U.S. Department

of Agriculture

Forest Service

National Technology &

Development Program

7700—Transportation Mgmt

0877 1804—SDTDC

September 2009

FOREST SERVICE

D E P A RTMENT OF AGRICU L T U R E

DEPARTMENT OF TRANSPORTATION

UNITED STATES OFAMERICA

Simplified User’s 

Guide to Time-DomainReflectometry 

Monitoring of Slope 

Stability
COVER PHOTO: Tom Collins, R8—Landslide along Blue Ridge Parkway on Grandfather RD, Pisgah NF, North Carolina

ACKNOWLEDGMENTS The authors would like to thank the National Technology and 

Development Program for funding the TDR technology and 

development project, and the Umpqua and Willamette National 

Forests for providing project testsites. We would also like to thank 

the Forest Service technical reviewers Pete Bolander, Bill Vischer, 

and Steve Romero, and the editors and publishers. 

This publication is the result of a partnership between the Forest 

Service technology and development program and the U.S. 

Department of Transportation, Federal Highway Administration, 

Coordinated Federal Lands Highway Technology Improvement 

Program.
Information contained in this document has been developed for the guidance of employees of the 

U.S. Department of Agriculture (USDA) Forest Service, its contractors, and cooperating Federal and 

State agencies. The USDA Forest Service assumes no responsibility for the interpretation or use of 

this information by other than its own employees. The use of trade, firm, or corporation names is for 

the information and convenience of the reader. Such use does not constitute an official evaluation, 

conclusion, recommendation, endorsement, or approval of any product or service to the exclusion of 

others that may be suitable.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities 

on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, 

familial status, parental status, religion, sexual orientation, genetic information, political beliefs, 

reprisal, or because all or part of an individual’s income is derived from any public assistance program. 

(Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative 

means for communication of program information (Braille, large print, audiotape, etc.) should contact 

USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, 

write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 

20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity 

provider and employer.

Simplified User’s Guide 

to Time-DomainReflectometry

Monitoring of Slope 

Stability

Edel R. Cortez, P.E., PhD, U.S. Department of the Army, 

Corps of Engineers, U.S. Army Cold Regions Research and 

Engineering Laboratory, Hanover, New Hampshire

Gordon L. Hanek, Geotechnical Engineer, U.S. Forest 

Service, Pacific Northwest Region, Umpqua National Forest

Mark A. Truebe, Geotechnical Engineer, U.S. Forest 

Service, Pacific Northwest Region, Willamette National Forest

Maureen A. Kestler, Geotechnical Engineer, U.S. Forest 

Service, San Dimas Technology & Development Center

September 2009

v

Introduction...................................................................................... 1

TDR Fundamentals ......................................................................... 1

System Components ....................................................................... 3

Cable Tester......................................................................... 4

TDR Cable........................................................................... 6

Grout.................................................................................... 6

Accessories ......................................................................... 7

Analysis Process ............................................................................. 8

Supplemental Resources .............................................................. 14

Publications ....................................................................... 14

Short Courses.................................................................... 15

TDR Listserver................................................................... 15

References .................................................................................... 15

Acknowledgments ......................................................................... 16

Appendix A—Practical Papers on Monitoring Slope Movement ... 17

Appendix B—Vendors ................................................................... 19 

Table of Contents

1

 INTRODUCTION Slope movement can be monitored by a number of methods and 

pieces of advanced equipment. However, using time domain 

reflectometry (TDR) is one of the least expensive methods.

This is a simplified guide for the implementation and use of a 

TDR cable system for monitoring the movement of known and 

potential landslides. For more detailed information, please refer 

to documents in the reference section, as well as the section 

on supplemental resources and appendix A. It provides a listing 

of practical papers on TDR technology for monitoring slope 

movement.

The purpose of this guide is to summarize basic information 

to assist field personnel in assembling and installing a TDR 

measurement system, as well as processing the TDR data. We 

(the authors) are not endorsing the specific equipment parts and 

manufacturers cited within the text. It is important to note that in all 

instances, we are simply recommending these parts or equivalent. 

A vendor list is included as appendix B. 

 TDR FUNDAMENTALS A TDR cable system for monitoring ground deformations and 

movements (figure 1) consists of a coaxial cable that is embedded 

in a borehole in the ground (figure 2) and is connected to a special 

apparatus. This apparatus is called a “cable tester” because 

the technique originated as a method to detect discontinuities 

or damage in electric cables (figure 3). The discontinuities or 

damage that we are trying to detect in slope-stability applications 

are caused by movement of one portion of the soil or rock mass 

relative to another portion. The cable is installed such that the slide 

surface will intersect the TDR cable and bend it, stretch it, or shear 

it. The signal that we collect with the TDR cable tester will show 

changes compared to the signal obtained originally when the cable 

was undamaged, allowing us to determine the depth, progression, 

and general magnitude of movement.

