Engineering Geology Revision Flashcards
What is the purpose of a desk study?
To determine:
Historical development
Constraints on development (engineering and environmental)
Ground Investigation strategy
What are the two key invasive species and associated issues?
Japanese Knotweed and Giant Hogweed
Affect mortgages, damage foundations, spread rapidly, expensive to remove
What data do you gain from the Geology stage of a desk study?
Borehole records
Solid and Superficial Geology
Hydrology and Hydrogeology
Made Ground?
Mining under site?
Flooding?
How do you go about an environmental assessment?
Preliminary Environmental Assessment
- Historical and Present Land uses
Potential Contaminants of Concern
- Metals, HCs, Solvents, Pesticides, Asbestos
Pollutant Linkage Conceptual Model
- Source, Pathway, Receptors
What Acts are Referenceable for Environmental Assessments?
Environmental Protection Act 1990
Section 57 Environmental Act 1995
What is included in an Environmental Qualitative Risk Assessment?
Likelihood of occurrence
Severity of consequences
Investigation required?
Give examples of Receptors
Humans (residents and workers) and animals
Plants
Buildings, property, and services
Controlled waters (surface and groundwaters)
How can humans act as a Pathway?
Inhalation of dust
Ingestion of dust/soil by hand or from vegetation
Dermal contact with soil/water
How can plants act as a Pathway?
Direct contact with soil/groundwater
Uptake of contaminants
How can buildings act as a Pathway?
Direct contact with soil/groundwater
Service trenches act as a migration pathway
How can controlled waters act as a Pathway?
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
How do you approach pollution linkages and risk assessments?
Can the linkages be completed?
How can they be broken?
Likelihood of occurrence
Severity of consequences
Investigation required?
How can linkages be broken?
Clean cover
Excavation of contamination hotspots
What are the Geotechnical constraints of Made Ground?
Variable engineering properties
Uncompacted
Large obstructions
Differential settlement
Name two geotechnical solutions to Made Ground
Pile foundations
Vibro-compaction
What are the Geotechnical constraints of Natural Soils?
Bearing capacity needs to be determined
Differential settlement
Name a geotechnical solution of Natural Soils
Pile foundations
What are the Geotechnical Constraints of mineral stability?
Presence of worked coal seams?
Other mining present?
Name two Geotechnical Solutions of mineral instability
Grouting
Pile foundations (location varies depending on voids)
What is the potential geotechnical issue with slopes?
Slope stability
(re-grading)
What are the main Ground Investigation objectives?
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
What are the Geotechnical Tests?
Moisture content
Grading analysis
Atterberg Limits
pH/sulphates
Undrained triaxial shear strength
Unconfined compressive strength
What are the three things to prepare for a GI?
Check for services (CAT Scanner and service plans)
Inspection pits (1.2m hand dug)
Overhead obstructions?
How are trial pits dug?
Dug using back-hoe excavator
Max depth 4-5m
Supported needed over 1.2m for entry
What do trial pits show?
Visual log of strata
Able to take samples from excavator bucket
What should be recorded while trial pitting?
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
