600R92200
UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY
GEOPHYSICS ADVISOR EXPERT SYSTEM VERSION 2.0
by
Gary R. Olhoeft r ^
Denver, Colorado . ¦¦^yJArsrjo irp |
: "*> I !-
U. S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
Report EPA/600/R-92/200
September 1992
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial
standards and nomenclature.
Use of brand names and model numbers in this report is for the sake of description only, and does not
constitute endorsement by the U.S. Geological Survey.
U.S. Geological Survey preliminary computer program for Geophysics Advisor Expert System. Written in
True BASIC 2.01 to run under Microsoft MS-DOS 2.0 or later on IBM-PC or true compatible computers with
640k or greater memory availa6lc to the program. No source code is available.
Although this program has been used by the U.S. Geological Survey, no warranty, expressed or implied, is
made by the USGS as to the accuracy and functioning of the program and related program material nor shall
the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS in
connection herewith.
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Geophysics Advisor Expert System Version 2.0
by Gary R. Olhoeft
This expert system program was created for the U.S. Environmental Protection Agency,
Environmental Monitoring Systems Laboratory, Las Vegas, Nevada. The expert system is
designed to assist and educate non-geophysicists in the use of geophysics at hazardous waste
sites. It is not meant to replace the expert advice of competent geophysicists. It is written to
run on any IBM MS-DOS compatible computer and to be very simple to use. This is
version 2.0 of the program.
Version 1.0 of the program was published as Olhoeft (1988), and asks questions about a site
and the contamination problem. Then, based upon the answers given, it recommends what
types of geophysics will most likely be useful at the site to solve problems such as
contaminant location and hydrogeological characterization of the site. It also annotates why
various geophysical techniques will likely work or not work at the site. The questions and
their allowable answers are tightly focused to decide on the use of geophysics to locate
contaminants and acquire hydrogeological information about the site.
Version 2.0 improves upon version 1.0 by adding a database of the physical and chemical
properties of the top Superfund organic contaminants. Version 1.0 asks questions about the
properties of the contaminants, such as "Are the organics miscible with water?" Version 2.0
presents a list of contaminants to select from (such as benzene). For the top Superfund
organic contaminants, it will know the answers to most questions. For other contaminants, it
will still ask the questions about properties. For some organic contaminants, the answers
are not known as the physical properties of the contaminants are unknown. The database
on which the answers are based is found in Lucius and others (1992).
To run this program, place the floppy diskette in drive A:, type 'A:' (without the quotes) and
press the 'Enter' key, then type 'EXPERT' and press the 'Enter' key. Follow the
instructions shown on the screen from that point on. Press 'Ctrl Break' (hold down the
'control' key and press 'break' key at same time) to exit the program without saving at any
point (this is not recommended when the program is writing to the disk), or press 'Alt-S'
(hold down the 'Alt' key and press 'S' at the same time) to exit and save a partial session.
During a session, questions may be answered and later changed by backing up with the 'Esc'
(escape) key, or by using the F10 key at the end when the recommendations are made.
After answering the questions posed by the program, it will recommend the types of
geophysics to use, then the session may be saved to disk (for later 'what if?' scenarios) and
printed. The appendix lists a typical session printout. As version 2.0 contains more
questions and allows the saving of partial sessions, old files created with version 1.0 are
incompatible with version 2.0 -- old sessions must be repeated starting from NEWFILE.
Quality Assurance requirements mandate that the program only be available in compiled
form and that datafiles be encrypted. However, the program and datafiles are not copy
protected and may be freely copied and distributed for no more than the cost of copying.
This program is not subject to U.S. Copyright Law. The program (EXPERT.EXE) and
datafiles (NEWFILE.EPA and DATABASE.ORG) may be copied and run from a hard
disk drive.
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References
Olhoeft, G. R., 1988, Geophysics advisor expert system: U.S. Geological Survey Open File
Report 88-399, 2p. + floppy disk (also available as U.S. EPA EMSL/LV Report
EPA/600/4-89/023).
Lucius, J. E., Olhoeft, G. R., Hill, P. L., and Duke, S. K., 1992, Properties and hazards of 108
selected substances - 1992 edition: U.S. Geological Survey Open File Report 92-527,
554p.
