Wood preservation facilites, pentachlorophenol thermal: chapter F, table 13


Table 13. Additional Recommended Design Features for PCPT Treatment Process Systems

(Use in conjunction with Part I, Chapter A - General Recommendations for All Wood Preservatives, Table 13.)

Objectives:

Design feature Recommendations
Shelter, configuration
  • Use exterior treatment tank.
  • Locate other process equipment and systems in a centralized area.
  • Provide heated (where necessary) enclosure for process controls, with any air emissions vented externally.
Tanks, piping and valves
  • Provide effective access and containment for all subsurface tanks and piping.
Process emissions to air
  • Locate treatment tanks so as to minimize downwind effects either to yard workers or to adjacent properties actively used for residential/commercial purposes.
  • Install any control equipment as necessary to comply with applicable emission limits.
  • Provide vapour traps for hot liquid tank vents and vacuum exhaust.
  • Vent tank vapours (cold storage) to outside.
Treating tanks
  • Engineer treatment tanks for long-term integrity.
  • Ensure that tanks are secured to prevent uplifting.
  • Provide secondary containment vessel or other impermeable containment around treatment tanks.
  • Install an effective protection device to prevent overfilling of treatment tanks with preservative:
    • Install independent overflow indication/alarm/pump interlocks between the treating tanks and the control point (where the tank is not visible from the control point).
    • Provide containment for collection and direct return of tank overflow.
    • Construct overflow connection as per the NFCC.
  • Provide corrosion protection of subsurface steel tanks as per the NFCC.
  • Provide for tank lids or roofing to reduce vapour emissions and to reduce or prevent rain and snow falling into tanks. Construct lids as per the NFCC.
  • Provide walkway grates (or alternative design) to prevent worker contact or tracking of chemicals.
  • Provide guard rails and other safety measures as required by provincial authorities for operations near open tanks.
  • Provide means to contain frothing and/or overflows.
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 of Chapter A.
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 (e.g. provide flow diagrams for process).

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