All posts by Jeffrey W. Coonse, PE

Congratulations to TJ Ju – a leading engineer, businessman and friend on becoming a US Citizen

Congratulations to TJ Ju, PE, on becoming a US Citizen.  TJ is our lead geotechnical design engineer, a partner at Subsurface, a volunteer in his community and our friend.  We sat down with TJ to see what makes him tick.

Briefly describe what you do all day.

I design excavation shoring and deep foundation systems, respond to various field issues for ongoing projects and brainstorm with team members on new proposal ideas.   I stay up to date reading technical papers from geotechnical engineering journals.

What’s the best thing about your job?

Each project is unique and demands the most creative solution for its success. From time to time I encounter a very challenging one, but I work with very talented team members including PMs and superintendents to get it through. This is very enjoyable and rewarding.

Whether I am designing a shoring wall or deep foundation system, I know our work is one of the first activities on site. Success of the whole project always requires a great start. Our design and construction are essential parts for the project’s success.

What’s the best thing about Subsurface?

Subsurface genuinely cares about people, not just our employees, but also our clients and project owners.  Subsurface works together as a team. We have very talented team members, engineers, estimators, PMs and superintendents. We always do our best and learn from each other.

What’s been one of your proudest moments working at Subsurface?

The most memorable moment in my 17 years at Subsurface was the day I was offered partnership. Since starting Subsurface in Spring 2002, I have tried my best to help the company grow. Then I felt that the founders had recognized the work I did for Subsurface. I was very thankful and truly felt Subsurface caring, not only its success, but also each employee’s growth and success.

What do you like to do when you’re not at the office?

I enjoy spending time with my family. We often go biking and swimming all together. NC is the best state for a family and I want to take advantage of it as much as possible. I also like to travel with family and read books.

What inspires you?

God. He always works through people around me to give inspiration.

Why engineering?

I enjoyed math and physics through my K-12 years and wanted to help practically people in need. Also, my father was an engineer (textile engineer, also businessman) and taught me what engineers could possibly do for the world. Truly it is a joy to see my designs being built and later being used by other people.

If you weren’t an engineer, what would you be doing?

Movie director. When I was in college in Korea, I used to work with a group of people making independent movies. I enjoyed it very much. At one point I seriously thought about becoming a movie director but gave it up due to some personal reasons.

What lead you to become a US citizen?

Below is a copy of my short note to a dear friend who congratulated me on becoming a US citizen. I think that this can be my answer to this question.

“I do appreciate your thoughtful and caring words. Now I can tell you this. Truly what led me to become an American today is not that it is the richest country in the world full of great opportunities, but Americans like you, everyone who has supported me, cared for me and treated me as a real friend of theirs for past 20 years. I assure that you are definitely one of them, my dear American friend. Once again thanks a lot for everything you have done for me and my family. May the Lord always be with you.”



Is this project a good fit for micropiles?


Is this project a good fit for micropiles? This is a question that I’m asked quite often.   Micropiles are an excellent deep foundation option to solve two common problems – difficult ground conditions or limited access.


Let’s start with a brief description.  A micropile is a drilled and grouted replacement pile less than 12 inches in diameter.  Capacities typically range from 50 kips to 500 kips with higher loads sometimes achieved with larger micropiles (>12”).  To install a pile, contractors typically advance casing through the overburden material to the top of rock then drill a rock socket.  Steel reinforcing is lowered into the casing and rock socket then grout is tremie pumped from the pile tip to the top of the pile displacing any ground water.  The grout bonds the reinforcing steel to the rock socket.  The load is predominantly carried by steel reinforcing – a pipe, threaded rod(s), or both.  The grout also contributes.

Difficult Ground Conditions

When deep foundations are required, and other pile solutions are not feasible due to difficult ground conditions, then micropiles are a great option.  Micropiles are commonly installed in situations where driving piles or installing auger cast piles are prohibitive due to obstructions such as construction debris or boulders.  Advanced overburden drilling technologies developed by the mining industry allow for installation of casing through concrete or boulders.  A recent micropile project we completed required installation of micropiles by drilling through 40’ to 50’ of debris laden fill to reach original ground.

Another common use of micropiles due to difficult ground conditions is limestone karst.  Karst is water soluble rock and is encountered in our region in the mountains of Virginia, West Virginia and eastern Tennessee.   In geologic time, ground water has dissolved rock leaving behind pockets of soft soil and voids.  The ground layers are often tilted or folded creating a situation where a pile will go through soil, then rock, then a void, and then rock again.  Due to the overburden drilling systems, micropiles can be advanced through these varied conditions to competent rock.  Often in karst, depth to rock varies wildly.  Since micropiles are installed in sections, the pile length can be increased as required.

Limited Access

Micropiles are also a great solution when deep foundations are required but access is limited.  When a vertical expansion is needed for an existing structure, micropiles can be installed in low headroom conditions (typically 8’ to 9’) to reinforce existing footings or to add new columns for the vertical expansion.  The small rigs operate with umbilical cords so that the diesel fumes are on the outside of the building.  Other limited access conditions may include drilling below bridges, between structures or in courtyards.  We have installed micropiles for a hospital vertical expansion while patients were treated on the other side of the wall.

Micropile Resources

DFI Micropile Committee

ADSC Micropile Resources

Chapter 18 IBC (now includes micorpiles)

FHWA Micropile Design Manual 2005 FHWA-NHI-05-39





Are you a Level 5 Leader?


Jim Collins in “Good to Great” defines Level 5 Leaders as those who blend personal humility with intense professional will.  While Collin’s team didn’t set out to focus on leadership, during their research they observed that Level 5 leaders were at the helm of every Good to Great company during their transition to greatness.   The difference between Level 4’s  and Level 5’s is one of direction.  While Level 4’s are effective, they focus inwardly on success.  Level 5’s use their immense energy to forward the larger cause rather than themselves.  Unlike conventional wisdom that may seek a larger than life CEO, successful companies require leaders that are a blend of personal humility and fierce resolve.

