by Tom Ward, Heritage Resource Management Branch, Alberta
Community Development.
• Background
Grain dust is an extremely volatile substance that can explode without warning when airborne. This is why active grain elevators are equipped with grain cleaners and dust collectors and why electrical switches, light fixtures and other sources of sparks are shielded with explosion-proof, sealed electrical boxes and glass fixture guards.
Grain dust that is not airborne but is left in place on surfaces does not readily explode but will increase the flame spread rating of interior wooden surfaces. This is the primary safety concern, with regard to grain dust, for grain elevators in Alberta that have been decommissioned by grain companies, and when the properties are sold to private, non-profit organizations. Additionally, there is a concern that grain dust, allowed to accumulate in wet piles, might be subjected to excessive internal heating and possible spontaneous combustion.
This Terms of Reference is intended to guide the removal of grain dust from all interior surfaces of grain elevators so that this apparent potential fire hazard is addressed and is not intended to be a prescriptive list precautions. Additionally, cleaning elevators is seen as a step required prior to the installation of fire suppression sprinkler systems, fire barriers and alarm systems that will further protect the building and occupants.
• Purpose
The purpose of removing grain dust and debris from the interior of grain elevators is not for cosmetic reasons, but to mitigate a potential fire hazard. Additionally, consideration must be given to these historic properties to ensure that the work is in keeping with the preservation principles outlined in the Standards and Guidelines for the Conservation of Historic Places in Canada , where the recommendation is to protect heritage value by calling for an approach of minimal intervention. That is to say that any work on a heritage building should be accomplished by the gentlest means possible in order to protect the character-defining elements and heritage value of the historic place. No changes to the structure should be implemented until approval is confirmed by the owner and the preservation advisor.
• Scope of Work
Working in close consultation with the building owner and with a preservation advisor from Alberta Community Development, the contractor is expected to provide the following services:
• Meet with a representative of the owner and a preservation advisor to tour the grain elevator, annex (if present) and ancillary buildings, before work commences in order to document the existing condition of grain dust on all surfaces – this will also provide a “benchmark” for determining the success of the cleaning process.
• Provide a work plan which will include a short written evaluation of the material to be cleaned (grain dust, bird and rodent droppings, debris, etc.), the method and equipment required to complete the dry vacuuming of all surfaces, the safety and fire precautions proposed during the cleaning process, the proposed safe disposal of the removed material and the expected duration of the dust removal process.
• It is expected that bins and areas that are not readily accessible will also be cleaned. The work plan should include proposed methods for cleaning inaccessible areas. If building material must be temporarily removed in order to access areas to be cleaned, the owner and preservation advisor must be contacted so that the method is confirmed to be the gentlest means possible to ensure that the heritage value of the building is not compromised.
• Safety and fire precautions must be implemented during the cleaning process since grain dust will again be airborne, creating the potential for dust explosion (outlined in Section 1.0), should a spark or flame be encountered. Possible ignition sources during the course of construction should be eliminated. All vacuum equipment should be sufficiently grounded and additional equipment such as radios, cell phones, and cameras should be certified as explosion proof or spark proof.
• A water pressure wash cleaning process is not acceptable.
• Provide a cost estimate and estimated duration time for the project.
• Provide sufficient Course of Construction insurance that will cover the replacement value of the structure as well as liability insurance and proof of WCB insurance to the satisfaction of the owner.
• Clean all surfaces that contain grain dust and debris in a timely manner, according to the agreed-upon schedule. Ensure that no unwanted material remains. Areas to be cleaned will incorporate all interior surfaces, including (but not limited to): entire grain storage bins and cross braces; hoppers; Gerber mechanisms, chutes and spouts; auger corridors; pits and boots; scoop belts, mezzanines, upper floors, projecting structural members, floor joists and structural members on the underside of the main floor framing system, scale mechanisms and dirt floor on the underside of the structure.
• Safely dispose of the removed material.
• Meet with a representative of the owner and the preservation advisor to tour the grain elevator (and annex if present) after work is completed in order to document the final condition and cleanliness of all surfaces so that the work may be certified.
Prepared by:
A
Alberta Community Development
Heritage Resource Management, Protection and Stewardship
8820 – 112 Street, Edmonton, Alberta, T6G 2P8
Tom Ward, Preservation Advisor Phone: 780-431-2326 email: tom.ward@gov.ab.ca
In collaboration with:
Alberta Grain Elevator Society
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