Wood preservation facilities, ammoniacal copper zinc arsenate: chapter C-10

10. Environmental and Workplace Monitoring

10.1 Baseline Environmental Evaluation

Ammonia, copper, zinc and arsenic are found naturally in the environment. Typical background levels of ACZA constituents are listed in Table 24. Considerable variation occurs in natural concentrations of copper, zinc and arsenic in soils and waters (5). Because ammonia concentrations may vary both in time and space (14), it is important to determine background levels immediately prior to operating a facility, to enable meaningful future assessments of pollution control. Older mills may not have this information available. A comparative site from a nearby property can be used as a reference. The facility may use the template provided in Table 24 from Chapter A.

10.2 Environmental Monitoring

There have been few studies of ACZA releases from wood preservation facilities to the adjacent environment. Environmental risk of release from ACZA facilities and CCA facilities can be very similar. On this indication, ACZA facilities have the potential to contaminate groundwater in the immediate vicinity of the facilities to levels that render it unsafe for human use. Stormwater runoff may contain at least one of the elements copper, zinc, ammonia or arsenic at levels in excess of existing water quality limits (7). The ratios of copper/zinc/arsenic/ammonia are not consistent within runoff waters and that may be due to differences in the ability of the components to bind to the yard soils or due to different sources within the yards (i.e. stored lumber washoff versus dripped material from freshly treated loads). Ammonia concentration can vary in time due to its vaporisation and biological decomposition/adsorption.

Arsenic is persistent in the environment and close monitoring studies (such as surface water discharges, groundwater and soil contamination) are recommended to properly assess the degree of such releases. Arsenic, copper, zinc and ammonia are the minimum components that should be monitored for ACZA facilities.

10.3 Workplace Exposure Monitoring

Workplace monitoring generally falls under provincial jurisdiction. Worker health programs should be developed with provincial and/or local regulatory agencies in consultation with a provincial workers’ compensation board and/or department of labour and/or industrial physician/industrial hygienist. It is important to complete baseline air monitoring immediately prior to operating a facility, to enable meaningful exposure assessments and determine appropriate controls.

The appropriate components of a site and worker exposure monitoring program are contained in Section 10.2 of Part I, Chapter A - General Recommendations for All Wood Preservatives: Table 25 - Recommended Routine Environmental Monitoring and Table 26 - Recommended Routine Workplace Monitoring.