All posts by Jeffrey W. Coonse, PE

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 actuates 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: https://www.osha.gov/Publications/OSHA3902.pdf
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

Drilling Safety – Always Critical

I am sharing an email from one of our industry safety leaders:

All,

This is yet another unfortunate reminder of how dangerous / deadly our work can be.  While the exact details are not known as yet, it is thought that some type of entanglement incident occurred between an employee and the rotating drill string (in this case the cfa) you see in the photos.

It is a reminder of just how close employees  get to “the work” during a tieback installation.  It is possible that the communication between the drill rig operator and the helper were poor, the employee was wearing loose fitting clothing (i.e. a safety vest), he was cleaning the auger flights with a 2×4 or some other object, the emergency shut off switch was not functional, or some other probable cause, leading up to the loss of this young man’s life.

Please try to use this article a learning tool.  Resist the temptation to look up the affected contractor and better spend your time looking at your own operations.  What can we do as individuals or as an association to help prevent a tragic accident such as this from occurring once again? Observe how you install a tieback or micropile.  How close do your employees get to the rotating drill steel?  How good are the communications between the operator and helper?  Does the emergency shut off switch actually work?  Do you inspect / check it every shift?   Remember too, this type of incident could take place on a drilled shaft project, any CFA type project, soil mixing or slurry wall project or any other environment where we have to work in close proximity to a rotating object.

Use this unfortunate accident to serve as a deadly reminder of just how dangerous our work is.

http://fox6now.com/2015/02/28/developing-construction-worker-killed-on-zoo-interchange-site/

 

Richard Marshall CHST | Safety Director

Richard Goettle, Inc.

12071 Hamilton Ave., Cincinnati, OH 45231

Phone: (513) 825-8100 | Fax: (513) 825-8107

Mobile: (513) 604-3009 | rmarshall@goettle.com

www.goettle.com