Lecture 5 Flashcards
(29 cards)
Definition of contaminated land.
“Contaminated land” is any land which appears to the local authority in whose
area it is situated to be in such a condition, by reason of substances in, on or
under the land, that—
(a) significant harm is being caused or there is a significant possibility of such harm
being caused; or
(b) significant pollution of controlled waters is being caused or there is a significant
possibility of such pollution being caused.”
Definition of risk.
combination of (a) the
likelihood that harm, or pollution of water, will occur as a result of
contaminants in, on or under the land; and (b) the scale and seriousness of
such harm or pollution if it did occur.
What must there be for a risk to exist?
one or more pathway-receptor linkages-contaminant linkage.
What is a source?
Contaminants or hazards presenting a degree of risk to human health or environment.
What is a pathway?
route by which hazard comes in contact with receptor or target.
What is a receptor?
entity that could be harmed through contact with the hazard.
EPA guidance
identify reasons for risk assessment
identify potential contaminant linkages
assess and evaluate the risk
3 tiered risk assessment
Preliminary risk assessment- initial conceptual site, establish potential risks.
Generic quantitative risk assessment - generic assessment criteria and assumptions to estimate risks.
Detailed quantitative risk assessment - uses site-specific to estimate risks.
Steps for each tier of risk assessment
Identify hazard - establish contaminant sources.
Assess the hazard- use SPR linkage to find if there is potential for unacceptable risk.
Estimate risk- predict degree of harm or pollution by using tier approach.
Evaluate the risk- decide if its unacceptable
What is needed to know the harm?
Quantitative data including:
CLEA (Contaminated Land Exposure Assessment) metals
Speciated TPH (Total Petroleum Hydrocarbons)
Remediation guidance
use lcrm:
Identify and assess if there is an unacceptable risk.
assess suitable remediation option plan and carry out.
verify remediation has worked.
Policy on brownfield lands
UK government policy that most new housing and development should take place on brownfield land, limiting urbanisation into countryside.
What is remediation?
reversing or stopping environmental damage.
Remediation EPA guidance
Identify feasible options
detailed evaluation of options.
select final remediation options (has to be sustainable).
S.P.R.
- Reducing or treating the contaminant part of the linkage
- Breaking, removing or disrupting the pathway parts of the linkage
- Protecting or removing the receptor.
What are 6 remediation methods?
Civil
Biological
Chemical
Physical
Stabilisation and solidification
Thermal
What is Ex-situ remediation?
Treatment is applied following excavation for solids or extraction for liquids of contaminated material.
What is In-situ remediation?
Where treatment is applied without prior removal of ground.
On site and Off site remediation.
Related to location.
All in situ remediation is carried out on site.
But ex situ may be carried out on site or off site.
Three types of civil engineering methods?
Removal/Extraction
Physical containment.
Hydraulic controls.
What is removal/extraction?
removal of contaminated soil from site prior to disposal or treatment in a process based system.
What is physical containment?
Impermeable barriers.
What are the 5 process based treatments?
Physical
Chemical
Biological
Thermal
Soil stabilisation and solidification
What is soil washing?
Aqeuous washing medium used to remove contaminants from soil particles.
