill areas or lands transitioning to residential development from other, out-moded land uses.

However, NPC-205 and NPC-232 have no such 5 dBA allowance. If a municipality extends this latitude to a residential developer, the presence of the new residential development and the resulting excess of up to 5 dBA would cause the industry to exceed the limits of NPC-205/232, thus breaching the conditions of its Certificate of Approval and contravening Section 9 of the Environmental Protection Act.

To address this discrepancy, NPC-300 introduces two new categorizations of “acoustic environment” with relaxed sound level limits. Common to all of the existing guidelines is a set of three classifications with differing sound level limits for stationary sources, depending upon the character of the typical background sound in the vicinity: Class 1 (Urban), Class 2 (Semi-urban) and Class 3 (Rural). A new class in NPC-300 – Class 4 – has less stringent “exclusionary minimum” sound level limits. (For definitions of Class 4 and Class 5 Environments, see definitions in Section A4 of NPC-300.)

Class 4 is intended to address urban intensification or areas of redevelopment. Once a municipality grants Class 4 status to a proposed development area adjacent to existing facilities hosting stationary sound sources, the relaxed sound level limits also become applicable to the environmental approvals of those facilities.

Once a municipality grants Class 4 status to a proposed development area adjacent to existing facilities hosting stationary sound sources, the relaxed sound level limits also become applicable to the environmental approvals of those facilities.

In situations where the background sound is low, the proposed sound level limits in Class 4 areas are 60 dBA during daytime hours and 55 dBA during nighttime hours, in the plane of a residential window and 55 dBA at any outdoor location on residential property – versus the limits of 50 dBA during daytime hours and 45 dBA during nighttime hours in the existing Class 1 and Class 2 designations. However, in cases where the background sound consistently exceeds the so called “exclusionary minimum” limits, the 5 dBA latitude allowed in LU-131 has been eliminated. The result is that the limits in Class 4 areas are considerably less stringent than the Class 1/2 limits for sites with low background sound, but potentially up to 5 dBA more stringent for sites with elevated background sound, relative to the latitude previously allowed under LU-131.

Under the existing guidelines, there is a contradiction between NPC-205 and LU-131 in the evening sound level limit for stationary sources impacting a point of reception in a Class 1 environment. (Evening is defined as the period from 19:00 to 23:00.) The limit in NPC-205 is 47 dBA, whereas in LU-131 the limit is 50 dBA. In resolving this discrepancy, NPC-300 adopts the less restrictive limit of 50 dBA during evening hours, for a Class 1 point of reception, and makes this limit applicable for the purposes of both industrial approvals and land use approvals. (See Tables B-1, B-2, C-5 and C-6 of the draft of NPC-300.)

Because the sound level limits in NPC-205/232 are intended for the purpose of approving a specific facility hosting stationary sources of noise, the limits apply to one facility. If there are multiple facilities (e.g., several industries), impacting one point of reception, each facility must meet its limit individually. From this perspective, there is no need to consider cumulative impact. Conversely, in LU-131 the issue of cumulative impact has always been ambiguous. LU-131 provides sound level limits which must be met at a proposed sensitive development, but there is no guidance provided about whether those limits apply to each neighbouring facility individually, or to the sum total of the sound from all neighbouring facilities combined. The more restrictive of the two possible interpretations (that the limits should be applied cumulatively, to the sum total of all neighbouring facilities) is at odds with the approach in NPC-205/232. NPC-300 clarifies this issue, by taking the less restrictive interpretation – it states explicitly that the limits apply individually to each neighbouring facility or site hosting stationary sources. (See Section C4 of the draft NPC-300.)  

There are numerous other minor changes and refinements, which may be less likely to have widespread ramifications. These include the introduction of the concept of “Enclosed Noise Buffer” balconies as an abatement measure, and modifications to the way that impulse noises are assessed, (See Tables B-3, B-4, C-6 and C-7 of the draft NPC-300) including the elimination of special limits for metal working facilities and gun clubs. Given that these two changes do not directly address discrepancies between LU-131 and NPC-205/232, it is debatable whether they should be implemented as part of this initial introduction of NPC-300. There are also many areas in which NPC-300 provides elaboration or refined language concerning various aspects of the noise guidelines. In most cases, the refinements bring in information previously contained in the Annexes to LU-131 and NPC-205, but in some instances include information previously only published in the course notes from the “Noise Assessment in Land Use Planning” training sessions that the MOE presented periodically in years past.