Assistance with Land Use Planning Strategies and Success Framework: Sewage Treatment Plants and Sensitive Land Uses

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In Ontario, the Planning Act and the supporting Provincial Policy Statement (PPS, 2020) require that adjacent land uses are “compatible,” or in lay terms, do not cause each problem.  There are many aspects to compatibility, but in the present article, we shall focus on environmental (air and noise) compatibility, as we are the foremost air quality assessment consultants in Ontario.

Air Quality Assessment

Environmental compatibility requirements are provided in s. of the PPS: “Major facilities and sensitive land use shall be planned and developed to avoid, or if avoidance is not possible, minimize and mitigate any potential adverse effects from odor, noise, and other contaminants, minimize risk to public health and safety, and to ensure the long-term operational and economic viability of major facilities in accordance with provincial guidelines, standards, and procedures.”

This section requires, at very least, a test for potential adverse effects.  Focussing on air emissions requires an assessment of air emissions from sewage treatment plants and their potential impacts on sensitive land uses, such as residential areas.  To support tests for adverse effects assessments, the (then) Ontario Ministry of the Environment developed the D-series set of documents.  I have provided a more fulsome overview in my earlier blog on Land Use Compatibility Assessments (LUCAs) on the 26 May.  At DiGiSci Environmental consultants we provide support to environmental planning consultants to conduct such tests.

Rather than have to complete a full air quality impact assessment for every facility, the (now) Ministry of the Environment, Conservation and Parks (MECP) developed screening guidance documents in 1995.  Unfortunately, they were developed in 1995 under the working arrangements at that time, where the MECP took the lead in reviewing proponent assessments.  These guides have also not been updated to account for advances in air quality science over the last 25 years.  They also do not provide screening methods for some facilities and environmental parameters (e.g., no screening guidance for transportation facilities and air emissions).

However, since these guides are all we have available we will take a closer look at the guide that is available for sewage treatment plants, Guide D-2.

D-2 Guide for Sewage Treatment Plants

Guide D-2 provides the ability to screen-out treatment plants of certain sizes instead of completing full air and noise assessments in all cases.  If a plant, or nearby sensitive receptor, meets the screening criteria then no further work is required, and the stated buffer distance is assumed to protect both uses from environmental incompatibility.  In the guide, plants are categorized into three classes: those with a design capacity equal to or less than 500 cubic metres of sewage per day (m3/d), those with a design capacity greater than 500 m3/day but less than 25,000 m3/day, and those with a capacity greater than 25,000 m3/d.

The guide provides separation distances that were thought to protect sensitive land uses from any air and noise emissions from sewage plants as shown in the table below:

air and noise emissions

* Individual, full air and noise assessments will be required

Separation distances are measured from the periphery of the on-site noise/odor-producing source-structure to the property/lot line of the sensitive land use.

Where distances between treatment plants and sensitive land uses are less than those shown, mitigation of noise and air/odor sources may be required based upon site-specific, full air, and noise studies.