CRH Canada Group Inc. operating as Ash Grove - Approval of a site-specific air standard

Background

CRH Canada Group Inc. operates the Ash Grove Mississauga Cement Plant facility (Ash Grove) in Mississauga, Ontario. Sulphur dioxide (SO₂) and nitrogen oxides (NO_x) are released to the atmosphere from various locations that exhaust emissions from the cement kiln and related operations. In 2024, Ash Grove submitted a request to the ministry for SO₂ and NO_x site-specific standards as the facility is presently not able to comply with the current air standards for these contaminants. The Ash Grove request included an action plan to significantly reduce emissions and comply with the current air standards for SO₂ and NO_x at the completion of the 10 year period.

The ministry has reviewed this request and is proposing to issue site-specific air standard approvals requiring that Ash Grove achieve compliance with the SO₂ and NO_x general air standards after approximately a six-year period. During this period Ash Grove will be required to implement emission reduction measures and will also be required to meet increasingly stringent site-specific air standards. The proposed approvals are attached in the Supporting Materials section of this notice.

Request Overview

Ash Grove is requesting a one-hour SO₂ site-specific standard of 1256 micrograms per cubic metre and a one-hour NO_x site-specific standard of 1653 micrograms per cubic metre for a duration of 10 years. These requested site-specific standard values have been calculated using an air dispersion model (CALPUFF) and represent the maximum predicted concentrations that can occur in the vicinity of the facility when emissions are at maximum levels and coincide with meteorological conditions that result in the highest predicted ground level concentrations. The maximum predicted concentrations for both contaminants occur along the Ash Grove facility property line with lower concentrations predicted in nearby residential areas during both maximum and typical emission scenarios for the facility.

The ministry's current one-hour air standards for SO₂ and NO_x are 100 micrograms per cubic metre and 400 micrograms per cubic metre, respectively. Both SO₂ and NO_x are respiratory irritants that can cause serious lung and heart problems, especially for people with asthma and other respiratory and cardiovascular conditions. These health effects may be made worse if exposure to both contaminants occurs simultaneously as both contaminants cause similar effects.

Ash Grove's site-specific standard request included an Action Plan report that describes an emission reduction strategy and timeline for the strategy to be implemented. The Action Plan includes a combination of add-on emission controls, stack improvements, process modifications and material substitution steps to that will reduce emissions over time and achieve compliance with the current air standards for SO₂ and NO_x.

Review of request

The ministry has reviewed and plans to accept the steps set out in the Ash Grove Action Plan and is of the opinion that the steps can be implemented more quickly than the ten years initially requested by Ash Grove. The ministry proposes to approve SO₂ and NO_x site-specific standards for a total duration of approximately six years. The proposed approvals include intermediate site-specific standards to ensure that reductions in off-property concentrations are enforceable while interim emission reduction projects are implemented by Ash Grove over time.

Proposed SO₂ Site-Specific Standard approval:

• 1256 micrograms per cubic metre - from date of approval to June 30, 2027
• 690 micrograms per cubic metre - from July 1, 2027 to December 31, 2028
• 320 micrograms per cubic metre - from January 1, 2029 to June 30, 2031

Proposed NO_x Site-Specific Standard approval:

• 1653 micrograms per cubic metre - from date of approval to December 31, 2026
• 800 micrograms per cubic metre - from January 1, 2027 to December 31, 2027
• 600 micrograms per cubic metre - from January 1, 2028 to June 30, 2031

Action Plan Summary

The Ash Grove Action Plan report proposes the implementation of the following projects:

SO₂ Action Plan Items:

• From date of Approval to December 31, 2026:

  • continued improvements to operating procedures and processes to minimize SO₂ emissions
  • installation of new or modified add-on controls for the Main Stack and Alkali By-Pass (ABP) Stack
• From December 31, 2026 to June 30, 2027:
  • verify effectiveness of the operating improvements and sorbent injection modifications at the Main Stack and ABP stack
• From date of Approval to July 30, 2028:
  • installation of new or modified sorbent injection systems for the Vertical Roller Mill (VRM) Stack and Aerofall Mill (AFM) Stack
• From July 30, 2028 to December 31, 2028:
  • verify effectiveness of sorbent injection modifications at the VRM Stack and AFM Stack

NO_x Action Plan Items:

• From date of Approval to December 31, 2027:
  • continued improvements to operating procedures and processes to minimize NO_x emissions
  • install new or make modifications to existing Selective Non-catalytic Reduction System (SNCR)

