By Robert J. Watters
The two largest waste volumes from typical pulp and paper mills are wood waste and sludge. The wood waste materials are largely bark and sawdust, which are waste materials from operation of the woodroom and/or sawmill. Sludges are settleable suspended solids (mainly fibre) present in the mill effluent stream which are removed through primary clarification.
Sludges are periodically disposed of through landspreading, and wood waste is periodically removed off-site by contractor, although burning and landfilling are the most common management techniques.
Pulp and paper mills have been burning wood waste and sludge in combination fuel-fired boilers from many years. This technology is not a new one. However, in an increasingly competitive world, economics are requiring that pulp mills become more self-sufficient. One effective means of addressing this is through self-production of stream and electricity within the mill property. This introduces cogeneration.
Cogeneration simply means "using the fuel twice", that is, for generation of shaft power and useable exhaust heat. A multifuelled cogeneration plan involves using more than one fuel. As examples of recent pulp mill power facilities, this means using wood waste/sludge and natural gas as fuels.
The following sections of this paper explore the role of cogeneration in the pulp and paper industry, focusing on the environment and permitting considerations.
The following represents some of the areas that a mill must consider when deciding whether or not to build a multifuelled cogeneration power plant:
Before continuing with development of a power plant, most developers conduct an initial screening-level investigation to determine whether or not development is feasible through consideration of economic, engineering and environmental factors. Some refer to this as a "fatal flaw" analysis, since the purpose of the exercise is to identify significant constraints or "no go's" to development.
Some of the areas to consider in the screening-level assessment, particularly for determining an appropriate size and design of facility, include:
From an environmental perspective, a proposed facility is feasible if it meets a number of criteria, including the following:
Haviing completed the feasibility analysis and selected a plant design, equipment and site, detailed impact assessment and permitting work can begin.
The environmental approvals process for a multifuelled cogeneration facility varies from province-to-province across Canada. In most provinces, however, approvals are required for:
A successful study approach (shown in the attached flow chart) includes the following major components:
At the beginning of each project, an initiation meeting(s) is held with the client to discuss specific objectives and design features of the proposed facility. At this time, the study team can provide input and identify potential environmental issues based on previous project experience. Design and site alternatives may be initially addressed in terms of environmental and facility options.
Following this meeting(s), a Project Introduction document is prepared. This provides information on the type (process), size and location of the proposed facility and the environmental studies to be undertaken. The document is provided to the regulatory agencies and other interested/affected groups to avoid confusion and expedite the approvals process. The key to a successful project is communication and interaction with regulatory agencies early in the project.
Review of Regulatory Requirements
Project introduction meetings are held with the appropriate regulatory agencies to introduce the project and determine the environmental permitting requirements for the facility. If the project is subject to an Environmental Assessment (EA) in the province in which it is proposed, then the environmental studies will follow the requisite EA process. An outline of the study program for the EA will be submitted and approved by the primary review agency prior to study initiation
If the project is not subject to a formal EA, then a list of all necessary permits and applications will be obtained and copied to the client. Provincial environmental policies and guidelines will also be reviewed. This information will be used to scope the environmental studies component of the approvals process, and ensure that key issues are identified and addressed early in the process.
Based on the approvals required, and the policies which necessitate those approvals, such as provincial guidelines for wastewater effluent quality, an environmental study scope will be prepared and submitted to the review agencies for comments. Subsequent meeting(s) will be held with the relevant agencies to negotiate the final scope of studies. It is important that the agencies support the study plan so that there are no later disagreements with the approach.
Prior to undertaking the environmental field studies, a site audit is commonly conducted. The purpose of a site audit is to determine whether previous land uses could present possible constraints and liabilities to the proposed development. A site audit, or prior use investigation, involves:
To assess the environmental impacts of the proposed facility, the existing environment at the site must be characterized to allow the facility's characteristics to be imposed on the environment and the impacts predicted. Based on information obtained through the scoping exercise, the site-specific environmental studies are undertaken to provide supplementary information. The environmental studies generally consist of four major components: terrestrial, aquatic, atmospheric/noise and heritage resources.
The terrestrial component includes an assessment of vegetation, wildlife, geology (surficial and bedrock), soils and agricultural capability, wetlands and land use.
The aquatic component includes an evaluation of fisheries habitat and community structure, water quality of receiving stream, hydrology of the site and receiving waters, and coastal engineering to assess nearshore bathymetry and currents.
The atmospheric component provides an assessment of the existing air quality, climatology and noise levels associated with the site. Heritage resource evaluations involve an assessment of whether archaeological or heritage resources are present in the site development area.
An Environmental Report is prepared, in consultation with the client, which describes the project proposal, the existing environment, impact predictions and mitigation measures.
A draft report is sent to the client for review and comment. Once the comments of the client have been addressed, a copy of the report is sent to the agencies and relevant interest groups for review and comment.
The consulting team members typically work together with the client's engineers to obtain the design information required for the applications. The permit applications are submitted to the regulatory agencies supported by the Environmental Report.
The project manager or client contact will liaise with the agencies prior to and following submission of the applications to expedite their review. The applications will either be rejected, approved, or approved with conditions. If liaison with the agencies has been conducted throughout the process, the applications should be readily approved, as any agency concern would have been identified early in the process.
Public involvement is an integral component of the environmental program. Generally, a public consultation program is initiated at the beginning of the project, as a means of introducing the proposal and identifying any potential issues or concerns. The scope of the program is determined by the type of facility proposed, the community, and potential socio-economic and environmental implications of the project. A public consultation program may involve conducting an Information Centre, which is an effective means of raising local awareness of the project and obtaining information and feedback. A proactive approach to public involvement can help avoid many misunderstandings and potential conflicts at later, critical stages of project development.