Unlike their Level 4 counterparts, Level 5’s see the future of their organizations as being brighter after their departure.  They work hard to set up their successor to be even more successful.  Rather than quick returns and personal accolades, Level 5’s seek to create an enduring organization.

While humble and outwardly looking, Level 5’s have a strong professional will to do what must be done to move the organization forward.  They are fanatically driven to produce results.  With high standards, Level 5’s often set aside tradition and nepotism to recruit the best possible team members.  They will change with the times and rebuild as needed.

Harry S. Truman said, “You can accomplish anything in life, provided that you do not mind who gets the credit.”

Recommended reading: “Built to Last” and “Good to Great” by Jim Collins

Silica Exposure Control Programs in the Drilling Industry

Silica Exposure Control Programs in the Drilling Industry

We are all gaining familiarity with “Table 1. SPECIFIED EXPOSURE CONTROL METHODS WHEN WORKING WITH MATERIALS CONTAINING CRYSTALLINE SILICA” of OSHA’s Crystalline Silica Rule for Construction –  a title that kind of rolls right off the tongue.  Table 1 was OSHA’s attempt to guide contractors in reducing silica exposure below the new permissible exposure limit (PEL) of 50 ug/m3.  For most of the construction industry, it largely works and boils down to two things – use water or use a vacuum.  Common tasks such as cutting, chipping, drilling and grinding concrete are listed in Table 1 along with the precautions the contractor must do to stay below the PEL.  Do these tasks with these precautions and you’re all set.  But what happens when your task is not listed?  This is the place that the drilling industry finds itself.

The tie-back and micropile industry drills rock on a regular basis.  According to Encyclopedia Britannica, “The mass of Earth’s crust is 59 percent silica, the main constituent of more than 95 percent of the known rocks.”  OSHA requires that exposure to safety or health hazards be eliminated through administrative or engineering controls if possible.  Our industry most commonly drills rock with down the hole hammers.  These hammers are single pistons at the bottom of the drill rods that actuate a bit up and down through the power of high pressure, high volume air compressors.  The primary engineering control is to drill with water.  The volume and pressure of the water must be sufficient to reduce silica exposure below the PEL.  So how do we know that we are protecting our workers during drilling?  We test.

The OSHA rule for silica exposure has two options for assessing employee exposure when not following Table 1 – the Performance Option and the Scheduled Monitoring Option.  The Performance Option requires assessing employee exposure based on any combination of testing and objective (read industry) data.  Unfortunately, we don’t have industry data, but we’re working on it.  More from ADSC on this in the future.  At Subsurface Construction are focusing on the Scheduled Monitoring Option for drilling.  Scheduled Monitoring means testing for respirable silica on individual employees while drilling with engineering controls in place.  Depending on the results, OSHA guides the employer as to what additional testing is required.  Unfortunately, monitoring is not a one-time event as the rock formations and drilling conditions can vary site to site.  To date, we have not been over the PEL when drilling rock with water, but we will continue to wear respirators as we gather more data.

Recommended reading:
Recommended action: Join an upcoming Silica Competent Person class through ABC, AGC or local safety training partners.
Duke University Bed Tower Secant Wall

Secant Pile Wall

Subsurface completed a permanent secant pile wall at the VA War Memorial.  The wall serves as a permanent basement wall and supports vertical load from the structure.

Freddie Mac Ground Shoring FM6

First driven soil nail wall is allowed in Fairfax County, VA

For the Freddie Mac Expansion project in McLean, VA, L.F. Jennings (G.C.) selected Subsurface Construction to design and install the ground shoring system around the perimeter of the site. Fairfax County has a shoring geotechnical review board with strict guidelines for allowable soil properties used in shoring design.  We were informed by the project geotechnical engineer that the review board never allows soil properties other than those stipulated by the board.

Always looking to innovate, T.J. Ju, P.E., Chief Design Engineer at Subsurface, made a compelling argument by presenting verifiable historical data and research results to the review board and convinced them to allow alternative soil properties that more closely matched the existing subgrade conditions found on site.  In conjunction with this data, Subsurface developed a program to verify the assumed properties by testing the soil at every lift and sending data to the client.  As a result, we were able to utilize our Driven Soil Nail System, developed by our company, which saved the owner time and money.

By working in close conjunction with the grading contractor, we were able to install as much as 1,300 sq. ft. of shoring in a single day, and completed the shoring installation 2 weeks ahead of schedule.  Innovation is a hallmark of our company and we are pleased to be a part of this progression for soil nail wall design in the Fairfax County region of Virginia.

Subsurface South Carolina Construction News

Subsurface is featured in SC Construction News

Engineers build successful Carolinas shoring construction business with participation of employee owners

South Carolina Construction News special feature

Formed in 1995 by three engineers, two structural and one geotechnical, Subsurface Construction Company LLC has grown over time to two regional offices, a staff of 35 and the capability of handling multiple, complex shoring and deep foundation projects at once.

The three founders started in the business as consulting engineers in Raleigh, NC, designing shoring systems for installation by contractors. Greg Sullivan, P.E., Subsurface’s managing member, says the group recognized that there were very few shoring contractors in the area, saw the market need, and launched Subsurface.

“We began in the shoring construction business by installing our driven soil nail walls, a unique shoring system that was developed by our company,” he said.

Read the full article >

Subsurface Construction Company Develops Senior Community Site

Subsurface Helps Develop Senior Community Site

Developer taps into demand created by Triangle’s growing senior population