Site Investigation Flashcards
What are the 5 main categories of contaminants?
Organics
Inorganics
Gases
Radionuclides
Heavy Metals
What is the difference between -ite and -ate suffix molecules?
-ite has one less oxygen than -ate
What are the 6 key sources of organic contamination?
Petrochemical manufacture
Solvents
Pesticides
Coal tar
Transformer fluids
Flame retardants
What are the hydrocarbon prefixes that denote 1, 2, 3 and 4 carbon atoms respectively?
Meth-
Eth-
Prop-
But-
How is a Haloalkane different from an Alkane and why is this distinction important?
Haloalkanes have a halogen in place of some of the hydrogen atoms
Alkanes are hydrophobic but haloalkanes may not be
What makes something an aromatic compound?
It contains at least one benzene ring
What is the structure of a benzene ring?
6 carbon atoms with alternating single and double bonds. The electrons are found in a cloud in the centre
What is the technical correct name for Polyaromatic Hydrocarbons and what are they?
Polycyclic Aromatic Hydrocarbons
Hydrocarbons with multiple benzene rings
Why are PFAS and PFOS problematic?
They are both toxic at low concentrations and non-biodegradable
How is the hydrophobicity of a liquid measured?
Observing the partition coefficient between water and octanol
What is the technical name for an emulsifier?
A surfactant
How does the partition coefficient P define the lipid and water phases?
log P > 0: Lipid Phase
log P < 0: Water Phase
Name 5 types of chemical reaction
Combustion
Synthesis
Decomposition
Single Displacement
Double Displacement
What does the acronym OIL RIG mean?
Oxidation Is Loss, Reduction Is Gain (of electrons)
What is a more comprehensible representation of 1ppm (part per million)?
1 milligram per kilogram
What are the 5 geological layers considered for decontamination?
Ground Surface
Vadose Zone
Capillary Fringe
Saturated Zone
Confining Bed
What is true of water in the Capillary Fringe region?
It is not free to move, as it is held there by surface tension
What are NAPLs? What are the 2 key types?
Non-Aqueous Phase Liquids
Dense and Light
What is true of non-aqueous contaminants that are in contact with water?
Small amounts of the contaminant will dissolve in the water even though the main plume is hydrophobic
What is the difference between porosity and permeability?
Porosity defines the amount of void space in a soil or rock, permeability defines the freedom of fluids to pass through a soil or rock
What is likely to happen with non-aqueous liquid contaminants passing through drained soil?
Residues of the contaminant will be left behind
What must be true for a dense, non-aqueous liquid contaminant to penetrate into saturated soil?
The pressure head of the contaminant exceeds the capillary pressure of the water
What is the condition for considering something a risk during risk assessment?
There is significant potential of significant harm
In what context is a conceptual site model created?
The final use case, not the current use case
What areas should be included in desk studies?
The site itself and relevant areas adjacent to the site
Why are children classified differently to adults when assessing risk?
Children are more susceptible to illness from contamination due to having lower body mass
What are the 3 phases of a risk assessment?
Phase 1: Preliminary
Phase 2: Generic Quantitative
Phase 3: Detailed Quantitative
What does quantitative mean in the context of a risk assessment?
Samples are taken, tests performed and results are found
What non-targeted sampling strategy is theoretically the best?
A herringbone pattern of sampling
Why is it not necessary to drill a large number of boreholes in cases of groundwater contamination?
The contamination is largely homogenous, so the boreholes are only needed to establish flow direction
Why may it be important to implement long-term gas monitoring on a site?
Seasonal changes in temperature can affect the volatilisation of liquids into gases
Why might samples need to be analysed quickly or frozen?
Microbes can degrade the contaminant within the sample
What are 2 quality control measures for site investigation?
Field blanks - containers opened on site
Collection of rinsewater
Trip blanks - containers which remain closed but travel
Describe preliminary risk assessment
The purpose of the preliminary risk assessment is to develop an initial conceptual model for the site and establish whether there are potentially unacceptable risks
Explain why generic and detailed quantitative risk assessments are carried out
After the preliminary assessment, intrusive investigation needs to be carried out to confirm which contaminants are present, at what concentrations, how they are moving and how they could pose harm. If generic assessment is found to be unsuitable for remediation to take place, detailed risk assessment must follow
Roughly how deep must a point of interest be below the ground surface for borehole investigation to be necessary?
> 5m
What are the 5 important points when selecting a sampling strategy?
-Whether it is targeted, random or a mix of both
-What media is to be sampled
-The number of samples required
-Sample depth
-Sample collection and storage methods
What does Soil Adsorption Coefficient (Kd/Koc) describe?
It measures the mobility of a substance in soil. A very high value means it is strongly adsorbed onto soil and organic matter and does not move. A very low value means it is highly mobile in soil
How do you make use of the Henry’s Law Constant?
Divide atmospheric pressure by the constant to find the dissolved gas concentration. If pressure above the liquid decreases, gas will leave solution and bubble out
What is a phenol?
One or more hydroxyl (OH-) bonded to a benzene ring
