Comments - Application of…

Comments - Application of New Excess Soil Standards
Since there are deviations from brownfield standard development, excess soil standards are developed by using more conservative assumptions, including larger soil source size, soil to groundwater to indoor pathways, etc. There are a few of potential implications listed as below in term of application of new excess soil standards:
• Standards for EC and SAR
As indicated in Rationale Document for Development of Excess Soil Standards, under O. Reg. 153/04, the component values for EC and SAR are for the protection of plants and soil organisms. In an excess soil scenario, EC and SAR act as “surrogates” for S-GW1 and S-GW3 values to protect soil to groundwater pathways for sodium and chloride. Note there are no component values of EC and SAR for soil leaching (S-GW1 & S-GW3) in Rational for Development of Reg. 153/04 Soil Standards. However, there is a component value for chloride (i.e. 220 ug/g, Soil Components for Table 2 – Full Depth, Potable Water Scenario).
Since excess standards are developed for protection of groundwater/surface water and the pathway is different with protection of plants and soil organisms, new component values of EC and SAR for soil leaching (i.e. similar to chloride value) is suggested to be developed to reflect the right pathway instead of using “surrogates” values for plants and soil organisms.
• Impacts on Phase Two Environmental Site Assessment
Are excess soil standards exclusively used for excess soil management (i.e. off-site soil disposal or reuse) or also applicable for Phase Two ESA (i.e. for scenarios of potential impact areas/volumes larger than the typical “spill” scenario – 350 m3)?
It may be questioned that application of the brownfield standards may not be sufficient to protect human health and environment if there are more stringent standards available. In addition, it may be questioned if more stringent groundwater standards should be developed using more conservative assumptions for excess soil scenarios.
• Impacts on large scale brown-field redevelopment projects
The volume independent standards are most stringent standards, which will be likely applied for large scale projects. Excess soil (i.e. being geo-technically non-suitable for on-site reuse in many cases) may have to end up landfill sites. Application of new excess soil standards may cause much greater excess soil volume disposed at landfill sites instead of being beneficial re-used.
It is understood that the Ministry intends to achieve more social, economic and environmental benefits by regulating excess soil movement and promoting local reuse of excess soil. However, further clarifications on development and application of new excess soil standards will be great.