Introduction
2

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Figure 1—Cracking and settlement along 

top of slide in asphalt road, Region 6.

Figure 1b—Scales Road slide, Plumas National 

Forest, Region 6. (Gordon Keller)

Figure 2—Installation of TDR coaxial cable 

into auger hole.
3

 SYSTEM COMPONENTS Figure 4 shows the basic components of a TDR measurement 

system suitable for landslide monitoring. More sophisticated 

systems incorporating automated and remote data collection, 

along with the capacity to monitor multiple sensor cables, may 

be implemented to improve efficiency and reliability. Cost-benefit 

estimates may guide investment decisions relative to the added or 

improved components.

System Components

Figure 3—Reading the TDR cables. 
4

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Figure 4—Basic TDR system components.

 Cable Tester A cable tester that has been used successfully for slope stability 

TDR measurements is the Tektronix Metallic Time-Domain 

Reflectometer model 1502B. This model was first sold in 1996. 

Unfortunately, Tektronix discontinued this instrument and they do 

not produce any replacement models. This model was a step1

 type 

of TDR, and the replacement must be similar to work well for this 

application.

TDR Cable Tester

Coaxial cable

Grout

Hose clamps

1-in diameter pvc pipe

Ground level

Direction

of

landslide

movement

1

There are two different technologies or types of operation on which TDRs 

are based: “step” and “pulse,” with step being the more advantageous 

technology to find a fault on a cable (DeWinter and Ashley). De Winter 

and Ashley compare pulse to AM radar, where short separate bursts 

of a sine wave are transmitted, and the receiver detects reflections, 

separated by dead zones or blind spots. Adjustments can be made to 

reduce this problem, but such adjustments also limit the TDR’s range. 

In contrast, step technology is compared to a Doppler radar, where the 

transmitter continuously emits energy, and the receiver simultaneously 

listens for returned signals, thus eliminating the dead zone drawback 

of pulse technology. The receiver looks at a constant signal so it can 

accurately detect information that pulse types cannot. Additionally, step 

technology enables noise to be reduced or eliminated. So overall, step 

TDR technology produces clearer and easier to interpret cable plots than 

pulse TDR units.
5

One example of a more current step TDR model of the cable tester 

is the 20/20B TDR® marketed by AEA Technology, Inc. (http://www.

aeatechnology.com). This is a hand-held unit with a BNC (Bayonet 

Neill Concelman) connector suitable to connect a coaxial cable. It 

is sold packaged with a computer serial cable and software used 

to transfer the TDR signals to a computer. In August 2007, this unit 

was priced at $1,350. Figure 5 shows this hand-held unit.

Figure 5—20/20 TDR hand-held apparatus (from http://www.

aeatechnology.com/html/pic_2020tdr.htm).

Another suitable step option now available is a PCMCIA card 

that turns a notebook computer into a measuring apparatus. An 

electronic brochure and ordering address for an example of this 

system can be found at http://www.ecadusa.com/3127bro.pdf. 

In August 2007, the package including the card, software, a 40-

foot coaxial cable, and computer connection cable cost $6,490. 

A related option includes a hand-held device that works the same 

as the PCMCIA card, but it gathers the data without a computer. 

This option costs $9,895. The price of this option is significantly 

higher than the option shown in figure 5 without appearing to offer 

an effective advantage over the hand-held unit. The reader also is 

encouraged to consult the vendor list in appendix B.

System Components
6

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

 TDR Cable An RG-58 coaxial cable (used for televisions) is the most common 

cable used for slope-stability TDR applications. A twist-on BNC 

connector connects the cable to the cable-reader apparatus. The 

literature also reports that the RG-59 coaxial cable has been used 

for TDR applications. Previous TDR slope monitoring (within the 

Forest Service) was done with a Belden 9913 RG-58 (manufacturer 

part number 9913 010100).

The RG-58 is a common cable and can be purchased from any 

cable supplier. A sample source for this cable is http://www.mouser.

com, and the specific product can be found at http://www.mouser.

com/search/refine.aspx?Msid=56610000&Mkw=Belden+9913. 

In August 2007, a 100-foot spool of RG-58 cable cost $140. Buying 

longer spools results in a small price reduction.