Combined SO₂ and NO_x Action Plan Item:

• From date of Approval to December 31, 2030:
  • complete engineering and construction of connecting the ABP, AFM and VRM exhausts to the Main Stack
• From January 1, 2031 to June 30, 2031:
  • verify effectiveness of connecting the ABP, AFM and VRM exhausts to the Main Stack

The proposed site-specific standard approvals will require a new Environmental Compliance Approval (ECA) to be issued with terms and conditions linked to the site-specific standards that include (see the link to the ERO posting for the ECA application):

• trial testing of sorbents and ammonia injection to optimize the performance of these systems
• requiring Ash Grove to use forecast modelling techniques to predict concentrations of sulphur dioxide and nitrogen oxides and implement contingency measures (i.e., operational adjustments to reduce emissions) when elevated levels are forecasted
• requiring that, at all times, any fuel oil burned in the cement kiln has a fuel sulphur content no greater than 0.5% by weight
• requiring the documentation and response to any environmental complaints and for necessary actions to be taken to address the cause of the complaint
• requiring continued operation of continuous emissions monitoring systems for the Main Stack, VRM Stack, AFM Stack and ABP Stack and system upgrades to allow monitoring of inlet and outlet concentrations of SO₂ and NO_x
• requiring Ash Grove to conduct ambient monitoring of sulphur dioxide and nitrogen oxides concentrations in the community
• requiring Ash Grove to maintain a community liaison committee that includes local Indigenous communities and Public Health representatives to provide timely information about operations and emissions of SO₂ and NO_x
• requiring Ash Grove to investigate the cause of any SO₂ discharge that results in a measured concentration at an ambient air monitoring station or forecasted concentrations off-property above the current SO₂ upper risk threshold of 690 micrograms per cubic metre and to implement corrective measures to mitigate the impact as soon as possible
• requiring Ash Grove to provide notifications when a measured or modelled one-hour sulphur dioxide concentration exceeds 320 micrograms per cubic metre and when measured or modelled one-hour nitrogen oxides concentration exceeds 400 micrograms per cubic metre
• requiring Ash Grove to prepare and implement a public engagement plan to engage with the local community and share information with the public and the ministry (e.g., emissions data from continuous monitoring systems and measurements data taken at the ambient monitors)
• requiring Ash Grove to maintain ongoing documentation that demonstrates compliance with approvals allowing the ministry to assess (and enforce) compliance

Regulating air contaminants in Ontario

In Ontario we regulate air contaminants to protect communities that reside close to industrial sites. Our regulatory approach has resulted in improvements in air emissions.

Ontario's Local Air Quality Regulation (O. Reg. 419/05: Air Pollution - Local Air Quality) works within the province's air management framework to address contaminants released to air into communities by various sources, including industrial and commercial facilities.

Air standards

We are working to ensure cleaner air for the people of Ontario by regulating air contaminants released into communities by local industrial and commercial facilities, including Ash Grove.

Our approach to improving local air quality starts with setting science-based standards to protect human health and the environment. The air standards are used to:

• assess the performance of regulated facilities
• identify those that need to do more to reduce their emissions

Facilities that are not able to meet an air standard due to technological or economic limitations may request a site-specific standard or a technical standard.

Site-specific standards

Site-specific standards are developed with public transparency through public meetings and consultations. They include technology benchmarking to determine what is feasible for a company to achieve in terms of controlling emissions of a contaminant over the period of the approval.

Compliance with a site-specific standard, just like a general air standard, must be demonstrated by using air dispersion modelling.

The ministry closely oversees the companies' progress to ensure that the desired results are achieved.

Subsection 35(1) of the Local Air Quality Regulation (O. Reg. 419/05) includes provisions for the approval of requests for site-specific standards and associated rules for making such requests. A site-specific standard may be set for a period of five to 10 years. If a facility receives a site-specific standard and continues to meet these requirements, then the facility is operating in compliance with O. Reg. 419/05. The site-specific standard becomes the legally enforceable standard for that facility for the time period of the site-specific standard. A facility may also request a subsequent site-specific standard. Further information regarding O. Reg. 419/05 and the site-specific standard process can be accessed at the ministry website.

Other public consultation opportunities

Ash Grove held a public meeting as required. The process and results are presented in the Public Consultation Report attached to the application submitted by Ash Grove.