A Sound Foundation for an Engineering Geologist Starts in the Field: Experiences from Home and Overseas

A Sound Foundation for an Engineering Geologist Starts in the Field:

Experiences from Home and Overseas

Baltimore, MD

SWE Annual Conference October 24–26, 2013

Louise Headland (PG, MSc, BSc)Louise Headland (PG, MSc, BSc)

CIVIL GOVERNMENT SERVICESMINING & METALSOIL, GAS & CHEMICALS POWER

SWE Annual Conference. October 24th – 26th, 2013. Baltimore MD© Bechtel | 2

Qualifications and Career

Qualifications

– BSc in Geology & Geomorphology , Liverpool University, UK (1993).

– MSc Engineering Geology, Imperial College, London, UK (1995).

– PG, Professional Geologist.

Career

– Stanger Science and Environment, UK.

– SRK Consultores, South America.

– Bechtel Mining and Metals, South America .

– Bechtel Power, USA


What is an Engineering Geologist ?

Geology for Engineers

– “Geological practice carried out for civil engineers. A branch of applied geology which is the application of geology to industrial needs, especially related to the design, construction and performance of engineering structures interacting with the ground”.

Engineering Geology

– “Training and experience in ground problems that arise in civil engineering and in the investigation, classification and performance of soils and rocks related to civil engineering situations.” (Fookes, 1997)

Origins of Engineering Geology

– William Smith (1769-1839).

– Woodward’s memoir (1897).

– Lapworth’s lectures on “The Principals of Engineering Geology”(1907).


A Career in the Field

Copper and Zinc Mine — Peru, South America


Peru

– Elevation of 15,000 feet

– Copper and zinc open pit mine

– Bechtel was Engineering Contractor

– US $2.2 billion construction program

Process:

– Ore mined

– Crushed ore to concentrator

– Ore milled to “pulp”

– Concentrate stored and transported via 300 km long pipeline to coast

– Residual material disposed of at Tailings Dam (highest in world)


Concentrator and Tailings Dam



Km 88 Landslide

– Along 120 km access road

– Occurred at Km 88

– ~ 1Km long; 50-60 slope

– Road stays open (ROW)

– Pipeline route



Km 22 Landslide

– Along 120 km access road

– Occurred at Km 22

– ~ ½ Km long; 40-50 slope

– Road stays open (ROW)

– Pipeline route



Subsurface Investigation:

– Geological mapping

– Boreholes

– Piezometers

– Ground Penetrating Radar (GPR)

– Benching/re-profiling/scaling

Challenges

– Poor ground conditions

– Accessibility of slope

– Land availability

– Heavy rainfall (rainfall of > 100mm)



Failure Mechanisms:

– Surface water (natural drainage disturbance).

– Ground water (high levels).

Failure Mechanisms:

– Steep slopes – limited space.

– Poor ground conditions: weathered soil and rocks.


A Career in the Field Remedial Measures:

– Re-grading (benches)

– Increased drainage

– Wire mesh

– Gabion walls

– Slope re-vegetation



Largest Peruvian producers of copper and zinc concentrate and tenth largest in the world in terms of operating volume.

Daily average of 430,000 tons of material extracted with mining operations 24 hours a day, 365 days a year, 12 hour shifts.

Mine began trial operations in May 2001 and commercial operations in October 2001



Coal-Fired Power Plant

– Two coal-fueled units

– Bechtel: Project management, engineering, procurement, construction and start-up

– Once-through cooling system with water intake tunnel 9,200 feet long



Cooling Water Intake Tunnel

– Convey cooling water to new and existing plants.

– System consists of:

» Intake structure

» Tunnel

» Offshore Shafts

– Total of 9,200 ft of tunnel

» Offshore tunnel: 7,800 ft long

» Onshore tunnel: 1,400 ft long



Cooling Water Intake Tunnel

– Constructed in Silurian-age dolomite.

– Approximately 100 feet below top of bedrock.

– Excavated diameter of 27 feet with finished diameter of ~ 25 feet (concrete lined).

– Offshore portion excavated using TBM.

– Onshore portion by drill and blast.

~278 feet

Silurian Dolomite



Subsurface Investigation: Onshore and Offshore

– Ordnance survey

– Borehole survey

– Drilling vertical and angle boreholes

– Permeability testing

– Downhole geophysics

– Acoustic televiewer logging

– Soil and rock laboratory testing

– Sub-bottom (seismic) profiling

– Bathymetric surveyOffshore Barge



Challenges of working offshore

– Emergency Action Plan (EAP)

– Health and Safety Plan

– Coast guard / barge crew

– Surveying


A Career in the Field Challenges of working offshore

– Working 24 hours a day, 7 days a week.

– Tidal restrictions: Wave height > 3ft stopped operations.

– Limited work space.

– Getting equipment / supplies on and off the barge.



Weather!!



Tunnel design life is 100 years.

High groundwater inflows experienced during excavation of the offshore portion of tunnel.

Support included dowels/bolts, channels, ribs and mesh, concrete liner.

Unit 1 began commercial operation in February 2010 and Unit 2 in January 2011.

Tunnel supplies ~ 2 billion gal / day of water.

Tunnel Construction


A Career in the Field QUESTIONS!!!

A Sound Foundation for an Engineering Geologist Starts in the Field: Experiences from Home and Overseas

Engineering

baltimore md bechtel

md swe annual conference

bechtel mining

bechtel power

units bechtel

field copper

overseas baltimore

field coal