 Grout Grout is used to refill the borehole once a TDR cable is installed. 

The grout is made of type I Portland cement, bentonite, and water. 

Normally, bentonite is sold in 50-pound bags and Portland cement 

is sold in 94-pound bags. The approximate proportions by weight 

are: 1 pound cement, 0.45 pounds bentonite, and 2 pounds water. 

Table 1 shows the proportions and strengths obtained with several 

grout mixes that were used to refill TDR boreholes in the past. 

The stiffness of the grout is an important parameter: A grout that is 

too soft allows the cable to move and slip without registering the 

movement. A grout that is too strong and too stiff reinforces the soil 

around the TDR cable and remains less deformed than the soil 

mass around it. Targeting a range of 10 to 20 times the estimated 

unconfined compressive strength of the soil facilitates development 

of a discrete shear plane that produces a localized stressing of the 

TDR cable.

Table 1—Examples of grout proportions used in the past.

Grout Cement Bentonite Water 28-day Strength (psi)

FS monitoring 

Site 1 1 0.3 2 236

FS monitoring 

Site 2 1 0.45 2 169

FS monitoring 

Site 3 1 0.3 1.8 378

 
7

One source for bentonite is http://www.deanbennett.com. Their 

bentonite products are found at http://www.deanbennett.com/

bentonite-sealing-agents.htm.

In August 2007, a bag of bentonite cost $7.75 with discounts for 

larger orders. This, or an equivalent product, is recommended. 

 Accessories Coaxial cables can be strapped with common hose clamps 

onto a slope inclinometer casing or a 1-inch-diameter plastic 

pipe. The Umpqua and Willamette National Forests used the 

plastic-pipe method for their TDR installations (figure 6). Other 

installations reported in the literature consisted of only a coaxial 

cable embedded in grout without any other pipe or support. The 

plastic pipe provides a means of inserting the flexible cable into 

the borehole and holds the coaxial cable centered in the borehole 

during backfilling. In this case, we assume that the plastic pipe is 

weak enough to yield to a ground-mass movement.

Figure 6—Hose clamp used to secure TDR cable to fabric-wrapped PVC 

tubing.

Metal hose clamps also can be used to pinch the coaxial cable 

enough to cause a spike in the TDR signal at the clamp location. 

These spikes are used to help scale the TDR signals to determine 

the depth of any perceived ground movement.

System Components
8

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

One source for the BNC connector at the end of a TDR cable is at 

http://www.cablestogo.com. This connector can be specified as an 

RG58 Male Twist-On Connector. In August 2007, it cost $4.49, plus 

shipping. Purchase hose clamps and PVC pipe at a local hardware 

store.

 ANALYSIS PROCESS TDR data analysis can be complex and extensive, depending on 

the purpose of the investigation. However, for monitoring groundmass movements related to slope stability, the analysis can be 

relatively simple. 

The data acquired with the cable tester are stored in files that can 

be imported into a Microsoft Excel spreadsheet. Figure 7 shows a 

view of the data from a Forest Service field testsite in region 6 that 

were imported into Excel. The window was split to show nonzero 

values in columns B and on. Column A is simply a sequence 

number to identify each scan point (representing an incremental 

point along the cable’s length).

The numbers in columns B through H indicate the reflected 

signal strength at each scan-point location for that particular test 

date. Thus, what we search for are relatively large differences 

in reflectivity between test dates, as indicated in column H. The 

header information in rows 1 and 2 identifies the date, time, site 

location, and cable-tester parameters.

Figure 7—View of raw data imported into Excel.
9

The test dates are added to each column of data, and the data 

are plotted. Figure 8 shows a sample chart from one region 6 

testsite. The vertical scale is a coefficient related to impedance. 

The horizontal scale represents the number of scan events created 

by the cable tester during a single reading. For the cable tester 

used to collect the data shown in figure 8, 1,200 incremental 

measurements of the vertical-scale parameter were made at 

10-picosecond intervals for each day’s data plot.

Figure 8—Sample chart from region 6 testsite. Vertical: Coefficient related 

to impedance (provided by cable tester). Horizontal: Number of scan 

events.

T3S

0

500

1000

1500

2000

2500

3000

3500

4000

0 200 400 600 800 1000 1200 1400

2/7/03

3/4/03

4/8/03

6/2/03

9/30/03

11/4/03

Analysis Process
10

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Figure 9 identifies the beginning and end of the cable. The 

beginning is where the signal becomes more or less stable. 

The end (or any break in the cable) is when the signal goes up 

dramatically.

