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