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Wood preservation facilities, general recommendations: chapter A, table 13

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Table 13. Recommended Design Features for Treatment Process Systems (All Preservatives)

Objectives:

Design feature Recommendations
Spill Containment
  • Provide spill containment capability of 110% of the volume for a single tank, and in multiple tank containment provide 100% of the largest tank plus 10% of the aggregate volume of the remaining tanks or 110% of the largest tank, whichever is greater.
  • Locate treatment cylinders and process tanks in an area with
    • continuous, structurally sound concrete floors or with slabs or sections with sealed joints;
    • sealed surfaces for impermeability and ease of cleaning;
    • reinforced dyke walls and sealed joints;
    • graded surfaces for ready drainage of wetted surfaces; and
    • walkway grates (or alternative design) to minimize worker exposure and prevent tracking of chemicals from containment areas -- keep surfaces clean.
  • Provide either an impermeable top coat to floors and dykes or a liner under the containment area.
  • Engineer containment for long-term integrity (leak-proof for infiltration and exfiltration).
  • Provide permanent, isolated drainage/transfer systems to direct all spills, washes and infiltrating water to tanks. Treat contaminated liquids to applicable limits before discharge.
  • Isolate control and transfer equipment to avoid damage from spilled liquids in containment areas.
Process control area
  • Segregate the operator control area from retort and tank spill containment areas.
  • Locate the process control area for maximum visibility of treatment systems.
  • Provide proper lighting in all operating areas.
Process emissions to air
  • Provide control equipment for air emissions including tank emissions and any emissions subject to environmental controls:
    • prevent worker exposure to vacuum pump exhausts;
    • install additional control equipment as required to comply with applicable air emissions limits;
    • provide traps on vents to remove entrained liquids or overflow;
    • assess levels of air contaminants in the workplace and provide ventilation in areas where excessive levels may occur; and
    • where applicable, condense emissions and return to storage.
  • Pumps, tanks, cylinders and other exhausts should be vented to the exterior. Interior equipment may be vented to a dedicated overflow tank, which should have an exterior vent designed to prevent the release of entrained liquids or overflow.
  • Equipment should not vent directly into the workplace.
Fire control
  • Refers to acceptable solutions in Division B, Part 5 of the National Fire Code of Canada 2010.
  • Provide appropriate site-specific rapid and effective fire control measures, in consultation with the local fire department, for fire detection and suppression.
  • Provide containment of liquid firefighting residues and treatment to required limits before discharge (e.g. blockage of storm drains, adjacent ditches).
  • Provide appropriate identification of fire control equipment.

Objectives:

Design feature Recommendations
Weather protection (winter operations)
  • Protect equipment from freezing temperatures, particularly where water is or may be present.
  • Winterize process control area.
Treatment cylinder
  • Treatment cylinder and pressurized components must meet all pressure vessel certifications stipulated by the provincial ministry responsible for such certification or by insurance requirements if there are no provincial requirements. If no requirements exist, then annual testing is required.
  • Install an effective protection device to prevent doors opening when the cylinder is pressurized or filled with preservative:
    • provide independent backup protection.
  • Install independent indication and/or alarm/interlocks between the cylinder door and the control point.
  • Design to facilitate drainage of excess preservative.
Piping and recycle systems
  • Design an overall system that is effective at containing and recycling all chemicals with minimum potential for release and dispersal and minimum infiltration of water.
  • Select and install piping as per Table 11.
Sumps
  • Provide leak-proof design (e.g. impermeable surfaces, sealed joints).
  • Provide a tertiary containment for sumps (e.g. steel lining or other suitable materials or devices) in addition to the concrete containment and impermeable liner or coating.
  • Provide overflow protection if sump is not in containment area (e.g. install independent high-level alarms).
Process controls
  • Design for simple, unambiguous operation (regardless of the degree of automation).
  • Establish a clear relationship between process controls and process functions in order to minimize operator error.
Ventilation
  • Provide adequate routine and emergency ventilation to control preservative component vapour levels in all work areas.
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