Figure 9—Identification of the beginning and end of the cable. Vertical: 

Coefficient related to impedance (provided by cable tester). Horizontal: 

Number of scan events.

Next, plot the data at a scale that maximizes our view of the area 

of interest, i.e., only the cable part of the signal (beginning-to-end 

of cable) and at a vertical scale that spreads the curves the most 

while still containing them. Figure 10 shows the rescaled graph 

corresponding to figure 9.

T3S

0

500

1000

1500

2000

2500

3000

3500

4000

0 200 400 600 800 1000 1200 1400

2/7/03

3/4/03

4/8/03

6/2/03

9/30/03

11/4/03

Beginning of cable

End of cable
11

Figure 10—Rescaled version of figure 9. Vertical: Coefficient related to 

impedance (provided by cable tester). Horizontal: Number of scan events.

We are interested in the signal changes with time. In order to 

see these changes more clearly, we subtract the values at each 

point for later dates from the corresponding points on the first 

measurement (baseline). We then plot the differences as shown in 

figure 11, noting the peaks observed on the last two test dates at a 

horizontal scale of about 720.

Figure 11—Plot of the point-by-point differences in signal values relative 

to the initial measurements. Vertical: Difference in coefficient related to 

impedance (provided by cable tester). Horizontal: Number of scan events.

T3S

800

850

900

950

1000

1050

1100

1150

50 150 250 350 450 550 650 750 850

2/7/03

3/4/03

4/8/03

6/2/03

9/30/03

11/4/03

Tiller Site 3

-100

-80

-60

-40

-20

0

20

40

60

80

100

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900

3/4/03

4/8/03

6/2/03

9/30/03

11/4/03

Analysis Process
12

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

By observing these two peaks we deduce that there was a 

ground movement. We want to know if it moved and stopped or 

if it continued moving. So, we subtract the point-by-point signals 

of subsequent dates from the first measurement that detected 

movement. Figure 12 shows this comparison for the September 

and November test dates. Because the variations are random and 

not concentrated on the same region where the peaks were found 

in figure 11, we conclude that the soil structure did not continue 

moving between these two dates.

Figure 12—Comparison of subsequent measurements to the one when 

movement was detected first. Vertical: Difference in coefficient related to 

impedance (provided by cable tester). Horizontal: Number of scan events.

Next we want to know how deep the slide plane is where the 

movement occurred. We use simple proportions between the 

number of scan points between the beginning and the end of 

the cable, and our previous knowledge of the cable length and 

the depth of the borehole. An example of the results is provided 

in figure 13. For this example, there are about 780 scan points 

(horizontal scale) between the beginning and end of the 40.4-footlong cable. Thus, each point corresponds to a cable length of about 

0.6215 inches. The observed peak occurs about 622 scan points 

from the beginning of the cable or 32.2 feet. So, the movement 

occurred 8.2 feet from the end of the cable. Because the last 11.5 

feet of the cable are installed vertically in a drill hole, it can be 

determined that movement occurred 3.3 feet below the ground’s 

surface.

-120

-100

-80

-60

-40

-20

0

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900
13

If the hose clamps are tightened correctly, and if accurate records 

are kept on the location of the clamps, the resulting small peaks 

can be used to more accurately scale-locate the depth where the 

new peaks are detected.

In summary, we are trying to detect changes in the TDR signals 

collected on several dates compared to a baseline signal collected 

on the initial survey. Cable deformations due to ground movement 

produce peaks, such as those shown in figure 11. The magnitude 

of the movement is difficult to establish, unless careful and 

extensive laboratory calibration was conducted prior to the cable 

installation, and the grout stiffness matches that of the surrounding 

soil. However, continued increases in the size of the peaks would 

indicate continued movement.

Figure 13—Example of TDR results. Vertical: Number of scan events. 

Horizontal: Difference in coefficient related to impedance (provided by 

cable tester).

Analysis Process
14

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

A similar TDR method is used to detect the depth of ground water. 

The instrumentation is the same as that used for ground-movement 

monitoring, except that a section of a special coaxial cable is 

connected at the end of a normal coaxial cable. The special 

cable normally is thicker and, instead of a solid plastic material 

separating the center coaxial wire and the outer conductive shell, it 

contains a plastic spiral that allows the penetration of air and water 

in between the center wire and the outer conductive shell. When 

water penetrates this cable substituting air, the TDR signal shows 

a marked drop in value that suggests the depth of the water table. 

This special cable, Heliax® coaxial type HL4RP-50, is available 

from http://www.Andrew.com. In August 2007, it cost about $5 per 

foot. The associated connectors are types L4PNM RC and L4PNFRC (the M stands for male; the F for female). These connectors 

cost about $40 each.

