Schedule B1: Guideline on investigation levels for soil & groundwater

Evaluation and conclusion
The results indicate a human health risk from TCE, PCE and derivatives to ground floor
occupants of the office building. The results indicate that appropriate responses to protect
human health, further management/assessment such as indoor air sampling to determine
actual exposure and detailed health risk assessment and mitigation measures are required.
This assessment is limited to health risk considerations from VOCC exposure and does not
consider any ecological risks related to soil and groundwater contamination, for example,
infiltration into sewer or stormwater drainage systems or discharge into a sensitive receptor.
3.4.1 Ecological assessment
EILs and ESLs provide screening criteria to assess the effect of contaminants on a soil
ecosystem. They afford the specified level of species protection within the SSD framework
for organisms that frequent or inhabit soil and protect essential soil processes.
<strong>Schedule</strong> A provides an overview of the site assessment process and the application of
investigation and screening levels for site-specific Tier 1 human health and ecological risk
assessment. While human health will drive the first stages of assessment, ecological
assessment will need consideration for all sites. Human health concerns may be addressed
by the HSLs for petroleum hydrocarbons. However, there are many HSLs that are denoted
as NL (refer footnotes to HSL Tables) and high levels of petroleum hydrocarbons, including
free phase, may be present at the site. Similarly, many HILs for individual elements or
compounds are elevated above the EILs.
In these circumstances, ecosystem risks may become the driver for site assessment. In other
sites impacted by petroleum hydrocarbons, human health and ecological risks and protection
of groundwater resources may be addressed and ‘management limits’ applied to ensure that
phase separated hydrocarbon and associated risks are appropriately considered.
3.4.1.1 Other considerations in assessing ecological risks
In assessing the overall risk to the ecosystem from soil contamination the following sitespecific
aspects should be considered with relevant ecological soil criteria and management
limits:
• the location of the site in relation to any sensitive receptors, e.g. watercourses, estuaries,
groundwater resources, sensitive ecological areas
• the existing or proposed land use
• the presentation of any contaminants including areal extent, depth below finished
ground level, the presence of barriers or containment that prevents or minimises the
migration of contamination
• the in-situ leaching characteristics of contaminants of concern and the potential for
leachate to adversely affect any accessible sensitive receptor
• the potential for any soil contaminant to be transported from the site at levels of concern
by erosive forces.
Site considerations in addition to the land-use categories will determine if any additional
assessment is required to address identified risks. For example, soil contaminants may cause
adverse ecological effects when the contaminant is in a highly leachable form or is
incorporated in exposed readily erodible soil. In this situation the contaminant may be at risk
of being transported off site by water and wind action.
<strong>Schedule</strong> B (1) - <strong>Guideline</strong> on Investigation Levels for Soil and Groundwater 26