The Green Zone is Crown land that can be leased for timber production, watershed, fish and wildlife, recreation, livestock grazing, and energy development. However, much of the Green Zone is forested, remote land, and not subject to regular human habitation.  PTAC supported a Technical Working Committee to develop risk-based Tier 1 and 2 guidelines for petroleum hydrocarbon fractions in the Green Zone evaluating site remoteness, land activities, and human health and ecological exposure pathways.

Initiative 1: New Management Limits

PTAC completed a literature review and laboratory experiments to propose new management limits for F2 and F3 fractions for fine and coarse grained soils. The new management limit guidelines can be applied in remote Green Zone providing there is no anticipated risk of inhalation exposure of workers in utility trenches, and the soil texture is not very coarse sand or gravel.

Initiative 2: Exclusion of Ecological Direct Contact at 1.5 m in Fine Soil

PTAC completed a literature review and supported field work to develop maximum rooting depths for typical Alberta coniferous and deciduous tree species and associated shrub understory in the Remote Green Zone. The ecological direct contact exposure pathway can be excluded at 1.5 m for F1 to F4 hydrocarbon fractions at any Green Zone site with fine-grained soil. The pathway is still applicable to 3 m for coarse-grained soil.

The risk-based soil hydrocarbon fractions were adopted by Alberta Environment and Parks (AEP) in 2014 as a result of the two initiatives. The initiatives have benefited industry by preventing unwarranted landfill disposal and improving soil conservation. The financial savings to industry have far exceeded the cost to fund the new guideline development.

A list of the PTAC funded Green Zone research projects that contributed to this initiative can be found at auprf.ptac.org. AEP’s related regulation titled “Subsoil Petroleum Hydrocarbon Guidelines for Remote Forested Sites in the Green Area” (September 2014) can be viewed on their webpage.