TDR data may be supplemented by slope-inclinometer 

measurements, by monitoring of surface cracks in paved areas, 

and by surveyed elevation measurements. To better understand the 

conditions at a site of interest, one should consider all the data.

 SUPPLEMENTAL

 RESOURCES TDR technology for geotechnical purposes has been around since 

the 1970s. Using it to monitor slope movement is far more recent, 

and advances in equipment are being made on a regular basis. The 

reader is encouraged to check the literature for further advances, 

and is strongly encouraged to seek added sources, such as those 

in appendix A. 

 Publications The reader is referred to GeoMeasurements by Pulsing TDR 

and Probes (O’Connor and Dowding 1999) for a comprehensive 

overview of TDR technology. The table of contents and chapter 1 

are available online at http://www.iti.northwestern.edu/publications/

dowding/book/index.html. 

Appendix A lists numerous practical short papers by private 

consultants on using TDR for monitoring slope movement. 

Another practical paper by Denis et al (2006) is available at https://

engineering.purdue.edu/TDR/Papers/41_Paper.pdf. 
15

Papers from the TDR symposiums held every few years discuss 

TDR applications (monitoring moisture content, etc.), however, a 

few discuss slope monitoring. Symposium papers can be accessed 

at http://www.iti.northwestern.edu/tdr/tdr2001/proceedings/Final/

TDR2001.pdf; and https://engineering.purdue.edu/TDR/Papers/. 

 

 Short Courses Courses are occasionally taught on automated and remote 

monitoring. They can be accessed at http://www.iti.northwestern.

edu/tdr/tdr2001/courses.html.

 TDR Listserver Finally (and a highly recommended method of learning about 

your particular needs and sharing lessons learned), information 

on signing up for an unmoderated forum for the “discussion 

and exchange of information regarding the use of time domain 

reflectometry in environmental, infrastructure and mining 

applications” is available at http://www.iti.northwestern.edu/tdr/

listserv.html.

All of the above sites were accessed March 2008. 

 REFERENCES Dennis, Norman D.; Ooi, Chong Wei; Wong, Voon Huei. 2006. 

Estimating movement of shallow slope failures using time domain 

reflectometry. Paper ID 41. Proc. TDR 2006. West Lafayette, IN: 

Purdue University. 16 p. https://engineering.purdue.edu/TDR/

Papers. (Accessed March 2008.)

DeWinter, Paul; Ashley, Bill. AEA Technology Inc., http://www.

aeatechnology.com/index.php (Accessed August 2009.)

Dowding, C. H.; Dussud, M. L.; Kane, W. F.; O’Connor, K. M. 2003. 

Geo monitoring deformation in rock and soil with TDR sensor 

cables. Geotechnical Instrumentation News. 21(2): 81-89.

References
16

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Kane, W. F.; Beck, T. J.; Hughes, J. J. 2001. Applications of 

time domain reflectometry to landslide and slope monitoring. 

Second International Symposium and Workshop on Time Domain 

Reflectometry for Innovative Geotechnical Applications. Evanston, 

IL: Northwestern University.

O’Connor, K.; Dowding, C. H. 1999. GeoMeasurements by pulsing 

TDR and probes. Washington, DC: CRC Press.

 
17

 APPENDIX A

 Practical Papers

 on Monitoring 

 Slope Movement List (by date) provided by Kane GeoTech

Kane, W. F. 2000. Monitoring slope movement with time domain 

reflectometry (TDR) Geotechnical Field Instrumentation: 

Applications for Engineers and Geologists. Sponsored by: ASCE 

Seattle Section Geotechnical Group Spring Seminar and the 

University of Washington Department of Civil Engineering, Seattle, 

WA.

Kane W. F.; Beck, T. J. 2000. Instrumentation practice for slope 

monitoring. Engineering Geology Practice in Northern California, 

Association of Engineering Geologists, Sacramento and San 

Francisco Sections.

Kane, W. F.; Beck, T. J. 1999. Advances in slope stability 

instrumentation: integrating TDR with remote data acquisition 

systems. Proceedings, Fifth International Symposium on Field 

Measurements in Geomechanics; Singapore.

Kane, W. F.; Beck, T. J. 1999. Advances in highway slope stability 

instrumentation. Proceedings, 50th Highway Geology Symposium; 

Roanoke, VA. 328-337.