APPENDIX 1: List of Chemicals in Database
Organic Contaminant
Acetic acid
Acetone
Acrolein
Acrylonitrile
Aldrin
Ammonia
Aniline
Aroclor 1260 (PCB 1260)
Benz(e)acephenanthrylene
Benz[a]anthracene
Benzene
Benzidine
Benzoic acid
Benzo[a]pyrene
Bis(2-chloroethyl) ether
Bis(chloromethyl) ether
Bis(2-ethylhexyl) phthalate
Bromoform
Bromomethane
2-Butanone
Carbon tetrachloride
Chlordane
Chlorobenzene
6-Chloro-m-cresol
Chloroethane
Chloroform
Chloromethane
Chrysene
o-Cresol
Cyclohexane
DDT
Dibenz[a,h]anthracene
Dibromochloromethane
1,2-Dibromoethane
Dibutyl phthalate
1.2-Dichlorobenzene
1.3-Dichlorobenzene
1.4-Dichlorobenzene
Dichlorodifluoromethane
1.1-Dichloroethane
1.2-Dichloroethane
1.1-Dichloroe chene
trans -1,2-Dichloroethene
Dichloromethane
2,4-Dichlorophenol
1.2-Dichloropropane
Chemical Abstract Service Registry Number
64-19-7
67-64-1
107-02-8
107-13-1
309-00-2
7664-41-7
62-53-3
11096-82-5
205-99-2
56-55-3
71-43-2
92-87-5
65-85-0
50-32-8
111-44-4
542-88-1
117-81-7
75-25-2
74-83-9
78-93-3
56-23-5
57-74-9
108-90-7
59-50-7
75-00-3
67-66-3
74-87-3
218-01-9
95-48-7
110-82-7
50-29-3
53-70-3
124-48-1
106-93-4
84-74-2
95-50-1
541-73-1
106-46-7
75-71-8
75-34-3
107-06-2
75-35-4
156-60-5
75-09-2
120-83-2
78-87-5
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Organic Contaminant Chemical Abstract Service Registry Number
Dieldrin 60-57-1
Diethyl phthalate 84-66-2
Dimethyl phthalate 131-11-3
Dimethyl sulfoxide 67-68-5
2,4-Dinitrophenol 51-28-5
2,4-Dinitrotoluene 121-14-2
2,6-Dinitrotoluene 606-20-2
1,4-Dioxane 123-91-1
Dioxins (TCDD) 1746-01-6
DNAPL (Generic chlorinated solvent)
Endrin 72-20-8
Ethanol 64-17-5
Ethylbenzene 100-41-4
Ethylene glycol 107-21-1
Ethylene oxide 75-21-8
Fluoranthene 206-44-0
Heptachlor 76-44-8
Hexachlorobenzene 118-74-1
Hexachlorobutadiene 87-68-3
c-Hexachlorocyclohexane (Lindane) 58-89-9
Hexachloroethane 67-72-1
Hydrocarbon (Generic gasoline, diesel, etc.)
Hydrogen cyanide 74-90-8
Isophorone 78-59-1
Methanol 67-56-1
4-Methyl-2-pentanone 108-10-1
Naphthalene 91-20-3
Nitrobenzene 98-95-3
N-Nitrosodiphenylamine 86-30-6
Pentachlorophenol 87-86-5
Phenanthrene 85-01-8
Phenol 108-95-2
Potassium cyanide 151-50-8
Quinoline 91-22-5
Sodium cyanide 143-33-9
1,1,2,2-Tetrachloroethane 79-34-5
Tetrachloroethene 127-18-40
Toluene 108-88-30
Toxaphene 8001-35-20
1,2,4-Trichlorobenzene 120-82-10
1.1.1-Trichloroethane 71-55-60
1.1.2-Trichloroethane 79-00-50
Trichloroethene 79-01-60
Trichlorofluoromethane 75-69-40
2,4,6-Trichlorophenol 88-06-20
Vinyl chloride 75-01-40
Xylene 108-38-30
2,4-Xylenol 105-67-90
NONE OF THE ABOVE
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APPENDIX 2: Typical session printout.
Disclaimer:
NOTICE
The information in this program has been funded wholly or in part by the
United States Environmental Protection Agency under interagency agreement
DW14934976 to the United States Geological Survey. It has been subject to the
Agency's peer and administrative review, and it has been approved for
publication as an EPA document. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
U.S. Geological Survey preliminary computer program for Geophysics Advisor
Expert System. Written in True BASIC 2.1 to run under Microsoft MS-DOS 2.0 or
later on IBM-PC or true compatible computers with 640k or greater memory
available to the program. No source code is available.
Use of brand names and model numbers is for the sake of description only, and
does not constitute endorsement by the U.S. Geological Survey.
Although this program has been used by the U.S. Geological Survey, no
warranty, expressed or implied, is made by the USGS as to the accuracy and
functioning of the program and related program material nor shall the fact of
distribution constitute any such warranty, and no responsibility is assumed by
the USGS in connection herewith.
SITE NAME: Test Example
This is a test example session.
EXPLANATION: (This is the first question.)
'Continuous leak (fixed)' means it is no longer leaking.
QUESTION: The source of contamination was:
ANSWERS:
Unknown
Single event
Continuous leak (fixed)
Continuing leak
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EXPLANATION: 'Surface spill' includes all types of contamination that start at
the surface (such as an oil slick, leaking surface tank or pipe, or any others
than those listed separately).
'Not a spill or leak' is something like an intact, lost barrel of waste.
If several sources are involved, do one session for each...
QUESTION: The contaminants originated from:
ANSWERS:
Unknown
Surface spill
Land treatment facility
Surface impoundment
Leaking landfill
Leaking underground storage tank
Leaking underground pipeline
Leaking trench
Deep injection well
Not a spill or leak
EXPLANATION: For 'Yes' or 'no' questions like this,
'Unknown' means you don't know. 'Maybe' is closer to 'Yes' than 'no',
and 'Need to know' means you'd like to know this.
QUESTION: Did the contaminants reach the surface? (or are they on the surface?)
ANSWERS:
Unknown
No
Maybe
Yes-
Need to know
QUESTION: Are the contaminants in the unsaturated subsurface? (above the water
table)
ANSWERS:
Unknown
No
Maybe
Yes-
Need to know
QUESTION: Are the contaminants in the saturated subsurface?
