ENGI 9621 – Soil Remediation Engineeringbaiyu/ENGI 9621_files/Spring 2012/Lecture 4.pdf9621 –...
Transcript of ENGI 9621 – Soil Remediation Engineeringbaiyu/ENGI 9621_files/Spring 2012/Lecture 4.pdf9621 –...
Spring 2012
Faculty of Engineering & Applied Science
Lecture 4: Contaminated Site
Characterization
1
9621 – Soil Remediation Engineering
Site characterization a systematic investigation
aimed at obtaining appropriate and adequate data in
order to define the type and extent of contamination as
well as to assess the fate and transport of contaminants
under various scenarios
(1) Information required for site characterization
4.1 Introduction
Geologic data
Hydro-geologic data
Contamination data
2
(2) Questions to be answered by site characterization
Nature and extent of contamination
where is it?
What is future migration and control
where is it going?
What are receptors and their risk
what harm will it do?
What are technical options for remediation
how do we fix it?
3
(3) General methodology for site characterization
Source: Sharma and Reddy, Geoenvironental Engineering, 2004
4
4.2 Preliminary and exploratory site assessment
to collect and review available or published site-specific
or regional data involves two tasks: literature review and
site visit
(a) Literature review
(1) Phase I: Preliminary site assessment
site use and history
site permits
water well logs and records
aerial photos
other sources
site personnel interviews
geological maps and reports
topographic maps
soil survey maps
5
Action I Get a topo map understand geographic
setting, topography, nearby water bodies
Action II Get background geologic data through
Effective actions:
consulting ground-water atlas of Canada
getting reports on geology, hydrology,
meteorology
checking for reports from province and national
geological surveys
Action III Investigate regional geology and hydrogeology
help to understand site geology and hydrology
understand effects on contaminant movement 6
Where were chemicals handled or disposed?
What site structures or activities are potential
sources?
What chemicals are and were handled? Prevention of costly mistakes such as multi-aquifer
wells
(b) Site visit observe/record all potential important
surface site features + collect surface water and near-
surface soils
7
to confirm findings in the preliminary assessment
to obtain preliminary site-specific data to facilitate
design of a detailed site investigation program
(2) Phase II: Exploratory site investigation
sampling and testing procedures
sampling locations and frequency
QA/QC plan
health and safety (H&S) plan
schedule
cost assessment
a written work plan for phase III
8
More information about H&S plan , visit http://www.worksafebc.com/publications
/health_and_safety/by_topic/assets/pdf/howtoimplement_ohs.pdf
Health and Safety Levels
Source: Rast, Environmental Remediation Estimating Methods, 1997
9
4.3.1 Methods of obtaining soil and rock data
4.3 Detailed site investigation
Phase III : detailed site investigation a
comprehensive field and laboratory test program,
along with S&H and QA/QC plans
Direct methods
Geophysical methods
Drive methods
10
Source: Sharma and Reddy, Geoenvironental Engineering, 2004
bucket augers; spiral or ram’s horn auger
Direct methods – near surface soil sampling
11
Direct methods – soil sampling by solid-stem
auger drilling
Source: Sharma and Reddy, Geoenvironental Engineering, 2004
Power-driven solid-stem augers: (a) solid-
flight auger; (b) relationship of surface
cuttings and subsurface
Drilling stop at the desired depth
augers remove from the borehole
a sampler is attached to the end
of the drill put the entire string
back to the borehole a sample is
taken from the bottom flight by
Only for sampling from soil, not
applicable to saturated zones
12
Direct methods – soil sampling by hollow-stem
auger drilling
Source: Sharma and Reddy, Geoenvironental Engineering, 2004
Typical components of a hollow-stem auger:
a hollow pipe with a continuous ramp of
upward-spiraling flight welded around them
Drilling a center rod (with a pilot
bit and plug) is lowered inside the
auger till the sampling position is
reached the center rod/bit/plug
are removed soil sampler is
applied
Applicable to soil/uppermost level
of groundwater sampling
13
solid-stem (left) and hollow-stem (right)
augur flights
a hollow-stem augur in action Source: DeJong & Boulanger, 2010
14
Source: Sharma and Reddy, Geoenvironental Engineering, 2004
