Go Vertical with Confidence®

Drill Displacement Column

Pressure Grout Ground Improvement

Slide 1

Maxwell practice field and parking garage at UC Berkeley. DDC - 18" diameter by 38' deep for seismic settlement and foundation support over the historic Strawberry creek Little Inch culvert.

Slide 2

Mission Piers in San Francisco, CA. DDC - 18" diameter by 42' deep for contaminated soil, liquefaction and lateral spread, and foundation support of the 7 story mixed-use structure.

Slide 3

Southern Wine & Spirits in Union City, CA. DDC - 18" diameter by 40' deep for deep liquefaction and foundation support in a ground water protection region for industrial distribution warehouse.

Slide 4

Cal Maritime Academy new Dining Hall in Vallejo, CA. DDC - 18" diameter by 38' deep for contaminated soil, liquefaction, lateral spread, and foundation and slab support of 3-story Dining Hall.

Slide 5

Berkeley Animal Center in Berkeley, CA. DDC – 18" diameter by 30 feet deep for liquefaction mitigation, contaminated soil, very near EBMUD 60" sewer pipe, and for mat foundation support of 3 story building.

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Drill Displacement Column™ (DDC) system is a deep, full displacement, pressure grout column, ground improvement method used to improve any soft/loose soil or contaminated soil for support of heavy loads on shallow footings and mats. The DDC offers a well-defined, grout column, with reliable, high vertical capacity in soft and loose soil. The large cavity expansion effect in the displaced soil produces the increased strength and ground improvement of the system. DDC construction produces low noise and no vibration with low spoil from the displacement tool. DDC ground improvement imitates compaction grouting on a large scale with a well-defined grout column. DDC ground improvement increases bearing capacity, increases soil stiffness & modulus, reduces soil compressibility, increases loose soil resistance to liquefaction, and increases composite soil shear strength. DDC improved soil supports heavy loads on shallow footings and mats with uniform and reduced settlement.

DDC Applications

Support footings, slab-on-grade, structural mats, slope/embankments, and industrial foundations. The ideal applications for DDC occur at:

  1. Soft and loose soil sites and bay mud / sensitive soil sites.
  2. Contaminated soil and undocumented debris fill sites.
  3. Groundwater protection regions.
  4. Sensitive project sites near critical structures.
  5. Sites near occupied offices and in dense urban areas.

DDC 4-Step Construction Process

Slide 1


Heavy crowd + high torque = drill displace to the design depth. Install cavity expansion.

Slide 2


Withdraw auger & pump concrete under pressure. Install pressure grout effect.

Slide 3

Step 3

Install aggregate cushion over DDC to minimize punching shear and decouple seismic forces.

Slide 4

Step 4

Finished DDC with ground improvement and footing and/or slab above.

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Testimonial Image

The Pierce

San Jose, CA

“I was pleased with the Farrell crew. They were great to work with. Ken Winters managed his crew and equipment well. I look forward to more work with Farrell.”

Gary Cunnington

Clark Builders


Technical Details

The Drill Displacement Column™ (DDC) method is an innovative upgrade to rigid inclusion ground improvement for foundation support. The DDC displacement tool is shaped to laterally displace and compact soil at the edges into the ground. The displacement tool and the pressure grout effect result in a coarse sided sand-cement column with finished diameters greater than 100% of neat tool diameter. The soil displacement produces cavity expansion effects that 1) increase shear strength, 2) increase density, 3) increase over-consolidation, 4) reduce void ratio, and 5) increase stiffness & modulus of the surrounding soil. These physical benefits of DDC construction result in reliable, high capacity, deep ground improvement columns.

DDC are sometimes installed with a single rebar for higher strength and to resist tension forces. DDC supported footings use a gravel cushion to reduce punching shear and to de-couple the footing from the DDC; typical thickness is 6” to 18” (152 to 456mm). DDC with an expanded base can achieve much higher end bearing capacity. Full-scale load tests are performed to confirm DDC design bearing capacity. Cone penetration tests are performed to confirm ground improvement in the soil within groups of DDC.

Farrell uses heavy, fixed mast, piling drill rigs to install DDC. Farrell operates Leibherr, Casagrande, and Bauer rigs. These rigs install DDC to depths of 16 to 80 feet (5 to 24m). Farrell installs DDC with full displacement tool diameters of 14” (356mm), 16” (406mm), 18” (457mm), and 24” (610mm). Partial displacement DDC tools are used in dense soil regions. The rigs are equipped with electronic monitoring to record drill torque, drill depth, drill speed, concrete pump pressures, and concrete volume for engineer review.

Drill Displacement Column™ DDC is a well-defined, very strong, ground improvement that supports your project to Go Vertical with Confidence®!

Drill Displacement Column is the trademark of Farrell Design-Build Inc. All Rights Reserved.

Drill Displacement Column™

Geologic Hazard Application

Soft/Loose Soil


Contaminated Soil

Lateral Spread

Slope Stability

Depth Limit

80 ft (24 m)

Compatible Soils

  • Contaminated Soil
  • Sand (SP, SM, SP)
  • Silt (ML, MH)
  • Clay (CL, CH)
  • Contaminated Soil
  • Undocumented Fill

Bearing Capacity Range

4,000 to 10,000 psf (192 to 479 kpa)

Key Advantages

  • Very high stiffness
  • No vibration
  • Low spoil
  • High bearing capacity
  • Well defined concrete column
  • Liquefaction mitigation
  • Uplift-tension hold-down

Key Considerations

  • Impermeable grout
  • Grout with low spoil
  • Concrete cleanup
  • Flat stable pad
  • Gravel cushion

Comparable To

  • Concrete piers
  • Driven piles
  • Stone columns
  • Soil-cement columns
  • Franki piers

Farrell Design-Build Inc.  |   Sacramento  530.621.4867   |   Irvine  949.428.9596

© 2017 Farrell Design-Build Inc.    Go Vertical with Confidence is the registered trademark of Farrell Design-Build.     All rights reserved.

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