(at or below the water table)
ANSWERS:
Unknown
No
Maybe
Yes-
Need to know
EXPLANATION: An areal search is a search across the surface of the earth for
the location of the contaminant problem.
A depth search is a search for the location of the contaminant problem versus
depth.
QUESTION: Is this an areal search, a depth search, or both?
ANSWERS:
Unknown
Areal
Depth
Both
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QUESTION: What is the urgency of the site investigation?
ANSWERS:
Unknown
Emergency Response (Hours)
Days
Weeks
Months
Years
EXPLANATION: 'Container' includes barrels and drums as well as pond and trench
liners.
QUESTION: Are the contaminants in a plume or in a container?
ANSWERS:
Unknown
Surface plume
Subsurface plume
Intact container
Leaky container
Both
QUESTION: Are radioactive contaminants present?
ANSWERS:
Unknown
No-
Maybe
Yes
Need to know
QUESTION: Are non-radioactive inorganic contaminants present?
ANSWERS:
Unknown
No-
Maybe
Yes
Need to know
EXPLANATION: 'Organics' includes hydrocarbons.
QUESTION: Are organics present?
ANSWERS:
Unknown
No
Maybe
Yes
Need to know
DATABASE CHOICE: Hydrocarbon (Generic gasoline, diesel, etc.)
FROM: Lucius, J. E., Olhoeft, G. R., Hill, P. L., and Duke, S. K., 1992,
Properties and hazards of 108 selected substances -1992 edition: U. S.
Geological Survey Open File Report 92-527,554p. (Order from: Books and Open
File Reports Section, Branch of Distribution, U. S. Geological Survey, P.O.
Box 25425 DFC, Denver, CO 80225,303-236-7476)
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EXPLANATION: Soluble or insoluble in water.
Soluble means they chemically dissolve in water (such as alcohol).
QUESTION: Are the organics water soluble or insoluble?
ANSWERS:
Unknown
Insoluble
Soluble
Mixed
EXPLANATION: Immiscible means they do not physically mix with water (such as
oil). Miscible means they mix with water.
QUESTION: Are the organics water miscible or immiscible?
ANSWERS:
Unknown
Miscible
Immiscible
Mixed
EXPLANATION: Lighter than water means they float. Heavier than water means they
sink.
QUESTION: Are the organics heavier or lighter than water?
ANSWERS:
Unknown
Neither
Heavier than water
Lighter than water
Both
EXPLANATION: Anionic means they are negatively charged in water.
Cationic means they are positively charged in water.
QUESTION: Are the organics polar?
ANSWERS:
Unknown
Nonpolar
Anionic
Cationic
Mixed
EXPLANATION: A soil is not wet by a liquid if the liquid forms beads on the
surface of the soil. Most silicate soils prefer to be water wet.
Many carbonates prefer to be organic-wet.
(But the detailed chemistry can make it go either way.)
QUESTION: Are the soils preferentially water-wet or organic-wet?
ANSWERS:
Unknown
Neither
Water
Organic
Both
EXPLANATION: (Aqueous means in the water.) (NAPL is NonAqueous Phase Liquid)
QUESTION: Arc the organics mostly in the water phase, adsorbed on soil solids,
in a separate organic phase, or in the gas phase?
ANSWERS:
Unknown
Aqueous
Soil
Gas
Separate Phase (NAPL)
All
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EXPLANATION: Modification processes include biodegradation, catalysis,
volatilization, and any other reactions.
QUESTION: Are the organics being modified by any processes?
ANSWERS:
Unknown
No
Maybe
Yes
Need to know
EXPLANATION: Are bacteria or other biological activity changing the chemistry
of the contaminants?
QUESTION: Is biodegradation of the organics occurring?
ANSWERS:
Unknown
No
Maybe
Yes-
EXPLANATION: For example, toluene is catalyzed on the surface of
montmorillonite to polymerize into bibenzyl.
QUESTION: Is catalysis of the organics occurring?
ANSWERS:
Unknown
No
Maybe
Yes
QUESTION: Is adsorption of the organics occurring?
ANSWERS:
Unknown
No
Maybe
Yes
EXPLANATION: Volatile means they produce a gaseous vapor at room temperature.
(typically that means they may smell.)
Consider the time of year the data are to be acquired.
QUESTION: Is volatilization of the organics occurring?
ANSWERS:
Unknown
No
Maybe
Yes
EXPLANATION: Volatile means they produce a gaseous vapor at room temperature,
(typically thai means they may smell.)
QUESTION: Are the organics volatile?
ANSWERS:
Unknown
Non volatile
Volatile
Both
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EXPLANATION: Organics present at the surface means in the air, on the ground
or in leaking containers at the surface.
QUESTION: Are there volatile organics present at the surface in the area of
study?
ANSWERS:
Unknown
No
Maybe
Yes--
QUESTION: Are the volatile organics present at the surface the same organics
as the contaminants?
ANSWERS:
Unknown
No
Maybe
Yes--
QUESTION: How old is the organic/hydrocarbon contamination?
ANSWERS:
Unknown
Hours
Days
Weeks
Months
Years
EXPLANATION: k* = relative dielectric permittivity (dielectric constant)
QUESTION: Are the organics good dielectrics?
