Geotechnical Instrumentation


We are highly skilled with the installation and use of the instruments listed below:


Frequent Applications:

  • Monitoring slopes and landslides to detect zones of movement and establish whether movement is constant, accelerating or responding to remedial measures.
  • Monitoring diaphragm walls and sheet piles to check that deflections are within design limits, that struts and anchors are performing as expected, and that adjacent buildings are not affected by ground movements.
  • Monitoring of dams, dam abutments and upstream slopes for movement during and after impoundment.
  • Monitoring the effects of tunneling operations and ensure that adjacent structures are not damaged by ground movements.
  • Proving the verticality of boreholes.
  • Checking the stability of retaining walls.
  • Controlling grid-spaced borings.

Vibrating Wire Piezometers

Frequent Applications:

  • Monitoring pore water pressures to determine safe rates of fill or excavation, and monitoring pore water pressure to evaluate slope stability.
  • Monitoring dewatering systems used for excavations.
  • Monitoring ground improvements systems, such as vertical drains and sand drains.
  • Monitoring pore pressures to check the performance of earth fill dams and embankments, and to check containment systems at landfills and tailing dams.


Extensometers are designed for the highly accurate measurement of strain and deflection. Extensometers measure strain, which is calculated as the change in length of a specimen divided by the original length (gauge length) of the specimen.

Deep Benchmark
Deep Benchmark

A Deep Benchmark consists of a pipe or rod, anchored at depth, surrounded by and disconnected from a sleeve pipe. The sleeve pipe protects the inner pipe or rod from drag caused by soil movement. The anchor is then grouted. The space between the rod and casing is filled with a bentonite slurry to minimize friction.

Benchmarks are typically regarded as stable points to provide references for elevations. In areas with expansive soils, special techniques are necessary to provide benchmarks that are free from ground movements. To prevent the movement of benchmarks due to heaving of expansive soils, benchmarks must be anchored below the depths where these movements originate.

Deep Benchmark

Test Pits

  • Rubber Tire and Track Mounted Excavators
  • Infiltration Testing

Craig Test Boring Co., Inc. and Craig Geotechnical Drilling Co., Inc.
Mailing Address: PO Box 427, Mays Landing, NJ 08330
Craig Test Boring Co., Inc.
5230 Atlantic Avenue
Mays Landing, NJ 08330
Craig Geotechnical Drilling Co., Inc.
3143 Bordentown Rd, Bldg 4B
Parlin, NJ 08859
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5230 Atlantic Ave., Mays Landing, NJ 08330. Phone 609-625-4862
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