Kane, W. F. 1998. Embankment monitoring time domain 

reflectometry. Proceedings, 5th International Conference on 

Tailings and Mine Waste ’98; Fort Collins, CO. 223-230.

Kane, W. F.; Beck, T. J.; Anderson, N. O.; Perez, H. 1996. Remote 

monitoring of unstable slopes using time domain reflectometry. 

Proceedings, Eleventh Thematic Conference and Workshops on 

Applied Geologic Remote Sensing, ERIM, Ann Arbor, MI, II, 431-

440.

Appendix A—Practical Papers
18

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Kane, W. F.; Beck, T. J. 1996. An alternative monitoring system for 

unstable slopes. Geotechnical News. 14(3): 24-26.

Beck, T. J.; Kane, W. F. 1996. Current and potential uses of time 

domain reflectometry for geotechnical monitoring. Proceedings, 

47th Highway Geology Symposium, Cody, WY, Wyoming 

Department of Transportation, 94-103.

Anderson, N. O.; Gwinnup-Greeen, M. D.; Kane, W. F. 1996. 

Monitoring of embankment stability using embedded coaxial 

cables. Proceedings, 1996 Annual Conference, Association of State 

Dam Safety Officials, Seattle, WA.

Kane, W. F.; Perez, H.; Anderson, N. O. 1996. Development of 

a time domain reflectometry system to monitor landslides. Final 

Report, FHWA/CA/TL-96/09, submitted to California Department of 

Transportation, Sacramento, CA, Contract #65W019, 72 p. (HTML 

Version Available from Time Domain Reflectometry Clearinghouse)

Kane, W. F.; Beck, T. J. 1994. Development of a time domain 

reflectometry system to monitor landslide activity. Proceedings, 

45th Highway Geology Symposium, Portland, OR, 163-173.
19

APPENDIX B

Vendors (as of January 18, 2005)

Links to Web sites for many of these vendors are 

available at http://www.iti.northwestern.edu/tdr/

vendors.html

Web sites for all companies that provided links 

were last accessed in March 2008. Those 

vendors whose sites were not accessible were 

removed by the authors. 

Original list was prepared by Kevin O’Connor

GeoTDR, Inc.

720 Greencrest Drive

Westerville, OH 43081

614–895–1400

614–895–1171 (fax)

E-mail: kevin@geotdr.com

E-mail: koconnor@gci2000.com

http://www.geotdr.com

http://www.gci2000.com

Applied Geomechanics Inc.,

1336 Brommer Street

Santa Cruz, CA 95062

Contact: Gary R. Holzhausen

831–462–2801

831–462–4418 (fax)

E-mail: holzhausen@geomechanics.com

Bicotest Limited 

Delamare Road 

Cheshunt, Hertfordshire EN8 9TG 

UNITED KINGDOM 

Contact: Wendy Seegar 

44–1992–629011 

44–1992–636170 (fax) 

E-mail: wendy.seegar@bicotest.com 

Biddle Instruments 

AVO International 

4651 S. Westmoreland Road

Dallas, TX 75237-1017

800–723–2861

214–333–3533 (fax)

E-mail: info@avointl.com

Campbell Scientific, Inc.

815 West 1800 North 

Logan, UT 84321-1784 

Contact: Jim Bilskie 

435–753–2342 

435–750–9540 (fax) 

Campbell Scientific Australia P/L 

P.O. Box 444 Thuringowa 

Central Kirawn, Queensland 4817

AUSTRALIA 

Contact: Jason Beringer or Steve Bailey 

61–77–254100 

61–77–254155 (fax) 

E-mail: csa@ultra.net.au 

Appendix B—Vendors
20

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Campbell Scientific Ltd. 

80 Hathern Road 

Shepshed, Leicestershire LE12 9RP 

UNITED KINGDOM 

Contact: Andrew Sandford 

44–0–1509–601141 

44–0–1509–601091 (fax) 

E-mail: andrew@campbellsci.co.uk 

CM Technologies Corporation 

1026 Fourth Avenue 

Coraopolis, PA 15108 

Contact: Greg Allan 

412–262–0734 

412–262–2250 (fax) 

E-mail: help@ecadusa.com

Durham Geo Slope Indicator

2175 West Park Court

Stone Mountain, GA 30087

Contact:

770–465–7557

770–465–7447 (fax) 

E-mail: dge-solutions@durhamgeo.com

Dynamax, Inc.