ANSWERS:
Unknown
k'<10
k*>10
QUESTION: What is the electrical resistivity of the organics?
ANSWERS:
Unknown
>100ohm-m (insulator)
<100 ohm-m
QUESTION: Are the organics known to react with clay minerals?
ANSWERS:
Unknown
No
Maybe
Yes
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EXPLANATION: Empty means land with few or no manmade features of any kind.
Rural means farm country (or 2 or less houses per acre suburbs).
Suburban means 3 or more houses per acre site density.
Urban means high density center-city housing and utility density.
Industrial means setting with high building and utility density.
Landfill means low surface density, high subsurface density clutter.
Military means active military base with many interference sources.
Service station means gasoline/diesel service station or refinery.
Choose the lowest density of buildings and utilities that characterize the
site itself.
QUESTION: What is the environment at the site?
ANSWERS:
Unknown
Empty
Rural
Suburban
Urban
Industrial
Landfill
Military base
Service station
QUESTION: Are metallic well casings installed at the site?
ANSWERS:
Unknown
No-
Maybe
Yes
EXPLANATION: In this context, 'buildings' means current or former buildings or
their foundations.
QUESTION: How much of the site is covered by buildings?
ANSWERS:
Unknown
None
<10%
10-25%
25-50%
50-75%
>75%
EXPLANATION: 'Difficult' means it is difficult to walk around the site.
'Walking' means most of the site is available to access on foot.
'ATV' means access by all terrain vehicle is possible.
'4-WD' means four-wheel drive jeeps can drive over most of the site.
'2-WD van' means two-wheel van-like vehicles can drive over most of the site.
QUESTION: What is the site access like?
ANSWERS:
Unknown
Difficult
Walking
ATV
4-WD
2-WD van (easy access)
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EXPLANATION: 'Inaccessible' includes site access problems due to property
ownership and trespass, excessive safety hazards such as explosive hazard, and
difficulties due to quicksand, swamp or other similar problems.
QUESTION: How much of the site is inaccessible?
ANSWERS:
Unknown
None
<10%
10-25%
25-50%
50-75%
>75%
QUESTION: What is the annual precipitation?
ANSWERS:
Unknown
<5cm <2in
5-20cm 2-8in
20-50cm 8-20in
>50cm >20in
EXPLANATION: (If so, what is the wet season?)
QUESTION: Does most precipitation occur in one season of the year?
ANSWERS:
Unknown
No
Spring
Summer
Fall
Winter
QUESTION: Are there natural organics present? (from forest, jungle, farm,
swamp, etc.)
ANSWERS:
Unknown
No
Maybe
Yes
EXPLANATION: Radio, TV and radar transmissions may interfere with some
geophysical methods.
In this context, also consider nearby active airports, police stations, and
other non-commercial radio stations.
Arc-welders in welding shops may also qualify as 'radio' transmitters.
QUESTION: Are there radio, TV or radar transmitters within 2 km of the site?
ANSWERS:
Unknown
No-
Maybe
Yes
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EXPLANATION: Some sounds may interfere with some geophysical methods.
Sources of acoustic noise include railroads, heavily travelled roads, airport
flight paths, and industrial plants.
Continuously windy sites also qualify as acoustically noisy.
QUESTION: Is the site acoustically noisy?
ANSWERS:
Unknown
No-
Maybe
Yes
EXPLANATION: These permeability features may modify the results of a soil gas
survey.
QUESTION: Are streams (past or present), utility or other trenches, glacial
scours or drains present in the site?
ANSWERS:
Unknown
No-
Maybe
Yes
Need to know
EXPLANATION: Concrete will interfere with some geophysical techniques.
QUESTION: How much of the areal extent of the site is surfaced by concrete?
ANSWERS:
Unknown
None
<25%
25-50%
50-75%
>75%
EXPLANATION: Asphalt will interfere with some geophysical techniques.
QUESTION: How much of the areal extent of the site is surfaced by asphalt?
ANSWERS:
Unknown
None
<25%
25-50%
50-75%
>75%
EXPLANATION: Some geophysical techniques require topographic correction for
proper interpretation.
QUESTION: What is the range of topographic relief across the site?
ANSWERS:
Unknown
10m >30ft
EXPLANATION: (Indications either from Karst geology or human activities like trenches or
fluid withdrawals.)
QUESTION: Arc there sinkholes or evidence of subsidence present at the site?
ANSWERS:
Unknown
No-
Maybe
Yes
Need to know
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QUESTION: What is the approximate area of the site?
ANSWERS:
Unknown
< 100 sq-m <0.03 acres
100-1,000 0.03-0.3
1,000-10,0000.3-3.-
>10,000 sq-m >3. acres
QUESTION: Is this a four-season site with freezing winters?
ANSWERS:
Unknown
No
Maybe
Yes-
QUESTION: What is the average depth of freeze?
ANSWERS:
Unknown
<0.3m < 1ft
0.3-lm l-3ft-
l-3m 3-10ft
>3m > 10ft
Need to know
QUESTION: What is the average depth to bedrock?
ANSWERS:
Unknown
<3m < 10ft
3-10m 10-30ft
10-30m 30-100ft
>30m > 100ft
QUESTION: Is the zone of interest above or below the bedrock interface?
