Transcript Message of This Presentation:

Responding to Soil Contamination in
the Moanataiari Subdivision
And when the NES does and does not apply
May 2012
Messages of this presentation:
• Managing human health risk remains the key
issue
• Until triggered, the NES does not apply to
ongoing lawfully established activities, regardless
of the soil contamination until there is a change
in use, subdivision, earthworks
• To more valuably inform of risk and appropriate
response, health risk assessment work is required
• In the meantime, health risk is being managed
within the guidelines issued by the MoH and
WDHB
What is the NES?
• A regulation under the Resource Management
Act, 1991
• National Environmental Standard for Assessing
and Managing Contaminants in Soil to Protect
Human Health (NES)
– NZ Regulation in force since 1 January 2012
– Purpose – a planning tool to ensure:
• Identification and assessment of land affected by contaminated soil
• Appropriate assessment of contaminated land at the time of land being
developed, subdivided, or disturbed; and,
• If necessary, remediation or contaminant containment to make land safe for
human use
– Reflects NZ government policy on acceptable increased risk
• Acceptable risk level is 1 in 100,000
– Developed Soil Contaminant Standards (SCS) for priority
contaminants
How does the NES apply to
Moanataiari?
• The NES
– Only triggered if the land is subdivided, developed
or disturbed
– Unless triggered, cannot require remediation to
be undertaken, even if the land is unfit for its
current use
– Once triggered, consents may be required to
undertake activities/land use
Acceptable Risk Level
• Contaminants in soil can have adverse effects
on human health
• Based on a number of factors, including the
reference health standard:
– Estimated daily amount that can be taken into the
body without exceeding an acceptable risk level
• The arsenic concentration in soil for a
standard residential scenario that gives rise to
this dose is 20 mg/kg (SCS for arsenic)
What is a Soil Contaminant Standard
• The SCS is a New Zealand risk based standard to
protect human health that: (NES or otherwise)
– Serves to indicate whether there is a potential risk to human
health
– When exceeded, serves as conservative clean-up targets for
many situations, i.e., where further investigation or sitespecific risk assessment is not warranted or economic
– Informs on-site management actions to address human
health risk issues
– Triggers further investigation to better assess the risk and/or
determine site-specific criteria as a Tier 2 assessment
How was arsenic SCS derived?
• Arsenic is considered a non-threshold contaminant
(cancer causing)
• Up to date methodology used that is not inconsistent
with other countries
• Uses New Zealand derived criteria:
SCS (Soil ingestion) =
RHS x ED x 106
IR adj x EF
Where:
RHS
= Reference health standard (mg/kg BW/day)
ED
= Life time exposure (days)
IR adj = Age adjusted ingestion rate (mg/day)
EF
= Exposure frequency (days/year)
Arsenic SCS Assumptions
• Assumptions
– Contaminants are 100% bioavailable
• Only a (as yet unknown) fraction of arsenic in the soil
will be absorbed and able to harm health
– 10% produce consumption for standard
residential scenario
• Not all households grow their own food
Current situation
• The detailed site investigations on individual
properties completed
• Total arsenic and lead concentrations in the
soils on Moanataiari exceed the SCS
• These soils also exceed soil guideline values
for thallium
• The NES has not been triggered for these
properties
What's next?
• Undertake a Tier 2 Health Risk Assessment
– The criteria that can be altered are limited
– Test the assumptions, especially bioavailability
• Trial underway
– Develop site specific soil values for Moanataiari
• Long term management of risks to human
health
– Consider the community’s expectations
– Understand options to remediate/mitigate or manage the
risks to health
– Determine methods for monitoring and maintaining any
health protection measures.
END
References
• Resource Management (National Environmental Standard for Assessing
and Managing Contaminants in Soil to Protect Human Health) Regulations
2011
(http://www.legislation.govt.nz/regulation/public/2011/0361/latest/DLM4052228.html?sear
ch=ts_regulation_contaminants_resel&p=1&sr=1)
• Users' Guide: National Environmental Standard for Assessing and
Managing Contaminants in Soil to Protect Human Health
(http://www.mfe.govt.nz/publications/rma/users-guide-nes-for-assessing-managingcontaminants-in-soil/)
• Methodology for Deriving Standards for Contaminants in Soil to Protect
Human Health (http://www.mfe.govt.nz/publications/hazardous/deriving-standards-forcontaminants-in-soil/index.html)
• Toxicological Intake Values for Priority Contaminants in Soil
(http://www.mfe.govt.nz/publications/hazardous/toxicological-intake-values-for-prioritycontaminants-in-soil/index.html)