Direct methods – popular samplers
A split-spoon sampler
Thin-walled tube samplers
15
Drilling boreholes drilling fluid is
pumped down hollow rotary drill rods
the fluid circulates back to surface
by moving up the annular space
between drill rods and borehole wall
stabilization of the borehole wall
installation of the
piezometer/monitoring wall
If the circulation medium is air instead
of water air rotary drilling
Source: Sharma and Reddy, Geoenvironental Engineering, 2004
Direct methods – Installing piezometers and
monitoring wells by wet rotary drilling
Direct mud rotary circulation system
16
Geophysical methods
Borehole geophysical methods a probe into the
borehole using a cable transmit signals to surface
instruments generate logs or charts
Surface geophysical methods no requirement of
boreholes conduct
electric/seismic/electromagnetic surveys as well as
the use of ground penetrating radar
17
Geophysical methods – Electrical resistivity
Source: van Ea, Geophysical Techniques for Sensing Buried Wastes and Waste Migration, 1985 18
Geophysical methods – Seismic reflection
Source: van Ea, Geophysical Techniques for Sensing Buried Wastes and Waste Migration, 1985 19
Geophysical methods – Electromagnetic Induction
Source: van Ea, Geophysical Techniques for Sensing Buried Wastes and Waste Migration, 1985 20
Geophysical methods – Ground penetrating radar
Source: van Ea, Geophysical Techniques for Sensing Buried Wastes and Waste Migration, 1985 21
Drive methods e.g. cone penetrometer technology
CPT a method of providing real-
time data for use in characterizing the
subsurface, as opposed to older methods
of analyzing subsurface conditions in the
laboratory
It consists of a steel cone that is
hydraulically pushed into the ground at
up to 40,000 pounds of pressure
Sensors on the tip of the cone collect
data
22
4.3.2 Methods of obtaining hydrogeologic data
Direct methods
Drive methods
Piezometers and monitoring wells
Water-level measurement
In-situ hydraulic conductivity test
Packer test
Slug test
Pumping test
23
Installing Piezometers with
a Manual Slide Hammer Structure of a piezometer
Piezometers a small-diameter observation well used to
measure the hydraulic head of groundwater in aquifers
Source: Shanahan, Waste Containment and Remediation Technology, 2004 24
Monitoring wells -- Structure
Source: Shanahan, Waste Containment and Remediation
Technology, 2004 25
Monitoring wells -- Development
Source: Shanahan, Waste Containment and Remediation Technology, 2004 26
Source: Shanahan, Waste Containment and Remediation Technology, 2004 27
Well development by surge block
Source: Shanahan, Waste Containment and Remediation Technology, 2004 28
A surge block
closely fits the casing
interior and is operated
like a plunger beneath
the water level it has
a very direct positive
action on the movement
in the well
Source: Shanahan, Waste Containment and Remediation Technology, 2004
29
Water-level measurement
Source: Shanahan, Waste Containment and Remediation Technology, 2004 30
(a) Applying a bailer a portion of the water is removed from the bore
hole after which measurement can commence The rise rate of the
groundwater is determined by using a measuring tape with a float and a
stopwatch
(b) The determination of the saturated water permeability using the Guelph
permeameter.
In-situ hydraulic conductivity test
(a) (b) Source: Eijkelkamp, Agrisearch Equipment, 2010 (http://www.eijkelkamp.com/)
31
Sources: Groundwater data collection, USGS Illinois Water Science Center Searchable Publications Database, 2010,
http://il.water.usgs.gov/pubs/ofr01-50_chapter4_8.pdf (Left)
Cutting Edge Drilling , 2010, http://cuttingedgecoredrilling.com/_wsn/page4.html (Right)
(a) The schematic of a packer test apparatus (b) Field packer test
Packer test
32
Source: Butler, et al., Analysis of slug tests in formations of high hydraulic conductivity, Ground
Water, v. 41, no. 5, 620-630, 2003
Slug test
33
Pumping test
Single well pumping test
Source: Sharma and Reddy, Geoenvironental Engineering, 2004 34
4.3.3 Methods of obtaining contaminant data
Contaminant in soil analyze the samples
from soil sampler
Contaminant in water analyze the samples
from piezometers and/or monitoring wells
Contaminant in soil vapor analyze the
samples from soil gas sampler
35
3.4 Case study
The Cantuar Field Scrubber Site located in
southwest Saskatchewan
Leaking underground storage tank of natural
gas condensates site contamination
Source: Zhang et al., 2007