ANSWERS:
Unknown
Above
At
Below
All
QUESTION: What is the average depth to the water table?
ANSWERS:
Unknown
<3m < 10ft
3-10m 10-30ft
10-30m 30-100ft
>30m > 100ft
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QUESTION: Is the zone of interest above or below the water table?
ANSWERS:
Unknown
Above
At
Below
All
EXPLANATION: In this context, consider lakes, rivers and other permanent
surface water bodies.
QUESTION: How much of the surface areal extent of the site is covered by water?
ANSWERS:
Unknown
None
<10%
10-25%
25-50%
50-75%
75-90%
>90wt%
QUESTION: How much of the surface areal extent of the site is regularly
irrigated?
ANSWERS:
Unknown
None
<10%
10-25%
25-50%
50-75%
75-90%
>90%
EXPLANATION: Resistivity in ohm-meters or (conductivity in millimho/meter).
QUESTION: What is the electrical resistivity of the ground water?
ANSWERS:
Unknown
<30 ohm-m (>30 mmho/m) [not fresh]
>=30 ohm-m (<30 mmho/m) [fresh]
QUESTION: How far away from the site is the nearest saltwater (ocean, bay,
etc.)?
ANSWERS:
Unknown
> 1000m >3000ft
100- 1000m 300-3000ft
<100m <300ft
EXPLANATION: 'Brine layers' include seawatcr intrusions and other salty waters.
QUESTION: Are there brine layers present at the site?
ANSWERS:
Unknown
No
Maybe
Yes
Need to know
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EXPLANATION: Some geophysical techniques are influenced by rock and soil type.
The sequence gravel to clay indicates coarse to fine particle size (not
mineralogy).
QUESTION: Whal is ihe dominant soil type at the site?
ANSWERS:
Unknown
Rock - no soil
Gravel
Sand
Till
Clay
EXPLANATION: Lacustrine means soils derived from old lake beds.
Fluvial means old rivers or streams.
Glacial means the leftovers after glacial retreat.
Aeolian means airborne particle deposition.
Colluvial means soils derived from degrading cliffs, and avalanche or
landslide debris. Diluvial means deposited by floods.
Deltaic soils are formed at the mouth of a river.
(Alluvial is the 'modem' version of several of these.)
QUESTION: What is the origin of the dominant soil type at the site?
ANSWERS:
Unknown
Lacustrine
Fluvial
Glacial
Aeolian
Colluvial
Diluvial
Deltaic
Marine
Volcanic
EXPLANATION: The presence of clay helps some geophysical techniques and
hinders others.
Clay in this context means mineralogical clay (such as montmorillonite) not
engineering-size-fraction 'clay'.
The depth penetration of ground penetrating radar in particular is strongly
limited by clay.
QUESTION: Is clay present at the site? (exclude a basal clay below depths of
interest)
ANSWERS:
Unknown
No-
Maybe
Yes
Need to know
EXPLANATION: 'Quickly' means in less than one day.
QUESTION: Does rainfall on the site surface sink in slowly or quickly?
ANSWERS:
Unknown
Run off
Pond
Sink in slowly
Sink in quickly-
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17
EXPLANATION: Resistivity in ohm-meters or (conductivity in millimho/meter).
QUESTION: What is the average electrical resistivity of the site in ohm-meters?
ANSWERS:
Unknown
<1 ohm-m (>1000 mmho/m)
1-10 (100-1000)
10-30 (33-100)
30-100(10-33)
100-300 (3-10)
>300 ohm-m (<3 mmho/m)
SITE: Test Example
0026 Ground penetrating radar methods recommended.
0007 Soil gas methods recommended.
0007 Electromagnetic induction methods recommended.
0007 Complex Resistivity methods recommended.
0000 Gravity methods not recommended.
-001 Seismic effectiveness is uncertain.
-001 Magnetic methods not recommended.
-010 Radiometric methods not recommended.
SITE: Test Example
Site specific comments: 0007 Electromagnetic induction methods recommended.
Use time domain EM for deep sounding.
EM techniques are better for areal searches.
EM induction may detect organics that displace water from soil surfaces.
EM induction methods can sometimes (but rarely) find some organic insulators.
Bedrock is too deep to sec with shallow frequency-domain EM.
Use time-domain EM to find deep bedrock.
0007 Electromagnetic induction methods recommended. EMI are electromagnetic
techniques that induce currents in the earth. They measure the secondary
magnetic field generated by the induced currents. The electrical conductivity
of the earth is proportional to the secondary magnetic field. The depth of
investigation is a function of the instrument coil spacing and orientation,
frequency of measurement, and the electrical conductivity of the ground. By
measuring and mapping the changes in electrical conductivity, EMI techniques
may directly locate plumes of inorganic contaminants, clay lenses, metallic
objects such as buried drums, and inhomogeneities in geology such as
fractures. EMI techniques are ineffective in areas with many fences,
pipelines, rebar, telephone cables, and other metallic interferences. EMI
techniques require topographic correction. EMI techniques are readily
available commercially, relatively inexpensive, and require 1 or 2 man crews.