10808 Fallstone, Suite 350 

Houston, TX 77099 

Contact: Michael Truitt 

800–727–3570 (domestic) 

281–564–5100 

281–564–5200 (fax) 

E-mail: dynamax@mail.pernet.net 

(U.S. and Canada) 

export@dynamax.com (International) 

Easy Test, Ltd 

Solarza 8b 

P.O. Box 24 20-815 

Lublin 56 

POLAND 

Contact: Marek Malicki 

81–744–5061 

81–744–5067 (fax) 

E-mail: henryk@gaja.ipan.lublin.pl 

Eclypse International Corporation

265 N. Joy Street, Suite 150

Corona, CA 92879

Contact: Christopher Teal

951–371–8008

951–371–8022 (fax) 

951–371–0781 (cell) 

E-mail: cteal@eclypse.org

Edgcumbe Instruments Limited 

Main Street 

Bothwell, Glasgow G71 8EZ 

SCOTLAND 

Contact: Jim McRae 

44–1698–852574 

44–1698–854442 (fax) 

E-mail: support@edgcumbe.co.uk 

Electro Rent Corporation 

6060 Sepulveda Boulevard 

Van Nuys, CA 91411-2512 

Contact: 

800–688–1111 

818–787–2100 

818–786–4354 (fax) 
21

E.S.I. Environmental Sensors Inc. 

100 - 4243 Glanford Avenue 

Victoria, B.C., Canada V8Z 4B9 

Contact: Michael Marek 

(North American inquiries) 

and Pierre Ballester 

(International inquiries)

800–799–6324 (U.S. and Canada) 

250–479–6588 

250–479–1412 (fax) 

E-mail: mmarek@esica.com and 

pballester@esica.com 

GE Capital 

800–GE–RENTS 

GeoTDR, Inc. 

(alternate Web address: http://www.gci2000.com)

720 Greencrest Drive

Westerville, OH 43081

Contact: Kevin O’Connor 

614–895–1400

614–895–1171 (fax) 

E-mail: kevin@geotdr.com 

E-mail: koconnor@gci2000.com

Hewlett Packard

P.O. Box 58059 

MS 51LSJ 

Santa Clara, CA 95052-8059 

Contact: Test and Measurement Products 

800–452–4844 

E-mail: RICHARD_GEORGE@

hp-usa-om7.om.hp.com 

HydroTek, Inc. 

Contact: Jerry Pagel or Marty Grogan 

509–735–9142 

E-mail: HydroTek@owt.com 

HYPERLABS 

13830 S.W. Rawhide Court 

Beaverton, OR 97008 

Contact: Agoston Agoston 

800–354–9432 

503–524–7771 

503–524–6372 (fax) 

E-mail: agoston@hyperlabsinc.com 

IMKO GmBH 

Im Stoeck 2 D-76275 

Ettlingen GERMANY 

Contact: Robin Fundinger 

49–7243–592110 

49–7243–90856 (fax) 

E-mail: IMKO-GmbH@t-online.de

Innovative Utility Products Corp.

P.O. Box 1667

Van Buren, AR 72957

Contact:

479–410–2098

479–410–3260 FAX

E-mail: iucorp@ipa.net

Appendix B—Vendors
22

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Instantel Inc.

309 Legget Drive

Kanata, Ontario, Canada, K2K 3A3

613–592–4642 

800–267–9111 

613–592–4296 (fax)

E-mail: blastmate@instantel.com

Intermountain Environmental, Inc.

601 W. 1700 S. #B

Logan, UT 84321

Contact: Josh Hanks

800–948–6236

435–755–0794 (fax)

E-mail: josh_hanks@inmtn.com

Irricrop Technologies Pty. Ltd.

P.O. Box 487 

Narrabri, NSW

AUSTRALIA 2390 

Contact: Stephen Laird 

61–67–922588 

61–67–923804 (fax) 

E-mail: sales@irricrop.com.au 

Jenkins Electric Company

5933 Brookshire Boulevard

Charlotte, NC 28216-3386

Contact: Darren Lingafeldt

800–438–3003 (main line)

704–969–8315 (direct line)

800–392–2612 (fax)

dlingafeldt@jenkins.com

http://www.jenkins.com

KANE GeoTech, Inc.

P.O. Box 7526

Stockton, CA 95267-0526 

Contact: William F. Kane, President

209–472–1822

209–472–0802

E-mail: wkane@kanegeotech.com 

Magraph 

800–352–2900 

MESA Systems Co. 

119 Herbert Street 

Framingham, MA 01702 

Contact: John Kussman 

508–820–1561 

508–875–4143 (fax) 

PermAlert ESP 

7720 North Lehigh Avenue 

Niles, IL 60714 

Contact: Dmitry Sliversteyn 

847–966–2190 

847–470–1204 (fax) 

Picosecond Pulse Labs, Inc. 

