Briefing Note

Recommendations on Minimum Setbacks and Siting Requirements for Large,

Stand-alone Natural Gas-Fired Electricity Generation Plants

There are currently no regulations regarding the locating of large, stand-alone natural gas fired electric generation plants in Ontario.

Government legislation and regulations are recommended that will enshrine sufficient minimum setbacks and siting requirements to ensure future projects are appropriately sited in Ontario, and fit with present and future neighbours. A clear policy on buffer zones for natural gas power plants, and a proper siting requirements process, will:

  • provide certainty to communities and power planners;
  • address the legitimate safety and health concerns of residents;
  • level the playfield for power developers; and,
  • ensure consitency with siting policies and requirements for other types of sensitive developments, including windfarms, railway corridors, propane stations, landfills, etc.

The purposes of this document is to outline recommendations on siting for future, standalone natural gas-fired power plants. In addition to Buffer Zones (setbacks), the following aspects should be included in policies for Ontario:

  1. Size of Site
  2. Location
  3. Safety
  4. Municipal zoning and land use policies
  5. Existing air/water quality of host community.

Buffer Zone Recommendations

In locating future gas fired power plants, the appropriate buffer zones must consider proximity, type, and density of the surrounding population. Historically there has been recognition of the need for separation; power plant developers have purchased homes close to (< 3 km) planned gas plants to relocate residents (Ocean State).

Large, standalone gas fired plants, with accompanying storage of toxic chemicals such as ammonia, should have a buffer zone appropriate to "High Hazard sites". In this case there should be a safety zone of about 500 m, in which no building/ residences are permitted.

There should be no significant population within 1500 meters of a large gas powered power plant.

Additional separation distances from schools and other sensitive land uses should be provided.

It is noted that wind turbines require a 550 m buffer zone from residences due to concerns of noise.

1. Size of Site

The proposed OGS was too small (five hectares) for a 975 MW plant but was appropriate for the previous 10 MW plant. By comparison, Halton Hills is 34 ha but generates about 680 MW.

Appropriate size allows appropriate technology and layout. If the area for process cooling is constrained it forces the use of environmentally unfriendly wet cooling towers. The size of the site should be suitable for air cooling, which is safer, as there are no fogging, icing, or visibility issues created by the large plume. Air cooling also has a lower health risk due to the production of less particulate and no concern of bacterial contamination.

If mechanical draft cooling must be used because of a small site, it requires greater buffer zones/separation distances for reasons such as:

  • Start-up plumes are heavier than air, so instead of rising vertically they drop to the ground and need space to disperse
  • Low wet cooling towers require separation to deal with drift, and biological aerosols.

The size should allow for setbacks of 100-150 m from the nearest roads, and there should be room for emergency vehicle staging in the event of an accident.

Sites should be of adequate size for effective landscaping, perimeter barriers, and noise mitigation.

If the site has numerous storage tanks, it requires space for adequate dikes to contain, and protect creeks from contamination. As well, distance is needed to dispel odors during tank filling.

A small site does not permit taking advantage of future technological developments that could reduce its greenhouse gas emissions. For example, the size of the proposed site should be sufficient for future carbon capture storage. In the UK draft policy on Electricity Infrastructure, the IPC requires developers to retain control over sufficient additional space (whether on or near the site) for carbon capture equipment; and to retain the ability to build carbon capture equipment on this space in the future.

2. Location

In assessing whether a location is appropriate for standalone natural gas power facilities, operating entities adjacent to a proposed site should be identified, as many disasters occur from errors that occur offsite and interact and cascade. Sites that should be avoided include:

  • Next to busy commuter rail corridor, and rail yards.
  • Near numerous buried petroleum product pipelines.
  • Under the flight path to busy airports, such as Pearson
  • Alongside busy roads e.g. 80 km/hr major exit, QEW/403.
  • Adjacent to transformers, switch station, and High Voltage lines.
  • Overhead lines need distance from cooling towers to prevent excess icing causing towers to collapse.
  • Adjacent to other massive infrastructure, e.g. Ford Motor Company assembly plant

Historical use of land should be considered e.g. Greenfield/ Brownfield Site.

3. Safety

Safety is enhanced by separation. The 120 - 140 m set back from the roads at existing plants (Portlands, Halton Hills, Goreway) is recommended, as any nearby roads or bridges would be very susceptible to rapid freezing due to cooling tower fogging and icing.

Greater separation gives greater security whether the threat comes from accidents, or terrorists. From a public safety and security standpoint, major energy infrastructure – including natural gas plants – need to be sited carefully to ensure that this infrastructure (and the neigbouring communities that surround them) do not become a target for terrorism.

Explosions of gas lines into a power plant have been known to break windows as far away as 5 km (Kleen Energy, Connecticut Feb 2010).

4. Zoning

Municipalities may have zoning or land use policies that provide guidance for power plant (such as natural gas) location.

The zoning should be consistent with adjacent lands. Natural gas power plants are not compatible with Business/ Employment zones. Property zoned employment, or with most neighbouring industries considered to be light industry, are not suitable for large gas power plants. There should be adequate room for land zoned T (transition).

Industrial zoned lands may be sub-categorized: Light Industrial (M1) to Heavy Industrial (M4), or there may be a "Utility Corridor".