EMI methods acquire data very quickly over large areas, whereas resistivity
methods are preferred for sounding to acquire depth information. For further
information, see: Greenhouse, J. and Harris, R., 1983, Migration of
contaminants in ground water at a landfill: a case study, 7. DC, VLF, and
inductive resistivity surveys, J.Hydrol., v.63, p.177-197. McNeill, J.D.,
1990, Use of electromagnetic methods for groundwater studies: in Geotechnical
and Environmental Geophysics, v.I, S.H.Ward, cd., Tulsa, Soc.Explor.Geophys.,
p.191-218.
Nabighian, M. N., 1987, Electromagnetic methods in applied geophysics --
theory, vol.1: Soc. Explor. Gcophys., Tulsa, OK, 513p.
Nabighian, M. N., 1991, Electromagnetic methods in applied geophysics --
applications, vol.2: Soc. Explor. Geophys., Tulsa, OK, 972p. SITE: Test Example
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18
Site specific comments: 0026 Ground penetrating radar methods recommended.
Radar can detect some kinds of organics.
Radar can find some insoluble organics.
Radar can detect some immiscible organics.
Radar can detect some organics that float on the water table (but not the
aqueous plume).
Radar can detect pooled DNAPL sources (but not the aqueous plume).
Radar can detect soil texture scattering changes from organic wet soils.
Radar can find some organic dielectrics.
Radar can find some organic insulators.
Perform radar during winter to exploit high resistivity of frozen ground.
Bedrock is too deep to see with radar.
Radar may determine the depth to the water table.
Ground (fresh) water resistivity is good for mapping hydrogeology with radar.
Radar may determine the depth to the clay.
High resistivity is good for mapping hydrogeology with radar.
0026 Ground penetrating radar methods recommended. GPR measures changes in
the propagation of electromagnetic eneTgy in the ground. Such changes are
power law sensitive to water content and bulk density. Thus, GPR is a
sensitive indicator of soil stratigraphy, bedrock fracturing and an excellent
way to map the water table. GPR may sometimes directly detect organic
contaminants either by changes in scattering properties (the texture of the
radar record) or dielectric contrast (such as oil floating on water). GPR
works well in high resistivity environments such as dry or fresh-water
saturated coarse sand or granite. Low resistivity salt water and clays such
as montmorillonite severely limit the depth of penetration and effectiveness
of GPR. In clay-free soil with resistivity above 30 ohm-m, GPR can provide
vertical sections of the earth to depths of 30 meters with resolution of a few
centimeters. For further information, see: Olhoeft, G.R., 1986, Direct
detection of hydrocarbon and organic chemicals with ground penetrating radar
and complex resistivity, in Proc. of the NWWA/API Conf. on Petroleum
hydrocarbons and organic chemicals in ground water - prevention, detection
and restoration, Nov.12-14, Houston, p.284-304. Olhoeft, G.R., 1988, Selected
bibliography on ground penetrating radar, in Proc.Symp.Appl.Geophys.Engr.&
Environ.Probl., Golden, CO, Soc.Engr.& Min.Explor.Geophys., p.462-520. Proc.
of the Four Int'l. Conf. on GPR: Tifton, GA (1986), Gainesville, FL (1988),
Lakewood, CO (1990), Rovaniemi, Finland (1992).
Fisher, E., McMechan, G. A., Annan, A. P. and Cosway, S. W., 1992, Examples of reverse-time migration of
single-channel, ground-penetrating radar profiles: Geophysics, v. 57, p. 577-586.
Hanninen, P. and Autio, S., 1992, Fourth International Conference on Ground Penetrating Radar, June 8-13,
1992, Rovaniemi, Finland: Geological Survey of Finland, Espoo, Special Paper 16, 365p.
Lucius, J. E., Olhoeft, G. R., and Duke, S. K., 1990, Third International Conference on Ground Penetrating
Radar, abstracts of the technical conference, May 14-18, 1990, Lakewood, CO, USA: U.S. Geological Survey
Open File Report 90-414,94p.
Powers, M. H., Duke, S. K., Huffman III, A. C., and Olhoeft, G. R., 1992, GPRMODEL: One-dimensional full
waveform modeling of ground penetrating radar data: U. S. Geological Survey Open File Report 92-532, 22p
+ floppy disk.
Sander, K. A., Olhoeft, G. R., and Lucius, J. E., 1992, Surface and borehole radar monitoring of a DNAPL
spill in 3D versus frequency, look angle and time: in Proc. of the Symp. on the Application of Geophysics to
Engineering and Ground Water Problems, R. S. Bell, ed., Soc. of Engineering and Mineral Geophysicists,
Golden, CO, p. 455-469.
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SITE: Test Example
Site specific comments: 0007 Complex Resistivity methods recommended.
DC resistivity techniques are better for depth searches.
DC resistivity may detect organics that displace water from soil surfaces.
