Engineering Geology Revision

Question 1

What is the purpose of a desk study?

Answer 1

To determine:
Historical development
Constraints on development (engineering and environmental)
Ground Investigation strategy

Question 2

What are the two key invasive species and associated issues?

Answer 2

Japanese Knotweed and Giant Hogweed

Affect mortgages, damage foundations, spread rapidly, expensive to remove

Question 3

What data do you gain from the Geology stage of a desk study?

Answer 3

Borehole records
Solid and Superficial Geology
Hydrology and Hydrogeology

Made Ground?
Mining under site?
Flooding?

Question 4

How do you go about an environmental assessment?

Answer 4

Preliminary Environmental Assessment
- Historical and Present Land uses
Potential Contaminants of Concern
- Metals, HCs, Solvents, Pesticides, Asbestos
Pollutant Linkage Conceptual Model
- Source, Pathway, Receptors

Question 5

What Acts are Referenceable for Environmental Assessments?

Answer 5

Environmental Protection Act 1990
Section 57 Environmental Act 1995

Question 6

What is included in an Environmental Qualitative Risk Assessment?

Answer 6

Likelihood of occurrence
Severity of consequences
Investigation required?

Question 7

Give examples of Receptors

Answer 7

Humans (residents and workers) and animals
Plants
Buildings, property, and services
Controlled waters (surface and groundwaters)

Question 8

How can humans act as a Pathway?

Answer 8

Inhalation of dust
Ingestion of dust/soil by hand or from vegetation
Dermal contact with soil/water

Question 9

How can plants act as a Pathway?

Answer 9

Direct contact with soil/groundwater
Uptake of contaminants

Question 10

How can buildings act as a Pathway?

Answer 10

Direct contact with soil/groundwater
Service trenches act as a migration pathway

Question 11

How can controlled waters act as a Pathway?

Answer 11

Runn-off enters water courses
Contaminants from soil leaching into groundwater
Movement of dissolved contaminants in soil pore water
Movement of contaminants via ground to surface water

Question 12

How do you approach pollution linkages and risk assessments?

Answer 12

Can the linkages be completed?
How can they be broken?
Likelihood of occurrence
Severity of consequences
Investigation required?

Question 13

How can linkages be broken?

Answer 13

Clean cover
Excavation of contamination hotspots

Question 14

What are the Geotechnical constraints of Made Ground?

Answer 14

Variable engineering properties
Uncompacted
Large obstructions
Differential settlement

Question 15

Name two geotechnical solutions to Made Ground

Answer 15

Pile foundations
Vibro-compaction

Question 16

What are the Geotechnical constraints of Natural Soils?

Answer 16

Bearing capacity needs to be determined
Differential settlement

Question 17

Name a geotechnical solution of Natural Soils

Answer 17

Pile foundations

Question 18

What are the Geotechnical Constraints of mineral stability?

Answer 18

Presence of worked coal seams?
Other mining present?

Question 19

Name two Geotechnical Solutions of mineral instability

Answer 19

Grouting
Pile foundations (location varies depending on voids)

Question 20

What is the potential geotechnical issue with slopes?

Answer 20

Slope stability

(re-grading)

Question 21

What are the main Ground Investigation objectives?

Answer 21

Depth and nature of Superficial Deposits
Extent and nature of Made Ground
Nature of underlying bedrock
Extent and condition of mine workings
Groundwater regime
Extent and type of contamination present
Presence of Ground Gas

Question 22

What are the Geotechnical Tests?

Answer 22

Moisture content
Grading analysis
Atterberg Limits
pH/sulphates
Undrained triaxial shear strength
Unconfined compressive strength

Question 23

What are the three things to prepare for a GI?

Answer 23

Check for services (CAT Scanner and service plans)
Inspection pits (1.2m hand dug)
Overhead obstructions?

Question 24

How are trial pits dug?

Answer 24

Dug using back-hoe excavator
Max depth 4-5m
Supported needed over 1.2m for entry

Question 25

What do trial pits show?

Answer 25

Visual log of strata
Able to take samples from excavator bucket

Question 26

What should be recorded while trial pitting?

Answer 26

Thickness and description of strata
Depth of strata
Position of each test/sample
Date, Time, Weather
Equipment details
Groundwater conditions
Stability
Ease of excavation
Installations?
Method of backfilling
Sketch and photographs