Small (<1 MW) or medium (1-12.5 MW) power generation facilities may be permitted on land zoned heavy industrial or in a utility corridor.

In some municipalities, power plants < 10-12.5 MW are zoned as small and may be permitted on Heavy Industrial zoned land.

Large plants (> 12.5 MW) would be located in a utility corridor.

The following Table shows the type of zoning where power plants might be permitted:

Town/City Zoning Power Plants Permitted?
Mississauga Industrial and Other Other – includes Utility, on which power plants are allowed

Employment zone - (business, general industrial GE1,2), retail, residential, mixed use

Brampton Industrial M3 zoning Permit a power generation plant
Hamilton A-K (heavy industrial)
Milton Zone M2 along the 401 business park
St Catharine's industrial arterial large lots with significant setbacks; industrial zones lands do not specifically mention power plants but mention undesirable heavy industry
Calgary, Alta

Other zones permit small plant (< 1MW) or have medium (1-12.4 MW) as discretionary - Utility corridor permits large plants >12.5 MW


5. Air Quality (or Water)

Power plants (gas fired) should not be located in what would be considered an "area for concern". This is an area where one or more pollutants do not meet standards (non-attainment).

Siting Board Option

From a review of power plant locating practices in other countries (US), it appears that energy companies generally look for appropriately zoned land before submitting a proposal. A siting board would typically review several proposals, and give preference to suitable sites, e.g. away from residential areas, not in an area of concern etc. Such a 'siting board' would select a suitable location over alternatives. If an inappropriate site was presented by a utility as an option, a siting board would give preference to more suitable sites. Sites are considered more desirable if:

  • There are no residences within the safety zone, or influence zone
  • There is limited population within the 'consequence' zone, so that risk associated with accidents would be considerably lower
  • There is sufficient land for future technological developments such as carbon capture storage


The position paper "Protecting Health: Air Quality and Land use compatibility", by Dr. B. Nosal, Feb 2009, provides suggested directions for consideration (and possible inclusion) in the Sustainable Halton and Halton Region Official Plan processes. It refers to 1995 MOE guidelines and procedures related to land use compatibility.

1.1 Ontario Ministry of the Environment (MOE)

The following MOE documents are potentially helpful. There were referred to in Dr. B. Nosal's Feb 2009 Position Paper "Protecting Health: Air Quality and Land Use Compatibility".

The MOE Guidelines are:

D-1 Land Use Compatibility (this provides a general approach) and D-6 - Compatibility Between Industrial Facilities and Sensitive Land Uses D-6 is intended to apply when a change in land use is proposed, and it recommends separation distances and other control measures to prevent or minimize adverse effects from the encroachment of incompatible land uses.

D-6 includes 'electrical production manufacturing' as an example of a Class II facility. A large power plant and use of mechanical draft cooling, which creates a plume, makes it a class III facility, ref Appendix A, Industrial Categorization Criteria

The guideline for potential influence area is 300m for a Class II facility and 1000 m for a Class 3 facility, Appendix C, Separation Distances. (Minimums are less) These are distances from edges of zoning.

Section 4.5 states that:

The potential influence areas, or where known, the actual influence areas (see Section 4.1 of the guideline) should act as a 'flag', and no sensitive land uses shall be permitted within the actual or potential influence areas of Class I, II or III industrial land uses, without evidence to substantiate the absence of a problem.

Section 4.5.2 states that:

In exceptional circumstances the Ministry shall recommend separation distances greater than the outer limit of the potential influence areas identified in Section 4.1.1 of this guideline. In such cases, the Ministry shall demonstrate the need for greater distance, such as historical data for similar facilities.

The distance from the edge of the industrial zoned land to a sensitive use (in T1 land though) a residential line should be adequate even for Category II facilities.

Section 4.5.3 - Irreconcilable Incompatibilities

When impacts from industrial activities cannot be mitigated or prevented to the level of a trivial impact (i.e. no adverse effects), new development, whether it be an industrial facility or a sensitive land use, shall not be permitted.

1.2 European Risk Assessment (Danish EPA)‐87‐7052‐920‐4/pdf/978‐87‐7052‐921‐1.pdf

A large gas fired plant, with accompanying storage of toxic chemicals such as ammonia, should have a buffer zone appropriate to "High Hazard sites". Typically there would be a safety zone of about 500 m - 1100m around a high hazard facility, in which no building/residences would be permitted. (A typical safety distance when ammonia, a Class II hazard, is present is 500 m, Table 12 of reference).

There would then be a consequence zone, outside the safety zone (typically to 1.5-3 km). In this consequence zone, there may be residences, but facilities such as shopping centres (where people congregate), elementary schools and Senior Centres (where rapid evacuation may be difficult) is discouraged.

1.3 Risk Management

In standard risk management evaluation, the risk of an accident at a High Hazard Facility would be evaluated and compared against standards. The risk is calculated by looking at the use within the consequence zone, typically 3000m consequence zone. In Alberta, residents within 3 km are notified of a proposed power plant; and emissions studies show that outside of a 3 km radius, the concentration of pollutants and particulate matter from the site is almost zero. In reported accidents at power plants/gas pipelines (e.g. Kleen Energy Connecticut, Feb 2010), consequences were noticeable up to 5 km from the source, but 3 km provides a degree of protection.

Buffer Zone Resources