0007 Complex Resistivity methods recommended. Resistivity techniques use
electrodes in contact with the ground to measure electrical resistivity
(reciprocal of conductivity). "Hie depth of investigation is a function of the
electrode spacing and geometry, (larger spacings see deeper). By measuring
and mapping the changes in electrical resistivity, these techniques may
directly locate plumes of inorganic contaminants, clay lenses, metallic
objects such as buried drums, and inhomogeneities in geology such as
fractures. Resistivity techniques are ineffective in areas with many fences,
pipelines, rebar, telephone cables, and other metallic interferences, and may
be difficult to do through concrete or asphalt. Resistivity techniques
require topographic correction, are readily available commercially, relatively
inexpensive, and require 1 or 2 man crews. Resistivity methods are preferred
for sounding to acquire depth information, whereas EM induction provides
easier and faster areal mapping. Complex resistivity measures resistivity as
a function of frequency. It can detect organic contaminants when they react
with clay minerals, but it is much more time consuming, expensive, and not
readily available commercially. For further information, see: Ward, S.H.,
1990, Resistivity and induced polarization methods: in Geotechnical and
Environmental Geophysics, v.I, S.H.Ward, ed., Tulsa, Soc.Explor.Geophys.,
p.147-190. Olhoeft, G.R., 1992, Geophysical detection of hydrocarbon and
organic chemical contamination: in Proc.of the Symp.on the Appl.of Geophys.to
Engrg. and Environ.Problems, R.S.Bell, ed., Oakbrook, IL, Soc. Engrg. &
Min.Explor.Geophys., Golden, CO, p.587-595.
SITE: Test Example
Site specific comments: -001 Seismic effectiveness is uncertain.
Seismic methods are difficult to employ in loose soils.
-001 Seismic effectiveness is uncertain. Seismic techniques measure
changes in the propagation of elastic compressional or shear waves in the
ground. They may be operated in reflection or refraction modes. They are
linearly sensitive to changes in density and water content. They are most
useful in defining subsurface geological and hydrological structure. They
cannot detect contaminants directly, though they may locate trenches or other
disturbed burial zones in the ground. In urban environments, high noise or
difficult coupling (such as through concrete or asphalt) may make their use
prohibitive. Seismic and radar techniques are complementary as seismic works
well in clay soils where radar does not, and radar works well in loosely
compacted sandy soil where seismic does not. Basic references are: Hasbrouck,
W.P., 1987, Hammer-impact, shear-wave studies, in Shear-wave exploration,
S.H.Danbom and S.N.Domenico, eds., Tulsa, SEG, p.97-121. Lankston, R.W.,
1990, High resolution refraction data acquisition and interpretation: in
Geotechnical and Environmental Geophysics, v.I, S.H.Ward, ed., Tulsa,
Soc.Explor.Gcophys., p.45-74. Steeples, D.W. and Miller, R.D., 1990, Seismic
reflection methods applied to engineering, environmental and groundwater
problems: in Geotechnical and Environmental Geophysics, v.I, S.H.Ward, ed.,
Tulsa, SocExplor.Geophys., p.1-30. Hasbrouck, W. P., 1991, Four
shallow-depth, shear wave feasibility studies: Geophysics, v.56, p.1875-1885.
Enslcy, R.A., 1987, Classified bibliography of shear-wave seismology, in
Shear-wave exploration, S.H.Danbom and S.N.Domenico, eds., Tulsa, SEG,
pp.255-275.
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SITE: Test Example
Site specific comments: -001 Magnetic methods not recommended.
No magnetic materials were identified at the site.
-001 Magnetic methods not recommended. Magnetic techniques
measure perturbations in the earth's natural magnetic field near magnetic
objects such as iron drums or barrels. Magnetic techniques cannot locate
non-metallic materials nor non-magnetic metallic objects. Large
concentrations of iron or steel fences, utilities, culverts, vehicles or
buildings may interfere with the technique. High iron content soils (such as
greensands, basalts, red hematitic soils) may be sufficiently magnetic to hide
objects detectable under other soil conditions. Basic references include:
Benson, R.C., Glaccum, R.A., and Noel, M.R., 1983, Geophysical techniques for
sensing buried wastes and waste migration, National Water Well Association,
Dublin, OH, 236p. Hinze, W.J., 1990, The role of gravity and magnetic methods
in engineering and environmental studies: in Geotechnical and Environmental
Geophysics, v.I, S.H.Ward, ed., Tulsa, Soc.Explor.Geophys., p.75-126.
Roberts, R.L., Hinze, W.J., and Leap, D.I., 1990, Data enhancement procedures
on magnetic data from landfill investigations: in Geotechnical and
Environmental Geophysics, v.II, S.H.Ward, ed., Tulsa, Soc.Explor.Geophys.,
p.261-266. Gilkeson, R.H., Gorin, S.R., and Laymon, D.E., 1992, Application
of magnetic and electromagnetic methods to metal detection: in Proc.of the
Symp.on the Appl.of Geophys.to Engrg. and Environ.Problems, R.S.Bell, ed.,
Oakbrook, IL, Soc. Engrg. & Min.Explor.Geophys., Golden, CO, p.309-328.
SITE: Test Example
Site specific comments: 0000 Gravity methods not recommended.
0000 Gravity methods not recommended. Gravity techniques
measure changes in the gravitational field of the earth. These changes are
interpreted in terms of changes in density and porosity in the ground.
Microgravity techniques may be useful in locating trenches, voids, and
incipient subsidence problems. They cannot directly detect contaminants.
Gravity techniques require accurate location and topographic surveying,
removal of regional gradients, and correction for tidal effects. Basic
references are: Butler, D.K., 1984, Microgravimetric and gravity gradient
techniques for detecting subsurface cavities, Geophysics, v.49, p.1084-1096.
