Contaminated Ground

Question 1

How are lands classified?

Answer 1

Use
Locations
Condition
Status

Question 2

What is brownfield land?

Answer 2

Previously developed land
Can be in current use or derelict or redundant or not used.
The soil and groundwater beneath may or may not be contaminated.

Question 3

What are the 6 principles of the National Brownfield Strategy?

Answer 3

1. Redevelop or reuse first
2. Reuse of urban land in towns and cities
3. Sensible cost (do sufficient to safeguard local environment. Do not over remediate)
4. Environmental impact
5. Highest standards compatible with economic limitations
6. Consultation

Question 4

What is involved in a phased approach to site investigation?

Answer 4

1. A thorough investigation of literature and available technical information.
2. Preliminary site aerial and ground reconnaissance.
3. Development of initial regions and site specific geologic conceptual models
4. Design of field investigation based upon the initial conceptual models.

Question 5

What are the basic principles of ground penetration radar (GPR)?

Answer 5

There are depth limits to this techniques.
Signal attenuation becomes more important at depths where pore fluids are present in quantity (because subsurface materials will have low electrical conductivity).
Optimum conditions are sandy or rocky soils in unsaturated zones if bedrock with low hydraulic conductivity.
Clay rich sediments that retain more water naturally will obtain poorer results
Reliable data are obtained in settings where pore fluids have a low specific conductance ( where significant amounts of petroleum products are present)

Question 6

What are the principles of Electromagnetic Conductivity (EM)

Answer 6

It produced results in conductivity units so it can be immediately used to determine water quality, quantify the soul salinity, determine the concentration of cations and heavy metals.

Question 7

What are the different types of drilling methods?

Answer 7

Percussion (or cable tool) drilling. 
Auger drilling 
-hand auger 
-mechanical augers
Rotary drilling

Question 8

What is dispersion.

Answer 8

The process of transport of solute as a result of a velocity through pore space.

Question 9

Why is contamination a problem?

Answer 9

Risk to human health and the environment.

Contaminants in the ground can change the mechanical properties of the soil.

Question 10

Advantages of a soil liner?

Answer 10

Clay can attenuate pollutants. 
Thickness provides redundancy, resistance to penetration. 
Long-lived
Self-healing 
Inexpensive if locally available

Question 11

Disadvantages of soil liner?

Answer 11

Construction is difficult as it requires heavy equipment.
Thickness reduces volume for waste
Subject to freeze thaw and cracking
Low tensile and shear strength so may shear or crack due to settlement.
May be degraded by chemicals.
Expensive if not available locally.

Question 12

Types of liner materials?

Answer 12

Geomembranes
Geosynthetic clay
Composite liners (usually calf and geomembrane)

Question 13

Linear failure modes

Answer 13

Tension
Liner slippage
Liner uplift by water pressure 
Liner uplift by wind 
At pipes, access ways, other structural details.