19 June 2001
these preservatives but is also highly toxic. Consult the Consumer Information
Sheet and your safety and environmental office before you consider using it.
3-18.104.22.168 Water-Borne. Water-borne preservatives are toxic metallic salts
dissolved in water for easier application. The water-borne preservatives include
chromated copper arsenate (CCA), ammoniacal copper zinc arsenate (ACZA),
and ammoniacal copper arsenate (ACA). Wood treated with one of these water-
borne preservatives can be used either above or below the waterline (wood used
below the waterline is treated at higher retention levels). In addition, these salts
in combination with creosote (dual treatment) are more effective in preventing
marine borer damage than any single treatment. Other water-borne preservatives
for use above the waterline include acid copper chromate (ACC), ammoniacal
copper citrate (CC), and ammoniacal copper quat (ACQ)-Type B.
3-22.214.171.124 Negative Aspects. All preservative treatments have drawbacks that
should be considered. Metallic salts, for example, will seriously embrittle wood.
More importantly, these toxic chemicals present environmental and personnel
safety concerns. All treated wood should be supplied with a Consumer
Information Sheet that provides use, handling, and disposal precautions. Proper
safety procedures should be carefully followed.
Plans for handling pressure-treated wood removed from service should
be carefully considered, especially in areas where the disposal of treated wood
may be restricted. Alternatives to landfilling include reuse as landscape timbers,
recycled as fuel, etc. Wood treated with CCA should never be used as a fuel, and
treated wood should not be recycled as mulch. Other restrictions may apply;
Consult with your environmental office.
3-2.3.2 Field Treating Exposed Areas of Wood Before Installation. Cut
surfaces of wood members, pile cutoffs, bolt holes, and any other exposed
surfaces of treated wood members must be treated in the field before installation.
All exposed, untreated wood should be treated in accordance with American
Wood Preservers' Association, Standard M4, Standard for the Care of
Preservative-Treated Wood Products. Treat holes for bolts and wood plugs
inserted in piles and timbers with the same general type of wood preservative
originally used for the member. Bolt holes should be treated under pressure with
a mechanical bolt hole treater, if available, or thoroughly saturated. Wood
preservatives are restricted use pesticides and must be applied in compliance
with applicable standards. Consult your safety office or nearest EFD applied
Timber pile tops, cut off after the pile is driven, expose the untreated
heartwood of the pile to rapid decay. AWPA Standard M4 provides
recommendations for preservative treatments for pile tops. Creosoted piles may
be field treated with creosote solutions, or where particularly heavy coatings are
required, a coal-tar roof cement meeting ASTM D-4022, Specification for Coal
Tar Roof Cement. Piles treated with ACA, ACZA, or CCA can be field treated