Rodrigues, E.B., 1987, Application of gravity and seismic methods in
hydrogeological mapping at a landfill site in Ontario, in Proc. of the First
National Outdoor Action Conference on Aquifer Restoration, Ground Water
Monitoring and Geophysical Methods, May 18-21,1987, Las Vegas, NWWA, Dublin
Ohio, p.487-503. Hinze, W.J., 1990, The role of gravity and magnetic methods
in engineering and environmental studies: in Geotechnical and Environmental
Geophysics, v.I, S.H.Ward, ed., Tulsa, Soc.Explor.Geophys., p.75-126.
Richard, B.H. and Wolfe, P.J., 1990, Gravity as a tool to delineate buried
valleys: in Proc.Symp.Appl.Gcophys.Engr.& Environ.Probl., Golden, CO,
Soc.Engr.& Min.Explor.Geophys., p.59-106. Butler, D. K., 1991, Engineering
and environmental applications of microgravity: in
Proc.Symp.Appl.Geophys.Engr.& Environ.Probl., Knoxville, TN, Soc.Engr.&
Min.Explor.Geophys., p.139-246.
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21
SITE: Test Example
Site specific comments: -010 Radiometric methods not recommended.
There are no radioactive materials present.
-010 Radiometric methods not recommended. Radiometric
techniques measure the radiation emitted from radioactive isotopes.
Radioactive contaminants may be masked by high background levels of natural
radioactivity or by roughly a meter of overlying soil cover (depending upon
the type and strength of the source and of the covering soil). These are
generally only useful at radioactive waste disposal sites. However, they may
be useful in locating natural radioactive hazards {such as radon gas sources),
early radium processing plants, mining mill tailings, and other similar sites.
Basic references are: EG&G Idaho Inc., 1983, Low-level radioactive waste
management handbook series: Environmental monitoring for low-level
waste-disposal sites, DOE/LLW-13Tg, available from NTIS, Springfield, VA,
var.pag.; Morse, J.G., ed., 1977, Nuclear methods in mineral exploration and
production, NY, Elsevier, 280p. Gregg, L.T. and Holmes, J.J., 1990, Radon
detection and measurement in soil and groundwater: in Geoiechnical and
Environmental Geophysics, v.I, S.H.Ward, ed., Tulsa, Soc.Explor.Geophys.,
p.251-262.
SITE: Test Example
Site specific comments: 0007 Soil gas methods recommended.
Contaminants on the surface may interfere with soil gas.
Soil gas can detect volatile organics. Soil gas detects volatile organics.
Soil gas may detect the products of organic biodegradation.
Soil gas may detect the products of organic catalytic reaction.
Surface contamination will interfere wiih soil gas (requires deep soil gas
probing). Older organic contamination is more likely degraded.
Soil gas probes should sample below depth of freeze in winter.
0007 Soil gas methods recommended. Soil gas techniques measure the variation
in concentration of subsurface gases. The sampling zone may be at or within a
few meters of the surface. The collected gases are analyzed by portabie gas
chromatographs and/or mass spectrometers to identify particular compounds of
interest. Airborne or near surface contamination may bias interpretation of
underground contaminants. Permeability variations at the site from utility
corridors, clay layers, or fractures will modify the apparent contaminant
patterns at the surface, requiring careful interpretation. Driving gas
sampling piobes into the ground to avoid surface or airborne contamination may
posea safety hazard if utilities or near-surface barrels are punctured. Soil
gas is insensitive to non-volatile organics and cannot detect inorganics.
Basic references include: Lappala, E. and G.Thompson, 19S4, Detection of
ground water contamination by shallow soil gas sampling in (he vadose zone:
theory and applications, in Proc. of the 5th National Conf.on Manag. of
Uncontrolled Hazardous Waste Sites, HMCRI, Silver Springs, MD, p.20-2S;
Kerfoot, H. and Mayer, C., 1986, The use of industrial hygiene samplers for
soil-gas surveying: Ground Water Monitoring Review, v.6, n.4, p.74-78; Marrin,
D.L. and G.M. Thompson, 1987, Gaseous behavior of TCE overlying a contaminated
aquifer, Ground Water, v.25, n.l, p.21-27. Marks, B.J. and Singh, M., 1990,
Comparison of soil-gas, soil, and groundwater contaminant levels of benzene
and toluene: Hazardous Materials Control, v.3, n.6, p.40-46. Godoy, F.E. and
Naleid, D.S., 1990, Optimizing the use of soil gas surveys: Hazardous
Materials Control, v.3, n.5, p.23-29.
Dcvitt, D. A., Evans, R. B., Jury, W. A., Starks, T. H., Eklund, B., and Ghalsan, A., 19S7, Soil gas sensing for
detection and mapping of volatile organics: USEPA EMSL, Las Vegas, NV, EPA/60Q/S-S7/036, 265p.
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Geophysics Advisor Expert System Version 2.0
by Gary R. Olhoeft
U. S. Geological Survey Open-File Report 92-526
U.S. EPA/EMSL Report EPA/600/R-92/200
September 1992 (MS-DOS 3.0 or later)
Start by typing EXPERT from the 'a:' prompt.
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