P.O. Box 44 

Boulder, CO 80306 

303–443–1249 

303–447–2236 (fax) 

E-mail: info@picosecond.com
23

Prenart Equipment ApS

Wildersgade 46B

1408 Copenhagen DENMARK

Contact: Hans Garde

+45–3295–0900

+45–3295–1801 (fax)

E-mail: hg@prenart.dk

RenTelco, a division of McGrath RentCorp

West Coast Sales Office 

5700 Las Positas Road 

Livermore, CA 94551 

925–606–9100 

925–453–3202 (fax)

E-mail: info@RenTelco.com

RenTelco, a division of McGrath RentCorp

East Coast Sales Office 

1600 10th. Street 

Plano, TX 75074

972–943–3300 

972–943–3301 (fax)

E-mail: info@RenTelco.com

Riser-Bond Instruments 

5101 N. 57th Street 

Lincoln, NE 68507 

800–688–8377 

E-mail: email@riserbond.com

Smart Rain Corporation, Inc. 

1505, Place de l’Hotel de Ville 

Suite 102 St-Bruno, 

Quebec J3V 5Y6 Canada 

Contact: Romain Gagnon 

514–441–4289 

514–441–2147 (fax) 

514–893–6506 (cell) 

E-mail: RGagnon@SmartRain.com 

Soilmoisture Equipment Corp. 

P.O. Box 30025 

Santa Barbara, CA 93105 

Contact: Megan Bryan, Sales Manager 

805–964–3525 

805–683–2189 (fax) 

E-mail: tdrsales@soilmoisture.com

Technical Diagnostic Services, Inc.

4300 Beltway Place, Suite 120

Arlington, TX 76006

Contact: Rob Wornell

817–465–9494

800–225–7271

817–465–9573 (fax)

Email: rob@technicaldiagnostic.com

Appendix B—Vendors
24

Simplified User’s Guide to Time-Domain-Reflectometry Monitoring of Slope Stability

Tektronix Inc

14150 S.W. Karl Braun Drive

Beaverton, OR 97077-0001

Contact: Randy L. Wilson

Technical Support Engineer

800–833–9200 (opt #3)

503–627–5695 (fax)

E-mail randy.l.wilson@tek.com

http://www.tek.com

Telogy 

3885 Bohannon Drive 

Menlo Park, CA 94025 

Contact: Mali Dahl 

800–835–6494 

415–462–5376 

415–592–2618 (fax) 

E-mail: mdahl@telogy1.com 

Tenzor Co. 

Box 86 Gagarina Avenue 

603009 N. Novgorod

RUSSIA 

Contact: Alexandr Andrianov 

007–8312–335352 

007–8312–652220 (fax) 

E-mail: andr@andr.kis.nnov.su 

TestEquity 

2450 Turquoise Circle 

Thousand Oaks, CA 91320 

Contact: Peter Kesselman 

800–664–3457 

800–732–3457 

800–498–9933 

800–272–4329 (fax) 

800–498–3733 (fax) 

E-mail: sales@testequity.com 

Troxler Electronic Laboratories, Inc. 

3008 Cornwallis Road 

P.O. Box 12057 

Research Triangle Park, NC 27709 

Contact: Ron W. Phillips 

919–549–8661 

919–549–0761 (fax) 

Tru Cal International, Inc. 

605G Country Club Drive 

Bensenville, IL 60106 

Contact: Brian Lottich 

630–238–8100 

630–238–8101 (fax) 
25

University of Amsterdam 

Laboratory of Physical Geography 

and Soil Science 

Nieuwe Prinsengracht 

130 Amsterdam 1081 VZ 

The Netherlands 

Contact: Timo J. Heimovaara 

31–20–525–7451 (phone or fax) 

E-mail: th@fgb.frw.uva.nl 

Vadose Zone Equipment Company 

1325 Parr Street 

Amarillo, TX 79106 

Contact: Priscilla Sheets 

806–352–3088 (phone or fax) 

Publications from the national technology and 

development program are available on the 

Internet at http://www.fs.fed.us/eng/pubs/

Forest Service and U.S. Department of the 

Interior, Bureau of Land Management employees 

also can view the national technology and 

development program’s videos, CDs, and 

individual project pages on their internal 

computer network at http://fsweb.sdtdc.wo.fs.fed.

us/

For additional information on using TDR for 

landslide and slope monitoring, contact SDTDC. 

Phone: 909–599–1267.

Appendix B—Vendors